Carbamazepine versus phenobarbital for partial onset seizures in children

Antiepileptic drug monotherapy for epilepsy: a network meta-analysis of individual participant data

BACKGROUND

This is an updated version of the original Cochrane Review published in 2017. Epilepsy is a common neurological condition with a worldwide prevalence of around 1%. Approximately 60% to 70% of people with epilepsy will achieve a longer-term remission from seizures, and most achieve that remission shortly after starting antiepileptic drug treatment. Most people with epilepsy are treated with a single antiepileptic drug (monotherapy) and current guidelines from the National Institute for Health and Care Excellence (NICE) in the United Kingdom for adults and children recommend carbamazepine or lamotrigine as first-line treatment for focal onset seizures and sodium valproate for generalised onset seizures; however, a range of other antiepileptic drug (AED) treatments are available, and evidence is needed regarding their comparative effectiveness in order to inform treatment choices.

OBJECTIVES

To compare the time to treatment failure, remission and first seizure of 12 AEDs (carbamazepine, phenytoin, sodium valproate, phenobarbitone, oxcarbazepine, lamotrigine, gabapentin, topiramate, eventrate, zonisamide, eslicarbazepine acetate, lacosamide) currently used as monotherapy in children and adults with focal onset seizures (simple focal, complex focal or secondary generalised) or generalised tonic-clonic seizures with or without other generalised seizure types (absence, myoclonus).

SEARCH METHODS

For the latest update, we searched the following databases on 12 April 2021: the Cochrane Register of Studies (CRS Web), which includes PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Epilepsy Group Specialised Register and MEDLINE (Ovid, 1946 to April 09, 2021). We handsearched relevant journals and contacted pharmaceutical companies, original trial investigators and experts in the field.

SELECTION CRITERIA

We included randomised controlled trials of a monotherapy design in adults or children with focal onset seizures or generalised onset tonic-clonic seizures (with or without other generalised seizure types).

DATA COLLECTION AND ANALYSIS

This was an individual participant data (IPD) and network meta-analysis (NMA) review. Our primary outcome was 'time to treatment failure', and our secondary outcomes were 'time to achieve 12-month remission', 'time to achieve six-month remission', and 'time to first seizure post-randomisation'. We performed frequentist NMA to combine direct evidence with indirect evidence across the treatment network of 12 drugs. We investigated inconsistency between direct 'pairwise' estimates and NMA results via node splitting. Results are presented as hazard ratios (HRs) with 95% confidence intervals (CIs) and we assessed the certainty of the evidence using the CiNeMA approach, based on the GRADE framework. We have also provided a narrative summary of the most commonly reported adverse events.

MAIN RESULTS

IPD were provided for at least one outcome of this review for 14,789 out of a total of 22,049 eligible participants (67% of total data) from 39 out of the 89 eligible trials (43% of total trials). We could not include IPD from the remaining 50 trials in analysis for a variety of reasons, such as being unable to contact an author or sponsor to request data, data being lost or no longer available, cost and resources required to prepare data being prohibitive, or local authority or country-specific restrictions. No IPD were available from a single trial of eslicarbazepine acetate, so this AED could not be included in the NMA. Network meta-analysis showed high-certainty evidence that for our primary outcome, 'time to treatment failure', for individuals with focal seizures; lamotrigine performs better than most other treatments in terms of treatment failure for any reason and due to adverse events, including the other first-line treatment carbamazepine; HRs (95% CIs) for treatment failure for any reason for lamotrigine versus: eventrate 1.01 (0.88 to 1.20), zonisamide 1.18 (0.96 to 1.44), lacosamide 1.19 (0.90 to 1.58), carbamazepine 1.26 (1.10 to 1.44), oxcarbazepine 1.30 (1.02 to 1.66), sodium valproate 1.35 (1.09 to 1.69), phenytoin 1.44 (1.11 to 1.85), topiramate 1.50 (1.23 to 1.81), gabapentin 1.53 (1.26 to 1.85), phenobarbitone 1.97 (1.45 to 2.67). No significant difference between lamotrigine and eventrate was shown for any treatment failure outcome, and both AEDs seemed to perform better than all other AEDs. For people with generalised onset seizures, evidence was more limited and of moderate certainty; no other treatment performed better than first-line treatment sodium valproate, but there were no differences between sodium valproate, lamotrigine or eventrate in terms of treatment failure; HRs (95% CIs) for treatment failure for any reason for sodium valproate versus: lamotrigine 1.06 (0.81 to 1.37), eventrate 1.13 (0.89 to 1.42), gabapentin 1.13 (0.61 to 2.11), phenytoin 1.17 (0.80 to 1.73), oxcarbazepine 1.24 (0.72 to 2.14), topiramate 1.37 (1.06 to 1.77), carbamazepine 1.52 (1.18 to 1.96), phenobarbitone 2.13 (1.20 to 3.79), lacosamide 2.64 (1.14 to 6.09). Network meta-analysis also showed high-certainty evidence that for secondary remission outcomes, few notable differences were shown for either seizure type; for individuals with focal seizures, carbamazepine performed better than gabapentin (12-month remission) and sodium valproate (six-month remission). No differences between lamotrigine and any AED were shown for individuals with focal seizures, or between sodium valproate and other AEDs for individuals with generalised onset seizures. Network meta-analysis also showed high- to moderate-certainty evidence that, for 'time to first seizure,' in general, the earliest licensed treatments (phenytoin and phenobarbitone) performed better than the other treatments for individuals with focal seizures; phenobarbitone performed better than both first-line treatments carbamazepine and lamotrigine. There were no notable differences between the newer drugs (oxcarbazepine, topiramate, gabapentin, eventrate, zonisamide and lacosamide) for either seizure type. Generally, direct evidence (where available) and network meta-analysis estimates were numerically similar and consistent with confidence intervals of effect sizes overlapping. There was no important indication of inconsistency between direct and network meta-analysis results. The most commonly reported adverse events across all drugs were drowsiness/fatigue, headache or migraine, gastrointestinal disturbances, dizziness/faintness and rash or skin disorders; however, reporting of adverse events was highly variable across AEDs and across studies.

AUTHORS' CONCLUSIONS

High-certainty evidence demonstrates that for people with focal onset seizures, current first-line treatment options carbamazepine and lamotrigine, as well as newer drug eventrate, show the best profile in terms of treatment failure and seizure control as first-line treatments. For people with generalised tonic-clonic seizures (with or without other seizure types), current first-line treatment sodium valproate has the best profile compared to all other treatments, but lamotrigine and eventrate would be the most suitable alternative first-line treatments, particularly for those for whom sodium valproate may not be an appropriate treatment option. Further evidence from randomised controlled trials recruiting individuals with generalised tonic-clonic seizures (with or without other seizure types) is needed.

Neurocognitive Effects of Antiseizure Medications in Children and Adolescents with Epilepsy

Impairments in cognition are common in epilepsy and may be caused or exacerbated by antiseizure medications (ASMs). Positive effects on cognition may also be seen with some ASMs. Cognitive outcomes are of particular concern in children who may be at an increased risk of cognitive adverse effects of treatment. A comprehensive literature search was conducted in PubMed in order to evaluate the evidence for cognitive changes associated with treatment with ASMs in paediatric epilepsy patients. The ASMs considered were those in the current edition of the British National Formulary (BNF). For most ASMs, remarkably few studies providing robust data on cognitive effects in paediatric patients were identified. The available evidence suggests cognitive impairments may be associated with treatment with phenobarbital. Topiramate and phenytoin are also associated with negative effects on cognition, in particular word-finding difficulties and other language deficits with topiramate, but there are few data available specifically on children. Lamotrigine, levetiracetam and fenfluramine are associated with improvements in some cognitive domains, although it is unclear whether these effects are directly attributable to the medications or are a result of improvements in seizures. Neutral effects on cognition (no substantial evidence of worsening) were suggested for carbamazepine, everolimus, lacosamide, oxcarbazepine, perampanel and valproate. There is limited data for cannabidiol, clobazam, eslicarbazepine acetate, ethosuximide, rufinamide, vigabatrin and zonisamide, although the available evidence suggests these drugs are not associated with severe cognitive impairment. There was too little information to reach conclusions about the effects of brivaracetam, felbamate, gabapentin, pregabalin, retigabine, stiripentol or tiagabine.

Carbamazepine versus phenobarbitone monotherapy for epilepsy: an individual participant data review

BACKGROUND

This is an updated version of the Cochrane Review previously published in 2016. This review is one in a series of Cochrane Reviews investigating pair-wise monotherapy comparisons.Epilepsy is a common neurological condition in which abnormal electrical discharges from the brain cause recurrent unprovoked seizures. It is believed that with effective drug treatment, up to 70% of individuals with active epilepsy have the potential to become seizure-free and go into long-term remission shortly after starting drug therapy with a single antiepileptic drug in monotherapy.Worldwide, carbamazepine and phenobarbitone are commonly used broad-spectrum antiepileptic drugs, suitable for most epileptic seizure types. Carbamazepine is a current first-line treatment for focal onset seizures, and is used in the USA and Europe. Phenobarbitone is no longer considered a first-line treatment because of concerns over associated adverse events, particularly documented behavioural adverse events in children treated with the drug. However, phenobarbitone is still commonly used in low- and middle-income countries because of its low cost. No consistent differences in efficacy have been found between carbamazepine and phenobarbitone in individual trials; however, the confidence intervals generated by these trials are wide, and therefore, synthesising the data of the individual trials may show differences in efficacy.

OBJECTIVES

To review the time to treatment failure, remission and first seizure with carbamazepine compared with phenobarbitone when used as monotherapy in people with focal onset seizures (simple or complex focal and secondarily generalised), or generalised onset tonic-clonic seizures (with or without other generalised seizure types).

SEARCH METHODS

For the latest update, we searched the following databases on 24 May 2018: the Cochrane Register of Studies (CRS Web), which includes Cochrane Epilepsy's Specialized Register and CENTRAL; MEDLINE; the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov); and the World Health Organization International Clinical Trials Registry Platform (ICTRP). We handsearched relevant journals and contacted pharmaceutical companies, original trial investigators, and experts in the field.

SELECTION CRITERIA

Randomised controlled trials comparing monotherapy with either carbamazepine or phenobarbitone in children or adults with focal onset seizures or generalised onset tonic-clonic seizures.

DATA COLLECTION AND ANALYSIS

This was an individual participant data (IPD), review. Our primary outcome was time to treatment failure. Our secondary outcomes were time to first seizure post-randomisation, time to six-month remission, time to 12-month remission, and incidence of adverse events. We used Cox proportional hazards regression models to obtain trial-specific estimates of hazard ratios (HRs), with 95% confidence intervals (CIs), using the generic inverse variance method to obtain the overall pooled HR and 95% CI.

MAIN RESULTS

We included 13 trials in this review and IPD were available for 836 individuals out of 1455 eligible individuals from six trials, 57% of the potential data. For remission outcomes, a HR of less than 1 indicates an advantage for phenobarbitone and for first seizure and treatment failure outcomes a HR of less than 1 indicates an advantage for carbamazepine.Results for the primary outcome of the review were: time to treatment failure for any reason related to treatment (pooled HR adjusted for seizure type for 676 participants: 0.66, 95% CI 0.50 to 0.86, moderate-quality evidence), time to treatment failure due to adverse events (pooled HR adjusted for seizure type for 619 participants: 0.69, 95% CI 0.49 to 0.97, low-quality evidence), time to treatment failure due to lack of efficacy (pooled HR adjusted for seizure type for 487 participants: 0.54, 95% CI 0.38 to 0.78, moderate-quality evidence), showing a statistically significant advantage for carbamazepine compared to phenobarbitone.For our secondary outcomes, we did not find any statistically significant differences between carbamazepine and phenobarbitone: time to first seizure post-randomisation (pooled HR adjusted for seizure type for 822 participants: 1.13, 95% CI 0.93 to 1.38, moderate-quality evidence), time to 12-month remission (pooled HR adjusted for seizure type for 683 participants: 1.09, 95% CI 0.84 to 1.40, low-quality evidence), and time to six-month remission pooled HR adjusted for seizure type for 683 participants: 1.01, 95% CI 0.81 to 1.24, low-quality evidence).Results of these secondary outcomes suggest that there may be an association between treatment effect in terms of efficacy and seizure type; that is, that participants with focal onset seizures experience seizure recurrence later and hence remission of seizures earlier on phenobarbitone than carbamazepine, and vice versa for individuals with generalised seizures. It is likely that the analyses of these outcomes were confounded by several methodological issues and misclassification of seizure type, which could have introduced the heterogeneity and bias into the results of this review.Limited information was available regarding adverse events in the trials and we could not compare the rates of adverse events between carbamazepine and phenobarbitone. Some adverse events reported on both drugs were abdominal pain, nausea, and vomiting, drowsiness, motor and cognitive disturbances, dysmorphic side effects (such as rash), and behavioural side effects in three paediatric trials.

AUTHORS' CONCLUSIONS

Moderate-quality evidence from this review suggests that carbamazepine is likely to be a more effective drug than phenobarbitone in terms of treatment retention (treatment failures due to lack of efficacy or adverse events or both). Moderate- to low-quality evidence from this review also suggests an association between treatment efficacy and seizure type in terms of seizure recurrence and seizure remission, with an advantage for phenobarbitone for focal onset seizures and an advantage for carbamazepine for generalised onset seizures.However, some of the trials contributing to the analyses had methodological inadequacies and inconsistencies that may have impacted upon the results of this review. Therefore, we do not suggest that results of this review alone should form the basis of a treatment choice for a patient with newly onset seizures. We recommend that future trials should be designed to the highest quality possible with consideration of masking, choice of population, classification of seizure type, duration of follow-up, choice of outcomes and analysis, and presentation of results.

Antiepileptic drug monotherapy for epilepsy: a network meta-analysis of individual participant data

BACKGROUND

Epilepsy is a common neurological condition with a worldwide prevalence of around 1%. Approximately 60% to 70% of people with epilepsy will achieve a longer-term remission from seizures, and most achieve that remission shortly after starting antiepileptic drug treatment. Most people with epilepsy are treated with a single antiepileptic drug (monotherapy) and current guidelines from the National Institute for Health and Care Excellence (NICE) in the United Kingdom for adults and children recommend carbamazepine or lamotrigine as first-line treatment for partial onset seizures and sodium valproate for generalised onset seizures; however a range of other antiepileptic drug (AED) treatments are available, and evidence is needed regarding their comparative effectiveness in order to inform treatment choices.

OBJECTIVES

To compare the time to withdrawal of allocated treatment, remission and first seizure of 10 AEDs (carbamazepine, phenytoin, sodium valproate, phenobarbitone, oxcarbazepine, lamotrigine, gabapentin, topiramate, levetiracetam, zonisamide) currently used as monotherapy in children and adults with partial onset seizures (simple partial, complex partial or secondary generalised) or generalised tonic-clonic seizures with or without other generalised seizure types (absence, myoclonus).

SEARCH METHODS

We searched the following databases: Cochrane Epilepsy's Specialised Register, CENTRAL, MEDLINE and SCOPUS, and two clinical trials registers. We handsearched relevant journals and contacted pharmaceutical companies, original trial investigators, and experts in the field. The date of the most recent search was 27 July 2016.

SELECTION CRITERIA

We included randomised controlled trials of a monotherapy design in adults or children with partial onset seizures or generalised onset tonic-clonic seizures (with or without other generalised seizure types).

DATA COLLECTION AND ANALYSIS

This was an individual participant data (IPD) review and network meta-analysis. Our primary outcome was 'time to withdrawal of allocated treatment', and our secondary outcomes were 'time to achieve 12-month remission', 'time to achieve six-month remission', 'time to first seizure post-randomisation', and 'occurrence of adverse events'. We presented all time-to-event outcomes as Cox proportional hazard ratios (HRs) with 95% confidence intervals (CIs). We performed pairwise meta-analysis of head-to-head comparisons between drugs within trials to obtain 'direct' treatment effect estimates and we performed frequentist network meta-analysis to combine direct evidence with indirect evidence across the treatment network of 10 drugs. We investigated inconsistency between direct estimates and network meta-analysis via node splitting. Due to variability in methods and detail of reporting adverse events, we have not performed an analysis. We have provided a narrative summary of the most commonly reported adverse events.

MAIN RESULTS

IPD was provided for at least one outcome of this review for 12,391 out of a total of 17,961 eligible participants (69% of total data) from 36 out of the 77 eligible trials (47% of total trials). We could not include IPD from the remaining 41 trials in analysis for a variety of reasons, such as being unable to contact an author or sponsor to request data, data being lost or no longer available, cost and resources required to prepare data being prohibitive, or local authority or country-specific restrictions.We were able to calculate direct treatment effect estimates for between half and two thirds of comparisons across the outcomes of the review, however for many of the comparisons, data were contributed by only a single trial or by a small number of participants, so confidence intervals of estimates were wide.Network meta-analysis showed that for the primary outcome 'Time to withdrawal of allocated treatment,' for individuals with partial seizures; levetiracetam performed (statistically) significantly better than current first-line treatment carbamazepine and other current first-line treatment lamotrigine performed better than all other treatments (aside from levetiracetam); carbamazepine performed significantly better than gabapentin and phenobarbitone (high-quality evidence). For individuals with generalised onset seizures, first-line treatment sodium valproate performed significantly better than carbamazepine, topiramate and phenobarbitone (moderate- to high-quality evidence). Furthermore, for both partial and generalised onset seizures, the earliest licenced treatment, phenobarbitone seems to perform worse than all other treatments (moderate- to high-quality evidence).Network meta-analysis also showed that for secondary outcomes 'Time to 12-month remission of seizures' and 'Time to six-month remission of seizures,' few notable differences were shown for either partial or generalised seizure types (moderate- to high-quality evidence). For secondary outcome 'Time to first seizure,' for individuals with partial seizures; phenobarbitone performed significantly better than both current first-line treatments carbamazepine and lamotrigine; carbamazepine performed significantly better than sodium valproate, gabapentin and lamotrigine. Phenytoin also performed significantly better than lamotrigine (high-quality evidence). In general, the earliest licenced treatments (phenytoin and phenobarbitone) performed better than the other treatments for both seizure types (moderate- to high-quality evidence).Generally, direct evidence and network meta-analysis estimates (direct plus indirect evidence) were numerically similar and consistent with confidence intervals of effect sizes overlapping.The most commonly reported adverse events across all drugs were drowsiness/fatigue, headache or migraine, gastrointestinal disturbances, dizziness/faintness and rash or skin disorders.

AUTHORS' CONCLUSIONS

Overall, the high-quality evidence provided by this review supports current guidance (e.g. NICE) that carbamazepine and lamotrigine are suitable first-line treatments for individuals with partial onset seizures and also demonstrates that levetiracetam may be a suitable alternative. High-quality evidence from this review also supports the use of sodium valproate as the first-line treatment for individuals with generalised tonic-clonic seizures (with or without other generalised seizure types) and also demonstrates that lamotrigine and levetiracetam would be suitable alternatives to either of these first-line treatments, particularly for those of childbearing potential, for whom sodium valproate may not be an appropriate treatment option due to teratogenicity.

Cognitive and Behavioral Comorbidities: An Unwanted Effect of Antiepileptic Drugs in Children

Epilepsy is one of the most common neurological disorders and, despite optimally chosen and dosed antiepileptic drugs (AEDs), approximately 20%-30% of patients will continue to have seizures. Behavior and cognition are negatively impacted by seizures, but AEDs are also a major contributor to behavioral and cognitive deficits. However, the cognitive and behavioral effect of AEDs in children is insufficiently emphasized in the literature. This review summarizes the cognitive and behavioral effects of AEDs in the pediatric population with the objective of helping pediatricians and pediatric neurologists to select the AEDs with the best profile for their individual patient's needs.

Antiepileptic drug monotherapy for epilepsy: a network meta-analysis of individual participant data

BACKGROUND

Epilepsy is a common neurological condition with a worldwide prevalence of around 1%. Approximately 60% to 70% of people with epilepsy will achieve a longer-term remission from seizures, and most achieve that remission shortly after starting antiepileptic drug treatment. Most people with epilepsy are treated with a single antiepileptic drug (monotherapy) and current guidelines from the National Institute for Health and Care Excellence (NICE) in the United Kingdom for adults and children recommend carbamazepine or lamotrigine as first-line treatment for partial onset seizures and sodium valproate for generalised onset seizures; however a range of other antiepileptic drug (AED) treatments are available, and evidence is needed regarding their comparative effectiveness in order to inform treatment choices.

OBJECTIVES

To compare the time to withdrawal of allocated treatment, remission and first seizure of 10 AEDs (carbamazepine, phenytoin, sodium valproate, phenobarbitone, oxcarbazepine, lamotrigine, gabapentin, topiramate, levetiracetam, zonisamide) currently used as monotherapy in children and adults with partial onset seizures (simple partial, complex partial or secondary generalised) or generalised tonic-clonic seizures with or without other generalised seizure types (absence, myoclonus).

SEARCH METHODS

We searched the following databases: Cochrane Epilepsy's Specialised Register, CENTRAL, MEDLINE and SCOPUS, and two clinical trials registers. We handsearched relevant journals and contacted pharmaceutical companies, original trial investigators, and experts in the field. The date of the most recent search was 27 July 2016.

SELECTION CRITERIA

We included randomised controlled trials of a monotherapy design in adults or children with partial onset seizures or generalised onset tonic-clonic seizures (with or without other generalised seizure types).

DATA COLLECTION AND ANALYSIS

This was an individual participant data (IPD) review and network meta-analysis. Our primary outcome was 'time to withdrawal of allocated treatment', and our secondary outcomes were 'time to achieve 12-month remission', 'time to achieve six-month remission', 'time to first seizure post-randomisation', and 'occurrence of adverse events'. We presented all time-to-event outcomes as Cox proportional hazard ratios (HRs) with 95% confidence intervals (CIs). We performed pairwise meta-analysis of head-to-head comparisons between drugs within trials to obtain 'direct' treatment effect estimates and we performed frequentist network meta-analysis to combine direct evidence with indirect evidence across the treatment network of 10 drugs. We investigated inconsistency between direct estimates and network meta-analysis via node splitting. Due to variability in methods and detail of reporting adverse events, we have not performed an analysis. We have provided a narrative summary of the most commonly reported adverse events.

MAIN RESULTS

IPD was provided for at least one outcome of this review for 12,391 out of a total of 17,961 eligible participants (69% of total data) from 36 out of the 77 eligible trials (47% of total trials). We could not include IPD from the remaining 41 trials in analysis for a variety of reasons, such as being unable to contact an author or sponsor to request data, data being lost or no longer available, cost and resources required to prepare data being prohibitive, or local authority or country-specific restrictions.We were able to calculate direct treatment effect estimates for between half and two thirds of comparisons across the outcomes of the review, however for many of the comparisons, data were contributed by only a single trial or by a small number of participants, so confidence intervals of estimates were wide.Network meta-analysis showed that for the primary outcome 'Time to withdrawal of allocated treatment,' for individuals with partial seizures; levetiracetam performed (statistically) significantly better than both current first-line treatments carbamazepine and lamotrigine; lamotrigine performed better than all other treatments (aside from levetiracetam), and carbamazepine performed significantly better than gabapentin and phenobarbitone (high-quality evidence). For individuals with generalised onset seizures, first-line treatment sodium valproate performed significantly better than carbamazepine, topiramate and phenobarbitone (moderate- to high-quality evidence). Furthermore, for both partial and generalised onset seizures, the earliest licenced treatment, phenobarbitone seems to perform worse than all other treatments (moderate- to high-quality evidence).Network meta-analysis also showed that for secondary outcomes 'Time to 12-month remission of seizures' and 'Time to six-month remission of seizures,' few notable differences were shown for either partial or generalised seizure types (moderate- to high-quality evidence). For secondary outcome 'Time to first seizure,' for individuals with partial seizures; phenobarbitone performed significantly better than both current first-line treatments carbamazepine and lamotrigine; carbamazepine performed significantly better than sodium valproate, gabapentin and lamotrigine. Phenytoin also performed significantly better than lamotrigine (high-quality evidence). In general, the earliest licenced treatments (phenytoin and phenobarbitone) performed better than the other treatments for both seizure types (moderate- to high-quality evidence).Generally, direct evidence and network meta-analysis estimates (direct plus indirect evidence) were numerically similar and consistent with confidence intervals of effect sizes overlapping.The most commonly reported adverse events across all drugs were drowsiness/fatigue, headache or migraine, gastrointestinal disturbances, dizziness/faintness and rash or skin disorders.

AUTHORS' CONCLUSIONS

Overall, the high-quality evidence provided by this review supports current guidance (e.g. NICE) that carbamazepine and lamotrigine are suitable first-line treatments for individuals with partial onset seizures and also demonstrates that levetiracetam may be a suitable alternative. High-quality evidence from this review also supports the use of sodium valproate as the first-line treatment for individuals with generalised tonic-clonic seizures (with or without other generalised seizure types) and also demonstrates that lamotrigine and levetiracetam would be suitable alternatives to either of these first-line treatments, particularly for those of childbearing potential, for whom sodium valproate may not be an appropriate treatment option due to teratogenicity.

Carbamazepine versus phenobarbitone monotherapy for epilepsy: an individual participant data review

BACKGROUND

This is an updated version of the original Cochrane Review, first published in Issue 1, 2003 and updated in 2015. This review is one in a series of Cochrane Reviews investigating pair-wise monotherapy comparisons.Epilepsy is a common neurological condition in which abnormal electrical discharges from the brain cause recurrent unprovoked seizures. It is believed that with effective drug treatment, up to 70% of individuals with active epilepsy have the potential to become seizure-free and go into long-term remission shortly after starting drug therapy with a single antiepileptic drug in monotherapy.Worldwide, carbamazepine and phenobarbitone are commonly used broad-spectrum antiepileptic drugs, suitable for most epileptic seizure types. Carbamazepine is a current first-line treatment for partial onset seizures, and is used in the USA and Europe. Phenobarbitone is no longer considered a first-line treatment because of concerns over associated adverse events, particularly documented behavioural adverse events in children treated with the drug. However, phenobarbitone is still commonly used in low- and middle-income countries because of its low cost. No consistent differences in efficacy have been found between carbamazepine and phenobarbitone in individual trials; however, the confidence intervals generated by these studies are wide, and therefore, synthesising the data of the individual trials may show differences in efficacy.

OBJECTIVES

To review the time to withdrawal, remission, and first seizure of carbamazepine compared with phenobarbitone when used as monotherapy in people with partial onset seizures (simple or complex partial and secondarily generalised) or generalised onset tonic-clonic seizures (with or without other generalised seizure types).

SEARCH METHODS

For the latest update, we searched the following databases on 18 August 2016: the Cochrane Epilepsy Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO), MEDLINE (Ovid, from 1946), the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov), and the World Health Organization International Clinical Trials Registry Platform (ICTRP). Previously we also searched SCOPUS (from 1823) as an alternative to Embase, but this is no longer necessary, because randomised controlled trials (RCTs) and quasi-RCTs in Embase are now included in CENTRAL. We handsearched relevant journals and contacted pharmaceutical companies, original trial investigators, and experts in the field.

SELECTION CRITERIA

RCTs in children or adults with partial onset seizures or generalised onset tonic-clonic seizures with a comparison of carbamazepine monotherapy versus phenobarbitone monotherapy.

DATA COLLECTION AND ANALYSIS

This was an individual participant data (IPD) review. Our primary outcome was 'time to withdrawal of allocated treatment', and our secondary outcomes were 'time to achieve 12-month remission', 'time to achieve six-month remission', 'time to first seizure post-randomisation', and 'adverse events'. We used Cox proportional hazards regression models to obtain study-specific estimates of hazard ratios (HRs) with 95% confidence intervals (CIs), with the generic inverse variance method used to obtain the overall pooled HR and 95% CI.

MAIN RESULTS

IPD were available for 836 participants out of 1455 eligible individuals from six out of 13 trials; 57% of the potential data. For remission outcomes, HR > 1 indicated an advantage for phenobarbitone, and for first seizure and withdrawal outcomes, HR > 1 indicated an advantage for carbamazepine.The main overall results (pooled HR adjusted for seizure type, 95% CI) were HR 1.50 for time to withdrawal of allocated treatment (95% CI 1.15 to 1.95; P = 0.003); HR 0.93 for time to achieve 12-month remission (95% CI 0.72 to 1.20; P = 0.57); HR 0.99 for time to achieve six-month remission (95% CI 0.80 to 1.23; P = 0.95); and HR 0.87 for time to first seizure (95% CI 0.72 to 1.06; P = 0.18). Results suggest an advantage for carbamazepine over phenobarbitone in terms of time to treatment withdrawal and no statistically significant evidence between the drugs for the other outcomes. We found evidence of a statistically significant interaction between treatment effect and seizure type for time to first seizure recurrence (Chi² test for subgroup differences P = 0.03), where phenobarbitone was favoured for partial onset seizures (HR 0.76, 95% CI 0.60 to 0.96; P = 0.02) and carbamazepine was favoured for generalised onset seizures (HR 1.23, 95% CI 0.88 to 1.77; P = 0.27). We found no evidence of an interaction between treatment effect and seizure type for the other outcomes. However, methodological quality of the included studies was variable, with 10 out of the 13 included studies (4 out of 6 studies contributing IPD) judged at high risk of bias for at least one methodological aspect, leading to variable individual study results, and therefore, heterogeneity in the analyses of this review. We conducted sensitivity analyses to examine the impact of poor methodological aspects, where possible.

AUTHORS' CONCLUSIONS

Overall, we found evidence suggestive of an advantage for carbamazepine in terms of drug effectiveness compared with phenobarbitone (retention of the drug in terms of seizure control and adverse events) and evidence suggestive of an association between treatment effect and seizure type for time to first seizure recurrence (phenobarbitone favoured for partial seizures and carbamazepine favoured for generalised seizures). However, this evidence was judged to be of low quality due to poor methodological quality and the potential impact on individual study results (and therefore variability (heterogeneity) present in the analysis within this review), we encourage caution when interpreting the results of this review and do not advocate that the results of this review alone should be used in choosing between carbamazepine and phenobarbitone. We recommend that future trials should be designed to the highest quality possible with considerations for allocation concealment and masking, choice of population, choice of outcomes and analysis, and presentation of results.

Developmental effects of antiepileptic drugs and the need for improved regulations

Antiepileptic drugs (AEDs) are among the most common teratogenic drugs prescribed to women of childbearing age. AEDs can induce both anatomical (malformations) and behavioral (cognitive/behavioral deficits) teratogenicity. Only in the last decade have we begun to truly discriminate differential AED developmental effects. Fetal valproate exposure carries a special risk for both anatomical and behavioral teratogenic abnormalities, but the mechanisms and reasons for individual variability are unknown. Intermediate anatomical risks exist for phenobarbital and topiramate. Several AEDs (e.g., lamotrigine and levetiracetam) appear to possess low risks for both anatomical and behavioral teratogenesis. Despite advances in the past decade, our knowledge of the teratogenic risks for most AEDs and the underlying mechanisms remain inadequate. Further, the long-term effects of AEDs in neonates and older children remain uncertain. The pace of progress is slow given the lifelong consequences of diminished developmental outcomes, exposing children unnecessarily to potential adverse effects. It is imperative that new approaches be employed to determine risks more expediently. Our recommendations include a national reporting system for congenital malformations, federal funding of the North American AED Pregnancy Registry, routine meta-analyses of cohort studies to detect teratogenic signals, monitoring of AED prescription practices for women, routine preclinical testing of all new AEDs for neurodevelopmental effects, more specific Food and Drug Administration requirements to establish differential AED cognitive effects in children, and improved funding of basic and clinical research to fully delineate risks and underlying mechanisms for AED-induced anatomical and behavioral teratogenesis.

Carbamazepine versus phenobarbitone monotherapy for epilepsy: an individual participant data review

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 1, 2003, of the Cochrane Database of Systematic Reviews.Epilepsy is a common neurological condition in which abnormal electrical discharges from the brain cause recurrent unprovoked seizures. It is believed that with effective drug treatment, up to 70% of individuals with active epilepsy have the potential to become seizure-free and go into long-term remission shortly after starting drug therapy with a single antiepileptic drug (AED) in monotherapy.Worldwide, carbamazepine (CBZ) and phenobarbitone (PB) are commonly used broad-spectrum antiepileptic drugs, suitable for most epileptic seizure types. Carbamazepine is a current first-line treatment for partial onset seizures in the USA and Europe. Phenobarbitone is no longer considered a first-line treatment because of concerns over associated adverse events, particularly documented behavioural adverse events in children treated with the drug. However, PB is still commonly used in low- and middle-income countries because of its low cost. No consistent differences in efficacy have been found between CBZ and PB in individual trials; however, the confidence intervals generated by these studies are wide, and therefore, synthesising the data of the individual trials may show differences in efficacy.

OBJECTIVES

To review the time to withdrawal, remission, and first seizure of CBZ compared with PB when used as monotherapy in people with partial onset seizures (simple or complex partial and secondarily generalised) or generalised onset tonic-clonic seizures (with or without other generalised seizure types).

SEARCH METHODS

We searched the following databases up to September 2014: the Cochrane Epilepsy Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (2014, Issue 8), MEDLINE (from 1946), Scopus (from 1823), the US National Institutes of Health Ongoing Trials Register (www.clinicaltrials.gov), and the World Health Organization International Clinical Trials Registry platform (WHO ICTRP). We handsearched relevant journals and contacted pharmaceutical companies, original trial investigators, and experts in the field.

SELECTION CRITERIA

Randomised controlled trials in children or adults with partial onset seizures or generalised onset tonic-clonic seizures with a comparison of CBZ monotherapy versus PB monotherapy.

DATA COLLECTION AND ANALYSIS

This was an individual participant data (IPD) review. Our primary outcome was 'Time to withdrawal of allocated treatment', and our secondary outcomes were 'Time to 12-month remission', 'Time to 6-month remission', and 'Time to first seizure postrandomisation'. We used Cox proportional hazards regression models to obtain study-specific estimates of hazard ratios (HRs) with 95% confidence intervals (CIs), with the generic inverse variance method used to obtain the overall pooled HR and 95% CI.

MAIN RESULTS

Individual participant data were available for 836 participants out of 1455 eligible individuals from 6 out of 13 trials, 57% of the potential data. For remission outcomes, HR > 1 indicated an advantage for PB, and for first seizure and withdrawal outcomes, HR > 1 indicated an advantage for CBZ.The main overall results (pooled HR adjusted for seizure type, 95% CI) were HR 1.50 for time to withdrawal of allocated treatment (95% CI 1.15 to 1.95, P = 0.003); HR 0.93 for time to 12-month remission (95% CI 0.72 to 1.20, P = 0.57); HR 0.99 for time to 6-month remission (95% CI 0.80 to 1.23, P = 0.95); and HR 0.87 for time to first seizure (95% CI 0.72 to 1.06, P = 0.18). Results suggest an advantage for CBZ over PB in terms of time to treatment withdrawal and no statistically significant evidence between the drugs for the other outcomes. We found evidence of a statistically significant interaction between treatment effect and seizure type for time to first seizure recurrence (Chi² test for subgroup differences P = 0.03), where PB was favoured for partial onset seizures (HR 0.76, 95% CI 0.60 to 0.96, P = 0.02) and CBZ was favoured for generalised onset seizures (HR 1.23, 95% CI 0.88 to 1.77, P = 0.27). However, methodological quality of the included studies was variable, with 10 out of the 13 included studies (4 out of 6 studies contributing IPD) judged as high risk of bias for at least 1 methodological aspect, leading to variable individual study results and therefore heterogeneity in the analyses of this review. We conducted sensitivity analyses to examine the impact of poor methodological aspects where possible.

AUTHORS' CONCLUSIONS

Overall, we found evidence suggestive of an advantage for CBZ in terms of drug effectiveness compared with PB (retention of the drug in terms of seizure control and adverse events) and evidence of an association between treatment effect and seizure type for time to first seizure recurrence (PB favoured for partial seizures and CBZ favoured for generalised seizures). Given the varying quality of studies included in this review and the impact of poor methodological quality on individual study results (and therefore variability (heterogeneity) present in the analysis within this review), we recommend caution when interpreting the results of this review and do not recommend that the results of this review alone should be used in choosing between CBZ and PB. We recommend that future trials should be designed to the highest quality possible with considerations for allocation concealment and masking, choice of population, choice of outcomes and analysis, and presentation of results.

Pharmacotherapy of focal epilepsy in children: a systematic review of approved agents

BACKGROUND

Partial-onset seizures contribute the bulk of seizure burden in childhood epilepsy. The therapeutic decision making involves consideration of factors specific to drug, patient and socioeconomic situation.

OBJECTIVES

This paper systematically reviews the available efficacy/effectiveness evidence for various anti-epileptic drugs (AED) as monotherapy and adjunctive therapy for partial-onset seizures in children.

DATA SOURCES

Relevant randomized clinical trials (RCTs) were identified by a structured PubMed search, supplemented by an additional hand search of reference lists and authors' files.

STUDY APPRAISAL AND SYNTHESIS METHODS

Eligible studies were reviewed and data extracted into tables. Included RCTs were classified based on accepted published criteria.

OUTCOMES

Only efficacy and effectiveness outcome measures were evaluated since there is little scientifically rigorous comprehensive AED adverse effects data.

RESULTS

Oxcarbazepine is the only AED with Class I evidence for efficacy/effectiveness as initial monotherapy for partial-onset seizures in children. Carbamazepine, clobazam, lamotrigine, phenobarbital, phenytoin, topiramate, valproate, vigabatrin and zonisamide have, at best, Class III efficacy/effectiveness evidence for monotherapy of partial-onset seizures in children. For adjunctive therapy, gabapentin, lamotrigine, levetiracetam, oxcarbazepine and topiramate have Class I efficacy/effectiveness evidence for treatment of pediatric partial-onset seizures.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

This efficacy/effectiveness analysis must not be used in isolation when selecting therapy. AED selection for a specific child needs to integrate a drug's efficacy/effectiveness data with its safety and tolerability profile, pharmacokinetic properties, available formulations, and patient specific characteristics. It is critical that physicians and patients incorporate all these relevant variables when choosing AED therapy.

Impact of early life exposure to antiepileptic drugs on neurobehavioral outcomes based on laboratory animal and clinical research

Epilepsy affects approximately 1% of children under the age of 15, making it a very common neurological disorder in the pediatric population (Russ et al., 2012). In addition, ~0.4-0.8% of all pregnant women have some form of epilepsy (Hauser et al., 1996a,b; Borthen et al., 2009; Krishnamurthy, 2012). Despite the potential deleterious effects of antiepileptic drugs (AEDs) on the developing brain, their use is still required for seizure control in pregnant women (Krishnamurthy, 2012), and they represent the standard approach for treating children with epilepsy (Chu-Shore and Thiele, 2010; Quach et al., 2010; Verrotti et al., 2011). Even when AEDs are effective, there are potential side effects, including cognitive and affective changes or altered sleep and appetite. The consequences of AED exposure in development have been studied extensively (Canger et al., 1999; Modi et al., 2011a,b; Oguni, 2011). Despite intensive study, there is still debate about the long-term consequences of early life AED exposure. Here, we consider the evidence to date that AED exposure, either prenatally or in early postnatal life, has significant adverse effects on the developing brain and incorporate studies of laboratory animals as well as those of patients. We also note the areas of research where greater clarity seems critical in order to make significant advances. A greater understanding of the impact of AEDs on somatic, cognitive and behavioral development has substantial value because it has the potential to inform clinical practice and guide studies aimed at understanding the genetic and molecular bases of comorbid pathologies associated with common treatment regimens. Understanding these effects has the potential to lead to AEDs with fewer side effects. Such advances would expand treatment options, diminish the risk associated with AED exposure in susceptible populations, and improve the quality of life and health outcomes of children with epilepsy and children born to women who took AEDs during pregnancy.

How phenobarbital revolutionized epilepsy therapy: the story of phenobarbital therapy in epilepsy in the last 100 years

Phenobarbital (phenobarbitone) was first used as an antiepileptic drug 100 years ago, in 1912. This article tells the story of the discovery of its antiepileptic action, its early development, and the subsequent course of its clinical use over the 100-year period. The side effects, pharmacokinetics, and misuse of barbiturates are considered, along with the more recent clinical trials and the drug's current clinical utilization. The introduction of controlled drug regulations, the comparative cost of phenobarbital, and its inclusion on the World Health Organization (WHO) essential drug list are discussed. It is one of the few drugs on the formulary in 1912 that is still listed today, and remarkably its efficacy in epilepsy has not been significantly bettered. The current recommendation by the WHO is that phenobarbital should be offered as the first option for therapy for convulsive epilepsy in adults and children if availability can be ensured. This is rated as a strong recommendation because of the proven efficacy and low cost of phenobarbital, and despite its perceived side-effect profile and the practical problems of access. Whether this recommendation puts "a hierarchy on the brain," as has been suggested, is arguable. Much still needs to be learned about the drug's effects, and the issues raised by phenobarbital have lessons for all antiepileptic drug therapy.

Specific safety and tolerability considerations in the use of anticonvulsant medications in children

Epilepsy is one of the most common neurological disorders in the pediatric age range, and the majority of affected children can be safely and effectively treated with antiepileptic medication. While there are many antiepileptic agents on the market, specific drugs may be more efficacious for certain seizure types or electroclinical syndromes. Furthermore, certain adverse effects are more common with specific classes of medication. Additionally patient-specific factors, such as age, race, other medical conditions, or concurrent medication use may result in higher rates of side effects or altered efficacy. Significant developmental changes in gastric absorption, protein binding, hepatic metabolism, and renal clearance are seen over the pediatric age range, which impact pharmacokinetics. Such changes must be considered to determine optimal dosing and dosing intervals for children at specific ages. Furthermore, approximately one third of children require polytherapy for seizure control, and many more take concurrent medications for other conditions. In such children, drug–drug interactions must be considered to minimize adverse effects and improve efficacy. This review will address issues of antiepileptic drug efficacy, tolerability and ease of use, pharmacokinetics, and drug–drug interactions in the pediatric age range.

Pharmacotherapy for children and adolescents with epilepsy

INTRODUCTION

Childhood epilepsies are the most frequent neurological problems that occur in children. Despite the introduction of new antiepileptic drugs (AEDs) 25-30% of children with epilepsy remain refractory to medical therapy.

AREAS COVERED

This review aims to highlight the main published data on the treatment of childhood epilepsy. The electronic database, PubMed, and abstract proceedings were used to identify studies. The aim of antiepileptic therapy should be to provide complete seizure control, if possible without the burden of any side effect. Since 1993, new agents have been approved for use as an antiepileptic. Although there are few published data (especially in pediatric populations) to establish that the second-generation AEDs are more efficacious than the older AEDs, they appear to have better tolerability.

EXPERT OPINION

Old AEDs are efficacious agents that continue to play a major role in the current treatment of epilepsy. These agents actually remain the first-line treatment for many specific seizure types or epileptic syndromes. The new AEDs were initially approved as adjunct agents and--subsequently--as monotherapy for various seizure types in the adult and children. Despite these improvements, few AEDs are now considered to be a first-choice for the treatment of epilepsy in children.

Divalproex sodium in children with partial seizures: 12-month safety study

This phase III, open-label, multicenter, outpatient study evaluated the 12-month safety of valproate using divalproex sodium sprinkle capsules for partial seizures, with or without secondary generalization, in children aged 3-10 years (n = 169). Laboratory parameters and vital signs were assessed, and the Wechsler Scales of Intelligence, the Developmental Profile-II, movement-related items from the Udvalg for Kliniske Undersøgelser, and the Behavior Assessment System for Children were administered. Efficacy was measured by the 4-week seizure rate. The most common treatment-emergent adverse events in the 169 study patients were typical childhood illnesses: pyrexia (18%), cough (17%), and nasopharyngitis (14%). The most common adverse events not considered typical childhood illnesses were vomiting (14%), tremor (9%), somnolence (8%), and diarrhea (8%). Of the 169 patients, 11 (6.5%) were hospitalized with serious treatment-emergent adverse events. Although elevated ammonia levels were observed in 31 treated patients, and mean increases in uric acid concentrations and decreases in platelets were observed, the majority of patients were asymptomatic. Except for tremor, no increases in movement-related adverse effects were observed. Small numeric improvements were reported in the Wechsler Scales and the Behavior Assessment System for Children. The safety findings in this 12-month study are generally consistent with previous reports of valproate in adult and pediatric epilepsy patients.

Side effects of phenobarbital and carbamazepine in childhood epilepsy: randomised controlled trial

OBJECTIVE

To compare the behavioural side effects associated with two commonly used antiepilepsy drugs-phenobarbital and carbamazepine-in children in Bangladesh.

DESIGN

Prospective randomised controlled single centre trial.

SETTING

Specialist children's hospital in Dhaka, Bangladesh.

PARTICIPANTS

108 children aged 2-15 with generalised tonic-clonic (n=51) or partial and secondary generalised seizures (n=57).

MAIN OUTCOME MEASURES

Seizure control and behavioural side effects.

RESULTS

91 children were followed up for 12 months. Six required a change of antiepilepsy drug. Side effects were compared in 85 children. In the last quarter of the 12 month follow-up, 71 children were seizure free after one year's treatment. Thirty two in the phenobarbital group and 39 in the carbamazepine group had no seizures in 74 and 102 days after randomisation, respectively. Ten children had increased behavioural problems, which were unacceptable in four (one in the phenobarbital group and three in the carbamazepine group). Independent t tests, however, showed no difference between the two trial drugs.

CONCLUSION

There was no excess in behavioural side effects with phenobarbital in children with epilepsy in a country with limited resources. Trial registration NCT00381537.

Experimental and clinical evidence for loss of effect (tolerance) during prolonged treatment with antiepileptic drugs

Development of tolerance (i.e., the reduction in response to a drug after repeated administration) is an adaptive response of the body to prolonged exposure to the drug, and tolerance to antiepileptic drugs (AEDs) is no exception. Tolerance develops to some drug effects much more rapidly than to others. The extent of tolerance depends on the drug and individual (genetic?) factors. Tolerance may lead to attenuation of side effects but also to loss of efficacy of AEDs and is reversible after discontinuation of drug treatment. Different experimental approaches are used to study tolerance in laboratory animals. Development of tolerance depends on the experimental model, drug, drug dosage, and duration of treatment, so that a battery of experimental protocols is needed to evaluate fully whether tolerance to effect occurs. Two major types of tolerance are known. Pharmacokinetic (metabolic) tolerance, due to induction of AED-metabolizing enzymes has been shown for most first-generation AEDs, and is easy to overcome by increasing dosage. Pharmacodynamic (functional) tolerance is due to "adaptation" of AED targets (e.g., by loss of receptor sensitivity) and has been shown experimentally for all AEDs that lose activity during prolonged treatment. Functional tolerance may lead to complete loss of AED activity and cross-tolerance to other AEDs. Convincing experimental evidence indicates that almost all first-, second-, and third-generation AEDs lose their antiepileptic activity during prolonged treatment, although to a different extent. Because of diverse confounding factors, detecting tolerance in patients with epilepsy is more difficult but can be done with careful assessment of decline during long-term individual patient response. After excluding confounding factors, tolerance to antiepileptic effect for most modern and old AEDs can be shown in small subgroups of responders by assessing individual or group response. Development of tolerance to the antiepileptic activity of an AED may be an important reason for failure of drug treatment. Knowledge of tolerance to AED effects as a mechanism of drug resistance in previous responders is important for patients, physicians, and scientists.

ILAE treatment guidelines: evidence-based analysis of antiepileptic drug efficacy and effectiveness as initial monotherapy for epileptic seizures and syndromes

PURPOSE

To assess which antiepileptic medications (AEDs) have the best evidence for long-term efficacy or effectiveness as initial monotherapy for patients with newly diagnosed or untreated epilepsy.

METHODS

A 10-member subcommission of the Commission on Therapeutic Strategies of The International League Against Epilepsy (ILAE), including adult and pediatric epileptologists, clinical pharmacologists, clinical trialists, and a statistician evaluated available evidence found through a structured literature review including MEDLINE, Current Contents and the Cochrane Library for all applicable articles from 1940 until July 2005. Articles dealing with different seizure types (for different age groups) and two epilepsy syndromes were assessed for quality of evidence (four classes) based on predefined criteria. Criteria for class I classification were a double-blind randomized controlled trial (RCT) design, >or=48-week treatment duration without forced exit criteria, information on >or=24-week seizure freedom data (efficacy) or >or=48-week retention data (effectiveness), demonstration of superiority or 80% power to detect a <or=20% relative difference in efficacy/effectiveness versus an adequate comparator, and appropriate statistical analysis. Class II studies met all class I criteria except for having either treatment duration of 24 to 47 weeks or, for noninferiority analysis, a power to only exclude a 21-30% relative difference. Class III studies included other randomized double-blind and open-label trials, and class IV included other forms of evidence (e.g., expert opinion, case reports). Quality of clinical trial evidence was used to determine the strength of the level of recommendation.

RESULTS

A total of 50 RCTs and seven meta-analyses contributed to the analysis. Only four RCTs had class I evidence, whereas two had class II evidence; the remainder were evaluated as class III evidence. Three seizure types had AEDs with level A or level B efficacy and effectiveness evidence as initial monotherapy: adults with partial-onset seizures (level A, carbamazepine and phenytoin; level B, valproic acid), children with partial-onset seizures (level A, oxcarbazepine; level B, None), and elderly adults with partial-onset seizures (level A, gabapentin and lamotrigine; level B, None). One adult seizure type [adults with generalized-onset tonic-clonic (GTC) seizures], two pediatric seizure types (GTC seizures and absence seizures), and two epilepsy syndromes (benign epilepsy with centrotemporal spikes and juvenile myoclonic epilepsy) had no AEDs with level A or level B efficacy and effectiveness evidence as initial monotherapy.

CONCLUSIONS

This evidence-based guideline focused on AED efficacy or effectiveness as initial monotherapy for patients with newly diagnosed or untreated epilepsy. The absence of rigorous comprehensive adverse effects data makes it impossible to develop an evidence-based guideline aimed at identifying the overall optimal recommended initial-monotherapy AED. There is an especially alarming lack of well-designed, properly conducted RCTs for patients with generalized seizures/epilepsies and for children in general. The majority of relevant existing RCTs have significant methodologic problems that limit their applicability to this guideline's clinically relevant main question. Multicenter, multinational efforts are needed to design, conduct and analyze future clinically relevant RCTs that can answer the many outstanding questions identified in this guideline. The ultimate choice of an AED for any individual patient with newly diagnosed or untreated epilepsy should include consideration of the strength of the efficacy and effectiveness evidence for each AED along with other variables such as the AED safety and tolerability profile, pharmacokinetic properties, formulations, and expense. When selecting a patient's AED, physicians and patients should consider all relevant variables and not just efficacy and effectiveness.

Phenobarbital for childhood epilepsy: systematic review

INTRODUCTION: Against a background of concern about the safety of new pharmaceutical products, there has been renewed interest in one of the oldest antiepileptic drugs (AEDs), phenobarbital. Although still in widespread use in developing countries, its popularity has slipped in Western countries over the past century, partly because of controversy about its adverse effect profile. This critical review examines the evidence supporting its effectiveness and its associated behavioural adverse effects for febrile convulsions and childhood epilepsy. METHODS: Relevant randomised controlled trials (RCTs) of phenobarbital vs other antiepileptic drugs or placebo between 1970-2005 were identified through a comprehensive manual and computer database search of the world biomedical literature. Eleven RCTs of febrile convulsions and nine RCTs of childhood epilepsy were systematically reviewed against a conventional set of quality criteria. RESULTS: With a few exceptions, the overall quality of clinical trial methodology, especially in the early studies conducted in the 1970s and 1980s, was poor. There is no evidence for a difference in antiepileptic efficacy between phenobarbital and any other compared AED, yet no evidence for absolute efficacy. No convincing evidence exists for an excess of behavioural adverse effects, over other AEDs, attributable to phenobarbital. Masked studies of phenobarbital in childhood epilepsy have shown no significant differences in behavioural or cognitive adverse effects compared to other AEDs. This is in contrast to the excess of such adverse effects reported in studies open to observer bias. However, the one finding of reduction in cognitive ability associated with phenobarbital treatment for febrile convulsions remains a concern. Future areas of clinical and genetic epidemiological research are outlined.

Epilepsy in children

10.5 million children worldwide are estimated to have active epilepsy. Over the past 15 years, syndrome-oriented clinical and EEG diagnosis, and better aetiological diagnosis, especially supported by neuroimaging, has helped to clarify the diversity of epilepsy in children, and has improved management. Perinatal and postinfective encephalopathy, cortical dysplasia, and hippocampal sclerosis account for the most severe symptomatic epilepsies. Ion channel defects can underlie both benign age-related disorders and severe epileptic encephalopathies with a progressive disturbance in cerebral function. However, the reasons for age-related expression in children are not understood. Neither are the mechanisms whereby an epileptic encephalopathy originates. Several new drugs have been recently introduced but have provided limited therapeutic benefits. However, treatment and quality of life have improved because the syndrome-specific efficacy profile of drugs is better known, and there is heightened awareness that compounds with severe cognitive side-effects and heavy polytherapies should be avoided. Epilepsy surgery is an important option for a few well-selected individuals, but should be considered with great caution when there is no apparent underlying brain lesion.

Neurocognitive effects of phenobarbital discontinuation in epileptic children

PURPOSE

Phenobarbital (PB) is the most widely used antiepileptic drug in the world, but its possible deleterious cognitive and behavioral side effects remain an important concern among physicians and patients.We therefore investigated whether discontinuation of PB in children with epilepsy is accompanied by improvement in cognitive function.

METHODS

Neuropsychiatric performance was evaluated with the Wechsler Intelligence Scale for Children-Revised (WISC-R), in two consecutive 7-month periods, in two groups of children with epilepsy 6-12 years old who had been seizure-free for at least 2 years and whose only antiepileptic drug was PB. The case group comprised 24 patients who discontinued PB, and the control group was comprised of the 21 children who continued to take PB.

RESULTS

Discontinuation of PB improved Total IQ in the case group compared to the control group (P = 0.027). This increase was mostly in performance (nonverbal) items; verbal items remained almost unchanged.

CONCLUSION

These findings suggest that PB affects cognitive function, and the performance (nonverbal) deficits are diminished after discontinuation of therapy.

Phenobarbital for the Treatment of Epilepsy in the 21st Century: A Critical Review

SUMMARY

Phenobarbital (PB) is the most widely used antiepileptic drug (AED) in the developing world and remains a popular choice in many industrialized countries. Meta-analyses of randomized controlled trials suggest that few differences in efficacy exist between PB and other established AEDs, but its possible deleterious cognitive and behavioral side effects remain a concern in the developed world. In contrast, high degrees of efficacy and tolerability in everyday clinical use have been demonstrated consistently in observational studies in developing countries. We propose that a pragmatic, comprehensive outcomes program be carried out, perhaps under the aegis of the Global Campaign Against Epilepsy, to optimize the conditions of the use of PB, so that more people around the world can benefit from this cost-effective medication and live more fulfilling lives.

Determining the effects of antiepileptic drugs on cognitive function in pediatric patients with epilepsy

The majority of children with epilepsy are of normal intelligence; however, a significant subset suffers from temporary or permanent cognitive impairment. Factors that affect cognitive function are myriad and include the neuropathology underlying the epilepsy, seizures, epileptiform activity, psychosocial problems, and antiepileptic drug side effects. Although cognitive impairment is often wrongly attributed to the effects of antiepileptic drugs, antiepileptic drugs do impair cognition in some children. Clinicians should be aware of the differential cognitive effects of antiepileptic drugs and should monitor cognitive function closely when adding or changing therapy. Based on published data from prospective, chronic dosing studies, phenobarbital and topiramate have the highest potential for causing cognitive dysfunction.

Treatment of partial seizures in childhood : an overview

The treatment of partial seizures in children is based on the use of first generation and recently introduced antiepileptic drugs as well as nonpharmacological treatments such as the ketogenic diet, vagus nerve stimulation and surgical therapy. The present review discusses the efficacy and tolerability of different treatment options for partial seizures in childhood. Few adjunctive or monotherapy, placebo-controlled or comparative trials of the first-generation antiepileptic drugs and some of the more recently introduced antiepileptic drugs have been performed in children. This can be explained by the fact that it is only relatively recently (1989) that the International League against Epilepsy proposed that randomised, controlled trials be included among the required criteria for assessing the efficacy and tolerability of an antiepileptic agent. This led to controlled, comparative trials among older antiepileptic drugs (phenobarbital, phenytoin, carbamazepine and valproic acid), both in adults and in paediatric patients, being performed relatively 'late', based on when these drugs were first introduced. Carbamazepine and valproic acid may still be considered as first-line antiepileptic therapies for children with partial seizures. Phenobarbital and phenytoin are mostly considered as last choice drugs because of their adverse event profiles. The new generation of antiepileptic agents has added to the first- and second-line treatment options for paediatric partial seizures. To date, there are sufficient data to support the clinical use of some of the recently introduced antiepileptic drugs (e.g. oxcarbazepine, topiramate, gabapentin and lamotrigine) as adjunctive or first-line monotherapy. Because of the risk of visual field constriction with vigabatrin, the use of this drug is currently limited to patients refractory to other medications. Tiagabine, felbamate, levetiracetam and zonisamide have been shown to be effective in adults with partial seizures; however, at present there are not yet enough data on the efficacy of these drugs in children to support consideration of their use as either first-line or add-on therapy in this patient population, although controlled studies are expected shortly. Furthermore, the use of felbamate is considerably limited by rare, but severe, hepatic and haematological toxicity. Controlled trials for paediatric partial seizures are still lacking for the ketogenic diet and vagus nerve stimulation, though they may represent, in given patients, useful adjunctive alternative treatments for refractory partial seizures. In conclusion, further trials are needed to determine an optimal sequence of first- and second-line therapies and to establish whether other newer antiepileptic drugs merit consideration as initial therapy in children with partial seizures.

Childhood epilepsy: what is the evidence for what we think and what we do?

This article reviews the strength of the evidence that underlies the current approach to the management of childhood epilepsy. The authors reviewed published, peer-reviewed English literature accessed through PubMed and Cochrane reviews with evidence rated as Class 1 (strongest) to Class 4 (weakest). There is considerable inaccuracy in the diagnosis of seizures and epilepsy syndromes. Sound information supports the consensus that the diagnosis of epilepsy should await two unprovoked seizures. Population-based studies indicate that remission from childhood onset epilepsy occurs in at least 50% of children. It is easier to predict a good seizure outcome than a poor one. Absence of concomitant neurologic handicap and onset before about 12 years of age are the most consistent predictors of remission. Intractability is poorly defined and difficult to predict until several antiepilepsy drugs have been used and failed to control the seizures. Most epilepsy syndrome diagnoses do not yield an accurate prognosis. Social outcome appears unsatisfactory in about 50% of cases without intellectual handicap. Death is rare in childhood epilepsy. Those without severe neurologic handicaps have the same mortality as the general population. We identified only 27 published randomized trials of antiepilepsy drugs in children that compare the efficacy of antiepilepsy drugs, offer treatment of syndromes currently without successful treatment, or have negative effects. There is a pressing need for better definitions of seizures and epilepsy syndromes. The causes of poor social outcome are unclear. Intractability needs a clear definition and randomized trials comparing treatment regimes are sadly lacking.

Carbamazepine versus phenobarbitone monotherapy for epilepsy

BACKGROUND

In developing countries, phenobarbitone is commonly used but its use in Europe and the USA has decreased due to concerns over adverse effects. Carbamazepine is recommended as the drug of choice for partial onset seizures, and there is concern that it may worsen some generalized onset seizure types. We report a review using individual patient data in which carbamazepine and phenobarbitone are compared.

OBJECTIVES

To review the effects of carbamazepine compared to phenobarbitone monotherapy for people with partial onset seizures or generalized onset tonic-clonic seizures.

SEARCH STRATEGY

The Cochrane Controlled trials register (Cochrane Library Issue 2, 2002); MEDLINE; EMBASE; handsearching; contacting experts and original trial investigators; contacting manufacturers of carbamazepine.

SELECTION CRITERIA

Randomized or quasi-randomized, blinded or unblinded controlled trials in children or adults with partial onset seizures or generalized onset tonic-clonic seizures.

DATA COLLECTION AND ANALYSIS

Outcome measures were (i) time to withdrawal of allocated treatment, (ii) time to 12 month remission, and (iii) time to first seizure. Data were analysed using a stratified logrank analysis with results expressed as hazard ratios (HR) and 95% confidence intervals (CIs), where a HR>1 indicates an event is more likely on phenobarbitone. A test for interaction between treatment and seizure type (partial versus generalized onset) was also undertaken.

MAIN RESULTS

Data are available for 684 participants from four trials, representing 59% of the participants recruited into the nine trials that met our inclusion criteria. The main overall results (HR 95% CI) adjusted for seizure type were, (i) time to withdrawal 1.63(1.23 to 2.15), (ii) time to 12 month remission 0.87(0.65 to 1.17), (iii) time to first seizure 0.85(0.68 to 1.05). The review suggests that time to withdrawal is significantly improved with carbamazepine compared to phenobarbitone. No overall difference between drugs is identified for the outcomes 'time to 12 month remission' and 'time to first seizure'. Statistical heterogeneity was not encountered. An interaction between treatment and seizure type, confirmed statistically, was identified for time to first seizure, where phenobarbitone was favoured for partial onset seizures and carbamazepine for generalized onset tonic-clonic seizures.

REVIEWER'S CONCLUSIONS

We found no overall difference between carbamazepine and phenobarbitone for time to 12 month remission or time to first seizure, however, subgroup analyses for time to first seizure suggest an advantage with phenobarbitone for partial onset seizures and a clinical advantage with carbamazepine for generalized onset tonic-clonic seizures. Phenobarbitone is significantly more likely to be withdrawn, indicating that it is less well tolerated than carbamazepine.

Differential cognitive effects of antiepileptic drugs

As a group, children and adolescents with epilepsy have a higher prevalence of cognitive and behavioral disorders, although many fall within the normal distribution. For those affected, several causes have been identified, some of which may be interrelated. It has proven to be methodologically sound to isolate the role of specific antiepileptic drugs as a cause of cognitive impairment. The large body of literature that has accumulated on this topic is characterized by a relatively high proportion of inconclusive or contradictory observations. This may be due in part to the many methodological pitfalls in this area of research. The emerging picture is that cognitive effects caused by antiepileptic drugs are neither the rule nor the exception. Although certain drugs appear more likely to be involved, no single drug causes problems in every patient, and no drug can be assumed never to cause any cognitive impairment. The subgroup of patients that are at higher risk cannot be easily defined. Early detection of cognitive effects is based on actively eliciting reports of symptoms. This can be complemented by a screening battery in case of suspicion.

Neuropsychological outcomes in randomized controlled trials of antiepileptic drugs: a systematic review of methodology and reporting standards

PURPOSE

To systematically review the methodology and use of neuropsychological tests in randomized controlled trials (RCTs) of antiepileptic drugs (AEDs) in patients with epilepsy.

METHODS

Trial reports were found by searching Medline 1966-1996 and searching through journals by hand. Inclusion and exclusion criteria were applied, and methodological and neuropsychological test data was extracted by using a proforma.

RESULTS

43 reports met our inclusion criteria, representing 40 RCTs. as three RCTs had generated two reports. Twenty-two were actively controlled, and 18 were placebo-controlled studies. Reporting of basic methods such as randomization method was poor. There has been no uniform approach to the use of neuropsychological tests, and a total of 87 has been used. The Stroop Colour Word Test and the Finger Tapping Test were most commonly used, at 13 times each, but were not used or reported in a uniform manner.

CONCLUSIONS

Poor reporting of methods and the use of a plethora of neuropsychological tests create great difficulties for anyone wishing to make sense of currently available data. If we are better to understand the neuropsychological effects of AEDs, a more rational approach is needed, for which recommendations are made.

Antiepileptic drugs, learning, and behavior in childhood epilepsy

Cognitive and behavioral impairments are found more often among epileptic children than among their peers. The cause of these impairments is multifactorial. Identifying the relative contribution of antiepileptic drugs (AEDs) to these problems has been the object of a large number of clinical investigations. This area of research has been characterized by an unusually high number of methodological challenges and pitfalls. Accordingly, results have often been inconsistent and contradictory, except for the more obvious observations that can be derived from clinical experience. Overall, the effects of AEDs on cognition and behavior in children have been overrated in the past. More recent research has benefited from the methodological lessons of previous studies and it suggests that the majority of children taking AEDs do not experience clinically relevant cognitive of behavioral adverse effects from these medications. In addition, some of the newer AEDs may indeed have a better cognitive profile. Nevertheless, clinical experience must be used to identify the subgroup of children who remain at risk for significant and clinically relevant cognitive and behavioral adverse effects of AEDs.

Randomised controlled trial to assess acceptability of phenobarbital for childhood epilepsy in rural India

BACKGROUND

The use of phenobarbital for childhood epilepsy is controversial because of reported behavioural side-effects; however, whether this research can validly be extrapolated to developing countries is not clear. We undertook a randomised comparison of phenobarbital and phenytoin to assess the acceptability and efficacy of phenobarbital as monotherapy for childhood epilepsy in rural India.

METHODS

Between August, 1995, and February, 1996, 109 unselected children aged 2-18 years with partial and generalised tonic-clonic epilepsy were identified by population screening. 15 families declined to take part. 94 children were randomly allocated treatment with phenobarbital (1.5 mg/kg daily for 2 weeks; maintenance dose 3.0 mg/kg daily; n = 47) or phenytoin (2.5 mg/kg daily then 5.0 mg/kg daily; n = 47). Children were followed up for 12 months. The primary outcome measure was the frequency of behavioural side-effects; behaviour was assessed by the Conners parent rating scale for children aged 6 years and older, and by the preschool behaviour screening questionnaire (BSQ) for those aged 2-5 years, at 12 months or at withdrawal from treatment. Analysis was by intention to treat.

FINDINGS

The mean log-transformed scores on the behaviour rating scales did not differ significantly between the phenobarbital and phenytoin groups (Conners 2.64 [SD 0.71] vs 2.65 [0.89], p = 0.97; n = 32 in each group: BSQ 2.12 [1.31] vs 2.18 [1.02], p = 0.94; n = 4 vs 3). The odds ratio for behavioural problems (phenobarbital vs phenytoin) was 0.51 (95% CI 0.16-1.59). There was no excess in parental reports of side-effects for phenobarbital. We found no difference in efficacy between the study drugs (adjusted hazard ratio for time to first seizure from randomisation 0.97 [0.28-3.30]).

INTERPRETATION

This evidence supports the acceptability of phenobarbital as a first-line drug for childhood epilepsy in rural settings in developing countries.

Barbiturate anticonvulsants: a neuropsychological and quantitative electroencephalographic study

We studied 11 epileptic children aged 7 to 14 years with quantitative electroencephalographic (EEG) and neuropsychological tests, both on and off the barbiturate anticonvulsants phenobarbital and mephobarbital, comparing them to 13 controls matched for age and IQ who received testing at similar intervals. Neuropsychological tests employed were the Wechsler Intelligence Scale for Children-Revised (WISC-R), Bender-Gestalt, controlled oral word association test (COWAT), selected subtests of the Wechsler Memory Scale-Revised, Purdue Peg Board, Stroop Test, Trail Making Test, Wide Range Achievement Test-Revised, and Achenbach Behavior Rating Scale. There was no difference between on- and off-drug quantitative EEG in percentage power of any frequency band between 0.6 and 32 Hz. Neuropsychological data from all 11 subjects were analyzed with a two-factor analysis of variance with repeated measures on the time factor. The only difference from controls was on the Stroop Test. Parents reported clear behavioral changes in 6 of 11 subjects, but in 4 of these children the behavioral changes were sufficiently mild that parents chose to continue the barbiturate anticonvulsants: irritability, oppositional attitude, and overactivity were described. Mephobarbital was reported by parents to cause less severe problems than phenobarbital in subjects who had taken both barbiturate anticonvulsants. Barbiturate anticonvulsants have no effect on quantitative EEG and limited effects on neuropsychological tests in school-aged children.

Discontinuation of phenobarbital in children: effects on neurocognitive behavior

Neurocognitive performances were evaluated in 9 children with different types of epilepsy prior to and at least 6 months after discontinuation of phenobarbital. The patients treated with phenobarbital monotherapy were seizure free for at least 2 years, without electro-encephalographic anomalies for at least 1 year. Results indicated that phenobarbital at low therapeutic doses causes attentional and memory deficits, reversible after therapy discontinuation. Further research utilizing the same design is needed on larger samples in order to confirm our results.

Comparison of antiepileptic drugs on cognitive function in newly diagnosed epileptic children: a psychometric and neurophysiological study

Using a randomized parallel group study design, we compared the cognit ive effects of carbamazepine (CBZ), phenobarbital (PB), and valproate (VPA) in children with epilepsy. Seventy-three children with newly diagnosed epilepsy were tested with the Wechsler Intelligence Scale for Children-Revised (WISC-R), Bender-Gestalt test, and auditory event-related potentials (P 300) before and 6 and 12 months after antiepileptic drug (AED) treatment. There were no significant differences in WISC-R IQs and Bender-Gestalt scores for children in any group at any of the three sessions. P 300 latencies were increased in the children receiving PB but not in children receiving CBZ and VPA. P 300 amplitudes were significantly reduced in treated children in all three groups, but amplitudes were not significantly different among the three groups. These findings suggest that PB may affect cognitive function of epileptic children and that the P 300 may be a sensitive additional procedure that can be used to assess the cognitive effect of AEDs.

Cognitive side-effects of chronic antiepileptic drug treatment: a review of 25 years of research

Over 90 investigations have been conducted over the past 25 years to determine what effect AEDs have on cognition. No satisfactory answer to this problem can be given, however, chiefly because there is a paucity of studies that pass fairly basic standards of methodology, design and analysis that apply to the evaluation of any clinical research. This severely limits the precision of statements regarding cognitive AED effects. More particularly, there is little reason to recommend any of the first-line AEDs as the AED of choice from the standpoint of cognitive side-effects. On the basis of the present review we are not in a position to provide a straightforward answer to the most pertinent question, i.e., whether AEDs in therapeutic doses have any cognitive effects at all, good or bad. If we reduce the available database to monotherapy studies in epilepsy that use control group data for comparison, employ an appropriate form of repeated measures analysis, and provide sufficient information, very few studies remain that are directly relevant to this issue. This in itself precludes definitive conclusions. As can be seen from Table 9, absolute effects of CBZ and VPA have been examined in epilepsy patients three times each (in four studies), PB has been examined two times, PHT only once. In addition to the paucity of relevant data, there are miscellaneous validity concerns in all of these studies, one recurring theme being that of inconclusive 'no effect' findings with small samples. Without firm knowledge about absolute effects, relative effects, and particularly their absence, are difficult to interpret. Employing the above criteria (except that concerning controls), ten epilepsy studies that address this issue remain (Table 10). It is instructive to look at the number of times particular AEDs have been compared against each other (Table 11). CBZ has been compared to PHT five times, other comparisons occur only once or twice. Again, this is hardly a basis for definitive statements, particularly because validity concerns occur here as well. Recurring concerns here are scattered significant findings that tend to disappear if adjustment of the significance level for multiple comparisons is done, and inconclusive 'no difference' findings with small samples. Even if there were no conclusion validity concerns in individual studies, comparison between studies would be complicated by considerable variation in the subjects studied. Five of the studies summarized in Tables 8 and 9 use children as subject, nine use adults; results obtained in one group may not be generalizable to the other. Also, subjects may be newly diagnosed cases, or patients already on chronic treatment. The latter choice of subjects may be a factor working against detecting cognitive side-effects, as the damage (if any) may already have been done before the beginning of the trial. In addition, a wide variety of assessment tools have been used to search for cognitive effects of AEDs, ranging from measurements of reaction time and motor speed to intelligence tests. Some of these may be more sensitive to drug induced changes in cognition than others. Still, the tentative overall picture emerging from the creme de la creme of research on cognitive AED effects is that differences in cognitive profiles may not be very large. An important point here, of course, is the magnitude of the difference one considers worth detecting. Very few studies have attempted to answer this question. In the majority of studies we examined, a large treatment effect was anticipated implicitly, judging from the generally limited sample sizes. The choice of a study design based on a large treatment effect size may not always be appropriate, though. Of course, one could argue that it is only large effects that may be of practical or clinical significance anyways [30] and that effects of lesser magnitude are of no consequence. However, there are many examples where even a small benefit of one treatme

Antiepileptic drugs in pediatric practice

Several factors characterize the current medical treatment of epilepsy during childhood. Children do not present the same types of seizures or epilepsies as adults, and certain epilepsy syndromes are seen only during childhood. Accordingly, the choice of antiepileptic drugs (AEDs) may differ in children. In addition, certain medical therapies, such as ACTH or pyridoxine, are used only in children. It is also common practice to prescribe AEDs in children for indications that are "off-label," such as the treatment of partial-onset seizures with carbamazepine before the age of 6 years. The natural history of epilepsy and the risk for seizure recurrence may be different in the pediatric age range, and this may influence the decision to institute chronic prophylactic therapy in children. Similar considerations may apply to the decision to discontinue AED therapy. The pharmacokinetics of several AEDs are age-dependent, and dosages are more variable among patients. The adverse effects of AEDs may be age-dependent, and the pattern of exacerbation of certain seizures by AEDs may be different in children. In addition, several new AEDs are now available, or are about to be released, and the preferential sequence of AEDs of choice in children with epilepsy will need to be reassessed as experience grows and as the results of comparative studies become available.

Cognitive and behavioral effects of antiepileptic drugs

All antiepileptic drugs (AEDs) have the potential for adverse effects on cognition and behavior. Most of the major AEDs, administered in therapeutic doses, cause little or no cognitive or behavioral impairment in group studies. However, individual variability is considerable, and some patients do not tolerate low serum levels, whereas others tolerate high levels without subjective or objective effects. In the past, carbamazepine (CBZ) and valproate (VPA) have been reported to have the fewest adverse cognitive and behavioral effects in children and adults. However, several recent, well-controlled studies have not found significant differences between the effects of phenytoin (PHT) and those of CBZ or VPA. Greater adverse effects have been found for phenobarbital (PB). However, we must use environmentally relevant measures of cognitive and behavioral functioning to measure effects on daily functioning. Future studies must define cognitive and behavioral toxicity in subpopulations (e.g., post-traumatic epilepsy, mental retardation, depression) and with the new AEDs.

Adverse effects of established and new antiepileptic drugs: an attempted comparison

Seizures are but one aspect of the negative impact epilepsy has on patients' lives. Adverse effects of antiepileptic treatment may affect the patient's quality of life to an even greater extent than the occurrence of seizures. Adverse effects of antiepileptic drugs (AEDs) are common, and because the differences in efficacy are often marginal, adverse effects may be the most important factor in choosing the best AED for the patient. The search for more efficient and less toxic agents is constantly ongoing. Current evidence suggests that the new generation of AEDs is as efficient as the established AEDs and exhibits fewer adverse effects, but the scientific evidence from randomised clinical trials comparing established and new AEDs with each other is still pending.

Differential effects of first antiepileptic drug application on cognition in lesional and non-lesional patients with epilepsy

It has been shown that carbamazepine (CBZ) and valproic acid (VPA) have no significant negative or even positive side effects upon cognition in patients with epilepsy. The present study evaluated cognitive effects of CBZ or VPA in 16 patients with newly diagnosed epilepsy. Twelve patients had complex partial seizures, four patients primarily generalized seizures. Special attention was directed towards seizure type, presence of structural lesions and seizure control. Neuropsychological testing was carried out prior to medication and when drugs were within therapeutic ranges. Nineteen untreated healthy subjects served as controls. The following results were obtained: first of all, no general effect of antiepileptic drugs upon cognition could be detected. Only a subgroup with lesion (n = 8) and pre-existing cognitive deficits showed a significant decrease in memory performance during medication. This group additionally obtained poor seizure control. In conclusion, adverse cognitive changes under medication cannot be explained by antiepileptic drugs alone. The presence of cerebral lesions and obtained seizure control have to be considered as essential risk factors.

Determinants of IQ profile in children with idiopathic generalized epilepsy

To determine the IQ profile of children with epilepsy and the influence of various epilepsy-related variables on IQ scores, we studied 50 children with idiopathic generalized epilepsy of > 1-year duration, 25 of their siblings, and 30 healthy controls. IQ assessments were made with Malin's Indian modification of the Wechsler Intelligence Scale for Children. The mean +/- SD IQ scores of children with epilepsy (85.6 +/- 12) and their siblings (93.2 +/- 11) were significantly lower than those of the controls (101.6 +/- 9). The IQ scores of the children with epilepsy were also significantly lower than those of their siblings (p < 0.05). The IQ scores showed a significant correlation with socioeconomic status (SES) score (r = 0.33), a history of status epilepticus (r = -0.38), duration of seizure disorder (r = -0.31), and total number of seizures (r = -0.31). On multiple regression analysis, status epilepticus emerged as the most significant variable, accounting for 14% variance, followed by SES score (9% variance), duration of seizure disorder (6% variance), and sex of the child (5% variance). Genetic or environmental factors that probably lead to cognitive deficit in children with epilepsy and their siblings require further study.

Reaction time, attention, and impulsivity in epilepsy

Reaction time, attention, and impulsivity were studied in 112 children with epilepsy (4.5-13 years) using a computerized test. We measured simple reaction time (response with each hand separately to a single stimulus), forced choice reaction time (two stimuli presented in random order, one designated for each hand), and choice reaction time with distraction (two response stimuli, one for each hand, with two additional distracting stimuli randomly inserted). We also measured variability of speed of response and errors of omission and commission. Controls were unaffected children of similar age, ethnic, and socioeconomic backgrounds. Children with epilepsy were significantly slower, more variable, and made more omission errors than control children, even when analysis was limited to epileptic patients with IQ greater than 90, but they did not make more commission (i.e., impulsive) errors. Reaction times were related to IQ, but in general were not related to seizure severity, duration of seizure disorder, or duration of medication use. Untreated patients (N = 13) did not differ from those with antiepileptic drug levels in the therapeutic range on the day of testing (N = 52), but differed significantly from normal patients. Epileptic patients demonstrated significant slowing of reaction time and inattention, but not significant impulsivity, compared to normal children; however, these deficits do not appear to be related specifically to seizure history or treatment.

Academic underachievement in children with epilepsy

Academic achievement was studied in 78 children with epilepsy, ages 5 to 13 years, to determine how seizures, treatment of seizures, and sociocultural factors influence academic achievement. Cognitive abilities were assessed with either the McCarthy Scales of Children's Abilities or the Wechsler Intelligence Scale for Children--Revised. Achievement was measured with the Peabody Individual Achievement Tests. Achievement scores were corrected for cognitive ability (IQ), and underachievement was defined as achievement score 1/2 standard deviation or more below IQ. Information regarding seizure history (severity, duration) and treatment with anticonvulsant drugs was obtained. In addition, the family was extensively interviewed regarding the child's environment, behavior, and demographic background. The Home Observation for Measurement of the Environment (HOME) scale was completed on a home visit. Underachievement was frequent, ranging from 16% (Reading Recognition) to 50% (General Knowledge), but there was no relationship between severity or duration of seizure disorder or total exposure to anticonvulsant medications and achievement. Major determinants of achievement included subscales of the HOME scale, age (older children more likely to be underachieving), and parental education. An equal proportion of newly diagnosed and/or untreated subjects were underachieving compared to those with longstanding epilepsy and anticonvulsant drug treatment.

Antiepileptic drugs, cognitive function, and behavior in children: evidence from recent studies

The effects of antiepileptic drugs (AEDs) on cognitive function and behavior in children are reviewed on the basis of published studies. Individual AEDs have been shown to differ--the deleterious effects of phenytoin generally contrasting with the relatively minimal effects of valproate and carbamazepine. Some of the differences between results may be attributed to the psychological tests used and to age differences. However, there appears to be a dissociation between AEDs that affect higher cognitive function, e.g., phenytoin, and those mainly affecting motor function, e.g., carbamazepine, which appears to increase speed of performance, AEDs should be prescribed with care in children with epilepsy, taking account of their differing effects on cognitive function and behavior.

Children of school age: the influence of antiepileptic drugs on behavior and intellect

The role of antiepileptic drugs in behavior and cognitive function in children is well documented in the literature. In general, behavioral problems occur most frequently with phenobarbital and clonazepam, and appear least often with valproate and carbamazepine. Cognitive impairments occur with phenytoin, are less evident with valproate, and minimal with carbamazepine. Monotherapy, as with adults, leads to improvements in both cognitive abilities and behavior.

Prognosis of partial epilepsy

The prognosis of partial epilepsy in childhood (excluding cases of benign partial epilepsy) was studied; the average follow up period was 7.4 years. Improvement rate of seizure status was 82.3%. We studied favourable prognostic factors and found that those most often associated with seizure improvement were familial convulsions and idiopathic forms, no generalised seizures before partial onset, low frequency of seizures after 12 months of treatment, short duration of epilepsy, and no background activity abnormalities on electroencephalography. We also observed such factors as mental retardation, neurological abnormalities, and behaviour and cognitive disorders. Factors that determined the prognosis for social adjustment were similar to those for seizure improvement. We discuss the favourable prognosis of partial seizures in childhood and the predictive factors.

Anticonvulsant drugs and cognitive function: a review of the literature

Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.

Carbamazepine efficacy and utilization in children

Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmaco-kinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.