Vigabatrin as a first-choice drug in the treatment of West syndrome

Efficacy of vigabatrin in the treatment of infantile epileptic spasms syndrome: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the efficacy of vigabatrin (VGB) in treating infantile epileptic spasms syndrome (IESS). Databases of PubMed, Embase, Web of Science, MEDLINE, and Cochrane Library were systematically searched. All the relevant randomized controlled trials (RCTs) and observational studies (OSs) of VGB for IESS were included and analyzed separately. The primary outcome was the cessation of epileptic spasms (ES). Five RCTs and nine OSs compared the efficacy of VGB vs hormonal monotherapy for IESS. Meta-analysis of the five RCTs showed that hormonal monotherapy was significantly better than VGB monotherapy (OR = 0.37, 95% CI = 0.20-0.67) for patients with new-onset IESS. Meta-analysis of the nine OSs agrees with the result from RCTs (OR = 0.61, 95% CI = 0.43-0.85). VGB was more effective in patients with TSC than in those with other etiologies (five OSs, OR = 5.59, 95% CI = 2.17-14.41). There was no significant difference in the efficiency of VGB combined with hormonal therapy vs hormonal monotherapy for IESS (two RCTs, OR = 0.75, 95% CI = 0.09-6.45). Hormonal monotherapy is better than VGB monotherapy for non-TSC-associated IESS. But for patients with IESS due to TSC, VGB is the first choice. VGB combined with hormone therapy does not definitely increase ES control rates compared with that of hormonal monotherapy.

Resective epilepsy surgery for West syndrome: The Hypsarrhythmic Asymmetric Scoring Scheme is a determining predictor of seizure outcome

OBJECTIVE

It has been suggested that asymmetric hypsarrhythmia is associated with structural etiology. We devised the Hypsarrhythmic Asymmetric Scoring Scheme (HASS) to quantify the degree of hypsarrhythmic asymmetry in a retrospective series of patients who underwent surgical treatment at our center. The present study aimed to investigate the role of HASS in predicting the postsurgical seizure outcomes.

METHODS

We retrospectively analyzed the records of 46 children with hypsarrhythmia who underwent resective epilepsy surgery between 2018 and 2020 and were followed up for at least 1 year after surgery. Hypsarrhythmia severity in each hemisphere was quantified and scored. The HASS score was calculated as the difference between the two hemispheres. Univariate results were submitted to logistic regression models to identify independent predictors for favorable surgical outcomes.

RESULTS

Of the 46 patients who underwent resective surgery, Engel's class I-Ⅱ outcomes were achieved in 34 (73.9%). The Engel I-Ⅱ group had a significantly higher HASS score than the Engel Ⅲ-Ⅳ group (p<0.001). Multivariate analysis showed that the HASS score was the only significant predictor of good outcomes (p = 0.011). Further receiver operating characteristic analysis showed that a threshold of 7 yielded a better seizure outcome with a sensitivity of 97.06% and specificity of 83.33%.

SIGNIFICANCE

As the first hypsarrhythmia scoring system specially designed for presurgical evaluation, the HASS score may contribute to predicting the postsurgical seizure outcome from the electroencephalography perspective.

Hormonal Therapy for Infantile Spasms: A Systematic Review and Meta-Analysis

Objective

The limitations of adrenocorticotrophic hormone (ACTH) treatment for infantile spasms (ISs), such as high costs, limited availability, and adverse effects (AEs), make it necessary to explore whether corticosteroids are optimal alternatives. Many other compelling treatments have gone through trials due to the suboptimal effectiveness of hormonal therapy. A systematic review and meta-analysis were performed to evaluate the effectiveness and safety of hormonal therapy for patients with ISs.

Methods

EMBASE, Ovid MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), and online registers were searched through April 2021 for randomized controlled trials (RCTs).

Results

A total of 19 RCTs (N = 1,279) were included. There was no significant difference in the effectiveness of oral corticosteroids and ACTH in electro-clinical response (risk ratio [RR] = 0.85, 95% CI 0.41–1.76). Low-dose ACTH had similar effectiveness in electro-clinical response compared to usual-dose group (RR = 0.94, 95% CI 0.60–1.47) but conferred a lower risk of AEs (RR = 1.71, 95% CI 1.08–2.71). ACTH was more beneficial in controlling spasms than vigabatrin (VGB) (RR = 1.31, 95% CI 1.05–1.64) for patients without tuberous sclerosis complex (TSC). All RCTs were connected through network meta-analysis, and we found that ketogenic diet (KD), zonisamide, methylprednisolone, or combined treatment of hormonal therapy with topiramate (TPM) or pyridoxine was not different in electro-clinical response compared to usual-dose ACTH.

Conclusion

Our analysis showed that oral corticosteroids could be optional alternatives when ACTH is not applicable, and ACTH is more beneficial for patients without TSC. Moreover, low-dose ACTH is recommended due to comparative effectiveness but lower risk of AEs. However, due to the high heterogeneity of included patients and treatment protocols, these results must be interpreted with caution. RCTs with multicentric involvement and larger sample size are needed for solid evaluation of other alternative treatments.

Derivatization of γ-Amino Butyric Acid Analogues for Their Determination in the Biological Samples and Pharmaceutical Preparations: A Comprehensive Review

γ-Aminobutyric acid (GABA) plays an important role in regulating neuronal excitability. Four structurally related drugs to GABA including pregabalin (PGB), gabapentin (GBP), vigabatrin (VGB), and baclofen are used for the treatment of central nervous system disorders. These drugs are small aliphatic molecules having neither fluorescent nor strong absorbance in the ultraviolet/visible region; therefore, direct determination of these analytes by optical methods is difficult. Additionally, their high boiling point makes gas chromatography impossible. Accordingly, the amine or acid moiety in these drugs is derivatized in order to improve their selectivity and sensitivity during determination in the biological samples. This review focuses on derivatization based methods and their different reactions for determination of PGB, GBP, VGB, and baclofen in the biological samples and pharmaceutical preparations reported between 1980 and 2020. High-performance liquid chromatography methods coupled with different detectors are a commonly used methods for determination of GABA analogs after derivatization. These methods cover 38.89% of all developed methods for determination of GABA analogs.

Management of infantile spasms

West syndrome, or infantile spasms syndrome is a frequently catastrophic infantile epileptic encephalopathy with a variety of etiologies. Despite the heterogeneous nature of causes of infantile spasms, a careful diagnostic evaluation can lead to diagnosis in many patients and may guide treatment choices. Magnetic resonance imaging (MRI) brain remains the highest yield initial study in determining the etiology in infantile spasms. Treatment of infantile spasms has little class I data, but adrenocorticotropic hormone (ACTH), prednisolone and vigabatrin have the best evidence as first-line medications. Other therapies including the ketogenic diet and other anti-epileptics medications may also prove useful in the treatment of infantile spasms. In general, more studies are needed to determine the best treatment regimen for this condition. Prognosis is generally poor, with the majority of patients having some or profound neurocognitive delays. Patients without delays at diagnosis and without an identifiable etiology, if treated appropriately, have the greatest likelihood of a normal outcome.

Epileptic encephalopathies in adults and childhood

Epileptic encephalopathies are motor-mental retardations or cognitive disorders secondary to epileptic seizures or epileptiform activities. Encephalopaties due to brain damage, medications, or systemic diseases are generally not in the scope of this definition, but they may rarely accompany the condition. Appropriate differential diagnosis of epileptic seizures as well as subclinical electroencephalographic discharges are crucial for management of seizures and epileptiform discharges and relative regression of cognitive deterioration in long-term followup. Proper antiepileptic drug, hormonal treatment, or i.v. immunoglobulin choice play major role in prognosis. In this paper, we evaluated the current treatment approaches by reviewing clinical electrophysiological characteristics of epileptic encephalopathies.

A comparison of antiepileptic drug therapy in patients with severe intellectual disability and patients with normal intellect

We describe and compare the antiepileptic drug (AED) management in patients with severe intellectual disability (ID) and those with normal intellect (NI) and focal epilepsy at a tertiary epilepsy center. Fifty patients with ID were compared to a control group of 50 patients with NI; the majority of the patients in both groups had medically refractory epilepsy. Patients with ID were currently taking and had been previously exposed to a greater number of different AEDs. Despite the fact that both groups of patients had beene qually exposed to both old and newer AEDs, patients with ID were more likely to be taking at least one old AED and were more commonly treated with benzodiazepines (clobazam was the most commonly used drug in this group). This difference is likely related to greater seizure frequency and co-morbid behavioral disturbance in the ID group as no bias was identified against utilization of the newer AEDs in patients with ID.

Coexisting seizures in patients with infantile spasms confirmed by long-term video-electroencephalography monitoring

PURPOSE

We performed this study to evaluate the frequency, types, and ictal electroencephalography (EEG) findings of coexisting seizures in patients with infantile spasms at the onset of spasms. We also evaluated the effect of coexisting seizures on short-term seizure control.

METHODS

We retrospectively reviewed the long-term video-EEG and electronic medical records of 109 patients (58 boys and 51 girls) diagnosed with infantile spasms at the Seoul National University Children's Hospital. Coexisting seizure types were classified according to the International League Against Epilepsy seizure and epilepsy classification. Ictal EEG findings were also reviewed. Short-term seizure control rates were compared between groups with or without coexisting seizures.

RESULTS

We identified 27 coexisting seizures in 24 of the 109 patients (22%). The most common type of seizure was generalized tonic seizure followed by myoclonic, focal tonic, tonic-clonic, hypokinetic, and versive seizures. Rates of preterm birth and birth asphyxia were significantly higher in patients with coexisting seizures. Initial anticonvulsant was vigabatrin (103 patients), valproic acid (five patients), and topiramate (one patient). There was no significant difference in short-term seizure freedom (overall seizure-free rates in patients without coexisting seizures vs. those with: 29.2% vs. 11.1% at 2 months, 36.1% vs. 22.2% at 4 months, and 41.7% vs. 27.8% at 6 months). Seizure freedom was significantly lower in the symptomatic groups compared with non-symptomatic groups.

CONCLUSIONS

Long-term video-EEG monitoring is required as an initial evaluation in patients with infantile spasms, especially when there are reports of coexisting seizures, or a history of preterm birth or birth asphyxia. Presence of coexisting seizures was not related to poor seizure control in the short-term treatment period.

"Electro-clinical syndromes" with onset in paediatric age: the highlights of the clinical-EEG, genetic and therapeutic advances

The genetic causes underlying epilepsy remain largely unknown, and the impact of available genetic data on the nosology of epilepsy is still limited. Thus, at present, classification of epileptic disorders should be mainly based on electroclinical features. Electro-clinical syndrome is a term used to identify a group of clinical entities showing a cluster of electro-clinical characteristics, with signs and symptoms that together define a distinctive, recognizable, clinical disorder. These often become the focus of treatment trials as well as of genetic, neuropsychological, and neuroimaging investigations. They are distinctive disorders identifiable on the basis of a typical age onset, specific EEG characteristics, seizure types, and often other features which, when taken together, permit a specific diagnosis which, in turn, often has implications for treatment, management, and prognosis. Each electro-clinical syndrome can be classified according to age at onset, cognitive and developmental antecedents and consequences, motor and sensory examinations, EEG features, provoking or triggering factors, and patterns of seizure occurrence with respect to sleep. Therefore, according to the age at onset, here we review the more frequently observed paediatric electro-clinical syndrome from their clinical-EEG, genetic and therapeutic point of views.

"Epileptic encephalopathy" of infancy and childhood: electro-clinical pictures and recent understandings

There is growing interest in the diagnosis of cognitive impairment among children with epilepsy. It is well known that status of seizures control has to be carefully investigated because it can be sufficient "per se" to cause progressive mental deterioration conditions. Subclinical electroencephalographic discharges may have subtle effects on cognition, learning and sleep patterns, even in the absence of clinical or sub-clinical seizures. In this respect, electroencephalographic monitoring (long-term and nocturnal recording) and in particular an all night video-polysomnography (V-NPSG) record can be crucial to detect the presence of unrecognized seizures and/or an inter-ictal nocturnal EEG discharge increasing. Epileptic encephalopathies (EE) are a group of conditions in which the higher cognitive functions are deteriorate as a consequence of epileptic activity, which, in fact, consists of frequent seizures and/or florid and prolonged interictal paroxysmal discharges, focal or generalized. AEDs represent the first line in opposing the burden of both, the poor seizures control and the poor interictal discharges control, in the cognitive deterioration of EE affected children. Thus, to improve the long-term cognitive/behavioural prognosis in these refractory epileptic children, it should be taken into account both a good seizures control and a strict sleep control, choosing carefully antiepileptic drugs which are able to control not only seizures clinically recognizable but even the EEG discharges onset and its increasing and spreading during sleep. Here, we review the efficacy and safety of the newer AEDs that, to date, are used in the treatment of EE in infancy and childhood.

The safety and tolerability of newer antiepileptic drugs in children and adolescents

The newer antiepileptic drugs (AEDs) provide more therapeutic options and overall improved safety and tolerability for patients. To provide the best care, physicians must be familiar with the latest tolerability and safety data. This is particularly true in children, given there are relatively fewer studies examining the effects of AEDs in children compared with adults. Since we now have significant paediatric literature on each of these agents, we provide a comprehensive and current literature review of the newer AEDs, focusing on safety and tolerability data in children and adolescents. Because the safety profiles in children differ from those in adults, familiarity with this literature is important for child neurologists and other paediatric caregivers. We have organized the data by organ system for each AED for easier reference.

Current trends in the treatment of infantile spasms

Infantile spasms are an epilepsy syndrome with distinctive features, including age onset during infancy, characteristic epileptic spasms, and specific electroencephalographic patterns (interictal hypsarrhythmia and ictal voltage suppression). Adrenocorticotropic hormone (ACTH) was first employed to treat infantile spasms in 1958, and since then it has been tried in prospective and retrospective studies for infantile spasms. Oral corticosteroids were also used in a few studies for infantile spasms. Variable success in cessation of infantile spasms and normalization of electroencephalograms was demonstrated. However, frequent significant adverse effects are associated with ACTH and oral corticosteroids. Vigabatrin has been used since the 1990s, and shown to be successful in resolution of infantile spasms, especially for infantile spasms associated with tuberous sclerosis. It is associated with visual field constriction, which is often asymptomatic and requires perimetric visual field study to identify. When ACTH, oral corticosteroids, and vigabatrin fail to induce cessation of infantile spasms, other alternative treatments include valproic acid, nitrazepam, pyridoxine, topiramate, zonisamide, lamotrigine, levetiracetam, felbamate, ganaxolone, liposteroid, thyrotropin-releasing hormone, intravenous immunoglobulin and a ketogenic diet. Rarely, infantile spasms in association with biotinidase deficiency, phenylketonuria, and pyridoxine-dependent seizures are successfully treated with biotin, a low phenylalanine diet, and pyridoxine, respectively. For medically intractable infantile spasms, some properly selected patients may have complete cessation of infantile spasms with appropriate surgical treatments.

[Treatment of West syndrome with vigabatrin: clinical and electroencephalographic evaluation of 13 patients]

We evaluated the efficacy of vigabatrin (VGB) as a first drug to be used as monotherapy for West syndrome (WS), its side effects and correlations with the electroencephalogram (EEG). The sample consisted of 13 infants examined between October 2001 and September 2002 at IMIP ambulatory patients office or private clinic. Administration of vigabatrin was around 118 mg/kg/day. Suppression of spasms was obtained in 4 children (31%), partial control in 3 (23%), 5 of them did not present therapeutic response (38%) and just one (8%) got worse. On the two patients with tuberous sclerosis, one was seizure-free and in another there was partial control. Side effects happened in 8 children (62%) and consisted of irritability, insomnia, somnolence and agitation, and all of them have been well tolerated. The second EEG showed disappearance of hipsarrhythmia in 6 patients (46%). Four of these were seizure-free. We conclude that VGB is effective and well tolerated as initial monotherapy for WS.

Topiramate monotherapy in infantile spasm

Infantile spasm is an age-related refractory epilepsy. Topiramate is a new anticonvulsant with multiple mechanisms of action, and it may be effective for treating pediatric epilepsies. To evaluate the efficacy and tolerability of first-line topiramate treatment for infantile spasm, 20 patients received topiramate monotherapy during this study. They were treated with an initial dose of 1mg/kg/day, with a progressive titration of 1 mg/kg a week until their spasms were controlled and a maximum dose of 12 mg/kg/day was achieved. The evaluation of the treatment efficacy was based on the spasm frequency data that was obtained by the scalp and video-EEG, and by the parental count of spasm. Thirty percent of the subjects became spasm-free during the study. Six of 20 subjects (30%) had cessation of spasm and disappearance of hypsarrhythmia as seen via the video EEG; four (50%) of eight idiopathic patients had a response, whereas two (17%) of 12 patients with symptomatic infantile spasm responded. Seventy of the patients, including the spasm-free patients, had a reduction in their seizure frequency of more than 50%, and 10% of the patients had a reduction in their seizure frequency of less than 50%. The clusters of spasm frequency decreased from 10.6 +/- 8.5 to 3.5 +/- 1.4 clusters/day. Topiramate is effective and tolerated in those patients suffering from infantile spasm. Our results suggest that this drug should be considered as a new first-line drug for treating infantile spasm.

Practice parameter: medical treatment of infantile spasms: report of the American Academy of Neurology and the Child Neurology Society

OBJECTIVE

To determine the current best practice for treatment of infantile spasms in children.

METHODS

Database searches of MEDLINE from 1966 and EMBASE from 1980 and searches of reference lists of retrieved articles were performed. Inclusion criteria were the documented presence of infantile spasms and hypsarrhythmia. Outcome measures included complete cessation of spasms, resolution of hypsarrhythmia, relapse rate, developmental outcome, and presence or absence of epilepsy or an epileptiform EEG. One hundred fifty-nine articles were selected for detailed review. Recommendations were based on a four-tiered classification scheme.

RESULTS

Adrenocorticotropic hormone (ACTH) is probably effective for the short-term treatment of infantile spasms, but there is insufficient evidence to recommend the optimum dosage and duration of treatment. There is insufficient evidence to determine whether oral corticosteroids are effective. Vigabatrin is possibly effective for the short-term treatment of infantile spasm and is possibly also effective for children with tuberous sclerosis. Concerns about retinal toxicity suggest that serial ophthalmologic screening is required in patients on vigabatrin; however, the data are insufficient to make recommendations regarding the frequency or type of screening. There is insufficient evidence to recommend any other treatment of infantile spasms. There is insufficient evidence to conclude that successful treatment of infantile spasms improves the long-term prognosis.

CONCLUSIONS

ACTH is probably an effective agent in the short-term treatment of infantile spasms. Vigabatrin is possibly effective.

Vigabatrin, but not gabapentin or topiramate, produces concentration-related effects on enzymes and intermediates of the GABA shunt in rat brain and retina

PURPOSE

The antiepileptic drug (AED) vigabatrin (VGB), which exerts its pharmacologic effects on the gamma-aminobutyric acid (GABA) system, causes concentric visual field constriction in >40% of exposed adults. This may be a class effect of all agents with GABA-related mechanisms of action. We compared the concentration-related effects of VGB in rat brain and eye with those of gabapentin (GBP) and topiramate (TPM), both of which have been reported to elevate brain GABA concentrations in humans.

METHODS

Adult male rats (n = 10) were administered 0.9% saline (control), VGB (250, 500, 1,000 mg/kg), GBP (50, 100, 200 mg/kg), or TPM (12.5, 25, 50, 100 mg/kg). At 2 h after dosing, animals were killed, a blood sample obtained, the brain dissected into eight distinct regions, and the retina and vitreous humor isolated from each eye. Samples were analyzed for several GABA-related neurochemical parameters, and serum and tissue drug concentrations determined.

RESULTS

VGB treatment produced a significant (p < 0.05) dose-related increase in GABA concentrations and decrease in GABA-transaminase activity in all tissues investigated. This effect was most pronounced in the retina, where VGB concentrations were 18.5-fold higher than those in brain. In contrast, GBP and TPM were without effect on any of the neurochemical parameters investigated and did not accumulate appreciably in the retina.

CONCLUSIONS

These findings corroborate a previously reported accumulation of VGB in the retina, which may be responsible for the visual field constriction observed clinically. This phenomenon does not appear to extend to other GABAergic drugs, suggesting that these agents might not cause visual field defects.

Infantile spasms in Down syndrome--effects of delayed anticonvulsive treatment

To investigate the impact of treatment lag in infantile spasms (IS) on treatment response, occurrence of later epilepsy, and long-term cognition and behavior in patients with one single etiological entity, we examined 18 patients with Down syndrome (DS) and earlier IS retrospectively (follow-up period of 32-180 months with a mean of 85.1 months), and determined their history and present condition, in terms of previously mentioned items. There was a statistically significant correlation between treatment lag and lag to cessation of spasms (R=0.55, P=0.02), developmental quotient (DQ) (R=-0.75, P=0.003), and score of autistic features (AF) (R=0.57, P=0.04). Moreover we found that the later the response to treatment of IS, the lower was the DQ (R=-0.86, P=0.001) and the higher was the score of autistic features (R=0.5, P=0.06). A long duration of spasms also determined a low DQ (R=-0.93, P<0.0001) and a high score of autistic features (R=0.66, P<0.01). All patients with persistent epilepsy (n=5) had had a treatment lag of over 2 months. Conversely, for all children treated within 2 months (n=8) spasms ceased within 3 months of treatment and none of them had later epilepsy. This group of patients with a treatment lag of less than 2 months had earlier treatment response (P=0.002), higher DQ (P=0.004) and lower score of autistic features (P=0.006). The data stress the importance of a short treatment lag in view of mental development and prevention of later epilepsy and autistic features, and raise the question of antiepileptogenic effect in this specific condition.

Treatment of infantile spasms: an evidence-based approach

The object of this work was to subject established empirical medical treatment regimens for infantile spasms to evidence-based medicine analysis in order to determine the current best practice for the treatment of infantile spasms in children. Clinical studies of infantile spasms reported during the presteroid era were reviewed critically to define the natural history of the disorder. Treatment trials of infantile spasms conducted since 1958 were rigorously assessed using MEDLINE and hand searches of the English language literature. Inclusion criteria were the documented presence of infantile spasms and hypsarrhythmia. Outcome measures included complete cessation of spasms, resolution of hypsarrhythmia, relapse rate, developmental outcome, the presence or absence of epilepsy, and/or an epileptiform electroencephalogram. Evidence was defined as class I, II, or III, and practice parameter recommendations were made using the framework devised by the American Academy of Neurology. Class I and III evidence support a standard of practice recommendation for the use of vigabatrin in the treatment of infantile spasms in children with tuberous sclerosis. Class I and III evidence support a guidelines recommendation for the use of either ACTH or vigabatrin in infantile spasms in nontuberous sclerosis patients. There is no strong evidence that successful treatment of infantile spasms improves the long-term prognosis for cognitive outcome or decreases the incidence of later epilepsy. A practice option recommendation for the use of oral corticosteroids in the treatment of infantile spasms is supported by limited and inconclusive class I and III data. Based on the evidence, no recommendation can be made for the use of pyridoxine, benzodiazepines, or the newer antiepileptic drugs in the treatment of infantile spasms. ACTH and vigabatrin are the most effective agents in the treatment of infantile spasms, but concerns remain about the risk/benefit profiles of these drugs.

Add-on treatment with pyridoxine and sulthiame in 12 infants with West syndrome: an open clinical study

To investigate the effect of sulthiame (STM) in West syndrome (WS) an open, uncontrolled add-on study was undertaken during initial pyridoxine (PDX) therapy in 12 infants, two with idiopathic and ten with symptomatic WS. All patients were initially treated with PDX (150-300 mg x kg (-1)body weight day(-1) ). In seven patients (58%) seizures and hypsarrhythmia stopped during the week after introduction of STM (10 mg x kg (-1)body weight day (-1)). In one the positive effect was temporary. Five of the responders (42%) remained seizure-free and without hypsarrhythmia under STM monotherapy, while one developed complex partial seizures after 25 months. STM was most effective in idiopathic WS (2 /2). During treatment with STM medication no patient suffered side effects attributable to the substance. Further controlled studies are necessary to evaluate the benefit of this potentially effective treatment.

Vigabatrin for infantile spasms

We reviewed 20 infants receiving vigabatrin for infantile spasms. Patients were not enrolled in a formal study. All families obtained the medication abroad. Age at initiation of vigabatrin ranged from 1 to 48 months; nine infants had received prior treatment with various antiepileptic medications. Patients were begun on the lowest practical dose of 125-250 mg/day, with gradual daily increments to a target of 100 mg/kg/day, but maintained at the lowest effective dosage. Video electroencephalogram was obtained to document resolution of spasms and hypsarrhythmia. Of 20 infants, 12 responded with cessation of spasms and resolution of hypsarrhythmia, at doses of 25-135 mg/kg/day (median = 58 mg/kg/day). Partial responses were observed in six patients, whereas two had no response at 111 and 125 mg/kg/day. Additional new seizure types developed in three infants after initial response to vigabatrin. Increasing the vigabatrin did not have any clinical benefit. Vigabatrin is an effective, well-tolerated treatment for infantile spasms. The response is dose-independent, suggesting that starting at a low dose and gradually increasing, rather than beginning with an arbitrary 100 mg/kg/day dose is advantageous.

Is refractory epilepsy preventable?

About a third of the patients diagnosed with epilepsy will not be fully controlled with antiepileptic drugs (AEDs), and many of them will have frequent and disabling seizures. These patients will undergo multiple drug trials, most often without complete seizure remission. Moreover, refractory epilepsy is associated with increased morbidity (from seizures and medications), social isolation, unemployment, and overall reduced quality of life. There is evidence that refractory epilepsy can be a progressive disorder, which, if controlled early, might never develop into a full syndrome with all of its associated sequelae. The difficulty lies in identifying at an early stage patients who are likely to progress to intractability. No currently known markers enable clinicians to make this identification with confidence. Advances in pharmacogenomics and our understanding of pharmacologic responsiveness in epilepsy may change this situation. Even now, we are able to identify many patients with a poor prognosis earlier than before, particularly in the pediatric population, in which syndromic classification may provide an approach to predict intractability. The early initiation of aggressive therapy may improve outcome and overall quality of life.

Treating epilepsy in the elderly: safety considerations

The incidence of epilepsy increases with advancing age. Epilepsy in the elderly has different aetiologies from that in younger populations, cerebrovascular disease being the most common condition associated with seizures. Partial seizures are the predominant seizure type in older patients. A diagnosis of epilepsy in the elderly is based mainly on the history and is frequently delayed. In addition, seizure imitators are especially frequent. In many cases ancillary tests for diagnosis may show normal age-related variants, sometimes making results difficult to interpret. Treating epilepsy in the elderly is problematic due to a number of issues that relate to age and comorbidity. The physical changes associated with increasing age frequently lead to changes in the pharmacokinetics of many anticonvulsants. The treatment of epilepsy in the elderly is also complicated by the existence of other diseases that might affect the metabolism or excretion of anticonvulsants and the presence of concomitant medications that might interact with them. Moreover, specific trials of anticonvulsants in the aged population are scarce. General guidelines for treatment include starting at lower doses, slowing the titration schedule, individualising the choice of anticonvulsant to the characteristics of the patient, avoiding anticonvulsants with important cognitive or sedative adverse effects, and where possible, treating with monotherapy.

Surgical treatment of West syndrome

The discovery of focal or multifocal cortical lesions using magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning in the majority of infants with West syndrome has led to a surgical approach in the treatment of some patients with intractable infantile spasms. The locations of these lesions should be concordant with localization of focal ictal and/or interictal electroencephalographic (EEG) abnormalities prior to proceeding with cortical resection. When a single lesion is present on the MRI or PET, and there is good correlation with EEG localization, surgical treatment is generally quite favorable in terms of both seizure control and cognitive development. Interictal glucose metabolism PET scans in children with intractable cryptogenic infantile spasms show unifocal cortical hypometabolism in about 20% of cases. In the majority, however, multifocal asymmetric hypometabolism is suggestive of multifocal underlying lesions, possibly multifocal cortical dysplasia. When the pattern of glucose hypometabolism is symmetric, a lesional etiology is less likely, thus neurometabolic or neurogenetic disorders should be considered. Therefore, the pattern of glucose hypometabolism on PET in infants with intractable cryptogenic spasms is a useful guide to decide whether a medical or surgical approach should be undertaken. In order to achieve the best cognitive outcome with surgery, it is important to resect the entire 'nociferous' area rather than just the seizure focus. Our research with new PET imaging probes has attempted to provide a comprehensive evaluation of the epileptogenic zone including the 'nociferous' cortex. We have used [(11)C]flumazenil (FMZ), which labels gamma aminobutyric acid(A) (GABA(A)) receptors, and have found this to be particularly useful in showing: (i) decreased receptor binding with medial temporal involvement thus indicating resection of medial temporal structures, (ii) the peri-lesional epileptogenic zone surrounding MRI lesions, (iii) the seizure onset zone in MRI-negative cases, and (iv) potential secondary epileptic foci. Another recently developed PET probe, alpha[(11)C]methyl-L-tryptophan (AMT) which is a precursor for the serotonin and the kynurenine metabolism pathways, is capable of differentiating between epileptogenic and non-epileptogenic tubers in patients with tuberous sclerosis complex and intractable epilepsy (including infantile spasms). Subsequently, we have applied AMT PET in patients with multifocal cortical dysplasia to determine the predominant seizure focus, and the results have been promising with regard to seizure control but not cognitive development. Thus, the introduction of newer more specific PET probes for epilepsy has led to improved and more accurate localization of seizure foci that should ultimately improve outcome of epilepsy surgery in West syndrome.

West syndrome--The University of Hong Kong experience (1970-2000)

OBJECTIVE

To study the clinical pattern of West syndrome (WS) in a university based hospital.

METHODOLOGY

The database of children seen in the Epilepsy Clinic of Queen Mary Hospital and Duchess of Kent Children's Hospital during a 30-year period (1970-2000) was reviewed.

RESULTS

A total of 105 cases had WS (1.9%). The number of new cases of WS admitted per year ranged from one to eight. The range of annual incidence of WS to newly diagnosed epilepsy was 0.8-4.8%. The etiology included idiopathic (N=19, 18%), cryptogenic (N=23; 22%), symptomatic (N=56; 53.3%) and unknown (N=7; 5.7%). Adrenocorticotropic hormone (ACTH) and/or prednisone were given to 42 children (40%). Most were effective in controlling WS on an all-or-none fashion. Seizure outcome included 12 with remission, persistent in the same form in two and persisting but changed to another form in the rest. Neurological outcome at the last follow up in 2000 December included multiple disabilities (N=16), cerebral palsy (N=22), mental retardation (N=94) and Lennox-Gastaut syndrome (N=13). We analysed the following risk factors in relation to poor outcome: age of onset, age of presentation, time lag before treatment, etiology, family history of epilepsy and hormonal treatment. Only etiology of WS has a positive correlation with poor outcome (P<0.0005).

CONCLUSIONS

WS is an uncommon epileptic syndrome. The majority had poor outcome, especially those with causes identified. Infantile spasm is a specific epileptic phenomenon in a maturational stage of a child when heterogeneous disorders can present with the same clinical epileptic and electroencephalographic phenomenon.

Topiramate in the catastrophic epilepsies of childhood

Several epileptic syndromes that occur during childhood are characterized by severe treatment-resistant seizures, progressive loss of higher intellectual functions, and characteristic electroencephalographic abnormalities. These catastrophic epileptic syndromes include epileptic encephalopathy with diffuse slow spike waves (Lennox-Gastaut syndrome), West syndrome, progressive myoclonic epilepsies, and electrical status epilepticus during sleep. This article summarizes each syndrome and reviews the most recent information concerning the effectiveness of topiramate with respect to each condition. Suggestions are offered to help clinicians maximize topiramate's efficacy and tolerability in patients suffering with these syndromes. Overall, topiramate is a valuable antiepileptic medication in the treatment of catastrophic pediatric epileptic syndromes.