Definition of refractory epilepsy: defining the indefinable?

The yield of long-term electrocardiographic recordings in refractory focal epilepsy

OBJECTIVE

To determine the incidence of clinically relevant arrhythmias in refractory focal epilepsy and to assess the potential of postictal arrhythmias as risk markers for sudden unexpected death in epilepsy (SUDEP).

METHODS

We recruited people with refractory focal epilepsy without signs of ictal asystole and who had at least one focal seizure per month and implanted a loop recorder with 2-year follow-up. The devices automatically record arrhythmias. Subjects and caregivers were instructed to make additional peri-ictal recordings. Clinically relevant arrhythmias were defined as asystole ≥ 6 seconds; atrial fibrillation < 55 beats per minute (bpm), or > 200 bpm and duration > 30 seconds; persistent sinus bradycardia < 40 bpm while awake; and second- or third-degree atrioventricular block and ventricular tachycardia/fibrillation. We performed 12-lead electrocardiography (ECG) and tilt table testing to identify non-seizure-related causes of asystole.

RESULTS

We included 49 people and accumulated 1060 months of monitoring. A total of 16 474 seizures were reported, of which 4679 were captured on ECG. No clinically relevant arrhythmias were identified. Three people had a total of 18 short-lasting (<6 seconds) periods of asystole, resulting in an incidence of 2.91 events per 1000 patient-months. None of these coincided with a reported seizure; one was explained by micturition syncope. Other non-clinically relevant arrhythmias included paroxysmal atrial fibrillation (n = 2), supraventricular tachycardia (n = 1), and sinus tachycardia with a right bundle branch block configuration (n = 1).

SIGNIFICANCE

We found no clinically relevant arrhythmias in people with refractory focal epilepsy during long-term follow-up. The absence of postictal arrhythmias does not support the use of loop recorders in people at high SUDEP risk.

Cytosolic phospholipase A2 is a key regulator of blood-brain barrier function in epilepsy

Blood-brain barrier dysfunction in epilepsy contributes to seizures and resistance to antiseizure drugs. Reports show that seizures increase brain glutamate levels, leading to barrier dysfunction. One component of barrier dysfunction is overexpression of the drug efflux transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Based on our previous studies, we hypothesized that glutamate released during seizures activates cytosolic phospholipase A2 (cPLA2), resulting in P-gp and BCRP overexpression. We exposed isolated rat brain capillaries to glutamate ex vivo and used an in vivo-ex vivo approach of isolating brain capillaries from rats after status epilepticus (SE) and in chronic epileptic (CE) rats. Glutamate increased cPLA2, P-gp, and BCRP protein and activity levels in isolated brain capillaries. We confirmed the role of cPLA2 in the signaling pathway in brain capillaries from male and female mice lacking cPLA2. We also demonstrated, in vivo, that cPLA2 inhibition prevents overexpression of P-gp and BCRP at the blood-brain barrier in rats after status epilepticus and in CE rats. Our data support the hypothesis that glutamate signals cPLA2 activation, resulting in overexpression of blood-brain barrier P-gp and BCRP.-Hartz, A. M. S., Rempe, R. G., Soldner, E. L. B., Pekcec, A., Schlichtiger, J., Kryscio, R., Bauer, B. Cytosolic phospholipase A2 is a key regulator of blood-brain barrier function in epilepsy.

Do neurologists agree in diagnosing drug resistance in adults with focal epilepsy?

OBJECTIVE

To evaluate interrater agreement in categorizing treatment outcomes and drug responsiveness status according to the International League Against Epilepsy (ILAE) definition of drug-resistant epilepsy.

METHODS

A total of 1053 adults with focal epilepsy considered by the investigators to meet ILAE criteria for drug resistance were enrolled consecutively at 43 centers and followed up prospectively for 18-34 months. Treatment outcomes for all antiepileptic drugs (AEDs) used up to enrollment (retrospective assessment), and on an AED newly introduced at enrollment, were categorized by individual investigators and by 2 rotating members of a 16-member expert panel (EP) that reviewed the patient records independently. Interrater agreement was tested by Cohen's kappa (k) statistics and rated according to Landis and Koch's criteria.

RESULTS

Agreement between EP members in categorizing outcomes on the newly introduced AED was almost perfect (90.1%, k = 0.84, 95% confidence interval [CI] 0.80-0.87), whereas agreement between the EP and individual investigators was moderate (70.4%, k = 0.57, 95% CI 0.53-0.61). Similarly, categorization of outcomes on previously used AEDs was almost perfect between EP members (91.7%, k = 0.83, 95% CI 0.81-0.84) and moderate between the EP and investigators (68.2%, k = 0.50, 95% CI 0.48-0.52). Disagreement was related predominantly to outcomes considered to be treatment failures by the investigators but categorized as undetermined by the EP. Overall, 19% of patients classified as having drug-resistant epilepsy by the investigators were considered by the EP to have "undefined responsiveness."

SIGNIFICANCE

Interrater agreement in categorizing treatment outcomes according to ILAE criteria ranges from moderate to almost perfect. Nearly 1 in 5 patients considered by enrolling neurologists to be "drug-resistant" were classified by the EP as having "undefined responsiveness."

Prediction error connectivity: A new method for EEG state analysis

Several models have been proposed to explain brain regional and interregional communication, the majority of them using methods that tap the frequency domain, like spectral coherence. Considering brain interareal communication as binary interactions, we describe a novel method devised to predict dynamics and thus highlight abrupt changes marked by unpredictability. Based on a variable-order Markov model algorithm developed in-house for data compression, the prediction error connectivity (PEC) estimates network transitions by calculating error matrices (EMs). We analysed 20 h of EEG signals of virtual networks generated with a neural mass model. Subnetworks changed through time (2 of 5 signals), from normal to normal or pathological states. PEC was superior to spectral coherence in detecting all considered transitions, especially in broad and ripple bands. Subsequently, EMs of real data were classified using a support vector machine in order to capture the transition from interictal to preictal state and calculate seizure risk. A single seizure was randomly selected for training. Through this approach it was possible to establish a threshold that the calculated risk consistently overcame minutes before the events. Using either spectral coherence or PEC we created 1000 models that successfully predicted 6 seizures (100% sensibility), a whole cluster recorded in a patient with hippocampal epilepsy. However, PEC resulted superior to coherence in terms of true seizure free time and amount of false warnings. Indeed, the best PEC model predicted 96% of interictal time (vs. 83% of coherence) of about 20 h of stereo-EEG. This analysis was extended to patients with neo/mesocortical temporal, neocortical frontal, parietal and occipital lobe epilepsy. Again PEC showed high performance, allowing the prediction of 31 events distributed across 10 days with ROC AUCs that reached 98% (average 93 ± 5%) in 6 different patients. Moreover, considering another state transition, PEC could classify and forecast up to 88% (average 85 ± 3%) of the REM phase both in deep and scalp EEG. In conclusion, PEC is a novel approach that relies on pattern analysis in the time-domain. We believe that this method can be successfully employed both for the study of brain connectivity, and also implemented in real-life solutions for seizure detection and prediction.

Estimating unmeasured invasive EEG signals using a reduced-order observer

Epilepsy affects around 50 million people worldwide. Over 30% of patients are drug-resistant where the only treatment may be surgical resection of the epileptogenic zone (EZ), the region of the brain that generates seizures. Identification of the EZ is often based on invasive EEG recordings. As such, surgical outcome relies heavily on precise and dense placement of EEG electrodes into the brain. Despite large brain regions being removed, success rates barely reach 65%. This gives rise to the "missing electrode problem", where clinicians want to know what neural activity looks like between sparsely implanted electrodes. Solving this problem will enable more accurate localization of the EZ. In this paper, we demonstrate the first steps towards developing a computational platform to estimate neural activity at the "missing electrodes" using a reduced-order observer from control theory. Specifically, we constructed a sequence of discrete time Linear Time-Invariant (LTI) models using the available EEG data from two epilepsy patients. Then, we used the models to simulate EEG data and remove selected signals ("missing" states) from the simulated data set. Finally, we used a reduced-order observer to estimate the signals of these "missing" states and evaluated performance by comparing the observer estimates to the simulated EEG time series.

Matrix Metalloproteinase-Mediated Blood-Brain Barrier Dysfunction in Epilepsy

The blood-brain barrier is dysfunctional in epilepsy, thereby contributing to seizure genesis and resistance to antiseizure drugs. Previously, several groups reported that seizures increase brain glutamate levels, which leads to barrier dysfunction. One critical component of barrier dysfunction is brain capillary leakage. Based on our preliminary data, we hypothesized that glutamate released during seizures mediates an increase in matrix-metalloproteinase (MMP) expression and activity levels, thereby contributing to barrier leakage. To test this hypothesis, we exposed isolated brain capillaries from male Sprague Dawley rats to glutamate ex vivo and used an in vivo/ex vivo approach of isolated brain capillaries from female Wistar rats that experienced status epilepticus as an acute seizure model. We found that exposing isolated rat brain capillaries to glutamate increased MMP-2 and MMP-9 protein and activity levels, and decreased tight junction protein levels, which resulted in barrier leakage. We confirmed these findings in vivo in rats after status epilepticus and in brain capillaries from male mice lacking cytosolic phospholipase A₂ Together, our data support the hypothesis that glutamate released during seizures signals an increase in MMP-2 and MMP-9 protein expression and activity levels, resulting in blood-brain barrier leakage.SIGNIFICANCE STATEMENT The mechanism leading to seizure-mediated blood-brain barrier dysfunction in epilepsy is poorly understood. In the present study, we focused on defining this mechanism in the brain capillary endothelium. We demonstrate that seizures trigger a pathway that involves glutamate signaling through cytosolic phospholipase A₂, which increases MMP levels and decreases tight junction protein expression levels, resulting in barrier leakage. These findings may provide potential therapeutic avenues within the blood-brain barrier to limit barrier dysfunction in epilepsy and decrease seizure burden.

Long-term outcome after epilepsy surgery in older adults

PURPOSE

The incidence of epilepsy in older adults is growing, as does the incidence of comorbidities. Therefore, when it comes to epilepsy surgery in medically intractable epilepsy, age is often seen as a limiting factor. To investigate the outcome after epilepsy surgery in a population of older adults, we compared the benefit for patients aged 50-59 years with those aged 60 years and older in respect of efficacy and safety.

METHOD

Patients aged ≥50 years with medically intractable epilepsy who underwent epilepsy surgery from 1990 to 2013 were selected from the database of a German epilepsy center. All of them received a standardised and detailed presurgical diagnostic evaluation. Follow-up included at least four scheduled visits with EEG, MRI and neuropsychological testing. Outcome was assessed using the Engel outcome scale.

RESULTS

79 patients aged between 50 and 67 years were followed-up for a median of 4.7 years (2-16 years). 68% of patients were free of disabling seizures (Engel class I, ≥60 years: 75%) and 58% were seizure-free (Engel class IA, ≥60 years: 70%). 90% of our patients suffered from temporal lobe epilepsy (TLE), 9% from frontal lobe epilepsy (FLE) and one occipital lobe epilepsy (OLE). After surgery, 9% discontinued or tapered their medication. Permanent surgical complications occurred in 10% of cases and transient neurological deficits were seen in 11%. Older patients had a higher risk for postoperative hygroma (≥60 years 15%; <60 years 8%) and were more prone to postoperative memory deficits (≥60 years 45%), especially after resection of the dominant temporal lobe. Verbal and figural memory testing did not differ significantly between the groups.

CONCLUSIONS

The results support the view that in selected older patients, epilepsy surgery shows equal or even higher success rates as compared to younger patients. However, patients of older age may be at greater risk for postoperative hygroma and memory deficits, especially after dominant temporal lobe resections.

Pharmacological Treatment of Drug-Resistant Epilepsy in Adults: a Practical Guide

More than 30 % of adults with epilepsy do not fully control on the currently available antiepileptic drugs (AEDs). For these and many other patients, combinations of agents, often possessing different mechanisms of actions, are employed with the aim of achieving seizure freedom or the best available prognosis in terms of reduced seizure numbers and severity. This review discusses my own approach to optimising outcomes in as many of these patients as possible by adjusting the drug burden using a combination of two, three or sometimes four or more AEDs. Modes of drug action are reviewed and practical strategies for treating different patients with drug-resistant epilepsy have been explored. Only for sodium valproate with lamotrigine is there good evidence of synergism. The final part of this practical paper consists of six individual illustrative cases with appropriate comments.

Drug-Level Monitoring on Admission for Presurgical Epilepsy Evaluation

OBJECTIVE

Evaluation for surgical treatment is offered to patients who do not respond to antiepileptic drugs. Pseudo-pharmacoresistance (PPR) has been described in the context of impaired compliance, incorrect diagnosis of epilepsy or pharmacological interference resulting in too low blood levels. We were interested to determine the frequency and causes of PPR in patients admitted for presurgical evaluation.

METHODS

We reviewed 553 drug levels in 199 patients and analyzed the relative frequency of drugs below reference range (10 and 20% below the range).

RESULTS

Patients who had at least one serum level below the 10% cut-off amounted to 33% and 9% of patients had at least one serum level below the 20% cut-off. Only in 2 patients (1%), this was due to poor compliance. Low levels were equally frequent in mono- or polytherapy. Drugs that were most frequently found out of range were phenytoin, valproate, and topiramate. In monotherapy, lamotrigine was often prescribed in too low dosages.

CONCLUSION

Low drug levels are frequently observed in surgical candidates due to pharmacological interference or insufficient dosing. Poor compliance or incorrect diagnosis does not appear to be a significant concern in this patient group. Our data strengthen the need for regular drug monitoring even in advanced chronic epilepsy to avoid unnecessary health costs by too low and ineffective dosages.

Deep brain and cortical stimulation for epilepsy

BACKGROUND

Despite optimal medical treatment, including epilepsy surgery, many epilepsy patients have uncontrolled seizures. Since the 1970s interest has grown in invasive intracranial neurostimulation as a treatment for these patients. Intracranial stimulation includes both deep brain stimulation (DBS) (stimulation through depth electrodes) and cortical stimulation (subdural electrodes). This is an updated version of a previous Cochrane review published in 2014.

OBJECTIVES

To assess the efficacy, safety and tolerability of DBS and cortical stimulation for refractory epilepsy based on randomized controlled trials (RCTs).

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialized Register on 29 September 2015, but it was not necessary to update this search, because records in the Specialized Register are included in CENTRAL. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 11, 5 November 2016), PubMed (5 November 2016), ClinicalTrials.gov (5 November 2016), the WHO International Clinical Trials Registry Platform ICTRP (5 November 2016) and reference lists of retrieved articles. We also contacted device manufacturers and other researchers in the field. No language restrictions were imposed.

SELECTION CRITERIA

RCTs comparing deep brain or cortical stimulation versus sham stimulation, resective surgery, further treatment with antiepileptic drugs or other neurostimulation treatments (including vagus nerve stimulation).

DATA COLLECTION AND ANALYSIS

Four review authors independently selected trials for inclusion. Two review authors independently extracted the relevant data and assessed trial quality and overall quality of evidence. The outcomes investigated were seizure freedom, responder rate, percentage seizure frequency reduction, adverse events, neuropsychological outcome and quality of life. If additional data were needed, the study investigators were contacted. Results were analysed and reported separately for different intracranial targets for reasons of clinical heterogeneity.

MAIN RESULTS

Twelve RCTs were identified, eleven of these compared one to three months of intracranial neurostimulation with sham stimulation. One trial was on anterior thalamic DBS (n = 109; 109 treatment periods); two trials on centromedian thalamic DBS (n = 20; 40 treatment periods), but only one of the trials (n = 7; 14 treatment periods) reported sufficient information for inclusion in the quantitative meta-analysis; three trials on cerebellar stimulation (n = 22; 39 treatment periods); three trials on hippocampal DBS (n = 15; 21 treatment periods); one trial on nucleus accumbens DBS (n = 4; 8 treatment periods); and one trial on responsive ictal onset zone stimulation (n = 191; 191 treatment periods). In addition, one small RCT (n = 6) compared six months of hippocampal DBS versus sham stimulation. Evidence of selective reporting was present in four trials and the possibility of a carryover effect complicating interpretation of the results could not be excluded in five cross-over trials without any or a sufficient washout period. Moderate-quality evidence could not demonstrate statistically or clinically significant changes in the proportion of patients who were seizure-free or experienced a 50% or greater reduction in seizure frequency (primary outcome measures) after one to three months of anterior thalamic DBS in (multi)focal epilepsy, responsive ictal onset zone stimulation in (multi)focal epilepsy patients and hippocampal DBS in (medial) temporal lobe epilepsy. However, a statistically significant reduction in seizure frequency was found for anterior thalamic DBS (mean difference (MD), -17.4% compared to sham stimulation; 95% confidence interval (CI) -31.2 to -1.0; high-quality evidence), responsive ictal onset zone stimulation (MD -24.9%; 95% CI -40.1 to -6.0; high-quality evidence) and hippocampal DBS (MD -28.1%; 95% CI -34.1 to -22.2; moderate-quality evidence). Both anterior thalamic DBS and responsive ictal onset zone stimulation do not have a clinically meaningful impact on quality life after three months of stimulation (high-quality evidence). Electrode implantation resulted in postoperative asymptomatic intracranial haemorrhage in 1.6% to 3.7% of the patients included in the two largest trials and 2.0% to 4.5% had postoperative soft tissue infections (9.4% to 12.7% after five years); no patient reported permanent symptomatic sequelae. Anterior thalamic DBS was associated with fewer epilepsy-associated injuries (7.4 versus 25.5%; P = 0.01) but higher rates of self-reported depression (14.8 versus 1.8%; P = 0.02) and subjective memory impairment (13.8 versus 1.8%; P = 0.03); there were no significant differences in formal neuropsychological testing results between the groups. Responsive ictal-onset zone stimulation seemed to be well-tolerated with few side effects.The limited number of patients preclude firm statements on safety and tolerability of hippocampal DBS. With regards to centromedian thalamic DBS, nucleus accumbens DBS and cerebellar stimulation, no statistically significant effects could be demonstrated but evidence is of only low to very low quality.

AUTHORS' CONCLUSIONS

Except for one very small RCT, only short-term RCTs on intracranial neurostimulation for epilepsy are available. Compared to sham stimulation, one to three months of anterior thalamic DBS ((multi)focal epilepsy), responsive ictal onset zone stimulation ((multi)focal epilepsy) and hippocampal DBS (temporal lobe epilepsy) moderately reduce seizure frequency in refractory epilepsy patients. Anterior thalamic DBS is associated with higher rates of self-reported depression and subjective memory impairment. There is insufficient evidence to make firm conclusive statements on the efficacy and safety of hippocampal DBS, centromedian thalamic DBS, nucleus accumbens DBS and cerebellar stimulation. There is a need for more, large and well-designed RCTs to validate and optimize the efficacy and safety of invasive intracranial neurostimulation treatments.

Refractory Lesional Parietal Lobe Epilepsy: Clinical, Electroencephalographic and Neurodiagnostic Findings

INTRODUCTION

Specialized centers, in the management and surgical treatment of medically refractory epilepsy, emphasize the importance of differentiating the varieties of localization related epilepsies. There has been considerable recent interest in temporal and frontal lobe epileptic syndromes and less attention has been paid to parietal and occipital lobe epilepsies.

METHODS

Here we report the clinical, electroencephalographic and neuroimaging characteristics of 46 patients with medically refractory lesional parietal lobe epilepsy who have been followed up for 1-10 years.

RESULTS

In this study auras were reported in 78.3% of the patients and included sensory symptoms (72.2%), headache (36.1%), nausea and vomiting (36.1%), psychic symptoms (36.1%) and visual symptoms (16.6%). The most common ictal behavioral changes were paresthesia (69.6%) and focal clonic activity (39.1%). Tonic posture, various automatisms, head deviation, staring, sensation of pain and speech disturbances occurred to a lesser extent. Simple partial seizures were present in 69.6%. Complex partial seizures occurred in 43.5% and secondary generalized tonic clonic seizures were reported in 58.7% of the patients. Interictal routine EEG disclosed abnormal background activity in 1/3 of the patients. Nonlocalising epileptiform abnormalities were found in 34.8% of the patients. EEG findings were normal in 34.8% of the patients. The most common presumed etiologic factors were as follows: posttraumatic encephalomalacia, stroke, tumor, malformation of cortical development, atrophy, and arteriovenous malformation.

CONCLUSION

Clinical, electrophysiological and neuroimaging features of the lesional symptomatic partial epilepsy patients may help us to localize the seizure focus in some patients with cryptogenic partial epilepsy. So that, the timing decision of the parietal lobe sampling with more invasive techniques like intracranial electrodes prior to epilepsy surgery would be easier.

Correlation between prescribed daily dose, seizure freedom and defined daily dose in antiepileptic drug treatment

Background Although defined daily doses (DDD) for antiepileptic drugs (AED) have been assigned only in combination therapy, based on the literature, most patients take them in monotherapy. Furthermore, discrepancies between DDD and prescribed daily dose (PDD) were observed. Objective First, to determine PDDs of AEDs and to reveal PDD/DDD ratio among seizure free versus not seizure free patients in everyday clinical practice. Second, to test the applicability of 75% cut-off of DDD to achieve seizure freedom. Furthermore, to find out what factors might influence PDD. Setting Outpatient data files at a Hungarian university hospital were studied. Methods A retrospective, 20-year cross-sectional database was compiled from 1282 epileptic outpatients' files. Main outcome measure Seizure freedom and PDD were used as outcome measures. Results The mean DDD% of all prescribed AEDs increased steadily from monotherapy, through bitherapy towards polytherapy (p < 0.0001). Most seizure free patients took AEDs in doses in the range of ≤75% of DDDs in monotherapy and bitherapy. Older AEDs (carbamazepine and valproate) were given in a significantly higher mean dose in bitherapy in the seizure free group. Among the newer types, only levetiracetam and lamotrigine had a significantly higher DDD% in mono-, bi-, and polytherapy. Confirmed by logistic regression analysis, gender, age, type of epilepsy, and number of AEDs had a significant impact on the value of 75% DDD. Conclusion No significant unfavourable impact of the lower ratio of PDD/DDD on the outcome of achieving seizure freedom has been confirmed. As a measure of seizure freedom, 75% of DDD may be used, although individual therapy must be emphasised. Precisely quantified DDD would provide a more accurate calculation of other derived values.

Anti-Epileptic Drug Combination Efficacy in an In Vitro Seizure Model - Phenytoin and Valproate, Lamotrigine and Valproate

In this study, we investigated the relative efficacy of different classes of commonly used anti-epileptic drugs (AEDs) with different mechanisms of action, individually and in combination, to suppress epileptiform discharges in an in vitro model. Extracellular field potential were recorded in 450 μm thick transverse hippocampal slices prepared from juvenile Wistar rats, in which “epileptiform discharges” (ED’s) were produced with a high-K⁺ (8.5 mM) bicarbonate-buffered saline solution. Single and dual recordings in stratum pyramidale of CA1 and CA3 regions were performed with 3–5 MΩ glass microelectrodes. All drugs—lamotrigine (LTG), phenytoin (PHT) and valproate (VPA)—were applied to the slice by superfusion at a rate of 2 ml/min at 32°C. Effects upon frequency of ED’s were assessed for LTG, PHT and VPA applied at different concentrations, in isolation and in combination. We demonstrated that high-K⁺ induced ED frequency was reversibly reduced by LTG, PHT and VPA, at concentrations corresponding to human therapeutic blood plasma concentrations. With a protocol using several applications of drugs to the same slice, PHT and VPA in combination displayed additivity of effect with 50μM PHT and 350μM VPA reducing SLD frequency by 44% and 24% individually (n = 19), and together reducing SLD frequency by 66% (n = 19). 20μM LTG reduced SLD frequency by 32% and 350μM VPA by 16% (n = 18). However, in combination there was a supra-linear suppression of ED’s of 64% (n = 18). In another independent set of experiments, similar results of drug combination responses were also found. In conclusion, a combination of conventional AEDs with different mechanisms of action, PHT and VPA, displayed linear additivity of effect on epileptiform activity. More intriguingly, a combination of LTG and VPA considered particularly efficacious clinically showed a supra-additive suppression of ED’s. This approach may be useful as an in vitro platform for assessing drug combination efficacy.

Neuropathology of epilepsy

Epilepsy is one of the most common neurologic disorders, affecting about 50 million people worldwide. The disease is characterized by recurrent seizures, which are due to aberrant neuronal networks resulting in synchronous discharges. The term epilepsy encompasses a large spectrum of syndromes and diseases with different etiopathogenesis. The recent development of imaging and epilepsy surgery techniques is now enabling the identification of structural abnormalities that are part of the epileptic network, and the removal of these lesions may result in control of seizures. Access of this clinically well-characterized neurosurgical material has provided neuropathologists with the opportunity to study a variety of structural brain abnormalities associated with epilepsy, by combining traditional routine histopathologic methods with molecular genetics and functional analysis of the resected tissue. This approach has contributed greatly to a better diagnosis and classification of these structural lesions, and has provided important new insights into their pathogenesis and epileptogenesis. The present chapter provides a detailed description of the large spectrum of histopathologic findings encountered in epilepsy surgery patients, addressing in particular the nonneoplastic pathologies, including hippocampal sclerosis, malformations of cortical development, Sturge-Weber syndrome, and Rasmussen encephalitis, and reviews current knowledge regarding the underlying molecular pathomechanisms and cellular mechanisms mediating hyperexcitability.

The Stereo-Electroencephalography Methodology

The stereo-electroencephalography (SEEG) methodology and technique was developed almost 60 years ago in Europe. The efficacy and safety of SEEG has been proven. The main advantage is the possibility to study the epileptogenic neuronal network in its dynamic and 3-dimensional aspect, with optimal time and space correlation, with the clinical semiology of the patient's seizures. The main clinical challenge for the near future remains in the further refinement of specific selection criteria for the different methods of invasive monitoring, with the ultimate goal of comparing and validating the results (long-term seizure-free outcome) obtained from different methods of invasive monitoring.

Outcomes in newly diagnosed epilepsy in adolescents and adults: Insights across a generation in Scotland

The outpatient services at the Epilepsy Unit in the Western Infirmary, Glasgow, Scotland was set up in September 1982. From the outset patient data were collected prospectively. A focused approach to patients with newly diagnosed epilepsy was developed and a series of 4 analyses have been undertaken over the intervening years, with results from the latest still being written up for publication. A total of 16 published papers have described patient outcomes over the years, focusing on response to different drug schedules. A number of factors contributing to a poorer prognosis has been identified and follow up data over 30 years has confirmed the lack of overall improvement in prognosis despite the introduction of 14 new AEDs for the common epilepsies in the UK with different mechanisms of action over this time. Patterns of response have confirmed that a majority of patients will go into remission with around 25% of the population appearing to have refractory epilepsy de novo. Since all available options are antiseizure and not antiepilepsy drugs, some patients, who are initially well controlled, are seen to relapse over time and to develop refractory epilepsy. A new approach in identifying and treating epileptogenesis is necessary, if this disappointing scenario is to be reversed with the next generation of antiepileptic drugs.

The course of language functions after temporal lobe epilepsy surgery: a prospective study

BACKGROUND AND PURPOSE

Anterior temporal lobectomy (ATL) within the language-dominant hemisphere can impair naming. This prospective study examined the pre-operative to post-operative course of different language components, clarifying which changes are relevant within the short-term and long-term outcome of language.

METHODS

Patients with drug-resistant temporal lobe epilepsy (TLE) were evaluated using the Token, Boston Naming and Word Fluency tests assessing sentence comprehension and word-finding on visual, semantic or phonemic cues.

RESULTS

A total of 106 patients were evaluated before and 6 months, 1 and 2 years after ATL; 60 patients were also evaluated after 5 years and 38 controls were assessed at baseline. Seizure outcome was comparable between the left and right TLE patients. Before surgery, naming and word fluency were impaired in the left and right TLE patients, whereas sentence comprehension was normal. After left or right ATL, word fluency progressively improved, naming showed early worsening and late improvement after left ATL and progressive improvement after right ATL, and sentence comprehension did not change. At the 5-year follow-up, naming improvement was clinically significant in 31% and 71% of the left and right TLE patients, respectively. Pre-operative naming, ATL laterality, schooling, and post-operative seizure frequency and number of antiepileptic drugs predicted post-operative naming. Pre-operative word fluency and schooling predicted post-operative word fluency.

CONCLUSIONS

Left or right TLE can impair word-finding but not sentence comprehension. After ATL, word-finding may improve for a long time, depending on TLE laterality, seizure control and mental reserve. These findings may clarify prognosis prior to treatment.

Which children receive vigabatrin? Characteristics of pediatric patients enrolled in the mandatory FDA registry

Vigabatrin (Sabril®) is an antiepileptic drug (AED) currently indicated in the US as a monotherapy for patients 1month to 2years of age with infantile spasms (IS) and as adjunctive therapy for patients ≥10years of age with refractory complex partial seizures (rCPS) whose seizures have inadequately responded to several alternative treatments and for whom the potential benefits outweigh the risk of vision loss. The approval required an FDA mandated registry. This article describes 5years of demographic and treatment exposure data from US pediatric patients (<17years). Participation is mandatory for all US Sabril® prescribers and patients. A benefit-risk assessment must be documented for patient progression to maintenance therapy. This includes demographic diagnosis and reports of ophthalmologic assessments (where available). Patient data were grouped by age as proxies for indication (IS: <3years, rCPS: ≥3 to <17years). As of August 26, 2014, 5546/6823 enrolled patients were pediatric/total; 4472 (81%) were vigabatrin-naïve. Seventy-one percent of patients were <3years of age; 29% were ≥3 to <17years of age. Etiologies of IS were identified as cryptogenic (21%), symptomatic tuberous sclerosis (17%), and symptomatic other (42%). The majority of patients with IS (56%) attempted no prior treatments; 16% received adrenocorticotropic hormone prior to vigabatrin. A third of patients with IS were receiving 1 concomitant treatment with vigabatrin. For patients with rCPS, 39% attempted 1-3 prior treatments; 27% were receiving 2 concomitant treatments at enrollment. A total of 1852 (41%) patients did not undergo baseline ophthalmological assessment; 25% of patients with IS and 42% of patients with rCPS were exempted for neurologic disabilities. Kaplan-Meier estimates predict that 71% and 65% of vigabatrin-naïve patients with IS and rCPS, respectively, would remain in the registry at 6months. Most pediatric vigabatrin patients have IS as an underlying diagnosis, especially those <3years of age. A proportion of those with rCPS remain on long-term vigabatrin despite the risk of adverse events.

Crowdsourcing reproducible seizure forecasting in human and canine epilepsy

See Mormann and Andrzejak (doi:10.1093/brain/aww091) for a scientific commentary on this article.  

Seizures are thought to arise from an identifiable pre-ictal state. Brinkmann et al. report the results of an online, open-access seizure forecasting competition using intracranial EEG recordings from canines with naturally occurring epilepsy and human patients undergoing presurgical monitoring. The winning algorithms forecast seizures at rates significantly greater than chance.

See Mormann and Andrzejak (doi:10.1093/brain/aww091) for a scientific commentary on this article.  

Accurate forecasting of epileptic seizures has the potential to transform clinical epilepsy care. However, progress toward reliable seizure forecasting has been hampered by lack of open access to long duration recordings with an adequate number of seizures for investigators to rigorously compare algorithms and results. A seizure forecasting competition was conducted on kaggle.com using open access chronic ambulatory intracranial electroencephalography from five canines with naturally occurring epilepsy and two humans undergoing prolonged wide bandwidth intracranial electroencephalographic monitoring. Data were provided to participants as 10-min interictal and preictal clips, with approximately half of the 60 GB data bundle labelled (interictal/preictal) for algorithm training and half unlabelled for evaluation. The contestants developed custom algorithms and uploaded their classifications (interictal/preictal) for the unknown testing data, and a randomly selected 40% of data segments were scored and results broadcasted on a public leader board. The contest ran from August to November 2014, and 654 participants submitted 17 856 classifications of the unlabelled test data. The top performing entry scored 0.84 area under the classification curve. Following the contest, additional held-out unlabelled data clips were provided to the top 10 participants and they submitted classifications for the new unseen data. The resulting area under the classification curves were well above chance forecasting, but did show a mean 6.54 ± 2.45% (min, max: 0.30, 20.2) decline in performance. The kaggle.com model using open access data and algorithms generated reproducible research that advanced seizure forecasting. The overall performance from multiple contestants on unseen data was better than a random predictor, and demonstrates the feasibility of seizure forecasting in canine and human epilepsy.

Ketogenic diet effects on neurobehavioral development of children with intractable epilepsy: A prospective study

OBJECTIVE

This study aimed to determine the impact of a ketogenic diet (KD) on neurobehavioral development when used to treat children with intractable epilepsy, confirming the efficacy of the KD, as well as the correlation between early electroencephalography (EEG) changes in the early stage with treatment efficacy.

METHODS

We enrolled 42 children who were starting treatment for intractable epilepsy with the classic KD protocol. The total development quotient as well as the development quotients for adaptability, gross motor movements, fine motor movements, language, and individual-social interaction on the Gesell developmental scales were assessed before and after 3, 6, 12, and 18 months of KD treatment. The efficacy assessment was based on changes in seizure frequency after KD as recorded by the parents. We conducted 24-h video-EEG before and after 1 month of KD treatment.

RESULTS

Developmental quotients of five energy regions in the Gesell developmental scales assessment were used to compare adaptability (P1=0.000), gross motor movements (P2=0.010), and fine motor movements (P3=0.000); the results showed significant differences. After KD treatment at different time points, 69.0%, 54.8%, 40.5%, and 33.3% patients, respectively, achieved a ≥50% reduction in seizure frequency. The reduction of epileptiform discharges in the awake state after 1 month of KD treatment correlated with the efficacy after 3 months of KD treatment.

CONCLUSIONS

Ketogenic diet treatment tends to be associated with improved neurobehavioral development, and more significant improvement can be obtained with prolonged treatment. The KD is safe and effective in treating children with intractable epilepsy. Early EEG changes correlate with clinical efficacy, to a certain degree.

Effectiveness of a hybrid corticosteroid treatment regimen on refractory childhood seizures and a review of other corticosteroid treatments

BACKGROUND

Many different corticosteroid treatment schedules have been used in order to treat refractory epileptic seizures with encouraging effects on seizure reduction in many epileptic syndromes.

OBJECTIVE

The objective is to report our experience with a hybrid treatment regimen for refractory seizures in children with epilepsies other than West and Landau-Kleffner syndrome. We hypothesized that a pulse of corticosteroids effectively reduces seizures while low-dosage maintenance treatment reduces side effects. The results are compared with results from a review of reported corticosteroid and ACTH treatments.

METHODS

In this retrospective observational study, 26 children diagnosed with epilepsy with refractory seizures other than West syndrome and Landau-Kleffner syndrome were eligible for a treatment regimen consisting of three days intravenous methylprednisolone (20 mg per kilogram per day) followed by twelve weeks oral prednisolone (0.5 mg per kilogram on alternate days), concluded with a taper phase. Data on effectiveness and side effects were obtained. End-points were the percentages of patients who became seizure free or responded well.

RESULTS

Twenty-one patients received the study treatment. Nine (43%) responded well and 6 (29%) became seizure free. All but one patient had a relapse of seizures. Four patients had reversible adverse effects. Data extracted from the literature were consistent with a good response in 48% of 192 children treated with different corticosteroids and in 69% of 103 patients treated with ACTH.

CONCLUSION

This new hybrid therapy of a pulse of intravenous methylprednisolone and alternate day oral prednisolone is effective with a favourable side effect profile. Results on efficacy and safety justify a randomized controlled trial.

Overview of Nrf2 as Therapeutic Target in Epilepsy

Oxidative stress is a biochemical state of imbalance in the production of reactive oxygen and nitrogen species and antioxidant defenses. It is involved in the physiopathology of degenerative and chronic neuronal disorders, such as epilepsy. Experimental evidence in humans and animals support the involvement of oxidative stress before and after seizures. In the past few years, research has increasingly focused on the molecular pathways of this process, such as that involving transcription factor nuclear factor E2-related factor 2 (Nrf2), which plays a central role in the regulation of antioxidant response elements (ARE) and modulates cellular redox status. The aim of this review is to present experimental evidence on the role of Nrf2 in this neurological disorder and to further determine the therapeutic impact of Nrf2 in epilepsy.

Electrically induced limbic seizures: preliminary findings in a rodent model

In epilepsy, novel pharmacological and nonpharmacological treatment approaches are commonly assessed in model systems of acute motor and often generalized seizures. We developed a rodent model with short-term electrical stimulation of the perforant path resulting in stereotyped limbic seizures. Limbic structures play a major role in human intractable epilepsy. In 10 rats, single electrical 5-second and 20-Hz stimuli to the perforant path reliably produced limbic seizures characterized by resting behavior and subtle motor signs. Electrophysiological recordings from the dentate gyrus demonstrated a seizure pattern with 4-Hz to 5-Hz discharges. Multiple inductions of seizures within 72 hours did not alter behavioral and electrophysiological seizure characteristics. Electrophysiological excitatory and inhibitory parameters assessed by evoked single and paired pulses did not change with increasing number of seizures. We present preliminary findings on a new model of electrically induced limbic seizures of mesiotemporal origin. This model may represent a reliable screening tool for new treatment approaches such as deep brain stimulation.

Diagnosis and management of childhood epilepsy

Epilepsy is a relatively common neurologic disorder in children that has important implications for development, parents, and society. Making the correct diagnosis starts with an accurate and complete history that consequently leads to a directed diagnostic workup. This article outlines a diagnostic and management approach to pediatric seizures and epilepsy syndromes. Making the correct diagnosis of epilepsy or nonepileptic imitators allows the practitioner to prescribe appropriate therapy. Initial management for typical epileptic syndromes and seizures and potential adverse effects are discussed. Alternative treatment options for pharmacologically resistant patients such as ketogenic diet, vagal nerve stimulation, and surgery are also discussed. While most children favorably respond to antiepileptic medications, early identification of medication failure is important to ensure optimal neurodevelopment.

Vagus nerve stimulation for drug-resistant epilepsy: a European long-term study up to 24 months in 347 children

OBJECTIVE

To gain insight into the long-term impact of vagus nerve stimulation (with VNS Therapy) in children with drug-resistant epilepsy, we conducted the largest retrospective multicenter study to date over an extended follow-up period of up to 24 months.

METHODS

The primary objective was to assess change in seizure frequency of the predominant seizure type (defined as the most disabling seizure) following VNS device implantation. Treating physicians collected data from patient records from baseline to 6, 12, and 24 months of follow-up.

RESULTS

The analysis population included 347 children (aged 6 months to 17.9 years at the time of implant). At 6, 12, and 24 months after implantation, 32.5%, 37.6%, and 43.8%, respectively, of patients had ≥ 50% reduction in baseline seizure frequency of the predominant seizure type. The responder rate was higher in a subgroup of patients who had no change in antiepileptic drugs (AEDs) during the study. Favorable results were also evident for all secondary outcome measures including changes in seizure duration, ictal severity, postictal severity, quality of life, clinical global impression of improvement, and safety. Post hoc analyses demonstrated a statistically significant correlation between VNS total charge delivered per day and an increase in response rate. VNS Therapy is indicated as adjunctive therapy in children with focal, structural epilepsies, who for any reason are not good candidates for surgical treatment following the trial of two or more AEDs. Children with predominantly generalized seizures from genetic, structural epilepsies, like Dravet syndrome or Lennox-Gastaut syndrome, could also benefit from VNS Therapy.

SIGNIFICANCE

The results demonstrate that adjunctive VNS Therapy in children with drug-resistant epilepsy reduces seizure frequency and is well tolerated over a 2-year follow-up period. No new safety issues were identified. A post hoc analysis revealed a dose-response correlation for VNS in patients with epilepsy.

Cardiorespiratory abnormalities during epileptic seizures

Sudden unexpected death in epilepsy (SUDEP) is a leading cause of death in young and otherwise healthy patients with epilepsy, and sudden death is at least 20 times more common in epilepsy patients as compared to patients without epilepsy. A significant proportion of patients with epilepsy experience cardiac and respiratory complications during seizures. These cardiorespiratory complications are suspected to be a significant risk factor for SUDEP. Sleep physicians are increasingly involved in the care of epilepsy patients and a recognition of these changes in relation to seizures while a patient is under their care may improve their awareness of these potentially life-threatening complications that may occur during sleep studies. This paper details these cardiopulmonary changes that take place in relation to epileptic seizures and how these changes may relate to the occurrence of SUDEP.

Deep brain and cortical stimulation for epilepsy

BACKGROUND

Despite optimal medical treatment, including epilepsy surgery, many epilepsy patients have uncontrolled seizures. In the last decades, interest has grown in invasive intracranial neurostimulation as a treatment for these patients. Intracranial stimulation includes both deep brain stimulation (DBS) (stimulation through depth electrodes) and cortical stimulation (subdural electrodes).

OBJECTIVES

To assess the efficacy, safety and tolerability of deep brain and cortical stimulation for refractory epilepsy based on randomized controlled trials.

SEARCH METHODS

We searched PubMed (6 August 2013), the Cochrane Epilepsy Group Specialized Register (31 August 2013), Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 7 of 12) and reference lists of retrieved articles. We also contacted device manufacturers and other researchers in the field. No language restrictions were imposed.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing deep brain or cortical stimulation to sham stimulation, resective surgery or further treatment with antiepileptic drugs.

DATA COLLECTION AND ANALYSIS

Four review authors independently selected trials for inclusion. Two review authors independently extracted the relevant data and assessed trial quality and overall quality of evidence. The outcomes investigated were seizure freedom, responder rate, percentage seizure frequency reduction, adverse events, neuropsychological outcome and quality of life. If additional data were needed, the study investigators were contacted. Results were analysed and reported separately for different intracranial targets for reasons of clinical heterogeneity.

MAIN RESULTS

Ten RCTs comparing one to three months of intracranial neurostimulation to sham stimulation were identified. One trial was on anterior thalamic DBS (n = 109; 109 treatment periods); two trials on centromedian thalamic DBS (n = 20; 40 treatment periods), but only one of the trials (n = 7; 14 treatment periods) reported sufficient information for inclusion in the quantitative meta-analysis; three trials on cerebellar stimulation (n = 22; 39 treatment periods); three trials on hippocampal DBS (n = 15; 21 treatment periods); and one trial on responsive ictal onset zone stimulation (n = 191; 191 treatment periods). Evidence of selective reporting was present in four trials and the possibility of a carryover effect complicating interpretation of the results could not be excluded in 4 cross-over trials without any washout period. Moderate-quality evidence could not demonstrate statistically or clinically significant changes in the proportion of patients who were seizure-free or experienced a 50% or greater reduction in seizure frequency (primary outcome measures) after 1 to 3 months of anterior thalamic DBS in (multi)focal epilepsy, responsive ictal onset zone stimulation in (multi)focal epilepsy patients and hippocampal DBS in (medial) temporal lobe epilepsy. However, a statistically significant reduction in seizure frequency was found for anterior thalamic DBS (-17.4% compared to sham stimulation; 95% confidence interval (CI) -32.1 to -1.0; high-quality evidence), responsive ictal onset zone stimulation (-24.9%; 95% CI -40.1 to 6.0; high-quality evidence) ) and hippocampal DBS (-28.1%; 95% CI -34.1 to -22.2; moderate-quality evidence). Both anterior thalamic DBS and responsive ictal onset zone stimulation do not have a clinically meaningful impact on quality life after three months of stimulation (high-quality evidence). Electrode implantation resulted in asymptomatic intracranial haemorrhage in 3% to 4% of the patients included in the two largest trials and 5% to 13% had soft tissue infections; no patient reported permanent symptomatic sequelae. Anterior thalamic DBS was associated with fewer epilepsy-associated injuries (7.4 versus 25.5%; P = 0.01) but higher rates of self-reported depression (14.8 versus 1.8%; P = 0.02) and subjective memory impairment (13.8 versus 1.8%; P = 0.03); there were no significant differences in formal neuropsychological testing results between the groups. Responsive ictal-onset zone stimulation was well tolerated with few side effects but SUDEP rate should be closely monitored in the future (4 per 340 [= 11.8 per 1000] patient-years; literature: 2.2-10 per 1000 patient-years). The limited number of patients preclude firm statements on safety and tolerability of hippocampal DBS. With regards to centromedian thalamic DBS and cerebellar stimulation, no statistically significant effects could be demonstrated but evidence is of only low to very low quality.

AUTHORS' CONCLUSIONS

Only short term RCTs on intracranial neurostimulation for epilepsy are available. Compared to sham stimulation, one to three months of anterior thalamic DBS ((multi)focal epilepsy), responsive ictal onset zone stimulation ((multi)focal epilepsy) and hippocampal DBS (temporal lobe epilepsy) moderately reduce seizure frequency in refractory epilepsy patients. Anterior thalamic DBS is associated with higher rates of self-reported depression and subjective memory impairment. SUDEP rates require careful monitoring in patients undergoing responsive ictal onset zone stimulation. There is insufficient evidence to make firm conclusive statements on the efficacy and safety of hippocampal DBS, centromedian thalamic DBS and cerebellar stimulation. There is a need for more, large and well-designed RCTs to validate and optimize the efficacy and safety of invasive intracranial neurostimulation treatments.

The long-term effect of vagus nerve stimulation on quality of life in patients with pharmacoresistant focal epilepsy: the PuLsE (Open Prospective Randomized Long-term Effectiveness) trial

OBJECTIVE

To evaluate whether vagus nerve stimulation (VNS) as adjunct to best medical practice (VNS + BMP) is superior to BMP alone in improving long-term health-related quality of life (HRQoL).

METHODS

PuLsE (Open Prospective Randomized Long-term Effectiveness) was a prospective, randomized, parallel-group, open-label, and long-term effectiveness study (conducted at 28 sites in Europe and Canada). Adults with pharmacoresistant focal seizures (n = 112) received VNS + BMP or BMP (1:1 ratio). Medications and VNS parameters could be adjusted as clinically indicated for optimal seizure control while minimizing adverse effects. Primary endpoint was mean change from baseline HRQoL (using Quality of Life in Epilepsy Inventory-89 total score; QOLIE-89). Secondary endpoints included changes in seizure frequency, responder rate (≥50% decrease in seizure frequency), Centre for Epidemiologic Studies Depression scale (CES-D), Neurological Disorders Depression Inventory-Epilepsy scale (NDDI-E), Clinical Global Impression-Improvement scale (CGI-I), Adverse Event Profile (AEP), and antiepileptic drug (AED) load. The study was prematurely terminated due to recruitment difficulties prior to completing the planned enrollment of n = 362. Results for n = 96 who had baseline and at least one follow-up QOLIE-89 assessment (from months 3-12) were included in this analysis. Mixed model repeated measures (MMRM) analysis of variance was performed on change from baseline for the primary and secondary endpoints.

RESULTS

Significant between-group differences in favor of VNS + BMP were observed regarding improvement in HRQoL, seizure frequency, and CGI-I score (respective p-values < 0.05, 0.03, and 0.01). More patients in the VNS + BMP group (43%) reported adverse events (AEs) versus BMP group (21%) (p = 0.01), a difference reflecting primarily mostly transient AEs related to VNS implantation or stimulation. No significant difference between treatment groups was observed for changes in CES-D, NDDI-E, AEP, and AED load.

SIGNIFICANCE

VNS therapy as a treatment adjunct to BMP in patients with pharmacoresistant focal seizures was associated with a significant improvement in HRQoL compared with BMP alone. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.

Rapid and efficient localization of depth electrodes and cortical labeling using free and open source medical software in epilepsy surgery candidates

Depth intracranial electrodes (IEs) placement is one of the most used procedures to identify the epileptogenic zone (EZ) in surgical treatment of drug resistant epilepsy patients, about 20–30% of this population. IEs localization is therefore a critical issue defining the EZ and its relation with eloquent functional areas. That information is then used to target the resective surgery and has great potential to affect outcome. We designed a methodological procedure intended to avoid the need for highly specialized medical resources and reduce time to identify the anatomical location of IEs, during the first instances of intracranial EEG recordings. This workflow is based on established open source software; 3D Slicer and Freesurfer that uses MRI and Post-implant CT fusion for the localization of IEs and its relation with automatic labeled surrounding cortex. To test this hypothesis we assessed the time elapsed between the surgical implantation process and the final anatomical localization of IEs by means of our proposed method compared against traditional visual analysis of raw post-implant imaging in two groups of patients. All IEs were identified in the first 24 H (6–24 H) of implantation using our method in 4 patients of the first group. For the control group; all IEs were identified by experts with an overall time range of 36 h to 3 days using traditional visual analysis. It included (7 patients), 3 patients implanted with IEs and the same 4 patients from the first group. Time to localization was restrained in this group by the specialized personnel and the image quality available. To validate our method; we trained two inexperienced operators to assess the position of IEs contacts on four patients (5 IEs) using the proposed method. We quantified the discrepancies between operators and we also assessed the efficiency of our method to define the EZ comparing the findings against the results of traditional analysis.

Investigating higher-order cognitive functions in temporal lobe epilepsy: cognitive estimation

Cognitive estimation, an ability to attribute measurements to concrete things, is relevant to adaptive behavior. This study evaluated cognitive estimation in patients with temporal lobe epilepsy (TLE) with the goal of verifying its relationship to temporal lobe damage and age of seizure onset. One hundred and eight patients with drug-resistant TLE and 51 healthy controls were evaluated using the Cognitive Estimation Task (CET), which requires simple and complex estimations providing the Total and Bizarreness scores. Different tests assessed reasoning, attention, executive, visuospatial, and lexical-semantic abilities. Patients with right TLE had earlier age of seizure onset than patients with left TLE and lower education than controls. Compared with controls, both patient groups obtained worse CET Total and Bizarreness scores, but only patients with right TLE were significantly impaired. Patients with seizure onset before age 12 showed worse scores than patients with later seizure onset irrespective of the side of TLE. The CET Total and Bizarreness scores were predicted by age of seizure onset and semantic fluency; the Bizarreness score also related to education, chronological age, and visual attention. Results highlight the complexity of the cognitive pattern associated with TLE. Cognitive estimation deficit primarily reflects early age of seizure onset and semantic difficulties. An involvement of visual mental operations mediated by the right hemisphere may accentuate the deficit, while cognitive reserve may play a protective role.

Uncontrolled epilepsy is not necessarily the same as drug-resistant epilepsy: differences between populations with newly diagnosed epilepsy and chronic epilepsy

BACKGROUND

A proportion of patients with seemingly "uncontrolled" epilepsy could still control their epilepsy with further pharmacological manipulations. It is possible that their epilepsy might not be truly "drug-resistant". We audited the patients with "uncontrolled epilepsy" using the recent ILAE definition of drug-resistant epilepsy.

METHODS

Patients with newly diagnosed epilepsy at Glasgow and patients with chronic epilepsy treated in Hong Kong were independently assessed at their last clinic visit. If the patient was not seizure-free, the epilepsy was considered "uncontrolled". In this latter situation, if the patient had adequate trials of two or more tolerated, appropriately chosen, and appropriately used AED schedules, the epilepsy was classified as "drug-resistant" in accordance with the ILAE definition. If not, the outcome was classified as "undefined", and the reason(s) for this was documented.

RESULTS

In the newly diagnosed cohort with uncontrolled epilepsy (n=311), outcome was "undefined" in 175 (56%). The most common reasons were trying just one AED usually at the patient's behest (n=68; 39%); intermittent compliance (60; 34%); adverse effects at low dosage (51; 29%); inadequate dosing (49; 28%); social issues such as imprisonment, alcohol, and recreational drug use (34; 19%); psychiatric problems affecting documentation, attendance, etc. (32; 18%); patient choice accepting less than optimal control (14; 8%); and seizure freedom of less than 12 months (12.7%). In the chronic cohort of 194 patients with uncontrolled epilepsy, drug responsiveness was "undefined" in just 79 (41%). The most common reasons were inadequate use of the AED(s) (35; 44%), followed by a lack of information on treatment response in the medical records (18; 23%) and failure of only one adequately used AED (11; 14%).

CONCLUSION

Uncontrolled epilepsy is not necessarily the same as drug-resistant epilepsy. Efforts should be made to understand why a patient is not seizure-free so that appropriate adjustment in AED regimen can be taken to enable the patient to attain long-term seizure freedom.

Modulation of Immunity and the Inflammatory Response: A New Target for Treating Drug-resistant Epilepsy

Until recently, epilepsy medical therapy is usually limited to anti-epileptic drugs (AEDs). However, approximately 1/3 of epilepsy patients, described as drug-resistant epilepsy (DRE) patients, still suffer from continuous frequent seizures despite receiving adequate AEDs treatment of sufficient duration. More recently, with the remarkable progress of immunology, immunity and inflammation are considered to be key elements of the pathobiology of epilepsy. Activation of inflammatory processes in brain tissue has been observed in both experimental seizure animal models and epilepsy patients. Anti-inflammatory and immunotherapies also showed significant anticonvulsant properties both in clinical and in experimental settings. The above emerging evidence indicates that modulation of immunity and inflammatory processes could serve as novel specific targets to achieve potential anticonvulsant effects for the patients with epilepsy, especially DRE. Herein we review the recent evidence supporting the role of inflammation in the development and perpetuation of seizures, and also discuss the recent achievements in modulation of inflammation and immunotherapy applied to the treatment of epilepsy. Apart from medical therapy, we also discuss the influences of surgery, ketogenic diet, and electroconvulsive therapy on immunity and inflammation in DRE patients. Taken together, a promising perspective is suggested for future immunomodulatory therapies in the treatment of patients with DRE.

Early predictors of outcome in newly diagnosed epilepsy

Longitudinal studies of newly diagnosed epilepsy in children and adults have identified prognostic factors that allow early identification of patients whose seizures are likely to remain uncontrolled with antiepileptic medication. Results from outcome studies may be subject to bias, depending on the setting (community versus clinic), design (retrospective versus prospective) and characteristics of the patient cohort studied (age, types of epilepsy, specific comorbidities). Nevertheless, factors such as early response to medication, underlying aetiology, and number of seizures prior to initiation of treatment have consistently been found to be predictive of seizure outcomes. Other variables such as age, electroencephalographic findings and the presence or absence of psychiatric co-morbidities have been correlated with outcomes in some analyses. This review has examined studies of seizure outcomes in adults and children with newly diagnosed epilepsy identifying the risk factors that are associated with subsequent refractory epilepsy.

Outcome of newly-diagnosed epilepsy in older patients

INTRODUCTION

The annual incidence of seizure disorders rises sharply after the age of 60. Treatment is complicated by the normal physiological changes of aging, comorbid diseases, and polypharmacy. Despite this, approximately 80% of the patients become seizure-free.

OBJECTIVES

The objectives of this study were to (1) analyze the outcome of a cohort of patients with newly-diagnosed epilepsy over the age of 65, (2) describe epilepsy etiology and seizure type, and (3) classify the outcome according to the latest ILAE classification proposal for drug-resistant epilepsy (2010).

METHODS

All patients with newly-diagnosed epilepsy over the age of 65 who were evaluated in two different institutions were included. Seizures and epilepsy syndromes were classified according to the International League Against Epilepsy proposal (2010). Epilepsy outcomes were also analyzed according to the proposal of the ILAE Commission on Therapeutic Strategies (2010).

RESULTS

One hundred and twenty-two patients were included with a median follow-up time of 15 months. Median age of diagnosis was 78 years. Seventy-seven patients (55%) had epilepsy of unknown cause, and 55 (45%) had structural-metabolic epilepsy. The proportions of seizure-free patients at 6, 12, 18, and 24 months were 90%, 77%, 74%, and 67%, respectively. Thirty percent of patients experienced adverse effects (AEs). We found a statistically significant trend toward a higher frequency of AEs as the number of concomitant medications rose and in younger patients. According to the 2010 ILAE classification proposal for drug-resistant epilepsy criteria, 55.8% of the patients were seizure-free, 12.3% had treatment failure, and 32% had undetermined seizure outcome.

CONCLUSION

Patients with newly-diagnosed epilepsy after the age of 65 have very good chances of achieving seizure control with AED treatment. It seems that fulfilling the ILAE classification proposal for drug-resistant epilepsy (2010) criteria for seizure freedom was more difficult in our cohort. Older patients also seem to be more prone to suffering from AEs.

Surgical treatment of epilepsy associated with cortical dysplasia: 2012 update

Cortical dysplasia is the most common etiology in children and the third most frequent finding in adults undergoing epilepsy neurosurgery. The new International League Against Epilepsy (ILAE) classification grades isolated cortical dysplasia into mild type I (cortical dyslamination), severe type II (dyslamination plus dysmorphic neurons and balloon cells), and dysplasia associated with other epileptogenic lesions (type III). Multilobar type II lesions present at an earlier age and with more severe epilepsy compared with focal type I abnormalities, often in the temporal lobe, and these findings are reflected in types and age of operations for cortical dysplasia. Presurgical evaluation of patients with epilepsy from cortical dysplasia can be challenging. Interictal and ictal scalp electroencephalography (EEG) accurately localizes cortical dysplasia with 50-66% accuracy. Structural magnetic resonance imaging (MRI) is negative in roughly 30% of cases, most often linked with mild type I cases. FDG-PET can be 80-90% accurate, but is not 100% sensitive. Chronic intracranial electrodes are used in about 50% of cases with cortical dysplasia, but often do not capture restricted ictal-onset zones. About 60% of patients with cortical dysplasia are seizure free after epilepsy neurosurgery, with much higher rates of becoming seizure free with complete (80%) compared with incomplete (20%) resections. The most common reason for incomplete resection is the risk of an unacceptable neurologic deficit. Future challenges include better tools in identifying subtle forms of type I cortical dysplasia, and development of adjunctive treatments from basic research for those undergoing incomplete resections.