Practice parameter: temporal lobe and localized neocortical resections for epilepsy: report of the Quality Standards Subcommittee of the American Academy of Neurology, in association with the American Epilepsy Society and the American Association of Neurological Surgeons

Epilepsies associated with hippocampal sclerosis

Hippocampal sclerosis (HS) is considered the most frequent neuropathological finding in patients with mesial temporal lobe epilepsy (MTLE). Hippocampal specimens of pharmacoresistant MTLE patients that underwent epilepsy surgery for seizure control reveal the characteristic pattern of segmental neuronal cell loss and concomitant astrogliosis. However, classification issues of hippocampal lesion patterns have been a matter of intense debate. International consensus classification has only recently provided significant progress for comparisons of neurosurgical and clinic-pathological series between different centers. The respective four-tiered classification system of the International League Against Epilepsy subdivides HS into three types and includes a term of "gliosis only, no-HS". Future studies will be necessary to investigate whether each of these subtypes of HS may be related to different etiological factors or with postoperative memory and seizure outcome. Molecular studies have provided potential deeper insights into the pathogenesis of HS and MTLE on the basis of epilepsy-surgical hippocampal specimens and corresponding animal models. These include channelopathies, activation of NMDA receptors, and other conditions related to Ca(2+) influx into neurons, the imbalance of Ca(2+)-binding proteins, acquired channelopathies that increase neuronal excitability, paraneoplastic and non-paraneoplastic inflammatory events, and epigenetic regulation promoting or facilitating hippocampal epileptogenesis. Genetic predisposition for HS is clearly suggested by the high incidence of family history in patients with HS, and by familial MTLE with HS. So far, it is clear that HS is multifactorial and there is no individual pathogenic factor either necessary or sufficient to generate this intriguing histopathological condition. The obvious variety of pathogenetic combinations underlying HS may explain the multitude of clinical presentations, different responses to clinical and surgical treatment. We believe that the stratification of neuropathological patterns can help to characterize specific clinic-pathological entities and predict the postsurgical seizure control in an improved fashion.

Drug-resistant epilepsy: definition and treatment alternatives

INTRODUCTION

Drug-resistant epilepsy affects 25% of all epileptic patients, and quality of life decreases in these patients due to their seizures. Early detection is crucial in order to establish potential treatment alternatives and determine if the patient is a surgical candidate.

DEVELOPMENT

PubMed search for articles, recommendations published by major medical societies, and clinical practice guidelines for drug-resistant epilepsy and its medical and surgical treatment options. Evidence and recommendations are classified according to the criteria of the Oxford Centre for Evidence-Based Medicine (2001) and the European Federation of Neurological Societies (2004) for therapeutic actions.

CONCLUSIONS

Identifying patients with drug-resistant epilepsy is important for optimising drug therapy. Experts recommend rational polytherapy with antiepileptic drugs to find more effective combinations with fewer adverse effects. When adequate seizure control is not achieved, a presurgical evaluation in an epilepsy referral centre is recommended. These evaluations explore how to resect the epileptogenic zone without causing functional deficits in cases in which this is feasible. If resective surgery is not achievable, palliative surgery or neurostimulation systems (including vagus nerve, trigeminal nerve, or deep brain stimulation) may be an option. Other treatment alternatives such as ketogenic diet may also be considered in selected patients.

Surgery for drug-resistant focal epilepsy

During the colloquium on drug-resistant epilepsy (DRE) at National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore on August 16-18, 2013, a number of presentations were made on the surgically remediable lesional epilepsy syndromes, presurgical evaluation, surgical techniques, neuropathology of drug resistance focal epilepsy and surgical outcome. This pictorial essay with the illustrative case examples provides an overview of the various surgical techniques for the management of drug-resistant focal epilepsy.

Characteristics and clinical impact of stimulation-evoked seizures during extraoperative cortical mapping

Extraoperative electrocortical stimulation mapping (ESM) is used to identify functional cortex prior to epilepsy surgery, with the goal of preserving function postoperatively. Although attempts are made to avoid stimulation-evoked seizure activity, the clinical impact of these events with regard to safety, clinical utility, functional outcome, and even disruption to the procedure itself is unknown. We conducted a retrospective review of 57 patients with pharmacoresistant focal epilepsy who underwent intracranial electrode implantation and ESM. Stimulation-evoked seizures (afterdischarges associated with clinical signs or symptoms) occurred in 19 patients (33%). Mapping sessions were disrupted for 11 of these patients (i.e., 19% of the full sample and 58% of the subgroup of patients with stimulation-evoked seizures). Patients who had ESM disruption were no less likely than patients without ESM disruption to be seizure-free at one year (p=0.63) and two years (p=0.57) postoperatively. Among 23 patients who underwent language assessment pre- and postoperatively, 4 (17%) had evoked seizures that disrupted language mapping; these patients were no more likely to show postoperative language declines relative to those who had no ESM disruption (p=0.26). Results suggest that evoked seizures occur frequently during ESM and can disrupt the procedure; however, these events do not appear to adversely affect postoperative outcomes. Nevertheless, attempts should be made to limit stimulation-evoked seizures in order to reduce patient discomfort, increase efficiency, and maximize the utility of ESM.

Advances in radiofrequency ablation of the cerebral cortex in primates using the venous system: Improvements for treating epilepsy with catheter ablation technology

BACKGROUND

Pharmacology frequently fails for the treatment of epilepsy. Although surgical techniques are effective, these procedures are highly invasive. We describe feasibility and efficacy of minimally invasive mapping and ablation for the treatment of epilepsy.

METHODS

Mapping and radiofrequency ablations were performed via the venous system in eleven baboons and three dogs.

RESULTS

Mapping in deep cerebral areas was obtained in all animals. High-frequency pacing was able to induce seizure activity of local cerebral tissue in 72% of our attempts. Cerebral activity could be seen during mapping. Ablative lesions were deployed at deep brain sites without steam pops or sudden impedance rise. Histologic analysis showed necrosis at the sites of ablation in all primates.

CONCLUSION

Navigation through the cerebral venous system to map seizure activity is feasible. Radiofrequency energy can be delivered transvenously or transcortically to successfully ablate cortical tissue in this animal model using this innovative approach.

The role of functional neuroimaging in pre-surgical epilepsy evaluation

The prevalence of epilepsy is about 1% and one-third of cases do not respond to medical treatment. In an eligible subset of patients with drug-resistant epilepsy, surgical resection of the epileptogenic zone is the only treatment that can possibly cure the disease. Non-invasive techniques provide information for the localization of the epileptic focus in the majority of cases, whereas in others invasive procedures are required. In the last years, non-invasive neuroimaging techniques, such as simultaneous recording of functional magnetic resonance imaging and electroencephalogram (EEG-fMRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), electric and magnetic source imaging (MSI, ESI), spectroscopy (MRS), have proved their usefulness in defining the epileptic focus. The combination of these functional techniques can yield complementary information and their concordance is crucial for guiding clinical decision, namely the planning of invasive EEG recordings or respective surgery. The aim of this review is to present these non-invasive neuroimaging techniques, their potential combination, and their role in the pre-surgical evaluation of patients with pharmaco-resistant epilepsy.

Health-related quality of life, mood, and patient satisfaction after epilepsy surgery in Sweden--a prospective controlled observational study

Objective

To evaluate health-related quality of life (HRQOL), mood, and patient satisfaction in epilepsy surgery candidates before and 2 years after epilepsy surgery or presurgical investigation.

Methods

In this prospective study of 141 patients, 96 underwent surgery and 45 did not. Questionnaires at baseline and at 2-year follow-up included the generic 36-item Short Form Health Survey (SF-36), the Hospital Anxiety and Depression scale (HAD), and operated patients answered patient satisfaction questions. SF-36 scores were compared with scores from a matched sample from the Swedish norm population. Numbers were calculated of patients achieving a minimum important change (MIC) in the SF-36 Physical Composite Summary (PCS) and Mental Composite Summary (MCS).

Results

At baseline, patients had significantly lower values than the norm on all SF-36 domains. At follow-up, operated patients were divided into seizure-free (International League Against Epilepsy [ILAE] class 1 and 2, n = 53) or with continued seizures (n = 43). No differences in baseline HAD or SF-36 values were found between these groups. Seizure-free patients reached the same levels as the norm in all SF-36 domains except Social Function. Operated patients with continued seizures and nonoperated patients had unchanged scores. Fifty-one percent of seizure-free patients had an improvement reaching MIC for PCS and 45% for MCS. Corresponding results for patients with continued seizures were 28% in PCS and 28% in MCS, for nonoperated 33% in PCS and 29% in MCS. HAD anxiety scores improved significantly in only the seizure-free patients. Of all operated patients, 80% were satisfied with having had surgery and 86% considered that they had benefited, whereas 20% thought that surgery caused some harm.

Significance

In patients who were seizure-free after epilepsy surgery HRQOL normalized and anxiety decreased. Operated patients overwhelmingly considered epilepsy surgery to be beneficial. Nonetheless, only about half of the seizure-free patients achieved important HRQOL improvements, suggesting that seizure freedom does not in and of itself guarantee improved patient well-being.

The role of functional neuroimaging in pre-surgical epilepsy evaluation

The prevalence of epilepsy is about 1% and one-third of cases do not respond to medical treatment. In an eligible subset of patients with drug-resistant epilepsy, surgical resection of the epileptogenic zone is the only treatment that can possibly cure the disease. Non-invasive techniques provide information for the localization of the epileptic focus in the majority of cases, whereas in others invasive procedures are required. In the last years, non-invasive neuroimaging techniques, such as simultaneous recording of functional magnetic resonance imaging and electroencephalogram (EEG-fMRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), electric and magnetic source imaging (MSI, ESI), spectroscopy (MRS), have proved their usefulness in defining the epileptic focus. The combination of these functional techniques can yield complementary information and their concordance is crucial for guiding clinical decision, namely the planning of invasive EEG recordings or respective surgery. The aim of this review is to present these non-invasive neuroimaging techniques, their potential combination, and their role in the pre-surgical evaluation of patients with pharmaco-resistant epilepsy.

Trace element, oxidant, and antioxidant enzyme values in blood of children with refractory epilepsy

PURPOSE

The aim of this study is to evaluate the serum levels of some trace elements, oxidants, and antioxidants in children with intractable epilepsy compared to healthy children.

PATIENTS AND METHODS

In a case-control study, 40 children (24 males and 16 females) suffering from refractory generalized epileptic seizures were compared with 40 sex- and age-matched healthy children serve as a control group. Serum selenium (Se), zinc (Zn), copper (Cu), and plasma malondialdehyde (MDA) as well as erythrocyte glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) values were measured in the patients and controls.

RESULTS

Plasma MDA values of the patient group were significantly ( p < 0.001) higher than those in control. Serum Zn, Se, and erythrocyte GSH-Px values of the patient group are significantly ( p < 0.001) lower than those in control, although there is no statistical difference in Cu and SOD values.

CONCLUSION

Plasma MDA, erythrocyte GSH-Px, and trace elements Zn and Se may play an important role in the pathogenesis of intractable epilepsy in children.

Two-year seizure reduction in adults with medically intractable partial onset epilepsy treated with responsive neurostimulation: final results of the RNS System Pivotal trial

OBJECTIVE

To demonstrate the safety and effectiveness of responsive stimulation at the seizure focus as an adjunctive therapy to reduce the frequency of seizures in adults with medically intractable partial onset seizures arising from one or two seizure foci.

METHODS

Randomized multicenter double-blinded controlled trial of responsive focal cortical stimulation (RNS System). Subjects with medically intractable partial onset seizures from one or two foci were implanted, and 1 month postimplant were randomized 1:1 to active or sham stimulation. After the fifth postimplant month, all subjects received responsive stimulation in an open label period (OLP) to complete 2 years of postimplant follow-up.

RESULTS

All 191 subjects were randomized. The percent change in seizures at the end of the blinded period was -37.9% in the active and -17.3% in the sham stimulation group (p = 0.012, Generalized Estimating Equations). The median percent reduction in seizures in the OLP was 44% at 1 year and 53% at 2 years, which represents a progressive and significant improvement with time (p < 0.0001). The serious adverse event rate was not different between subjects receiving active and sham stimulation. Adverse events were consistent with the known risks of an implanted medical device, seizures, and of other epilepsy treatments. There were no adverse effects on neuropsychological function or mood.

SIGNIFICANCE

Responsive stimulation to the seizure focus reduced the frequency of partial-onset seizures acutely, showed improving seizure reduction over time, was well tolerated, and was acceptably safe. The RNS System provides an additional treatment option for patients with medically intractable partial-onset seizures.

Temporal lobectomy with delayed amnesia following a new lesion on the other side

PURPOSE

To describe a delayed severe complication of temporal lobectomy for intractable epilepsy.

METHOD

A case of amnesia occurring 24 years after surgery is described and five similar cases from the literature reviewed.

RESULTS

Mean age at surgery (5 right) was 40 years (19-62 years), 3 female. Four of five tested had impaired visual and verbal memory preoperatively but not sufficient to contraindicate surgery. Pathology was mesial temporal sclerosis in 3, 1 cavernoma, 1 dysembryoplastic neuroepithelial tumor (DNET) and 1 normal. Postoperatively, four were seizure free 3-12 years off medication and two continued with seizures. There was no unexpected postoperative memory change until incapacitating anterograde amnesia developed 1-24 years after surgery. In five patients, including ours, this followed definite or possible status epilepticus with new mesial temporal sclerosis on the opposite side in the four that were investigated by MRI. One patient developed a glioblastoma in the opposite temporal lobe.

CONCLUSION

Continuing or late recurrence of seizures from the remaining temporal lobe after temporal lobectomy can result in incapacitating amnesia if status epilepticus occurs. Other new lesions on the opposite side to surgery can have the same effect.

Rates and predictors of seizure freedom in resective epilepsy surgery: an update

Epilepsy is a debilitating neurological disorder affecting approximately 1 % of the world's population. Drug-resistant focal epilepsies are potentially surgically remediable. Although epilepsy surgery is dramatically underutilized among medically refractory patients, there is an expanding collection of evidence supporting its efficacy which may soon compel a paradigm shift. Of note is that a recent randomized controlled trial demonstrated that early resection leads to considerably better seizure outcomes than continued medical therapy in patients with pharmacoresistant temporal lobe epilepsy. In the present review, we provide a timely update of seizure freedom rates and predictors in resective epilepsy surgery, organized by the distinct pathological entities most commonly observed. Class I evidence, meta-analyses, and individual observational case series are considered, including the experiences of both our institution and others. Overall, resective epilepsy surgery leads to seizure freedom in approximately two thirds of patients with intractable temporal lobe epilepsy and about one half of individuals with focal neocortical epilepsy, although only the former observation is supported by class I evidence. Two common modifiable predictors of postoperative seizure freedom are early operative intervention and, in the case of a discrete lesion, gross total resection. Evidence-based practice guidelines recommend that epilepsy patients who continue to have seizures after trialing two or more medication regimens should be referred to a comprehensive epilepsy center for multidisciplinary evaluation, including surgical consideration.

Patient satisfaction with temporal lobectomy/selective amygdalohippocampectomy for temporal lobe epilepsy and its relationship with Engel classification and the side of lobectomy

PURPOSE

The aim of this study was to investigate not only the effectiveness of epilepsy surgery in improving seizure control but also patient satisfaction with the result of the procedure in a sample of patients operated on at a specialized epilepsy unit.

METHODS

Patients with temporal lobe epilepsy who had undergone epilepsy surgery (temporal lobectomy/amygdalohippocampectomy) were interviewed in a standardized telephone survey about their satisfaction with the results of the surgery. The morbidity of the surgery was also analyzed retrospectively. The initial study population consisted of 6 amygdalohippocampectomy and 102 temporal lobectomy patients and was reduced to a final sample consisting of 4 amygdalohippocampectomy and 67 lobectomy patients, as the other patients were not available for interview. Surgical results were based on the Engel classification, and satisfaction with the surgery was assessed by asking patients to rate their result and state whether they would make the same decision (to be operated on) again.

RESULTS

A significant number of patients classified as Engel I or II, who considered the surgical outcome good or excellent, said they would have the surgery again (p<0.001). Left temporal lobectomy patients whose results fell in the Engel III/IV bracket were less satisfied (p=0.001) than right temporal lobectomy patients with the same Engel classifications (0.048). Left temporal lobectomy patients who were classified as Engel class III and IV were less likely to have the surgery again if they had the choice (p=0.016).

DISCUSSION

Patient satisfaction with the results of epilepsy surgery may depend not only on achieving seizure control but also on the temporal lobe resected. Since worse results were associated with lower satisfaction rates only for left temporal resection patients, it is possible that the cognitive consequences of this procedure compound the worse surgical result, leading to decreased satisfaction.

Epilepsy surgery series: a study of 502 consecutive patients from a developing country

Purpose. To review the postoperative seizure outcomes of patients that underwent surgery for epilepsy at King Faisal Specialist Hospital & Research Centre (KFSHRC). Methods. A descriptive retrospective study for 502 patients operated on for medically intractable epilepsy between 1998 and 2012. The surgical outcome was measured using the ILAE criteria. Results. The epilepsy surgery outcome for temporal lobe epilepsy surgery (ILAE classes 1, 2, and 3) at 12, 36, and 60 months is 79.6%, 74.2%, and 67%, respectively. The favorable 12- and 36-month outcomes for frontal lobe epilepsy surgery are 62% and 52%, respectively. For both parietal and occipital epilepsy lobe surgeries the 12- and 36-month outcomes are 67%. For multilobar epilepsy surgery, the 12- and 36-month outcomes are 65% and 50%, respectively. The 12- and 36-month outcomes for functional hemispherectomy epilepsy surgery are 64.2% and 63%, respectively. According to histopathology diagnosis, mesiotemporal sclerosis (MTS) and benign CNS tumors had the best favorable outcome after surgery at 1 year (77.27% and 84.3%, resp.,) and 3 years (76% and 75%, resp.,). The least favorable seizure-free outcome after 3 years occurred in cases with dual pathology (66.6%). Thirty-four epilepsy patients with normal magnetic resonance imaging (MRI) brain scans were surgically treated. The first- and third-year epilepsy surgery outcome of 17 temporal lobe surgeries were (53%) and (47%) seizure-free, respectively. The first- and third-year epilepsy surgery outcomes of 15 extratemporal epilepsy surgeries were (47%) and (33%) seizure-free. Conclusion. The best outcomes are achieved with temporal epilepsy surgery, mesial temporal sclerosis, and benign CNS tumor. The worst outcomes are from multilobar surgery, dual pathology, and normal MRI.

The role of high-frequency oscillations in epilepsy surgery planning

BACKGROUND

Epilepsy is a serious brain disorder characterized by recurrent unprovoked seizures. Approximately two-thirds of seizures can be controlled with antiepileptic medications (Kwan 2000). For some of the others, surgery can completely eliminate or significantly reduce the occurrence of disabling seizures. Localization of epileptogenic areas for resective surgery is far from perfect, and new tools are being investigated to more accurately localize the epileptogenic zone (the zone of the brain where the seizures begin) and improve the likelihood of freedom from postsurgical seizures. Recordings of pathological high-frequency oscillations (HFOs) may be one such tool.

OBJECTIVES

To assess the ability of HFOs to improve the outcomes of epilepsy surgery by helping to identify more accurately the epileptogenic areas of the brain.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialized Register (15 April 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2013, Issue 3), MEDLINE (Ovid) (1946 to 15 April 2013), CINAHL (EBSCOhost) (15 April 2013), Web of Knowledge (Thomson Reuters) (15 April 2013), www.clinicaltrials.gov (15 April 2013), and the World Health Organization International Clinical Trials Registry Platform (15 April 2013).

SELECTION CRITERIA

We included studies that provided information on the outcomes of epilepsy surgery at at least six months and which used high-frequency oscillations in making decisions about epilepsy surgery.

DATA COLLECTION AND ANALYSIS

The primary outcome of the review was the Engel Class Outcome System. Secondary outcomes were responder rate, International League Against Epilepsy (ILAE) epilepsy surgery outcome, frequency of adverse events from any source and quality of life outcomes. We intended to analyse outcomes via an aggregated data fixed-effect model meta-analysis.

MAIN RESULTS

Two studies met the inclusion criteria. Both studies were small non-randomised trials, with no control group and no blinding. The quality of evidence for all outcomes was very low. The combination of these two studies resulted in 11 participants who prospectively used ictal HFOs for epilepsy surgery decision making. Results of the postsurgical seizure freedom Engel class I to IV outcome were determined over a period of 12 to 38 months (average 23.4 months) and indicated that six participants had an Engel class I outcome (seizure freedom), two had class II (rare disabling seizures), three had class III (worthwhile improvement). No adverse effects were reported. Neither study compared surgical results guided by HFOs versus surgical results guided without HFOs.

AUTHORS' CONCLUSIONS

No reliable conclusions can be drawn regarding the efficacy of using HFOs in epilepsy surgery decision making at present.

Surgical treatment of epilepsy

PURPOSE OF REVIEW

This article outlines indications for neurosurgical treatment of epilepsy, describes the presurgical workup, summarizes surgical approaches, and details expected risks and benefits.

RECENT FINDINGS

There is class I evidence for the efficacy of temporal lobectomy in treating intractable seizures, and accumulating documentation that successful surgical treatment reverses much of the disability, morbidity, and excess mortality of chronic epilepsy.

SUMMARY

Chronic, uncontrolled focal epilepsy causes progressive disability and increased mortality, but these can be reversed with seizure control. Vigorous efforts to stop seizures are warranted. If two well-chosen and tolerated medication trials do not achieve seizure control, an early workup for epilepsy surgery should be arranged. If this workup definitively identifies the brain region from which the seizures arise, and this region can be removed with a low risk of disabling neurologic deficits, neurosurgery will have a much better chance of stopping seizures than further medication trials.

The significance of insular hypometabolism in temporal lobe epilepsy in children

BACKGROUND AND PURPOSE

Temporal lobe epilepsy is one of the most common forms of medically refractory epileptic syndromes. In a small percentage, temporal lobectomy fails to control the seizures in patients with epilepsy of clear temporal origin, and in some of these patients, seizures originating from the insular cortex is believed to be the cause behind the surgical failures. We retrospectively analyzed the [(18)F]FDG-positron emission tomography (PET) results of patients who received temporal lobe surgery for presence of insular hypometabolism, and compared the surgical outcome to verify whether insular hypometablism was related with difference in post-operative results.

METHODS

13 patients were enrolled, and clinical variables, post-operative pathology, magnetic resonance imaging and PET results were analyzed for possible differences between the patients with or without insular hypometabolism.

RESULTS

7 patients showed insular hypometabolism, while 6 patients were clear of insular lesion on PET exam. 8 patients received anterior temporal lobectomy with amygdalohippocampectomy (AH), 2 patients received radical temporal lobectomy with AH, and 3 patients received insular cortisectomy. Post-operative results were favorable in 8 patients and unfavorable in 5, with unfavorable outcomes in all recipients of insular cortisectomy. Presence of insular hypometabolism did not have any significant relationship with the post-surgical outcome (p=0.266), but its trend showed a tendency towards favorable outcome if insular hypometabolism was not present.

CONCLUSIONS

Presence of insular hypometabolism in [(18)F]FDG-PET analysis was not significantly correlated with the post-operative outcome, and recipients of insular cortisectomy among our patients with insular hypometabolism resulted in poor surgical outcome. However, the outcome trend showed a tendency towards better surgical outcome with absence of hypometabolic lesion in the ipsilateral insular cortex. Further studies employing a larger patient group is needed.

An evidence-based checklist to assess neuropsychological outcomes of epilepsy surgery: how good is the evidence?

PURPOSE

We aimed to assess the quality of evidence on neuropsychological outcomes after epilepsy surgery (ES). Accordingly, we created an evidence-based neuropsychology (EBNP) checklist to assess neuropsychological outcomes and applied this tool to studies from a systematic review.

METHODS

The EBNP checklist was created using clinical expert input, scale development methodology for item generation and reduction and inter-rater reliability, and critical appraisal guidelines for studies about treatment. The checklist was applied to articles obtained through a systematic review of resective ES neuropsychological outcomes. The proportion of studies fulfilling the quality criteria and the total quality score were used to assess the quality of the evidence.

RESULTS

An initial 45-item checklist was applied to 147 articles, with excellent inter-rater agreement (kappa=0.80). The mean quality score was 23 (SD: 4, range: 12-33). There was substantial variability in the percentage of studies meeting the criteria for specific items (0-99%). The median proportion of papers fulfilling various quality criteria was 1.4% for items related to group comparisons, 37% for clinical applicability, 67% for patient description, 78% for outcome assessment, and 91% for interventions. Higher quality correlated with longitudinal design, reporting presurgical IQ, seizure frequency and antiepileptic drugs, and using validated measures of change in individual patients. The final EBNP checklist consisted of 19 items.

DISCUSSION

The EBNP checklist reliably identified quality strengths and threats to validity of neuropsychological outcome studies in ES. Studies would be most improved by the inclusion of random allocation to interventions or at minimum blinded outcome assessment, empirically based measures of reliable change and completeness of reporting of follow-up.

Long-range neural activity evoked by premotor cortex stimulation: a TMS/EEG co-registration study

The premotor cortex is one of the fundamental structures composing the neural networks of the human brain. It is implicated in many behaviors and cognitive tasks, ranging from movement to attention and eye-related activity. Therefore, neural circuits that are related to premotor cortex have been studied to clarify their connectivity and/or role in different tasks. In the present work, we aimed to investigate the propagation of the neural activity evoked in the dorsal premotor cortex using transcranial magnetic stimulation/electroencephalography (TMS/EEG). Toward this end, interest was focused on the neural dynamics elicited in long-ranging temporal and spatial networks. Twelve healthy volunteers underwent a single-pulse TMS protocol in a resting condition with eyes closed, and the evoked activity, measured by EEG, was compared to a sham condition in a time window ranging from 45 ms to about 200 ms after TMS. Spatial and temporal investigations were carried out with sLORETA. TMS was found to induce propagation of neural activity mainly in the contralateral sensorimotor and frontal cortices, at about 130 ms after delivery of the stimulus. Different types of analyses showed propagated activity also in posterior, mainly visual, regions, in a time window between 70 and 130 ms. Finally, a likely “rebounding” activation of the sensorimotor and frontal regions, was observed in various time ranges. Taken together, the present findings further characterize the neural circuits that are driven by dorsal premotor cortex activation in healthy humans.

Non-pharmacological treatment options for refractory epilepsy: an overview of human treatment modalities and their potential utility in dogs

Refractory epilepsy is a common disorder both in humans and dogs and treatment protocols are difficult to optimise. In humans, different non-pharmacological treatment modalities currently available include surgery, the ketogenic diet and neurostimulation. Surgery leads to freedom from seizures in 50-75% of patients, but requires strict patient selection. The ketogenic diet is indicated in severe childhood epilepsies, but efficacy is limited and long-term compliance can be problematic. In the past decade, various types of neurostimulation have emerged as promising treatment modalities for humans with refractory epilepsy. Currently, none of these treatment options are used in routine daily clinical practice to treat dogs with the condition. Since many dogs with poorly controlled seizures do not survive, the search for alternative treatment options for canine refractory epilepsy should be prioritised. This review provides an overview of non-pharmacological treatment options for human refractory epilepsy. The current knowledge and limitations of these treatments in canine refractory epilepsy is also discussed.

Triple pathology in patients with temporal lobe epilepsy: A case report and review of the literature

The coexistence of three intracranial lesions related to epileptic pathogenesis is known as ‘triple pathology’ and has rarely been reported. In this study we report a case of temporal lobe epilepsy (TLE) with the coexistence of hippocampal sclerosis (HS), focal cortical dysplasia (FCD) and ganglioglioma in the temporal lobe. A 29-year-old male who had experienced recurrent seizures for four years was admitted to hospital. Cerebral magnetic resonance imaging (MRI) was conducted and T2-weighted and fluid-attenuated inversion recovery sequence (FLAIR) images revealed a reduced hippocampal volume with an increased FLAIR signal on the right side and a slightly enlarged temporal horn, which are typical imaging findings for HS and FCD. The patient underwent resectioning of the right anterior temporal lobe, hippocampus and amygdala, in addition to the lesion located in the medial temporal lobe. Immunohistochemical analysis of the medial temporal lobe lesion confirmed a ganglioglioma (WHO grade I) in the medial temporal lobe. During the first eight months following surgery, the patient's seizures were controlled with zonisamide and phenytoin. Electroencephalogram (EEG) assessment post-surgery confirmed the absence of epileptic discharges. Based on a literature review and a detailed review of this case, we postulate two possible explanations for the pathogenesis of ‘triple pathology’: i) ‘triple pathology’ is a combination of pathological progression and occasionality; and ii) ‘triple pathology’ lesions have similar pathological origins.

Presurgical connectome and postsurgical seizure control in temporal lobe epilepsy

OBJECTIVES

The objective of this study was to evaluate whether patients with surgically refractory medial temporal lobe epilepsy (MTLE) exhibit a distinct pattern of structural network organization involving the temporal lobes and extratemporal regions.

METHODS

We retrospectively studied 18 healthy controls and 20 patients with medication refractory unilateral MTLE who underwent anterior temporal lobectomy for treatment of seizures. Patients were classified as seizure-free or not seizure-free at least 1 year after surgery. The presurgical brain connectome was calculated through probabilistic connectivity from MRI-diffusion tensor imaging from 83 anatomically defined regions of interest encompassing the whole brain. The connectivity patterns were analyzed regarding group differences in regional connectivity and network graph properties.

RESULTS

Compared with controls, patients exhibited a decrease in connectivity involving ipsilateral thalamocortical regions, with a pathologic increase in ipsilateral medial temporal lobe, insular, and frontal connectivity. Among patients, those not seizure-free exhibited a higher connectivity between structures in 1) the ipsilateral medial and lateral temporal lobe, 2) the ipsilateral medial temporal and parietal lobe, and 3) the contralateral temporal pole and parietal lobe. Patients not seizure-free also exhibited lower small-worldness in the subnetwork within the ipsilateral temporal lobe, with higher subnetwork integration at the expense of segregation.

CONCLUSIONS

MTLE is associated with network rearrangement within, but not restricted to, the temporal lobe ipsilateral to the onset of seizures. Networks involving key components of the medial temporal lobe and structures traditionally not removed during surgery may be associated with seizure control after surgical treatment of MTLE.

Acceptance of epilepsy surgery in the pediatric age - what the parents think and what the doctors can do

Epilepsy surgery (ES) in pediatrics is safe and effective but can be underutilized. Possible barriers could be parental resistance and doctor inertia. We surveyed 138 parents of pediatric patients with epilepsy and found that 25.2% were opposed to this treatment. However, upon completing the questionnaire that contained factual information about ES, 50.4% of the responders stated that they had become more favorable vs. 3.3% more contrary and 46.3% unchanged. Parents of prepubescent patients were most receptive (p=0.0343) and more likely to shift to a more favorable attitude. Thus, pediatric neurologists should not hesitate to discuss ES as soon as indicated, providing all necessary information to increase acceptance. However, among 60 child neurologists surveyed, 60% did not fully comply with guidelines or follow accepted standards of practice, indicating that they may not be apt to provide proper parental guidance. We conclude that education of both practicing neurologists and parents is needed to facilitate the process.

Effects of temporal lobectomy on consciousness-impairing and consciousness-sparing seizures in children

PURPOSE

Most children with medically refractory temporal lobe epilepsy (TLE) become seizure free after temporal lobectomy, but some individuals continue to seize. As studies of temporal lobectomy typically focus on seizure freedom, the effect of surgery on seizure type and frequency among children with persistent seizures is poorly understood. Seizures which impair consciousness are associated with increased morbidity compared to consciousness-sparing seizures.

METHODS

A retrospective cohort study was performed to evaluate the effects of temporal lobectomy on seizure type and frequency in children with intractable TLE.

RESULTS

Among 58 pediatric TLE patients with a mean (±SEM) age of 14.0 ± 0.7 years who received temporal lobectomy, 46 (79.3%) individuals achieved an Engel class I seizure outcome, including 38 (65.5%) children who became completely seizure free (Engel IA). Mean follow-up was 2.7 ± 0.4 years. While the number of patients experiencing simple partial seizures (SPSs) (consciousness sparing) decreased by only 23 % after surgery, the number of children having complex partial seizures and generalized tonic-clonic seizures (consciousness impairing) diminished by 87 and 83%, respectively (p < 0.01). SPS was the predominant seizure type in only 11.3% of patients before resection, but in 42.1% of patients with postoperative seizures (p < 0.01). Children with postoperative seizures experienced a 70% reduction in overall seizure frequency compared to baseline (p < 0.05), having consciousness-impairing seizures 94% less frequently (p < 0.05), but having consciousness-sparing seizures 35% more frequently (p = 0.73).

CONCLUSIONS

Seizure type and frequency are important considerations in the medical and surgical treatment of children with epilepsy, although complete seizure freedom remains the ultimate goal.

Interleukin-1β secretion in hippocampal sclerosis patients with mesial temporal lobe epilepsy

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is a common medically intractable epilepsy syndrome. Although pathogenesis of HS still remains highly controversial, genetics may play a role as a predisposing factor. Previous evidence in a Japanese population revealed that the homozygotes for allele T at position -511 of the interleukin (IL)-1β gene promoter region (IL-1β-511 T/T) confers susceptibility to the development of HS. However, whether this polymorphism has an effect on IL-1β levels in MTLEHS patients was not demonstrated. This study aimed to analyze the distribution of this particular polymorphism in a group of Turkish HS patients and correlate the polymorphism with IL-1β secretion from the lymphocytes, thus revealing a functional role for IL-1β in the etiopathogenesis of HS. A single base pair polymorphism at position -511 in the promoter region of the IL-1β gene was analyzed. The spontaneous and 1 ng/mL lipopolysaccharidestimulated production of IL-1β by peripheral blood mononuclear cells after 4 and 24 h of incubation were measured by ELISA method. The heterozygous type (-511 C/T) was the most common genotype. There was no difference in frequency of allele -511 T between patients and controls. Analysis of IL-1β levels, genotype and allele distributions showed no significant difference among the groups (P>0.05). Nevertheless, it was seen that patients who carry a T allele at position -511 of the IL-1β gene had increased IL-1β levels. T-allele carriage may be important. Only IL-1β secretion from the lymphocytes has been assessed in this study. Considering the importance of IL-1β in the etiopathogenesis of HS, further studies are needed to evaluate locally produced IL-1β levels.

Why is there still doubt to cut it out?

Surgical treatment for epilepsy has made tremendous strides in the past few decades as a result of advances in neurodiagnostics-particularly structural and functional neuroimaging-and improved surgical techniques. This has not only resulted in better outcomes with respect to epileptic seizures and quality of life, and reduced surgical morbidity and mortality, but it has also increased the population of patients now considered as surgical candidates, particularly in the pediatric age range, and enhanced cost-effectiveness sufficient to make surgical treatment available to countries with limited resources. Yet surgical treatment for epilepsy remains arguably the most underutilized of all accepted medical interventions. In the United States, less than 1% of patients with pharmacoresistant epilepsy are referred to epilepsy centers. Although the number of epilepsy surgery centers has increased appreciably over the past two decades, the number of therapeutic surgical procedures performed for epilepsy has not increased at all. For patients who are referred, the average delay from onset of epilepsy to surgery is more than 20 years-too late for many to avoid a lifetime of disability or premature death. Not only has there been no consistent message to convince neurologists and primary care physicians to refer patients for surgery, but the increase in epilepsy surgery centers in the United States has appeared to result in a divergence of approaches to surgical treatment. Efforts are still needed to further improve the safety and efficacy of surgical treatment, including the identification of biomarkers that can reliably determine the extent of the epileptogenic region; however, the greatest benefits would derive from increasing access for potential surgical candidates to epilepsy surgery facilities. Information is needed to determine why appropriate surgical referrals are not being made. Consensus conferences are necessary to resolve controversies that still exist regarding presurgical evaluation and surgical approaches. Standards should be established for certifying epilepsy centers as recommended by the Institute of Medicine's report on epilepsy. Finally, the epilepsy community should not be promoting epilepsy surgery per se but instead emphasize that epilepsy centers do more than epilepsy surgery, promoting the message: All patients with disabling pharmacoresistant seizures deserve evaluation by specialists at epilepsy centers who can provide a variety of advanced diagnostic and therapeutic services.

Expression analysis and clinical correlation of aquaporin 1 and 4 genes in human hippocampal sclerosis

Mesial temporal sclerosis (MTS) is the most frequent cause of drug resistant symptomatic partial epilepsy. The mechanism and genetic background of this unique pathology are not well understood. Aquaporins (AQP) are regulators of water homeostasis in the brain and are expressed in the human hippocampus. We explored the role of AQP genes in the pathogenetic mechanisms of MTS through an evaluation of gene expression in surgically removed human brain tissue. We analyzed AQP1 and 4 mRNA levels by quantitative real-time polymerase chain reaction and normalized to ABL and cyclophilin genes, followed by immunohistochemistry for AQP4. Relative expressions were calculated according to the delta Ct method and the results were compared using the Mann-Whitney U test. Brain specimens of 23 patients with epilepsy who had undergone surgery for MTS and seven control autopsy specimens were investigated. Clinical findings were concordant with previous studies and 61% of the patients were seizure-free in the postoperative period. AQP1 and 4 gene expression levels did not differ between MTS patients and control groups. Immunofluorescence analysis of AQP4 supported the expression results, showing no difference. Previous studies have reported contradictory results about the expression levels of AQP in MTS. To our knowledge, only one study has suggested upregulation whereas the other indicated downregulation of perivascular AQP4. Our study did not support these findings and may rule out the involvement of AQP in human MTS.

Seizure outcomes after temporal lobectomy in pediatric patients

Temporal lobe epilepsy (TLE) is the most common form of epilepsy in adults and is responsible for 15%-20% of epilepsy cases in children. Class I evidence strongly supports the use of temporal lobectomy for intractable TLE in adults, but fewer studies have examined seizure outcomes and predictors of seizure freedom after temporal lobectomy in pediatric patients. The authors performed a systematic review and meta-analysis of studies including 10 or more pediatric patients (age ≤ 19 years) published over the last 20 years examining seizure outcomes after temporal lobectomy for TLE. Thirty-six studies met their inclusion criteria. These 36 studies included 1318 pediatric patients with a mean age (± SEM) of 10.7 ± 0.3 years. Overall, seizure freedom (Engel Class I outcome) was achieved in 1002 cases (76%); 316 patients (24%) continued to have seizures (Engel Class II-IV outcome). All patients had at least 1 year of follow-up. Statistically significant predictors of seizure freedom after surgery included lesional epilepsy etiology (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.02-1.15), abnormal findings on preoperative MRI (OR 1.27, 95% CI 1.16-1.40), and lack of generalized seizures (OR 1.36, 95% CI 1.20-1.56). Among lesional epilepsy cases, there was a trend toward better outcome with gross-total lesionectomy than with subtotal resection. Approximately three-fourths of pediatric patients with TLE attain seizure freedom after temporal lobectomy. Favorable outcomes may be predicted by lesional epilepsy etiology, abnormal MRI, and lack of generalized seizures. Pediatric patients with medically refractory TLE should be referred to a comprehensive pediatric epilepsy center for surgical evaluation.

Seizure outcomes after resective surgery for extra-temporal lobe epilepsy in pediatric patients

While temporal lobe epilepsy (TLE) is the most common epilepsy syndrome in adults, seizures in children are more often extratemporal in origin. Extra-temporal lobe epilepsy (ETLE) in pediatric patients is often medically refractory, leading to significantly diminished quality of life. Seizure outcomes after resective surgery for pediatric ETLE vary tremendously in the literature, given diverse patient and epilepsy characteristics and small sample sizes. The authors performed a systematic review and meta-analysis of studies including 10 or more pediatric patients (age ≤ 19 years) published over the last 20 years examining seizure outcomes after resective surgery for ETLE, excluding hemispherectomy. Thirty-six studies were examined. These 36 studies included 1259 pediatric patients who underwent resective surgery for ETLE. Seizure freedom (Engel Class I outcome) was achieved in 704 (56%) of these 1259 patients postoperatively, and 555 patients (44%) continued to have seizures (Engel Class II-IV outcome). Shorter epilepsy duration (≤ 7 years, the median value in this study) was more predictive of seizure freedom than longer (> 7 years) seizure history (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.07-2.14), suggesting that earlier intervention may be beneficial. Also, lesional epilepsy was associated with better seizure outcomes than nonlesional epilepsy (OR 1.34, 95% CI 1.19-1.49). Other predictors of seizure freedom included an absence of generalized seizures (OR 1.61, 95% CI 1.18-2.35) and localizing ictal electroencephalographic findings (OR 1.55, 95% CI 1.24-1.93). In conclusion, seizure outcomes after resective surgery for pediatric ETLE are less favorable than those associated with temporal lobectomy, but seizure freedom may be more common with earlier intervention and lesional epilepsy etiology. Children with continued debilitating seizures despite failure of multiple medication trials should be referred to a comprehensive pediatric epilepsy center for further medical and surgical evaluation.

Subclinical abnormal gyration pattern, a potential anatomic marker of epileptogenic zone in patients with magnetic resonance imaging-negative frontal lobe epilepsy

BACKGROUND

Epilepsy surgery for magnetic resonance imaging (MRI)-negative patients has a less favorable outcome.

OBJECTIVE

Detection of subclinical abnormal gyration (SAG) patterns and their potential contribution to assessment of the topography of the epileptogenic zone (EZ) is addressed in MRI-negative patients with frontal lobe epilepsy.

METHODS

Between September 1998 and July 2005, 12 MRI-negative frontal lobe epilepsy patients underwent stereoelectroencephalography with postcorticectomy follow-up of longer than 1 year (average, 3.3 years). Original software (BrainVISA/Anatomist, http://brainvisa.info) trained on a database of normal volunteers was used to determine which sulci had morphology out of the normal range (SAG). Topography of the EZ, SAG pattern, corticectomy, postoperative seizure control, and histopathology were analyzed.

RESULTS

At last follow-up, 8 of 12 patients (66.7%) were Engel class I (7 IA and 1 IB), 2 class II, and 2 class IV. Small focal cortical dysplasia was histologically diagnosed in 9 of the 12 patients (75%), including 7 of 8 seizure-free patients (87.5%). A SAG pattern was found to be in the EZ area in 9 patients (75%), in the ipsilateral frontal lobe out of the EZ in 2, and limited to the contralateral hemisphere in 1.

CONCLUSION

SAG patterns appear to be associated with the topography of the EZ in MRI-negative frontal lobe epilepsy and may have a useful role in preoperative assessment. Small focal cortical dysplasia not detected with MRI is often found on histopathological examination, particularly in the depth of the posterior part of the superior frontal sulcus and intermediate frontal sulcus, suggesting a specific developmental critical zone in these locations.

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.

Patient perceptions and barriers to epilepsy surgery: evaluation in a large health region

PURPOSE

Despite evidence that carefully selected patients with refractory focal epilepsy benefit from epilepsy surgery, significant delays remain. We examined patient knowledge and perceptions regarding epilepsy surgery.

METHODS

A 5-minute questionnaire was administered to consecutive adults with focal epilepsy seen in the epilepsy clinic in a large Canadian health region. Survey items assessed the following: (1) knowledge of surgical options, (2) perceptions about the risks of surgery vs. ongoing seizures, (3) disease disability, (4) treatment goals, and (5) demographic and socioeconomic variables. Patient responses were compiled to calculate a "Barriers to Epilepsy Surgery Composite" (BESC) score.

RESULTS

Of 129 eligible patients, 107 completed the questionnaire (response rate: 83%). The average BESC score was 60/100. Apprehension about epilepsy surgery was less likely among patients who had previously undergone epilepsy surgery and those born in Canada.

DISCUSSION

People with epilepsy often have hindering perceptions that can contribute to delays in surgical care.

Clinical practice guidelines and practice parameters for the child neurologist

Guidance about how to practice child neurology has been around for decades. Recently, however, clinical practice guidelines, practice parameters, and standardized clinical assessment and management plans are gaining increasing attention. This overview, written for child neurologists, addresses such issues as the following: what are clinical practice guidelines, why are they needed, how are they created, how should they be created, how well are they accepted and adhered to, what influences acceptance and adherence, do guidelines improve care, do they reduce costs, will they be viewed by courts as the standard of care, how can they be updated and improved, and are there better alternatives?