Does epilepsy surgery lower the mortality of drug-resistant epilepsy?

Sudden unexpected death in epilepsy during cenobamate clinical development

OBJECTIVE

We assessed mortality, sudden unexpected death in epilepsy (SUDEP), and standardized mortality ratio (SMR) among adults treated with cenobamate during the cenobamate clinical development program.

METHODS

We retrospectively analyzed deaths among all adults with uncontrolled focal (focal to bilateral tonic-clonic [FBTC], focal impaired awareness, focal aware) or primary generalized tonic-clonic (PGTC) seizures who received ≥1 dose of adjunctive cenobamate in completed and ongoing phase 2 and 3 clinical studies. In patients with focal seizures from completed studies, median baseline seizure frequencies ranged from 2.8 to 11 seizures per 28 days and median epilepsy duration ranged from 20 to 24 years. Total person-years included all days that a patient received cenobamate during completed studies or up to June 1, 2022, for ongoing studies. All deaths were evaluated by two epileptologists. All-cause mortality and SUDEP rates were expressed per 1000 person-years.

RESULTS

A total of 2132 patients (n = 2018 focal epilepsy; n = 114 idiopathic generalized epilepsy) were exposed to cenobamate for 5693 person-years. Approximately 60% of patients with focal seizures and all patients in the PGTC study had tonic-clonic seizures. A total of 23 deaths occurred (all in patients with focal epilepsy), for an all-cause mortality rate of 4.0 per 1000 person-years. Five cases of definite or probable SUDEP were identified, for a rate of .88 per 1000 person-years. Of the 23 overall deaths, 22 patients (96%) had FBTC seizures, and all 5 of the SUDEP patients had a history of FBTC seizures. The duration of exposure to cenobamate for patients with SUDEP ranged from 130 to 620 days. The SMR among cenobamate-treated patients in completed studies (5515 person-years of follow-up) was 1.32 (95% confidence interval [CI] .84-2.0), which was not significantly different from the general population.

SIGNIFICANCE

These data suggest that effective long-term medical treatment with cenobamate may reduce excess mortality associated with epilepsy.

Association Between Standardized Mortality Ratio and Utilization of Care in US Veterans With Drug-Resistant Epilepsy Compared With All US Veterans and the US General Population

Importance

Drug-resistant epilepsy (DRE) is thought to be associated with increased mortality, but larger population-based studies are lacking. Additionally, the benefit of effective management in DRE lacks evidence.

Objective

To examine the association of utilization of care with mortality in US veterans with DRE.

Design, Setting, and Participants

Observational cohort study conducted between October 1, 2013, and March 31, 2020. Mortality statistics in US veterans with DRE were compared to the US general population and all veterans within the Veterans Health Administration. Epilepsy was defined as use of 1 or more antiseizure medications (ASMs) for 30 days or longer with a seizure diagnosis or 1 inpatient or 2 outpatient encounters with an epilepsy diagnosis. DRE was defined as the use of 2 or more ASMs. Among 9.6 million US veterans, 164 435 (1.7%) had epilepsy, of whom 55 571 (33.8%) had DRE. Epilepsy and DRE were administratively identified based on criteria noted in design. Identified participants were included for analysis.

Exposures

Veterans with DRE.

Main Outcomes and Measures

Standardized mortality ratio (SMR).

Results

Among US veterans with DRE, the mean (SD) age was 58.3 (15.4) years, and 49 430 individuals (88.9%) were male. Of ethnicity data gathered, 3170 individuals (5.7%) were Hispanic or Latino, 50 599 (91.1%) were not Hispanic or Latino, 842 (1.5%) declined to answer, and 960 (1.7%) were recorded as unknown. Of race data gathered, 516 individuals (0.9%) were American Indian or Alaskan Native, 270 (0.5%) were Asian, 11 316 (20.4%) were Black or African American, 587 (1.1%) were of multiple races, 453 (0.8%) were Native Hawaiian or Pacific Islander, 39 543 (71.2%) were White, 1697 (3.1%) declined to answer, and 1189 (2.1%) were recorded as unknown. SMR was 1.50 (95% CI, 1.47-1.53) compared with the US general population and 1.56 (95% CI, 1.53-1.59) compared with all veterans. Utilization rates were 81.1% (n = 45 057) for neurology clinic evaluation, 66.4% (n = 36 905) for magnetic resonance imaging (MRI), and 49.6% (n = 27 546) for electroencephalography (EEG) testing. Only 8350 individuals (15.0%) had comprehensive epilepsy evaluations and 3357 (6.0%) had epilepsy monitoring. Multivariable analysis revealed an association between lower mortality and neurology clinic evaluation, EEG, MRI, epilepsy monitoring, and the use of more than 2 ASMs after adjusting for age and comorbidities.

Conclusions and Relevance

Mortality rates were significantly higher in US veterans with DRE compared to the general population. Better utilization of comprehensive epilepsy care, diagnostic services, and medications were each associated with reduced mortality. These findings indicate that appropriate management of DRE is critical in this population.

Autonomic manifestations of epilepsy: emerging pathways to sudden death?

Epileptic networks are intimately connected with the autonomic nervous system, as exemplified by a plethora of ictal (during a seizure) autonomic manifestations, including epigastric sensations, palpitations, goosebumps and syncope (fainting). Ictal autonomic changes might serve as diagnostic clues, provide targets for seizure detection and help us to understand the mechanisms that underlie sudden unexpected death in epilepsy (SUDEP). Autonomic alterations are generally more prominent in focal seizures originating from the temporal lobe, demonstrating the importance of limbic structures to the autonomic nervous system, and are particularly pronounced in focal-to-bilateral and generalized tonic-clonic seizures. The presence, type and severity of autonomic features are determined by the seizure onset zone, propagation pathways, lateralization and timing of the seizures, and the presence of interictal autonomic dysfunction. Evidence is mounting that not all autonomic manifestations are linked to SUDEP. In addition, experimental and clinical data emphasize the heterogeneity of SUDEP and its infrequent overlap with sudden cardiac death. Here, we review the spectrum and diagnostic value of the mostly benign and self-limiting autonomic manifestations of epilepsy. In particular, we focus on presentations that are likely to contribute to SUDEP and discuss how wearable devices might help to prevent SUDEP.

The Transient Receptor Potential Melastatin 7 (TRPM7) Inhibitors Suppress Seizure-Induced Neuron Death by Inhibiting Zinc Neurotoxicity

Transient receptor potential melastatin 7 (TRPM7) is an ion channel that mediates monovalent cations out of cells, as well as the entry of divalent cations, such as zinc, magnesium, and calcium, into the cell. It has been reported that inhibitors of TRPM7 are neuroprotective in various neurological diseases. Previous studies in our lab suggested that seizure-induced neuronal death may be caused by the excessive release of vesicular zinc and the subsequent accumulation of zinc in the neurons. However, no studies have evaluated the effects of carvacrol and 2-aminoethoxydiphenyl borate (2-APB), both inhibitors of TRPM7, on the accumulation of intracellular zinc in dying neurons following seizure. Here, we investigated the therapeutic efficacy of carvacrol and 2-APB against pilocarpine-induced seizure. Carvacrol (50 mg/kg) was injected once per day for 3 or 7 days after seizure. 2-APB (2 mg/kg) was also injected once per day for 3 days after seizure. We found that inhibitors of TRPM7 reduced seizure-induced TRPM7 overexpression, intracellular zinc accumulation, and reactive oxygen species production. Moreover, there was a suppression of oxidative stress, glial activation, and the blood–brain barrier breakdown. In addition, inhibitors of TRPM7 remarkably decreased apoptotic neuron death following seizure. Taken together, the present study demonstrates that TRPM7-mediated zinc translocation is involved in neuron death after seizure. The present study suggests that inhibitors of TRPM7 may have high therapeutic potential to reduce seizure-induced neuron death.

Learnings from 30 years of reported efficacy and safety of vagus nerve stimulation (VNS) for epilepsy treatment: A critical review

Three decades after its introduction as an adjuvant therapeutic option in the management of selective drug-resistant epilepsy cases (DRE), vagus nerve stimulation (VNS) retains growing interest. An implantable device was first approved for epilepsy in Europe in 1994 and in the United States (US) in 1997. Subsequent modifications improved the safety and the efficacy of the system. The most recent application of vagal neurostimulation is represented by transcutaneous devices that are claimed to have strong therapeutic potential. In this review, we sought to analyze the most meaningful available data describing the indications, safety and efficacy of the different approaches of VNS in clinical practice. Therefore, we identified studies reporting VNS efficacy and/or safety in epilepsy and its comorbidities from January 1990 to February 2020 from various databases including PubMed, Scopus, Cochrane, US government databases and VNS manufacturer published resources. In general, VNS efficacy becomes optimal around the sixth month of treatment and a 50-100 % seizure frequency reduction is achieved in approximately 45-65 % of the patients. However, some clinically relevant differences have been reported with specific factors such as epilepsy etiology or type, patient age as well as the delay of VNS therapy onset. VNS efficacy on seizure frequency has been demonstrated in both children and adults, in lesional and non-lesional cases, in focal and generalized epilepsies, on both seizures and epilepsy comorbidities. Regarding the latter, VNS can lead to an improvement of about 25-35 % in depression scores, 35 % in anxiety scores and 25 % in mood assessment scores. If non-invasive devices are undeniably safer, their efficacy is limited due to the scarcity of large cohort studies and the disparity of methodological approaches (study design and stimulation parameters). Overall, we believe that there is a progress margin for improving the safety of implantable devices and, above all, the effectiveness of the various VNS approaches.

Can We Prevent Sudden Unexpected Death in Epilepsy (SUDEP)?

Sudden unexpected death in epilepsy (SUDEP) remains an important cause of epilepsy-related mortality, especially in patients with refractory epilepsy. The exact cause is not known, but postictal cardiac, respiratory, and brainstem dysfunctions are implicated. SUDEP prevention remains a big challenge. Except for low-quality evidence of preventive effect of nocturnal supervision for SUDEP, no other evidence-based preventive modality is available. Other potential preventive strategies for SUDEP include reducing the occurrence of generalized tonic-clonic seizures using seizure detection devices, detecting cardiorespiratory distress through respiratory and heart rate monitoring devices, preventing airway obstruction (safety pillows), and reducing central hypoventilation using selective serotonin reuptake inhibitors and adenosine and opiate antagonists. However, none of the above-mentioned modalities has been proven to prevent SUDEP. The present review intends to provide insight into the available SUDEP prevention modalities.

Epilepsy surgery in low- and middle-income countries: A scoping review

BACKGROUND

Epilepsy surgery is an important treatment option for people with drug-resistant epilepsy. Surgical procedures for epilepsy are underutilized worldwide, but it is far worse in low- and middle-income countries (LMIC), and it is less clear as to what extent people with drug-resistant epilepsy receive such treatment at all. Here, we review the existing evidence for the availability and outcome of epilepsy surgery in LMIC and discuss some challenges and priority.

METHODS

We used an accepted six-stage methodological framework for scoping reviews as a guide. We searched PubMed, Embase, Global Health Archives, Index Medicus for South East Asia Region (IMSEAR), Index Medicus for Eastern Mediterranean Region (IMEMR), Latin American & Caribbean Health Sciences Literature (LILACS), African Journal Online (AJOL), and African Index Medicus (AIM) to identify the relevant literature.

RESULTS

We retrieved 148 articles on epilepsy surgery from 31 countries representing 22% of the 143 LMIC. Epilepsy surgery appears established in some of these centers in Asia and Latin America while some are in their embryonic stage reporting procedures in a small cohort performed mostly by motivated neurosurgeons. The commonest surgical procedure reported was temporal lobectomies. The postoperative seizure-free rates and quality of life (QOL) are comparable with those in the high-income countries (HIC). Some models have shown that epilepsy surgery can be performed within a resource-limited setting through collaboration with international partners and through the use of information and communications technology (ICT). The cost of surgery is a fraction of what is available in HIC.

CONCLUSION

This review has demonstrated the availability of epilepsy surgery in a few LMIC. The information available is inadequate to make any reasonable conclusion of its existence as routine practice. Collaborations with international partners can provide an opportunity to bring high-quality academic training and technological transfer directly to surgeons working in these regions and should be encouraged.

[Surgical treatment patients with drug-resistant unilateral MRI-positive temporal forms of epilepsy]

AIM

To evaluate the results of surgical treatment of patients with unilateral MRI-positive temporal forms of drug-resistant epilepsy.

MATERIAL AND METHODS

A prospective analysis of 50 patients with unilateral MRI-positive temporal forms of drug-resistant epilepsy, who had undergone resective surgery in the Scientific Research Institute of Emergency Medicine of N.V. Sklifosovsky (Moscow) and in University Clinic of Moscow State University of Medicine and Dentistry between 01.01.14 and 12.12.17, has been performed. MRI-positive temporal symptomatic epilepsy was identified in 79 (55%) patients. MRI results showed unilateral temporal epileptogenic lesions in 50 (67%) patients. These patients were assigned to medial frontal lobectomy.

RESULTS

82% patients become 'seizure free' 12 and 24 months after surgical treatment. In other cases, seizures become less frequent and severe.

CONCLUSION

The results confirm the efficacy and safety of surgical treatment of drug-resistant MRI-positive temporal forms of epilepsy.

[Outcomes of surgical treatment of patients with pharmacoresistant epilepsy]

AIM

To evaluate the results of surgical treatment of patients with pharmacoresistant epilepsy.

MATERIAL AND METHODS

Examination and surgical treatment of 61 patients with pharmacoresistant forms of symptomatic epilepsy were performed from 01.01.14 to 01.05.16.

RESULTS AND CONCLUSION

The results confirmed the safety and efficacy of the surgical treatment of pharmacoresistant epilepsy. After 12 months, seizures were controlled in 69% of operated patients. The necessity of complex examination of all patients with pharmacoresistant epilepsy to make a decision about possible surgery is shown.

Temporal lobe epilepsy in patients with nonlesional MRI and normal memory: an SEEG study

OBJECT

Temporal lobe epilepsy (TLE) in the absence of MRI abnormalities and memory deficits is often presumed to have an extramesial or even extratemporal source. In this paper the authors report the results of a comprehensive stereoelectroencephalography (SEEG) analysis in patients with TLE with normal MRI images and memory scores.

METHODS

Eighteen patients with medically refractory epilepsy who also had unremarkable MR images and normal verbal and visual memory scores on neuropsychological testing were included in the study. All patients had seizure semiology and video electroencephalography (EEG) findings suggestive of TLE. A standardized SEEG investigation was performed for each patient with electrodes implanted into the mesial and lateral temporal lobe, temporal tip, posterior temporal neocortex, orbitomesiobasal frontal lobe, posterior cingulate gyrus, and insula. This information was used to plan subsequent surgical management.

RESULTS

Interictal SEEG abnormalities were observed in the mesial temporal structures in 17 patients (94%) and in the temporal tip in 6 (33%). Seizure onset was exclusively from mesial structures in 13 (72%), exclusively from lateral temporal cortex and/or temporal tip structures in 2 (11%), and independently from mesial and neocortical foci in 3 (17%). No seizure activity was observed arising from any extratemporal location. All patients underwent surgical intervention targeting the temporal lobe and tailored to the SEEG findings, and all experienced significant improvement in seizure frequency with a postoperative follow-up observation period of at least 1 year.

CONCLUSIONS

This study demonstrates 3 important findings: 1) normal memory does not preclude mesial temporal seizure onset; 2) onset of seizures exclusively from mesial temporal structures without early neocortical involvement is common, even in the absence of memory deficits; and 3) extratemporal seizure onset is rare when video EEG and semiology are consistent with focal TLE.

Outcome of lesionectomy in medically refractory epilepsy due to non-mesial temporal sclerosis (non-MTS) lesions

OBJECTIVES

To analyze the seizure outcome of lesionectomy for refractory epilepsy secondary to non-mesial temporal sclerosis (non-MTS) lesions.

METHODS

Sixty-eight patients with non-MTS lesions (M:F=42:26; age at onset: 11.7±9.6 years; age at surgery: 21.1±9.4 years), who underwent lesionectomy for refractory epilepsy were analyzed. The age at onset, frequency/type of seizure, MRI findings, video-EEG, histopathology and Engel's grading at 1 year/last follow up were recorded.

RESULTS

The duration of epilepsy at surgery was 9.9±6.9 years. The location of lesions were: temporal: 41 (60.3%); frontal: 21 (30.9%); parietal: 6 (8.8%). The type of lesionectomies performed were temporal 41 (60.3%), extra-temporal: 25 (36.8%), temporo-frontal and temporo-parietal: 1 (1.5%) patient each. The histopathological diagnosis were neoplastic: 32 (47.1%), cortical dysplasia: 19 (27.9%), other focal lesions: 17 (25%). At mean follow up of 2.9±2.1 years (median: 2.6 years), outcome was - Engel's class I: 43 (63.2%), IIa: 14 (20.6%), III: 7 (10.3%), IV: 4 (5.9%). Good seizure control (Engel's class I/IIa) was achieved in 57 (83.8%) patients. The good prognostic markers included temporal seizures, extended lesionectomy and AEDs after surgery while poor prognostic marker was gliotic lesion on histopathology.

CONCLUSION

Following lesionectomy due to non-MTS lesions, seizure freedom (Engel I) was noted in about 63.2% of patients, which is comparable to other series and reiterates the effectiveness of lesionectomy for seizure control.

Prevention of sudden unexpected death in epilepsy: a realistic goal?

Sudden unexpected death in epilepsy (SUDEP) represents one of the most severe consequences of drug-resistant epilepsy, for which no evidence-based prevention is available. Development of effective prevention will depend on the following: (1) better understanding of the pathophysiology of SUDEP to define the most appropriate targets of intervention, and (2) identification of risk factors for SUDEP that would allow for the design of feasible clinical trials to test targeted interventions in high-risk populations. The most important known risk factor is the occurrence and frequency of generalized tonic-clonic seizure (GTCS), a seizure type that triggers the majority of witnessed SUDEP. Therefore, one likely way to prevent SUDEP is to minimize the risk of GTCS with optimal medical management and patient education. However, whether one might prevent SUDEP in patients with refractory epilepsy by using more frequent review of antiepileptic treatment and earlier referral for presurgical evaluation, remains to be seen. Another hypothetical strategy to prevent SUDEP is to reduce the risk of GTCS-induced postictal respiratory distress. This might be achieved by using lattice pillow, providing nocturnal supervision, reinforcing interictal serotoninergic tone, and lowering opiate- or adenosine-induced postictal brainstem depression. Promising interventions can be tested first on surrogate markers, such as postictal hypoxia in epilepsy monitoring units (EMUs), before SUDEP trials can be implemented. EMU safety should also be improved to avoid SUDEP occurrence in that setting. Finally, the development of ambulatory SUDEP prevention devices should be encouraged but raises a number of unsolved issues.

A Novel Postoperative Seizure Classification for Long-term Mortality of Patients With Intractable Epilepsy: Comparison With the Engel System

BACKGROUND:

To explore the association of clinical seizure pattern with the long-term prognosis after epilepsy surgery is important for patient counseling and risk management.

OBJECTIVE:

To study the long-term mortality after surgery of intractable epilepsy patients with a novel classification of clinical patterns by long-term frequency and duration of seizure compared with the Engel classification.

METHODS:

We conducted a longitudinal cohort study by enrolling 280 patients with epilepsy who underwent anterior temporal lobectomy between 1987 and 2002. In addition to the Engel classification, we proposed a novel classification of clinical patterns pertaining to at least 1 year of follow-up of the frequency and duration of seizures after surgery (inactive, delayed, intermittent, and intensive groups). We followed the vital status of these members until 2007 to obtain a 15-year survival rate for each classification. The standardized mortality ratio and hazard ratios with proportional hazards regression model by the extent of severity were estimated.

RESULTS:

The overall 15-year survival rate for patients who underwent anterior temporal lobectomy was 95.1%. The standardized mortality ratio estimates (95% confidence interval) for our classification showed a gradient relationship from 0.6 (0.1-2.3), 2.5 (0.7-6.3), 7.6 (0.8-27.3), and 8.9 (3.2-19.3) for inactive, delayed, intermittent, and intensive groups, respectively (Trend test, P = .04), whereas the corresponding estimates were 0.8 (0.2-2.2), 5.9 (1.2-17.2), 6.7 (2.5-14.7), and 7.2 (0.8-25.9) for Engel I to IV, respectively, which showed a less increasing trend (Trend test, P = .82). Similar findings were noted for hazard ratios for the 2 classifications.

CONCLUSION:

The proposed novel classification with long-term observed frequency and duration of seizures after surgery is more informative for predicting long-term mortality than the Engel classification.

A review of sudden unexpected death in epilepsy: prediction of patients at risk

This review attempts to provide up-to-date quantitative data from published reports on sudden unexpected death in epilepsy (SUDEP) appearing on Medline and, especially, to provide a means to predict the probability of SUDEP in a given patient. The mean incidence of SUDEP was 1.8/1000, similar to the median of 1.5. The mean standardized mortality ratio was 6.8, and the mean percentage of SUDEP cases among deaths from epilepsy was 16.6. Seventeen risk factors were identified, each given a value according to the number of studies in the literature that specified that condition as a significant risk. The addition of these 17 values then indicated the risk for a given patient. The author calculated these for a group of 91 patients who died of SUDEP and also for 91 live patients. Many of their values for the different risks were significantly different. The sensitivity of these SUDEP values was 71.3%, the specificity 81.8%, and the positive predictive value 84.6%. A discussion includes the question of whether the death in SUDEP is primarily cardiac or pulmonary and the suggestion that it may be either or both in a given patient. The most important risk factor in this study was noncompliance with antiepileptic medication, and the main message of this study to caregivers is that therapeutic drug levels are crucial to avoid SUDEP.

Outcomes of epilepsy surgery in adults and children

Surgery is widely accepted as an effective therapy for selected individuals with medically refractory epilepsy. Numerous studies in the past 20 years have reported seizure freedom for at least 1 year in 53-84% of patients after anteromesial temporal lobe resections for mesial temporal lobe sclerosis, in 66-100% of patients with dual pathology, in 36-76% of patients with localised neocortical epilepsy, and in 43-79% of patients after hemispherectomies. Reported rates for non-resective surgery have been less impressive in terms of seizure freedom; however, the benefit is more apparent when reported in terms of significant seizure reductions. In this Review, we consider the outcomes of surgery in adults and children with epilepsy and review studies of neurological and cognitive sequelae, psychiatric and behavioural outcomes, and overall health-related quality of life.

[Does epilepsy surgery really lower mortality?]

Patients with epilepsy suffer from a two to three fold increased death rate as compared to age and sex matched control population. This increased risk culminate to five fold in patients with drug resistant partial epilepsy eligible for epilepsy surgery, with the majority of deaths classified as sudden unexpected death in epilepsy (SUDEP). The pathophysiology of SUDEP remains uncertain, but all witnessed cases occurred during or immediately after a seizure. Several studies have evaluated the impact of epilepsy surgery on the risk of seizure related death and SUDEP. Four series have concentrated on operated patients, and have compared the death rates in those seizure free and non seizure free post-operatively. Three of these studies reported a significantly lower risk of SUDEP in patients cured by surgery as compared to those still seizing. Four other series have compared the mortality in surgically versus medically treated patients with refractory partial epilepsy. Three of these studies failed to show any significant difference in death or SUDEP rates between operated and and non operated patients. All the above series suffer various types of methological limitations, hampering any definite conclusion regarding the impact of epilepsy surgery on mortality. The launching of novel and large multicentric studies, which address the pitfalls of prior series, should allow to provide conclusive results within the next three years.

Mortality in epilepsy

All studies report an increased mortality risk for people with epilepsy compared with the general population. Population-based studies have demonstrated that the increased mortality is often related to the cause of the epilepsy. Common etiologies include neoplasia, cerebrovascular disease, and pneumonia. Deaths in selected cohorts, such as sudden unexpected death in epilepsy (SUDEP), status epilepticus (SE), suicides, and accidents are more frequently epilepsy-related. SUDEP is a particular cause for concern in younger people, and whether and when SUDEP should be discussed with patients with epilepsy remain problematic issues. Risk factors for SUDEP include generalized tonic-clonic seizures, increased seizure frequency, concomitant learning disability, and antiepileptic drug polypharmacy. The overall incidence of SE may be increasing, although case fatality rates remain constant. Mortality is frequently secondary to acute symptomatic disorders. Poor compliance with treatment in patients with epilepsy accounts for a small proportion of deaths from SE. The incidence of suicide is increased, particularly for individuals with epilepsy and comorbid psychiatric conditions. Late mortality figures in patients undergoing epilepsy surgery vary and are likely to reflect differences in case selection. Future studies of mortality should be prospective and follow agreed guidelines to better quantify risk and causation in individual populations.

SUDEP in the Netherlands: A retrospective study in a tertiary referral center

OBJECTIVE

To evaluate risk factors for sudden and unexpected death in epilepsy (SUDEP) in a high-risk population, i.e. patients treated in a Dutch tertiary referral center for epilepsy.

METHODS

All patients who died between January 1999 and April 2004 while under treatment of the epilepsy center were identified. Based on clinical data, deaths were classified as definite, probable, possible or non-SUDEP. Potential risk factors were compared in SUDEP cases and non-SUDEP cases.

RESULTS

SUDEP incidence was 1.24 per 1000 patient years. SUDEP patients died at a younger age than patients from the control group of non-SUDEP deaths with epilepsy and had an earlier onset of epilepsy. However, the frequently mentioned factors in previous studies, i.e. male sex, generalized tonic-clonic seizures, high seizure frequency, specific AEDs, polytherapy with several AEDs, mental retardation, psychiatric illness and psychotropic comedication, were not found to be correlated with SUDEP.

CONCLUSIONS

Even in this high-risk population of patients with refractory epilepsy, treated in a tertiary referral center, SUDEP is not a frequently occurring phenomenon. Specific risk factors could not be identified within an already high-risk population.

Neurosurgery for the treatment of epilepsy

PURPOSE OF REVIEW

Epilepsy is a common condition that is estimated to afflict 0.5-1.0% of the world's population. Frequently commencing in childhood, it is often associated with life-long disability. Approximately one-third of patients with epilepsy are refractory to antiepileptic drug therapy and many of these patients are candidates for surgical treatment. A growing body of evidence supports the safety and efficacy of surgery for the treatment of selected patients with epilepsy. Little information is available in the anesthesia literature regarding the presurgical assessment of candidates for surgical treatment.

RECENT FINDINGS

The presurgical identification of suitable candidates involves a multidisciplinary approach to assessment. Recent advances, particularly in neuroimaging techniques, are dramatically enhancing the capacity to accurately identify patients who are most likely to benefit from surgery. Epilepsy surgery is underused worldwide and in developed countries. In view of current efforts to increase opportunities to provide surgical treatment to more patients and to offer surgery earlier in the course of the disorder, the number of patients requiring specialized perioperative anesthetic care is expected to increase.

SUMMARY

This article provides anesthesiologists with an overview of the assessment process, investigation techniques and current rationale that influence the selection of appropriate candidates for surgical treatment and the associated need for specialized anesthetic care.

Demystifying Sudden Unexplained Death in Epilepsy?Are We Close?

The cause of sudden unexplained death in epilepsy (SUDEP) is still elusive, despite multiple studies over the past few decades. This review assesses recent progress in the understanding of risk factors (situations that predispose patients to SUDEP) and terminal events (events immediately associated with death) that potentially contribute to SUDEP. Recent studies strongly support a close relationship between seizure episodes (especially generalized convulsions) and SUDEP. The lethal nature of some seizure-induced cardiorespiratory events has been documented fortuitously in rare patient cases, and these events have been consistently reproduced in SUDEP animal models. Nonetheless, SUDEP likely does not have a single cause, and risk factors identified thus far may vary in importance among persons with epilepsy. In the absence of a complete understanding of the pathophysiologic mechanisms underlying SUDEP, potential preventive measures for high-risk patients are offered for consideration. Seizure control is most important for reducing SUDEP risk. Circumstantial data suggest that heightened supervision of patients with frequent seizures may be beneficial. Relatively simple interventions may be sufficient to interrupt potentially lethal events such as periictal suffocation or apnea. However, application of these preventive measures to all epilepsy patients has not been proven to substantially reduce the rate of SUDEP. Additional clinical and laboratory investigations are needed to identify and confirm pathogenic factors and preventive measures.

Suicide after surgical treatment in patients with epilepsy: a meta-analytic investigation

Suicide is a major issue in surgically treated epileptic patients. A meta-analysis was performed comparing suicides in a sample of such patients and in the general population. The Index Medicus and the World Health Statistics Annual were searched to ascertain the suicide rates in the age groups indicated in the studies of epileptic patients for specific years and country. 11 studies were selected, comprising 2,425 patients, 24 of whom committed suicide. Data obtained for each study were processed together to calculate the mean number of suicides per 100,000 individuals with surgically treated epilepsy for each year. This meta-analysis shows that suicide in patients with epilepsy after surgical treatment is more frequent than in the general population. Results are discussed with particular attention to possible causative factors.

Sudden unexpected death in epilepsy: from mechanisms to prevention

PURPOSE OF REVIEW

To discuss the pathophysiology and potential prevention of sudden unexpected death in epilepsy.

RECENT FINDINGS

Long-term electrocardiogram monitoring over several months has detected ictal asystole in three out of 20 (15%) patients with refractory epilepsy, suggesting that high-risk ictal arrhythmias occur in a greater proportion of patients with refractory epilepsy than previously thought. In case-control studies, sudden unexpected death in epilepsy was found to be associated with frequent generalized tonic-clonic seizures and greater ictal maximal heart rate, especially during nocturnal attacks. Conversely, supervision at night was associated with a lower risk of occurrence. The impact of epilepsy surgery on the risk of death and sudden unexpected death in epilepsy remains unclear, with comparable long-term survival in an epilepsy surgery cohort compared with a matched population of patients with refractory epilepsy who did not undergo surgery. Previous results may have been partly confounded by the association observed between preoperative decreased heart rate variability and poor postoperative seizure outcome.

SUMMARY

Ictal arrhythmias may represent a more prevalent cause of sudden unexpected death in epilepsy than previously thought. No clear recommendations have emerged from the literature regarding the most appropriate therapeutic strategies to prevent the event, apart from the supervision at night of patients with refractory epilepsy.

Long-term survival after epilepsy surgery compared with matched epilepsy controls and the general population

This study evaluates if there was a difference in long-term survival between epilepsy surgery patients, individually matched controls with intractable epilepsy, and controls from the general population. In a cohort study, we compared the survival of patients operated with epilepsy surgery in Norway 1948-1988 with: (1) a control group with prolonged medical treatment for intractable epilepsy individually matched for age, gender, and seizure type (n = 139), and (2) expected mortality for matched individuals in historical cohorts of the general population (n = 196). Survival was compared using Kaplan-Meier curves and stratified proportional hazards analysis. After on average 25 years of observation after surgery, there was no difference in survival between the epilepsy surgery group and the controls with intractable epilepsy (p = 0.18). The risk ratio for death after epilepsy surgery was 0.6 (95% CI 0.4-1.1; p = 0.08) compared with the control group. However, survival of epilepsy surgery patients was lower than that of a matching general population (p < 0.001), with a risk ratio for death of 6.2 (95% CI 3.1-12.6; p < 0.001). In this long-term study of a national cohort of epilepsy surgery patients, we found no beneficial effect of epilepsy surgery on survival compared with a control group of medically treated patients with intractable epilepsy. The mortality after epilepsy surgery was higher than expected in the general population.

Medical risks in epilepsy: a review with focus on physical injuries, mortality, traffic accidents and their prevention

The present review aims at highlighting selective aspects of the medical risks in epilepsy and their prevention. Emphasis is put on accidents and physical injuries, including risk factors and effectiveness of prevention; mortality, its causes, risk factors and prevention of seizure-related deaths, as well as traffic accidents, their risk factors and the effectiveness of prevention. Accidents and injuries are slightly more frequent among people with epilepsy than in the general population. This increased risk is probably most prevalent in patients with symptomatic epilepsy and frequent seizures, most often in combination with associated handicaps. The majority of accidents are trivial and occur at home. The most frequent injuries among patients with epilepsy are contusions, wounds, fractures, abrasions and brain concussions. The standardised mortality ratio (SMR; the ratio of observed number of deaths in a population with epilepsy to that expected, based on age and sex-specific mortality rates in a reference population) in population-based studies of epilepsy is 2-3 compared to the general population. This increased mortality is largely related to the etiology of the epilepsy and is probably not influenced by the treatment of the epilepsy. On the other hand, most fatalities in patients with chronic, therapy resistant epilepsy seem to be seizure-related and often sudden unexpected deaths (SUDEP). The frequency of such seizure-related deaths is most likely to be reduced by intensified treatment aiming at early seizure control, although appropriate studies for definitive evidence are still lacking. Apparently, there is an increased rate of traffic accidents in drivers with epilepsy, even if population-based prospective data are lacking. Many of these accidents are seizure-related. Probably, the extent to which physicians report their patients with uncontrolled epilepsy to the authorities is too low, but this has not yet been explored. Moreover, the preventive measures in legislation may be ignored by many people with epilepsy.

The impact of temporal lobe surgery on cure and mortality of drug-resistant epilepsy: summary of a workshop

The Third International Spring Epilepsy Research Conference took place in Georgetown, Cayman Islands from April 26 to May 3, 2003. One workshop discussed the impact of epilepsy surgery on seizure outcome and mortality of antiepileptic drug (AED)-resistant temporal lobe epilepsy. This article summarizes the information presented at this workshop. Although two-thirds of adult patients undergoing epilepsy surgery become seizure-free with continued AED treatment, current clinical experience shows that seizure recurrence occurs in one-third of patients when AEDs are withdrawn under medical supervision. Additional seizure recurrence occurring after AED taper, poor drug compliance and even while patients continue on AEDs after surgery leave only approximately one-third of patients cured after temporal lobe resection. Mostly because so many patients prefer to stay on AEDs although they are free of disabling seizures after surgery, a randomised controlled trial of AED discontinuation is needed to determine if in fact only one-third of patients are cured after surgery. Based on the functional anatomy of temporal lobe surgery two hypotheses are presented why only a minority of patients are cured after surgery. The type and the prognostic significance of seizures after surgery is discussed. Recent studies have suggested that successful temporal lobe surgery may be able to normalize the increased standard mortality ratio (SMR) of drug-resistant temporal lobe epilepsy. However, pre-existing differences in SMR between those cured and those not cured by temporal lobe surgery and other unresolved methodological issues make it difficult at present to fully evaluate the impact of surgery on mortality. Future studies are thus warranted to specifically address the impact of temporal lobe surgery on cure and mortality.