Long-term outcome of extratemporal epilepsy surgery among 154 adult patients

Twenty-five years of epilepsy surgery at a Central European comprehensive epilepsy center-Trends in intervention delay and outcomes

OBJECTIVE

We analyzed trends in patients' characteristics, outcomes, and waiting times over the last 25 years at our epilepsy surgery center situated in Central Europe to highlight possible areas of improvement in our care for patients with drug-resistant epilepsy.

METHODS

A total of 704 patients who underwent surgery at the Brno Epilepsy Center were included in the study, 71 of those were children. Patients were separated into three time periods, 1996-2000 (n = 95), 2001-2010 (n = 295) and 2011-2022 (n = 314) based on first evaluation at the center.

RESULTS

The average duration of epilepsy before surgery in adults remained high over the last 25 years (20.1 years from 1996 to 2000, 21.3 from 2001 to 2010, and 21.3 from 2011 to 2020, P = 0.718). There has been a decrease in rate of surgeries for temporal lobe epilepsy in the most recent time period (67%-70%-52%, P < 0.001). Correspondingly, extratemporal resections have become more frequent with a significant increase in surgeries for focal cortical dysplasia (2%-8%-19%, P < 0.001). For resections, better outcomes (ILAE scores 1a-2) have been achieved in extratemporal lesional (0%-21%-61%, P = 0.01, at least 2-year follow-up) patients. In temporal lesional patients, outcomes remained unchanged (at least 77% success rate). A longer duration of epilepsy predicted a less favorable outcome for resective procedures (P = 0.024) in patients with disease duration of less than 25 years.

SIGNIFICANCE

The spectrum of epilepsy surgery is shifting toward nonlesional and extratemporal cases. While success rates of extratemporal resections at our center are getting better, the average duration of epilepsy before surgical intervention is still very long and is not improving. This underscores the need for stronger collaboration between epileptologists and outpatient neurologists to ensure prompt and effective treatment for patients with drug-resistant epilepsy.

Cognitive decline and quality of life after resective epilepsy surgery

OBJECTIVES

The objectives of this study were to examine the association between cognitive decline and quality of life (QoL) change in a large sample of individuals with drug-resistant epilepsy who underwent resective surgery and to examine whether the association between cognitive decline and QoL is differentially affected by seizure classification outcome (Engel Class 1 vs. 2-4) or side of surgery (left vs. right hemisphere).

MATERIALS AND METHODS

The sample comprised 224 adults (ages ≥ 18) with drug-resistant focal epilepsy treated with resective surgery who underwent comprehensive pre-operative and post-operative evaluations including neuropsychological testing and the Quality of Life in Epilepsy Inventory - 31 between 1991 and 2020. Linear mixed-effects models were fit to examine subject-specific trajectories and assess the effects of time (pre- to post-operative), cognitive decline (number of measures that meaningfully declined), and the interaction between time and cognitive decline on pre- to post-operative change in QoL.

RESULTS

Increases in QoL following resection were observed (B = -10.72 [SE = 1.22], p < .001; mean difference between time point 1 and time point 2 QoL rating = 8.11). There was also a main effect of cognitive decline on QoL (B = -.85 [SE = .27], p = .002). Follow-up analyses showed that the number of cognitive measures that declined was significantly associated with post-surgical QoL, (r = -.20 p = .003), but not pre-surgical QoL, (r = -.04 p = .594), and with pre-to post-surgery raw change in QoL score, (r = -.18 p = .009). A cognitive decline by time point interaction was observed, such that those who had greater cognitive decline had less improvement in overall QoL following resection (B = .72 [SE = .27], p = .009). Similar results were observed within the Engel Class 1 outcome subgroup. However, within the Engel Class 2-4 outcome subgroup, QoL improved following resection, but there was no main effect of cognitive decline or interaction between cognitive decline and time point on QoL change. There was no main effect of resection hemisphere on overall QoL, nor were there interactions with hemisphere by time, hemisphere by cognitive decline, or hemisphere by time by cognitive decline.

CONCLUSIONS

Quality of life improves following epilepsy surgery. Participants who had cognitive decline across a greater number of measures experienced less improvement in QoL post-operatively overall, but there was no clear pattern of domain-specific cognitive decline associated with change in QoL. Our results indicate that cognitive decline in a diffuse set of cognitive domains negatively influences post-operative QoL, particularly for those who experience good seizure outcomes (i.e., seizure freedom), regardless of the site or side of resection.

Source-sink connectivity: a novel interictal EEG marker for seizure localization

Over 15 million epilepsy patients worldwide have drug-resistant epilepsy. Successful surgery is a standard of care treatment but can only be achieved through complete resection or disconnection of the epileptogenic zone, the brain region(s) where seizures originate. Surgical success rates vary between 20% and 80%, because no clinically validated biological markers of the epileptogenic zone exist. Localizing the epileptogenic zone is a costly and time-consuming process, which often requires days to weeks of intracranial EEG (iEEG) monitoring. Clinicians visually inspect iEEG data to identify abnormal activity on individual channels occurring immediately before seizures or spikes that occur interictally (i.e. between seizures). In the end, the clinical standard mainly relies on a small proportion of the iEEG data captured to assist in epileptogenic zone localization (minutes of seizure data versus days of recordings), missing opportunities to leverage these largely ignored interictal data to better diagnose and treat patients. IEEG offers a unique opportunity to observe epileptic cortical network dynamics but waiting for seizures increases patient risks associated with invasive monitoring. In this study, we aimed to leverage interictal iEEG data by developing a new network-based interictal iEEG marker of the epileptogenic zone. We hypothesized that when a patient is not clinically seizing, it is because the epileptogenic zone is inhibited by other regions. We developed an algorithm that identifies two groups of nodes from the interictal iEEG network: those that are continuously inhibiting a set of neighbouring nodes ('sources') and the inhibited nodes themselves ('sinks'). Specifically, patient-specific dynamical network models were estimated from minutes of iEEG and their connectivity properties revealed top sources and sinks in the network, with each node being quantified by source-sink metrics. We validated the algorithm in a retrospective analysis of 65 patients. The source-sink metrics identified epileptogenic regions with 73% accuracy and clinicians agreed with the algorithm in 93% of seizure-free patients. The algorithm was further validated by using the metrics of the annotated epileptogenic zone to predict surgical outcomes. The source-sink metrics predicted outcomes with an accuracy of 79% compared to an accuracy of 43% for clinicians' predictions (surgical success rate of this dataset). In failed outcomes, we identified brain regions with high metrics that were untreated. When compared with high frequency oscillations, the most commonly proposed interictal iEEG feature for epileptogenic zone localization, source-sink metrics outperformed in predictive power (by a factor of 1.2), suggesting they may be an interictal iEEG fingerprint of the epileptogenic zone.

Utility of 18F-fluorodeoxyglucose positron emission tomography in presurgical evaluation of patients with epilepsy: A multicenter study

OBJECTIVE

18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) is widely used in presurgical assessment in patients with drug-resistant focal epilepsy (DRE) if magnetic resonance imaging (MRI) and scalp electroencephalography (EEG) do not localize the seizure onset zone or are discordant.

METHODS

In this multicenter, retrospective observational cohort study, we included consecutive patients with DRE who had undergone FDG-PET as part of their presurgical workup. We assessed the utility of FDG-PET, which was defined as contributing to the decision-making process to refer for resection or intracranial EEG (iEEG) or to conclude surgery was not feasible.

RESULTS

We included 951 patients in this study; 479 had temporal lobe epilepsy (TLE), 219 extratemporal epilepsy (ETLE), and 253 epilepsy of uncertain lobar origin. FDG-PET showed a distinct hypometabolism in 62% and was concordant with ictal EEG in 74% in TLE and in 56% in ETLE (p < .001). FDG-PET was useful in presurgical decision-making in 396 patients (47%) and most beneficial in TLE compared to ETLE (58% vs. 44%, p = .001). Overall, FDG-PET contributed to recommending resection in 78 cases (20%) and iEEG in 187 cases (47%); in 131 patients (33%), FDG-PET resulted in a conclusion that resection was not feasible. In TLE, seizure-freedom 1 year after surgery did not differ significantly (p = .48) between patients with negative MRI and EEG-PET concordance (n = 30, 65%) and those with positive MRI and concordant EEG (n = 46, 68%). In ETLE, half of patients with negative MRI and EEG-PET concordance and three quarters with positive MRI and concordant EEG were seizure-free postsurgery (n = 5 vs. n = 6, p = .28).

SIGNIFICANCE

This is the largest reported cohort of patients with DRE who received presurgical FDG-PET, showing that FDG-PET is a useful diagnostic tool. MRI-negative and MRI-positive cases with concordant FDG-PET results (with either EEG or MRI) had a comparable outcome after surgery. These findings confirm the significance of FDG-PET in presurgical epilepsy diagnostics.

[Long-term postoperative outcomes in patients with drug-resistant epilepsy]

Epilepsy surgery is effective in 30-82% of patients with drug-resistant epilepsy. However, risk factors of unfavorable outcomes after epilepsy surgery require further study.

OBJECTIVE

To evaluate risk factors of favorable and unfavorable long-term postoperative outcomes in patients with drug-resistant epilepsy.

MATERIAL AND METHODS

Postoperative outcomes in a large cohort of patients with epilepsy are reported for the first time in the Russian Federation. There were 271 patients with drug-resistant scheduled for surgery. Preoperative examination and surgical treatment were carried out between January 1, 2014 and December 12, 2019 at the Evdokimov Moscow State University of Medicine and Dentistry and Sklifosovsky Research Institute for Emergency Care. We used Engel grading system to assess postoperative outcomes after 12, 24, 48 and 60 months. We distinguished favorable (Engel I-II) and unfavorable (Engel III-IV) outcomes and analyzed the factors influencing postoperative results in these patients.

RESULTS

There were 319 surgical procedures in 271 patients (217 primary resections, implantation of vagus nerve stimulator in 31 patients, 9 redo resections and 8 radiosurgical procedures). Focal cortical dysplasia (FCD) was found in 162 (60%) patients, «dual pathology» - in 118 (44%) cases. In 12 months after surgery, favorable outcomes (Engel l-II) were observed in 69% of patients (n=148), after 24 months - in 71% (n=127) of patients. Postoperative complications occurred in 6 (1.9%) patients. There was no mortality. The earlier onset of epilepsy (p=0.01), multifocal (p=0.002) and bilateral lesions (p=0.0038) were the most significant risk factors of unfavorable postoperative outcomes.

CONCLUSION

Surgical resection is effective approach for drug-resistant epilepsy.

Long-term mood, quality of life, and seizure freedom in intracranial EEG epilepsy surgery

OBJECTIVES

To determine the long-term outcomes in patients undergoing intracranial EEG (iEEG) evaluation for epilepsy surgery in terms of seizure freedom, mood, and quality of life at St. Vincent's Hospital, Melbourne.

METHODS

Patients who underwent iEEG between 1999 and 2016 were identified. Patients were retrospectively assessed between 2014 and 2017 by specialist clinic record review and telephone survey with standardized validated questionnaires for: 1) seizure freedom using the Engel classification; 2) Mood using the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E); 3) Quality-of-life outcomes using the QOLIE-10 questionnaire. Summary statistics and univariate analysis were performed to investigate variables for significance.

RESULTS

Seventy one patients underwent iEEG surgery: 49 Subdural, 14 Depths, 8 Combination with 62/68 (91.9%) of those still alive, available at last follow-up by telephone survey or medical record review (median of 8.2 years). The estimated epileptogenic zone was 62% temporal and 38% extra-temporal. At last follow-up, 69.4% (43/62) were Engel Class I and 30.6% (19/62) were Engel Class II-IV. Further, a depressive episode (NDDI-E > 15)was observed in 34% (16/47), while a 'better quality of life' (QOLIE-10 score < 25) was noted in 74% (31/42). Quality of life (p < 0.001) but not mood (p = 0.24) was associated with seizure freedom.

SIGNIFICANCE

Long-term seizure freedom can be observed in patients undergoing complex epilepsy surgery with iEEG evaluation and is associated with good quality of life.

Frontal disconnection surgery for drug-resistant epilepsy: Outcome in a series of 16 patients

OBJECTIVE

To evaluate the effectiveness of frontal disconnection surgery in seizure control and related consequences in a consecutive patient series.

METHODS

We conducted a retrospective analysis of patients who underwent frontal disconnection surgery for drug-resistant epilepsy (DRE). Baseline epilepsy characteristics, detailed presurgical evaluation including epileptogenic zone (EZ) localization, magnetic resonance imaging (MRI) detection of epileptogenic lesion, and pathological findings were reviewed. Patients were followed postoperatively for seizure outcome at 1 year.

RESULTS

A total of 16 patients were identified (six children and 10 adults). Most patients had a childhood onset of DRE with a median duration of epilepsy of 6.5 years (interquartile range 3.5-17.5 years) before surgery. In 10 (62.5%) patients, the EZ was localized to the frontal lobe, while in six patients, the EZ involved also adjacent lobes or consisted of multiple foci. In 10 (62.5%) patients, an epileptogenic lesion was detected on presurgical MRI, four of which (40%) had all MRI abnormalities confined to the frontal lobe. Two-thirds of the patients (11/16; 68.8%) underwent isolated frontal disconnection procedure, while remaining patients had frontal disconnection combined with resection of an adjacent lobe. Of the 12 patients in whom biopsy was taken from the disconnected frontal lobe, six (50%) had pathology-proven focal cortical dysplasia. We observed surgical-related complications in three (18.8%) cases, neurological deficits in other three (18.8%) patients, and worsening cognitive abilities in one (6.3%) patient. Overall, eight (50%) patients became completely seizure-free (ILAE 1) at one-year follow-up.

SIGNIFICANCE

Frontal disconnection surgery for DRE can result in seizure freedom in certain patients, especially when the EZ is strictly limited to the ipsilateral frontal region, and the MRI shows an epileptogenic lesion that is purely frontal in location. Frontal lobe disconnection procedure is safe and has a limited complication rate. However, further studies with larger patient population will yield more significance.

European Expert Opinion on ANT-DBS therapy for patients with drug-resistant epilepsy (a Delphi consensus)

INTRODUCTION

Although deep brain stimulation of the anterior nucleus of the thalamus (ANT-DBS) represents an established third-line therapy for patients with drug-resistant focal epilepsy, guiding reports on practical treatment principles remain scarce.

METHODS

An Expert Panel (EP) of 10 European neurologists and 4 neurosurgeons was assembled to share their experience with ANT-DBS therapy. The process included a review of the current literature, which served as a basis for an online survey completed by the EP prior to and following a face-to-face meeting (Delphi method). An agreement level of ≥71 % was considered as consensus.

RESULTS

Out of 86 reviewed studies, 46 (53 %) were selected to extract information on the most reported criteria for patient selection, management, and outcome. The Delphi process yielded EP consensus on 4 parameters for selection of good candidates and patient management as well as 7 reasons of concern for this therapy. Since it was not possible to give strict device programming advice due to low levels of evidence, the experts shared their clinical practice: all of them start with monopolar stimulation, 79 % using the cycling mode. Most (93 %) EP members set the initial stimulation frequency and pulse width according to the SANTE parameters, while there is more variability in the amplitudes used. Further agreement was achieved on a list of 7 patient outcome parameters to be monitored during the follow-up.

CONCLUSIONS

Although current evidence is too low for definite practical guidelines, this EP report could support the selection and management of patients with ANT-DBS.

Outcome after individualized stereoelectroencephalography (sEEG) implantation and navigated resection in patients with lesional and non-lesional focal epilepsy

BACKGROUND

Refined localization of the epileptogenic zone (EZ) in patients with pharmacoresistant focal epilepsy proceeding to resective surgery might improve postoperative outcome. We here report seizure outcome after stereo EEG (sEEG) evaluation with individually planned stereotactically implanted depth electrodes and subsequent tailored resection.

METHODS

A cohort of consecutive patients with pharmacoresistant focal epilepsy, evaluated with a non-invasive evaluation protocol and invasive monitoring with personalized, stereotactically implanted depth electrodes for sEEG was analyzed. Co-registration of post-implantation CT scan to presurgical MRI data was used for 3D reconstructions of the patients' brain surface and mapping of neurophysiology data. Individual multimodal 3D maps of the EZ were used to guide subsequent tailored resections. The outcome was rated according to the Engel classification.

RESULTS

Out of 914 patients who underwent non-invasive presurgical evaluation, 85 underwent sEEG, and 70 were included in the outcome analysis. Median follow-up was 31.5 months. Seizure-free outcome (Engel class I A-C, ILAE class 1-2) was achieved in 83% of the study cohort. Patients exhibiting lesional and non-lesional (n = 42, 86% vs. n = 28, 79%), temporal and extratemporal (n = 45, 80% vs. n = 25, 84%), and right- and left-hemispheric epilepsy (n = 44, 82% vs. n = 26, 85%) did similarly well. This remains also true for those with an EZ adjacent to or distant from eloquent cortex (n = 21, 86% vs. n = 49, 82%). Surgical outcome was independent of resected tissue volume.

CONCLUSION

Favourable post-surgical outcome can be achieved in patients with resistant focal epilepsy, using individualized sEEG evaluation and tailored navigated resection, even in patients with non-lesional or extratemporal focal epilepsy.

Quality of Life After Epilepsy Surgery in Children: A Systematic Review and Meta-Analysis

BACKGROUND

Pediatric epilepsy surgery is a treatment modality appropriate for select patients with debilitating medication-resistant seizures. Previous publications have studied seizure freedom as the main outcome of epilepsy surgery. However, there has been no systematic assessment of the postoperative life quality for these children.

OBJECTIVE

To estimate the quality of life (QOL) long-term outcomes after surgery for intractable epilepsy in pediatric patients.

METHODS

A systematic search of the PubMed and Cochrane databases was performed. Studies reporting questionnaire-assessed QOL at least 12 months postoperatively were included. QOL means and standard deviations were compared between surgically and medically managed patients, between the preoperative and postoperative state of each patient, and were further stratified into patients achieving seizure freedom, and those who did not. Meta-analysis was performed using fixed effects models for weighted mean differences (WMD), 95% confidence intervals (CI) and sensitivity analyses. Funnel plots and Begg's tests were utilized to detect publication bias.

RESULTS

The search yielded 18 retrospective studies, reporting 890 surgical patients. Following epilepsy surgery, children had significant QOL improvement compared to their preoperative state (WMD: 16.71, 95% CI: 12.19-21.22, P < .001) and better QOL than matched medically treated controls (WMD: 12.42, 95% CI: 6.25-18.58, P < .001). Patients achieving total seizure freedom after surgery had significant postoperative QOL improvement (WMD: 16.12, 95% CI: 7.98-24.25, P < .001), but patients not achieving seizure freedom did not achieve statistical significance (P = .79).

CONCLUSION

Epilepsy surgery can effectively improve QOL in children with medication-resistant seizures, through seizure freedom, which was associated with the greatest improvement in life quality.

Predictors of seizure outcome following resective surgery for drug-resistant epilepsy associated with focal gliosis

OBJECTIVE

The authors studied the clinical characteristics and postoperative outcomes of drug-resistant epilepsy associated with focal gliosis.

METHODS

From their epilepsy surgery database, the authors selected the patients with drug-resistant epilepsy and MRI-defined focal gliosis who underwent focal resective surgery. All patients underwent standard presurgical evaluation. Intracranial electroencephalography (EEG) was performed in patients with discordant presurgical data, ill-defined lesions, and lesions close to eloquent regions. Completeness of resection was defined on the basis of extraoperative and intraoperative electrocorticography studies. Favorable postoperative outcome was defined as Engel class I outcome during the last 2 years of follow-up.

RESULTS

Sixty-six patients fulfilled inclusion criteria. An initial precipitating injury was present in 38 (57.6%) patients, mainly in the form of perinatal injury (n = 10), trauma (n = 10), and meningoencephalitis (n = 8). Gliosis involved a single lobe in 38 (57.6%) patients and 2 adjacent lobes in 14 (21.2%) patients; the remaining 14 (21.2%) patients had multilobar gliosis. In patients with unilobar or bilobar gliosis, the posterior region of the head was involved in 34 (65%) patients and the frontal lobes in 12 (23%) patients. During a median follow-up of 4 years (range 2-9 years), 41 (62.1%) patients had favorable outcome. On multivariate analysis, the presence of a well-defined aura (p = 0.019), electrocorticographically defined completeness of resection (p = 0.024), and normal postoperative EEG findings at 1 year (p = 0.003) were predictive of favorable postoperative seizure outcome.

CONCLUSIONS

Focal gliosis is a common etiology for drug-resistant extratemporal epilepsy in developing countries and is most often located in the posterior region of the head. The majority of these patients have perinatal injuries or neurological infections as initial precipitating injuries. Patients with focal gliosis have good postoperative seizure outcomes after well-planned resective surgery.

The long-term outcomes of epilepsy surgery

Objective

Despite modern anti-epileptic drug treatment, approximately 30% of epilepsies remain medically refractory and for these patients, epilepsy surgery may be a treatment option. There have been numerous studies demonstrating good outcome of epilepsy surgery in the short to median term however, there are a limited number of studies looking at the long-term outcomes. The aim of this study was to ascertain the long-term outcome of resective epilepsy surgery in a large neurosurgery hospital in the U.K.

Methods

This a retrospective analysis of prospectively collected data. We used the 2001 International League Against Epilepsy (ILAE) classification system to classify seizure freedom and Kaplan-Meier survival analysis to estimate the probability of seizure freedom.

Results

We included 284 patients who underwent epilepsy surgery (178 anterior temporal lobe resections, 37 selective amygdalohippocampectomies, 33 temporal lesionectomies, 36 extratemporal lesionectomies), and had a prospective median follow-up of 5 years (range 1–27). Kaplan-Meier estimates showed that 47% (95% CI 40–58) remained seizure free (apart from simple partial seizures) at 5 years and 38% (95% CI 31–45) at 10 years after surgery. 74% (95% CI 69–80) had a greater than 50% seizure reduction at 5 years and 70% (95% CI 64–77) at 10 years. Patients who had an amygdalohippocampectomy were more likely to have seizure recurrence than patients who had an anterior temporal lobe resection (p = 0.006) and temporal lesionectomy (p = 0.029). There was no significant difference between extra temporal and temporal lesionectomies. Hippocampal sclerosis was associated with a good outcome but declined in relative frequency over the years.

Conclusion

The vast majority of patients who were not seizure free experienced at least a substantial and long-lasting reduction in seizure frequency. A positive long-term outcome after epilepsy surgery is possible for many patients and especially those with hippocampal sclerosis or those who had anterior temporal lobe resections.

New Techniques and Progress in Epilepsy Surgery

While open surgical resection for medically refractory epilepsy remains the gold standard in current neurosurgical practice, modern techniques have targeted areas for improvement over open surgical resection. This review focuses on how a variety of these new techniques are attempting to address these various limitations. Stereotactic electroencephalography offers the possibility of localizing deep epileptic foci, improving upon subdural grid placement which limits localization to neocortical regions. Laser interstitial thermal therapy (LITT) and stereotactic radiosurgery can minimally or non-invasively ablate specific regions of interest, with near real-time feedback for laser interstitial thermal therapy. Finally, neurostimulation offers the possibility of seizure reduction without needing to ablate or resect any tissue. However, because these techniques are still being evaluated in current practice, there are no evidence-based guidelines for their use, and more research is required to fully evaluate their proper role in the current management of medically refractory epilepsy.

Long-term outcomes of surgical treatment for epilepsy in adults with regard to seizures, antiepileptic drug treatment and employment

PURPOSE

There is Class I evidence for short-term efficacy of epilepsy surgery from two randomized controlled studies of temporal lobe resection. Long-term outcome studies are observational. The aim of this narrative review was to summarise long-term outcomes taking the study methodology into account.

METHODS

A PubMed search was conducted identifying articles on long-term outcomes of epilepsy surgery in adults with regard to seizures, antiepileptic drug treatment and employment. Definitions of seizure freedom were examined in order to identify the proportions of patients with sustained seizure freedom. The quality of the long-term studies was assessed.

RESULTS

In a number of high-quality studies 40-50% of patients had been continuously free from seizures with impairment of consciousness 10 years after resective surgery, with a higher proportion seizure-free at each annual follow-up. The proportion of seizure-free adults in whom AEDs have been withdrawn varied widely across studies, from 19-63% after around 5 years of seizure freedom. Few long-term vocational outcome studies were identified and results were inconsistent. Some investigators found no postoperative changes, others found decreased employment for patients with continuing seizures, but no change or increased employment for seizure-free patients. Having employment at baseline and postoperative seizure freedom were the strongest predictors of employment after surgery.

CONCLUSIONS

Long-term studies of outcomes after epilepsy surgery are by necessity observational. There is a need for more prospective longitudinal studies of both seizure and non-seizure outcomes, considering individual patient trajectories in order to obtain valid outcome data needed for counselling patients about epilepsy surgery.

Anterior temporal lobectomy for older adults with mesial temporal sclerosis

OBJECTIVE

To compare postoperative seizure-free survival between older and younger adults.

METHODS

A retrospective cohort of 107 temporal lobe epilepsy patients with a diagnosis of mesial temporal sclerosis (MTS) received anterior temporal lobectomy (ATL) between 1993 and 2014. We divided the lower three quartiles (younger) and top quartile (older, all 47+ years) of patients, then reviewed patient registry and electronic medical records to determine time to first self-reported seizure after ATL, the primary outcome (mean=3.5years of follow-up, SD=3.6). We also assessed Engel classifications, intraoperative and postoperative treatment complications, and social disability. We used Cox proportional hazard models to assess the association between individual traits and time of seizure recurrence.

RESULTS

During follow-up, 35/107 (32.7%) patients had post-operative seizure(s). After adjustment for potential confounders there were no significant differences in the probability of post-operative seizures between the older and younger groups, though we had limited precision (hazard ratio of 0.67 [0.28-1.59]), (p=0.36). There were more treatment complications and disability in older patients (18% vs. 1.3% for any complications, 84.62% vs. 58.23% for driving disability, and 84.6% vs. 60.7% for work disability, p<0.05).

CONCLUSION

Older patients appear to have more complications after ATL, compared with younger patients. Age, however, does not appear to have a large independent association with seizure recurrence.

Outcomes of multilobar resections for epilepsy in Sweden 1990-2013: a national population-based study

BACKGROUND

Reports on outcome after multilobar resection (MLR) are scarce and most are retrospective single-centre studies or case studies with few patients. The aim of this study is to present seizure and complication outcomes 2 years after MLR in a prospective population-based series.

METHOD

The Swedish National Epilepsy Surgery Registry (SNESUR) provides prospective population-based data on outcome and complications after epilepsy surgery. For this study, we have analysed data on seizure outcome and complications after MLR from the SNESUR between 1990 and 2013.

RESULTS

Fifty-seven patients underwent MLR; 40/57 surgeries were performed between 1990 and 2000. Sixteen operations were classified as partial hemispherotomy. Resections were right-sided in 33 (58 %) patients. Mean age was 17.3 years (range, 0.3-63.4 years) and mean duration of epilepsy before surgery was 11.0 years (range, 0.2-37 years). Preoperative neurological deficits were seen in 19 patients (33.3 %). Learning disability (LD) was seen in 18 patients (31.6 %), six had severe LD (IQ <50). Seizure outcome after 2 years was available for 53 patients. Thirteen (24.5 %) were seizure-free and 12 (22.6 %) had >75 % seizure frequency reduction. Three (5.3 %) patients suffered major complications: infarction of the middle cerebral artery, epidural abscess and hemiparesis. Minor complications were seen in ten patients. There was no mortality.

CONCLUSIONS

This prospective, population-based study provides data on seizure outcome and complications after MLR. In selected patients MLR can be considered, but expectations for seizure freedom should not be too high and patients and parents should be counselled appropriately.

Meta-analysis of vagus nerve stimulation treatment for epilepsy: correlation between device setting parameters and acute response

BACKGROUND

Vagus nerve stimulation (VNS) is an adjunctive neurophysiological treatment for those patients who have pharmacoresistant or surgically resistant partial onset epilepsy.

OBJECTIVE

The aim of this study is to determine the effects of high and low stimulation paradigms on a responder rate of ≥50 and ≥75% reduction in seizure frequency and associated adverse effects in adults and children.

METHOD

A literature search was performed using Medline, PubMed, EMBASE, and Cochrane library for studies using vagus nerve stimulation published from January 1980 until July 2014 for medically or surgically resistant partial onset seizures, in children and adults. No restrictions on languages were imposed.

DATA COLLECTION AND ANALYSIS

Four authors reviewed and selected studies for inclusion and exclusion. The search identified five randomized control trials that fit with our inclusion criteria. The following outcomes were evaluated: 50% or greater reduction in total seizure frequency, 75% or greater reduction in total seizure frequency, and adverse effects.

RESULTS

Four randomized controlled trials were analyzed in this meta-analysis. Results indicate high stimulation is more effective in adult patients who experienced ≥50 and ≥75% reduction in seizure frequency with a significant difference within both high and low stimulation groups. In children, there was no significant difference between the two groups and patients with ≥50 % reduction in seizures. Adverse effects such as hoarseness and dyspnea were more common in the high stimulation group where the remaining side effects were not statistically different among both groups.

CONCLUSION

High stimulation is more effective than low stimulation in producing a greater reduction in seizure frequency in patients with medically and surgically resistant epilepsy.

Prognostic Role of Functional Neuroimaging after Multilobar Resection in Patients with Localization-Related Epilepsy

To investigate the usage of functional neuroimaging as a prognostic tool for seizure recurrence and long-term outcomes in patients with multilobar resection, we recruited 90 patients who received multilobar resections between 1995 and 2013 with at least 1-year follow-up (mean 8.0 years). All patients were monitored using intracranial electroencephalography (EEG) after pre-surgical evaluation. Clinical data (demographics, electrophysiology, and neuroimaging) were reviewed retrospectively. Surgical outcomes were evaluated at 1, 2, 5 years after surgery, and at the end of the study. After 1 year, 56 patients (62.2%) became Engel class I and at the last follow-up, 47 patients (52.2%) remained seizure-free. Furthermore, non-localized 18F-fluorodeoxyglucose positron emission tomography (PET), identifying hypometabolic areas not concordant with ictal onset zones, significantly correlated with seizure recurrence after 1 year. Non-lesional magnetic resonance imaging (MRI) and left-sided resection correlated with poor outcomes. In the last follow-up, non-localized PET and left-sided resection significantly correlated with seizure recurrence. Both localized PET and ictal-interictal SPECT subtraction co-registered to MR (SISCOM) predicted good surgical outcomes in the last follow-up (69.2%, Engel I). This study suggests that PET and SISCOM may predict postoperative outcomes for patients after multilobar epilepsy and shows comparable long-term surgical outcomes after multilobar resection.

Long-term seizure and psychosocial outcomes after resective surgery for intractable epilepsy

Resective surgery is considered an effective treatment for refractory localization-related epilepsy. Most studies have reported seizure and psychosocial outcomes of 2-5 years postsurgery and a few up to 10 years. Our study aimed to assess long-term (up to 15 years) postsurgical seizure and psychosocial outcomes at our epilepsy center. The Henry Ford Health System Corporate Data Store was accessed to identify patients who had undergone surgical resection for localization-related epilepsy from 1993 to 2011. Demographics including age at epilepsy onset and surgery, seizure frequency before surgery, and pathology were gathered from electronic medical records. Phone surveys were conducted from May 2012 to January 2013 to determine patients' current seizure frequency and psychosocial metrics including driving and employment status and use of antidepressants. Surgical outcomes were based on Engel's classification (classes I and II=favorable outcomes). McNemar's tests, chi-square tests, two sample t-tests, and Wilcoxon two sample tests were used to analyze the relationships of psychosocial and surgical outcomes with demographic and surgical characteristics. A total of 470 patients had resective epilepsy surgery, and of those, 50 (11%) had died since surgery. Of the remaining, 253 (60%) were contacted with mean follow-up of 10.6±5.0years (27% of patients had follow-up of 15 years or longer). Of the patients surveyed, 32% were seizure-free and 75% had a favorable outcome (classes I and II). Favorable outcomes had significant associations with temporal resection (78% temporal vs 58% extratemporal, p=0.01) and when surgery was performed after scalp EEG only (85% vs 65%, p<0.001). Most importantly, favorable and seizure-free outcome rates remained stable after surgery over long-term follow-up [i.e., <5 years (77%, 41%), 5-10 years (67%, 29%), 10-15 years (78%, 38%), and >15 years (78%, 26%)]. Compared to before surgery, patients at the time of the survey were more likely to be driving (51% vs 35%, p<0.001) and using antidepressants (30% vs 22%, p=0.013) but less likely to be working full-time (23% vs 42%, p<0.001). A large majority of patients (92%) considered epilepsy surgery worthwhile regardless of the resection site, and this was associated with favorable outcomes (favorable=98% vs unfavorable=74%, p<0.001). The findings suggest that resective epilepsy surgery yields favorable long-term postoperative seizure and psychosocial outcomes.

Long-term outcome and predictors of resective surgery prognosis in patients with refractory extratemporal epilepsy

PURPOSE

We analyzed the long-term postoperative outcome and possible predictive factors of the outcome in surgically treated patients with refractory extratemporal epilepsy.

METHODS

We retrospectively analyzed 73 patients who had undergone resective surgery at the Epilepsy Center Brno between 1995 and 2010 and who had reached at least 1 year outcome after the surgery. The average age at surgery was 28.3±11.4 years. Magnetic resonance imaging (MRI) did not reveal any lesion in 24 patients (32.9%). Surgical outcome was assessed annually using Engel's modified classification until 5 years after surgery and at the latest follow-up visit.

RESULTS

Following the surgery, Engel Class I outcome was found in 52.1% of patients after 1 year, in 55.0% after 5 years, and in 50.7% at the last follow-up visit (average 6.15±3.84 years). Of the patients who reached the 5-year follow-up visit (average of the last follow-up 9.23 years), 37.5% were classified as Engel IA at each follow-up visit. Tumorous etiology and lesions seen in preoperative MRI were associated with significantly better outcome (p=0.035; p<0.01). Postoperatively, 9.6% patients had permanent neurological deficits.

CONCLUSION

Surgical treatment of refractory extratemporal epilepsy is an effective procedure. The presence of a visible MRI-detected lesion and tumorous etiology is associated with significantly better outcome than the absence of MRI-detected lesion or other etiology.

Long-term seizure outcome following resective surgery for epilepsy: to be or not to be completely cured?

Surgical intervention is expected to improve the quality of life in patients with intractable epilepsy by providing adequate seizure control. Although many previous studies showed various rates of seizure freedom, definite conclusions have not yet been made regarding outcomes. In order to clarify the long-term postoperative outcome for a period up to 10 years, a retrospective review of our patients was performed longitudinally by using the survival analysis method. The postoperative state of epilepsy in 76 patients who underwent resection surgery was assessed based on Engel’s criteria. In addition, Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom. In this patient group, abnormal lesion were detected by MRI in 70 out of 76 cases, and the ictal onset zone was finally identified within temporal lobe in 51 cases. The most favorable outcome, defined as Engel Class Ia, was observed in 26 (37%), 24 (40%), and 18 (41%) cases at 2, 5, and 10 years after surgery, respectively. The Kaplan-Meier survival curve in the overall group estimated the probability of seizure freedom as 75% (95% confidence interval [CI] 70–80%), 67% (62–72%), and 51% (45–57%) at 2, 5, and 10 years follow up, respectively. Half of all seizure recurrences occurred within the first 2 postoperative years. In this study, we showed that long-term favorable outcome of seizure control following resection surgery can be achieved in more than half of the patients.

Current management and surgical outcomes of medically intractable epilepsy

Epilepsy is one of the most common neurologic disorders in the world. While anti-epileptic drugs (AEDs) are the mainstay of treatment in most cases, as many as one-third of patients will have a refractory form of disease indicating the need for a neurosurgical evaluation. Ever since the first half of the twentieth century, surgery has been a major treatment option for epilepsy, but the last 10-15 years in particular has seen several major advances. As shown in relatively recent studies, resection is more effective for medically intractable epilepsy (MIE) than AED treatment alone, which is why most clinicians now endorse a neurosurgical consultation after approximately two failed regimens of AEDs, ultimately leading to decreased healthcare costs and increased quality of life. Temporal lobe epilepsy (TLE) is the most common form of MIE and comprises about 80% of epilepsy surgeries with the majority of patients gaining complete seizure-freedom. As the number of procedures and different approaches continues to grow, temporal lobectomy remains consistently focused on resection of mesial structures such as the amygdala, hippocampus, and parahippocampal gyrus while preserving as much of the neocortex as possible resulting in optimum seizure control with minimal neurological deficits. MIE originating outside the temporal lobe is also effectively treated with resection. Though not as successful as TLE surgery because of their frequent proximity to eloquent brain structures and more diffuse pathology, epileptogenic foci located extratemporally also benefit from resection. Favorable seizure outcome in each of these procedures has heavily relied on pre-operative imaging, especially since the massive surge in MRI technology just over 20 years ago. However, in the absence of visible lesions on MRI, recent improvements in secondary imaging modalities such as fluorodeoxyglucose positron emission computed tomography (FDG-PET) and single-photon emission computed tomography (SPECT) have lead to progressively better long-term seizure outcomes by increasing the neurosurgeon's visualization of supposed non-lesional foci. Additionally, being historically viewed as a drastic surgical intervention for MIE, hemispherectomy has been extensively used quite successfully for diffuse epilepsies often found in pediatric patients. Although total anatomic hemispherectomy is not utilized as commonly today, it has given rise to current disconnective techniques such as hemispherotomy. Therefore, severe forms of hemispheric developmental epilepsy can now be surgically treated while substantially decreasing the amount of potential long-term complications resulting from cavitation of the brain following anatomical hemispherectomy. Despite the rapid pace at which we are gaining further knowledge about epilepsy and its surgical treatment, there remains a sizeable underutilization of such procedures. By reviewing the recent literature on resective treatment of MIE, we provide a recent up-date on epilepsy surgery while focusing on historical perspectives, techniques, prognostic indicators, outcomes, and complications associated with several different types of procedures.

Comparing the effects of cortical resection and vagus nerve stimulation in patients with nonlesional extratemporal epilepsy

The main purpose of this retrospective study was to compare the effects of resective surgery (RESgr-26 patients) and vagus nerve stimulation (VNSgr-35 patients) on seizure frequency (2 and 5years after surgery) in patients with nonlesional extratemporal epilepsy (NLexTLE). We analyzed hospital admission costs directly associated with epilepsy (HACE) in both groups at the same follow-up. The decrease in seizure frequency from the preoperative levels, in both VNSgr and RESgr, was statistically significant (p<0.001). The seizure frequency reduction did not differ significantly between the follow-up visits for either group (p=0.221 at 2years and 0.218 at 5years). A significantly higher number of Engel I and Engel I+II patients were found in RESgr than in VNSgr at both follow-up visits (p=0.04 and 0.007, respectively). Using McHugh classification, we did not find statistically significant differences between both groups at both follow-up visits. Hospital admission costs directly associated with epilepsy/patient/year in both RESgr and VNSgr dropped significantly at 2- and 5-year follow-up visit and this reduction was not statistically different between RESgr and VNSgr (p=0.232). Both VNS and resective surgery cause comparably significant seizure reduction in NLexTLE. Resective surgery leads to a greater number of patients with excellent postoperative outcome (Engel I+II). The HACE reduction is statistically comparable between both groups.

The pathology of magnetic-resonance-imaging-negative epilepsy

Patients with magnetic-resonance-imaging (MRI)-negative (or 'nonlesional') pharmacoresistant focal epilepsy are the most challenging group undergoing presurgical evaluation. Few large-scale studies have systematically reviewed the pathological substrates underlying MRI-negative epilepsies. In the current study, histopathological specimens were retrospectively reviewed from MRI-negative epilepsy patients (n=95, mean age=30 years, 50% female subjects). Focal cortical dysplasia cases were classified according to the International League Against Epilepsy (ILAE) and Palmini et al classifications. The most common pathologies found in this MRI-negative cohort included: focal cortical dysplasia (n=43, 45%), gliosis (n=21, 22%), hamartia+gliosis (n=12, 13%), and hippocampal sclerosis (n=9, 9%). The majority of focal cortical dysplasia were ILAE type I (n=37) or Palmini type I (n=39). Seven patients had no identifiable pathological abnormalities. The existence of positive pathology was not significantly associated with age or temporal/extratemporal resection. Follow-up data post surgery was available in 90 patients; 63 (70%) and 57 (63%) attained seizure freedom at 6 and 12 months, respectively. The finding of positive pathology was significantly associated with seizure-free outcome at 6 months (P=0.035), but not at 12 months. In subgroup analysis, the focal cortical dysplasia group was not significantly correlated with seizure-free outcome, as compared with the negative-pathology groups at either 6 or 12 months. Of note, the finding of hippocampal sclerosis had a significant positive correlation with seizure-free outcome when compared with the negative-pathology group (P=0.009 and 0.004 for 6- and 12-month outcome, respectively). Absence of a significant histopathology in the resected surgical specimen did not preclude seizure freedom. In conclusion, our study highlights the heterogeneity of epileptic pathologies in MRI-negative epilepsies, with focal cortical dysplasia being the most common finding. The existence of positive pathology in surgical specimen may be a good indication for short-term good seizure outcome. There is a small subset of cases in which no pathological abnormalities are identified.

Pediatric epilepsy surgery: long-term 5-year seizure remission and medication use

BACKGROUND

It is unclear whether long-term seizure outcomes in children are similar to those in adult epilepsy surgery patients.

OBJECTIVE

To determine 5-year outcomes and antiepilepsy drug (AED) use in pediatric epilepsy surgery patients from a single institution.

METHODS

The cohort consisted of children younger than 18 years of age whose 5-year outcome data would have been available by 2010. Comparisons were made between patients with and without 5-year data (n = 338), patients with 5-year data for seizure outcome (n = 257), and seizure-free patients on and off AEDs (n = 137).

RESULTS

Five-year data were available from 76% of patients. More seizure-free patients with focal resections for hippocampal sclerosis and tumors lacked 5-year data compared with other cases. Of those with 5-year data, 53% were continuously seizure free, 18% had late seizure recurrence, 3% became seizure free after initial failure, and 25% were never seizure free. Patients were more likely to be continuously seizure free if their surgery was performed during the period 2001 to 2005 (68%) compared with surgery performed from 1996 to 2000 (61%), 1991 to 1995 (36%), and 1986 to 1990 (46%). More patients had 1 or fewer seizures per month in the late seizure recurrence (47%) compared with the not seizure-free group (20%). Four late deaths occurred in the not seizure-free group compared with 1 in the seizure-free group. Of patients who were continuously seizure free, 55% were not taking AEDs, and more cortical dysplasia patients (74%) had stopped taking AEDs compared with hemimegalencephaly patients (18%).

CONCLUSION

In children, 5-year outcomes improved over 20 years of clinical experience. Our results are similar to those of adult epilepsy surgery patients despite mostly extratemporal and hemispheric operations for diverse developmental etiologies.

Surgical Outcomes in Patients With Extratemporal Epilepsy and Subtle or Normal Magnetic Resonance Imaging Findings

BACKGROUND:

Surgery is an important therapeutic option in patients with medically refractory epilepsy. The combination of an extratemporal epileptic focus and nonlesional magnetic resonance imaging (MRI) was often believed to portend a poor outcome.

OBJECTIVE:

To investigate the outcome and analyze potential prognostic predictors in patients without lesions on MRI who underwent extratemporal resections.

METHODS:

Clinical, presurgical evaluation, invasive monitoring, and postoperative data of patients with high-resolution MRI that was initially reported as nonlesional were reviewed. Patients were reclassified as MRI-positive if an MRI abnormality related to the epilepsy was revealed at the multidisciplinary presurgical patient management conference, or as MRI-negative if imaging remained normal or revealed incidental findings.

RESULTS:

Sixty patients were identified; 72% were MRI-negative. In the original cohort, the median seizure-free duration was 1.32 years (95% confidence interval [CI], 0.16-2.0); probability of seizure freedom at 2 years was 36% (95% CI, 30%–43%). In the MRI-negative group, the median seizure-free duration was 1.52 years (95% CI, 0.12-5.17); probability of seizure freedom at 2 years was 42% (95% CI, 33%–50%). Complete resection of ictal onset areas and absence of acute postoperative seizures were significantly associated with longer seizure freedom (risk ratio 4.9, P = .004; 95% CI, 1.6-16.7 and 22.1, P &lt; .001; 95% CI, 5.9-94.7, respectively).

CONCLUSION:

Among patients with medically refractory MRI nonlesional extratemporal epilepsy, detailed evaluation and subsequent resection leads to seizure freedom in 42% of patients at 2 years.

Seizure outcome after extratemporal epilepsy surgery in childhood

AIM

The aim of the study was to describe seizure outcome following surgery for focal extratemporal epilepsy and identify factors associated with prolonged postsurgical freedom from seizures.

METHOD

In this retrospective cohort study, children with drug-resistant focal extratemporal epilepsy were treated surgically and followed up in a single tertiary care centre between 1997 and 2008.

RESULTS

Eighty children were identified for inclusion in the study (42 males, 38 females; median age 9y 1mo, range 3mo-18y 7mo). The aetiology was identified as focal cortical dysplasia (n=37), low-grade tumour (n=22), tuberous sclerosis (n=9), or non-specific (n=12). Children were followed for a median of 3 years 1 month (range 8mo-10y 7mo) after surgery. Overall, at last follow-up, 50% of the children had been completely seizure free since surgery (Engel class Ia); of these 40 individuals, 15 had discontinued all antiepileptic drugs. Several presurgical factors were associated with a favourable outcome. However, after controlling for confounding factors, aetiology appeared to be the only determinant of long-term seizure outcome as non-specific lesion pathology was associated with seizure recurrence (hazard ratio 10.43; 95% confidence interval 3.26-33.39).

INTERPRETATION

In 50% of cases, children with surgically treated drug-resistant extratemporal epilepsies have an excellent long-term outcome. The aetiology of the epileptogenic lesion appears to be the only significant determinant of surgical outcome in this population of children. It is difficult to correctly identify non-specific pathology on presurgical magnetic resonance imaging.

Neurosurgical management of frontal lobe epilepsy in children

OBJECT

Pediatric frontal lobe epilepsy (FLE) remains a challenging condition for neurosurgeons and epileptologists to manage. Postoperative seizure outcomes remain far inferior to those observed in temporal lobe epilepsies, possibly due to inherent difficulties in delineating and subsequently completely resecting responsible epileptogenic regions. In this study, the authors review their institutional experience with the surgical management of FLE and attempt to find predictors that may help to improve seizure outcome in this population.

METHODS

All surgically treated cases of intractable FLE from 1990 to 2008 were reviewed. Demographic information, preoperative and intraoperative imaging and electrophysiological investigations, and follow-up seizure outcome were assessed. Inferential statistics were performed to look for potential predictors of seizure outcome.

RESULTS

Forty patients (20 male, 20 female) underwent surgical management of FLE during the study period. Patients were an average of 5.6 years old at the time of FLE onset and 11.7 years at the time of surgery; patients were followed for a mean of 40.25 months. Most patients displayed typical FLE semiology. Twenty-eight patients had discrete lesions identified on MRI. Eight patients underwent 2 operations. Cortical dysplasia was the most common pathological diagnosis. Engel Class I outcome was obtained in 25 patients (62.5%), while Engel Class II outcome was observed in 5 patients (12.5%). No statistically significant predictors of outcome were found.

CONCLUSIONS

Control of FLE remains a challenging problem. Favorable seizure outcome, obtained in 62% of patients in this series, is still not as easily obtained in FLE as it is in temporal lobe epilepsy. While no statistically significant predictors of seizure outcome were revealed in this study, patients with FLE continue to require extensive workup and investigation to arrive at a logical and comprehensive neurosurgical treatment plan. Future studies with improved neuroimaging and advanced invasive monitoring strategies may well help define factors for success in this form of epilepsy that is difficult to control.

Neuropsychological outcome after extra-temporal epilepsy surgery

BACKGROUND

The neuropsychological results of temporal lobe epilepsy surgery are well reported in the literature. The aim of this study was to analyse the neuropsychological outcome in a consecutive series of patients with extra-temporal epilepsy.

METHODS

We retrospectively analysed the data of patients operated between 1996 and 2008 for extra-temporal epilepsy. Standard neuropsychological tests were applied. We assessed the neuropsychological outcome after surgery and the correlation of the neuropsychological outcome with (1) side and localisation of surgery, (2) Engel scale for seizure outcome and (3) timing of surgery.

FINDINGS

Patients had a better neuropsychological outcome when undergoing non-frontal resection [χ2 (2) =6.66, p = 0.036]. Subjects who had undergone left or right resection showed no difference in outcome [χ2 (2) =0.533, p = 0.766]. The correlation between the Engel scale for seizure re-occurence and the neuropsychological scores showed only a tendency for better outcome (Spearman ρ = -0.437; p = 0.069). The global measure of change did not correlate significantly with delay of surgery (Spearman ρ = -0.163; p = 0.518).

CONCLUSIONS

Resective epilepsy surgery improves neuropsychological status outcome in patients with extra-temporal epilepsy even if the patient did not become seizure free. The outcome is better for non-frontal localisation.

Temporoparietooccipital disconnection in children with intractable epilepsy

OBJECT

Temporoparietooccipital (TPO) disconnection is described mainly in children with diffuse posterior quadrant lesions and concordant electroencephalography (EEG) findings. The authors report on 16 children who underwent TPO surgery, including 4 with no definite epileptogenic lesion and 8 with generalized electroclinical manifestations.

METHODS

The authors conducted a retrospective review of clinical, neuropsychological, EEG, imaging, and histopathological data in 16 children with intractable epilepsy who underwent TPO disconnection and/or resection at their center between December 1998 and March 2010.

RESULTS

Seizure onset occurred between the ages of 1 and 24 months, and TPO surgery was performed between the ages of 0.2 and 17 years. All children had refractory seizures, including epileptic spasms in 10 and tonic seizures in 7, and all had developmental delay. Twelve children had epileptogenic lesions on MR imaging, including 6 with posterior quadrant dysplasia. Four children had only subtle white matter signal change or unusual sulcation on MR imaging, associated with subtle but concordant EEG and functional imaging abnormalities. After a mean follow-up of 52 months (range 12-114 months), 9 children (56%) are seizure-free and 5 (31%) experienced seizure reduction of greater than 50%. Focal or regional background slowing on EEG was correlated with favorable seizure outcome. Five children showed developmental progress and 3 had acceleration in development following surgery. None of the children developed new motor deficits postoperatively.

CONCLUSIONS

Temporoparietooccipital disconnection is an effective, motor-sparing epilepsy surgery procedure for selected children with refractory focal or generalized seizures with localization to the posterior quadrant on 1 side, with or without a discrete lesion on MR imaging.

Long term outcome in patients not initially seizure free after resective epilepsy surgery

PURPOSE

To assess the long-term seizure outcome and find predictors of outcome for patients who were not initially seizure free 6 months after epilepsy surgery.

METHODS

We retrospectively reviewed all adult patients who underwent epilepsy surgery at the Epilepsy Center Bethel, between 1992 and 2003. There were 266 patients included in this analysis.

RESULTS

Of the 266 patients who were included in this study, the probability of becoming seizure free was 12% (95%CI 8-16%) after 2 years, 19.5% (95%CI 15-24%) after 5 years and 34.7% (95%CI 28-41%) after 10 years. In patients who had auras only, the probability of being seizure free was 18.2% after 2 years, 25.5% after 5 years, and 39.1% after 10 years. In the multiregression analysis, the EEG carried out 2 years after surgery, a psychic aura, the frequency of postoperative focal seizures and hypermotor seizures predicted seizure remission in the long-term outcome.

CONCLUSIONS

The frequency and type of postoperative seizures are critical determinants for long-term outcome. Seizure semiology may be the clue to a precise diagnosis and long-term prognosis of epilepsy.

Selecting patients for epilepsy surgery: identifying a structural lesion

One of the most important components of presurgical evaluation of patients with epilepsy is structural imaging, predominantly using magnetic resonance imaging. This study is now part of the basic assessment of patients with epilepsy and is as important as the electroencephalogram. Epilepsy protocol magnetic resonance imaging studies must be part of the overall assessment of the patient. To understand the basis of the epileptic disorder, interpretation of these investigations relies on knowledge of the clinical details and features of the seizures, the functional abnormality in the brain as shown on the electroencephalogram, and structural assessment of the brain with a magnetic resonance imaging study optimized for epilepsy. This review considers the essential elements of this issue and gives a broad overview of what imaging options are available for the investigation of the patient with epilepsy from the perspective of the practicing epileptologist.

Epilepsy surgery in a pediatric population: a retrospective study of 129 children from a tertiary care hospital in a developing country along with assessment of quality of life

PURPOSE

To assess the outcome of a pediatric population operated for drug-resistant epilepsy from a large tertiary care center in India.

METHODS

Retrospectively: quality of life (QOL); prospectively: preoperative assessment included interictal EEG, MRI (as per epilepsy protocol), video-EEG. Ictal SPECT (with subtraction) and PET were performed when required. QOL scores were assessed using the HASS or SSQ for seizure severity, Quality of Life in Childhood Epilepsy (QOLCE) for QOL, and Child Behavior Check List (CBCL) for behavior.

RESULTS

142 were operated from January 2000 to June 2011 by the senior author. 118 patients with at least 1 year of follow-up were included in the study. Mean age at surgery was 9.8 ± 4.3 years. In addition, 40 patients underwent QOL assessment prospectively both before and after surgery. Mean duration of epilepsy was 5.3 ± 3.3 years. A class I outcome (Engel's) was seen in 79.5% patients, class II in 8.6%, class III in 10.7%, and class IV in 1 patient. As per surgical procedures, class I outcome in patients who underwent temporal resection, hemispherotomy and extratemporal resection was 76, 87 and 72%, respectively. QOL scores correlated with duration of seizures, epileptic encephalopathy and outcome of surgery, but not with side of surgery, age and sex.

CONCLUSIONS

This study, the largest reported from India, has demonstrated satisfactory results for epilepsy surgery in children.

Long-term outcome of vagus nerve stimulation therapy after failed epilepsy surgery

OBJECTIVE

Adequate control of intractable epilepsy continues to be a challenge. Little is known about the role of VNS therapy in intractable epilepsy in patients who failed to respond to surgical management. The objective of the present study is to determine the efficacy of vagus nerve stimulation therapy in patients with intractable epilepsy who have failed surgical and medical therapy.

METHODS

All the patients who had persistent seizures after cranial surgery who subsequently underwent vagus nerve stimulator (VNS) placement at our institution from 1998 to 2008 were included in the study. Thirty-seven consecutive patients were enrolled and followed for the outcome measures of seizure burden, anti-epileptic drug (AED) burden and quality of life (QoL). Minimum follow-up was 18 months.

RESULTS

Overall, 24 (64.9%), 9 (24.3%), 4 (10.8%) patients reported less than 30%, between 30% and 60% and greater than 60% reduction in seizure frequency after VNS placement, respectively at a mean of 5 years follow-up period. Post-VNS anti-epileptic requirement exhibited a decreasing trend. 17 patients (45.9%) report an improvement in QoL (better or much better).

CONCLUSION

VNS therapy in patients who have failed medical and surgical therapies only provides marginal improvement in seizure control but has greater likelihood to improve subjective QoL issues. In addition, VNS has the potential to reduce AED burden without adversely impacting seizure management. Given the low surgical risk of VNS placement, vagus nerve stimulation as a therapeutic modality should be individualized to achieve best clinical response and fewest side effects.

Comparison between Initial and Recent Surgical Outcome of 15-Year Series of Surgically Remediable Epilepsy

OBJECTIVE

The aim of this study is to compare the surgical outcome of the initial and recent surgical cases, during our 15-years experience, in terms of the surgical strategies and the prognostic factors for surgically remediable epilepsy.

METHODS

We retrospectively reviewed and compared the surgical outcomes between the initial 256 (Group I) and recent 139 (Group II) patients according to the time period of operation for a total of 518 consecutive epilepsy surgeries at our institution since 1992. The patients of the middle intermediate period, which were subjected to changed surgical strategies, were excluded.

RESULTS

The surgical outcome data from the initial and recent groups showed a much improved outcome for patients who underwent temporal lobe epilepsy (TLE) surgery over time. The number of patients with a good outcome (Engel class I-II) was much increased from 87.7% (178 TLE cases of Group I) to 94.8% (79 TLE cases of Group II) and this was statistically significant (p = 0.0324) on univariate analysis. Other remarkable changes were the decreased performance of intracranial invasive studies from 43.5% in Group I to 30.9% in Group II due to the advanced neuroimaging tools. The strip/grid ratio was reduced from 131/32 in Group I to 17/25 in Group II, because of a markedly reduced mesial TLE surgery and an increased extratemporal epilepsy surgery.

CONCLUSION

Our results show that surgical outcome of epilepsy surgery has improved over time and it has shown to be efficient to control medically intractable epilepsy. Appropriate patient selection, comprehensive preoperative assessments and more extensive resection are associated with good postoperative outcomes.

Surgery for extratemporal nonlesional epilepsy in adults: an outcome meta-analysis

PURPOSE

To better evaluate surgery for extratemporal lobe epilepsy (ETLE) in adults, we conducted a meta-analysis of previous studies that analyzed postoperative seizure outcomes for ETLE.

METHODS

After searching PubMed for appropriate studies, patient data were reviewed, and data on patients who fit the authors' criteria were extracted. Statistical analysis compared each variable with surgical outcome to determine if an association existed.

RESULTS

For the 131 patients who were included in the analysis, the age at surgery, age of seizure onset, and duration of epilepsy were not found to be statistically and significantly related to seizure outcome. Similarly, seizure semiology, abnormality on magnetic resonance imaging, lateralization of the seizures, the need for intracranial monitoring, pathological findings, and the type and location of surgery did not appear to be associated with outcome.

CONCLUSIONS

This meta-analysis confirms the findings of other centers: ETLE surgical outcomes are less desirable than those for temporal lobe epilepsy. None of the factors studied in adults showed significant association with outcome. Contrary to some reports, shortening the duration of epilepsy by pursuing surgery as early as possible also does not appear to improve outcomes. The creation of standard protocols among epilepsy centers is needed to allow for a detailed evaluation of outcomes across different centers and, ultimately, to better assess the factors associated with improved outcomes.

Surgery for extratemporal nonlesional epilepsy in children: a meta-analysis

PURPOSE

Previous small studies have demonstrated that seizure outcomes following surgery for extratemporal lobe epilepsy (ETLE) in children are worse than those for temporal lobe epilepsy. We have conducted a meta-analysis of the available literature to better understand ETLE surgical outcomes in children.

METHODS

We searched PubMed (1990-2009) for appropriate studies using the following terms: ETLE, ETLE surgery, ETLE surgery outcome, frontal lobe epilepsy, occipital lobe epilepsy, and parietal lobe epilepsy. Our collected data included patient age at seizure onset and surgery, the cerebral lobe involved with epileptogenesis, MRI findings, predominant seizure semiology, intracranial monitoring use (electrode implantation), epileptic region histopathology, and postoperative seizure outcome. Statistical analysis was performed to determine associations among these variables and postoperative outcome.

RESULTS

Ninety-five patients from 17 studies satisfied the inclusion criteria. Pathological findings (p = 0.039) and seizure type (p = 0.025) were significantly associated with outcome: A larger proportion of patients with cortical dysplasia and complex partial seizures experienced better outcomes. Age at surgery (p = 0.073) and the cerebral resection site (p = 0.059) were marginally associated with seizure outcome.

CONCLUSIONS

This study confirms previous reports: Surgical outcomes for ETLE epilepsy are significantly worse than those for temporal lobe epilepsy. The reasons for this difference may include the diffuse nature of the pathology involved in ETLE, difficulty in localizing the seizure focus in young children, and involvement of "eloquent" nonresectable cortex in epileptogenesis. Because of the reporting variability among different epilepsy centers, more uniform protocols are necessary for fair evaluation and comparison of outcomes among the different centers.