Predicting long-term seizure outcome after resective epilepsy surgery: The Multicenter Study

Surgical techniques for the treatment of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common form of medically intractable epilepsy. Advances in electrophysiology and neuroimaging have led to a more precise localization of the epileptogenic zone within the temporal lobe. Resective surgery is the most effective treatment for TLE. Despite the variability in surgical techniques and in the extent of resection, the overall outcomes of different TLE surgeries are similar. Here, we review different surgical interventions for the management of TLE.

Impact of epilepsy surgery on seizure control and quality of life: a 26-year follow-up study

PURPOSE

The short-term efficacy and safety of epilepsy surgery relative to medical therapy has been established, but it remains underutilized. There is a lack of data regarding the long-term seizure-control rates and quality of life outcomes after epilepsy surgery. This study represents the longest follow-up study to date, with a mean follow-up duration of 26 years.

METHODS

We studied the seizure and health-related quality of life outcomes of patients who underwent epilepsy surgery by Dr. Sidney Goldring from 1967 to 1990. Retrospective clinical chart reviews gathered perioperative data and surveys obtained follow-up data. Seizure outcome was evaluated using the Engel classification system.

KEY FINDINGS

Of 361 patients, 117 (32.4%) completed follow-up interviews. Fifty-six patients (48%) were Engel class I. Mean overall Quality of Life in Epilepsy (QOLIE-31) questionnaire score for the cohort was 68.2 ± 16. Eighty percent of patients reported their overall quality of life now as being better than before surgery. Seizure freedom was associated with better quality of life. We did not observe a statistically significant association between postoperative complications and long-term outcome. Patients who underwent temporal lobe resection achieved better seizure outcomes than those who underwent other types of procedures. Astatic seizures and bilateral surgery were associated with a worse Engel class outcome.

SIGNIFICANCE

Our study demonstrates that the beneficial effects of epilepsy surgery are sustained over decades, and that these beneficial effects are correlated with an improved quality of life. The confirmation of its durability makes us optimistic that the outcomes from modern epilepsy surgery will be even better and that our present enthusiasm for this treatment modality is not misplaced.

Epilepsy. Outcome patterns in epilepsy surgery--the long-term view

Predicting response to therapy in individual patients with epilepsy is not straightforward. An exploration of long-term surgical outcomes in an epilepsy cohort has identified seven patterns of remission and relapse, and the probability of each outcome has been calculated. The study provides new predictors of postoperative outcomes in epilepsy.

Surgical outcome in PET-positive, MRI-negative patients with temporal lobe epilepsy

PURPOSE

Fluorodeoxyglucose positron emission computed tomography (FDG-PET) hypometabolism is important for surgical planning in patients with temporal lobe epilepsy (TLE), but its significance remains unclear in patients who do not have evidence of mesial temporal sclerosis (MTS) on magnetic resonance imaging (MRI). We examined surgical outcomes in a group of PET-positive, MRI-negative patients and compared them with those of patients with MTS.

METHODS

We queried the Thomas Jefferson University Surgical Epilepsy Database for patients who underwent anterior temporal lobectomy (ATL) from 1991 to 2009 and who had unilateral temporal PET hypometabolism without an epileptogenic lesion on MRI (PET+/MRI-). We compared this group to the group of patients who underwent ATL and who had MTS on MRI. Patients with discordant ictal electroencephalography (EEG) were excluded. Surgical outcomes were compared using percentages of Engel class I outcomes at 2 and 5 years as well as Kaplan-Meier survival statistic, with time to seizure recurrence as survival time. A subgroup of PET+/MRI- patients who underwent surgical implantation prior to resection was compared to PET+/MRI- patients who went directly to resection without implantation.

KEY FINDINGS

  There were 46 PET+/MRI- patients (of whom 36 had 2-year surgical outcome available) and 147 MTS patients. There was no difference between the two groups with regard to history of febrile convulsions, generalized tonic-clonic seizures, interictal spikes, depression, or family history. Mean age at first seizure was higher in PET+/MRI- patients (19 ± 13 vs.14 ± 13 years, Mann-Whitney test, p = 0.008) and disease duration was shorter (14 ± 10 vs. 22 ± 13 years, student's t-test, p = 0.0006). Class I surgical outcomes did not differ significantly between the PET+/MRI- patients and the MTS group (2 and 5 year outcomes were 76% and 75% for the PET+/MRI- group, and 71% and 78% for the MTS group); neither did outcomes of the PET+/MRI- patients who were implanted prior to resection versus those who went directly to surgery (implanted patients had 71% and 67% class I outcomes at 2 and 5 years, whereas. nonimplanted patients had 77% and 78% class I outcomes, p = 0.66 and 0.28). Kaplan-Meier survival statistics for both comparisons were nonsignificant at 5 years. Dentate gyrus and hilar cell counts obtained from pathology for a sample of patients also did not differ between groups.

SIGNIFICANCE

PET-positive, MRI-negative TLE patients in our study had excellent surgical outcomes after ATL, very similar to those in patients with MTS, regardless of whether or not they undergo intracranial monitoring. These patients should be considered prime candidates for ATL, and intracranial monitoring is probably unnecessary in the absence of discordant data.

Predicting seizure freedom after two or more chronic invasive evaluations in patients with intractable epilepsy

OBJECTIVE

In patients with intractable epilepsy, failure to localize and/or resect the epileptic focus after invasive monitoring is multifactorial. Rarely do these patients return for a second invasive evaluation, and their outcome is not clearly characterized. This study aims to determine the seizure outcome after a second invasive electroencephalographic (EEG) evaluation, and its possible predictors.

METHODS

We retrospectively reviewed 30 patients who underwent two or more invasive evaluations at Cleveland Clinic between 1980 and 2007. Clinical, surgical, imaging, and pathology information was analyzed using a multivariate regression model. A favorable outcome was defined as complete seizure freedom, allowing for auras and seizures restricted to the first postoperative week.

RESULTS

Ten patients (33%) became seizure free after the second operation (mean follow-up duration 3.13 years [range 6 months-17 years]). Seizure freedom was more likely in patients reporting fewer seizures per month preoperatively (mean 19 seizures/mo), and in those with a predominantly regional/lateralized scalp EEG ictal pattern (32% seizure free), as opposed to those with higher seizure frequency (mean 70 seizures/month; P = 0.02) or diffuse ictal EEGs (0% seizure free; P = 0.04). There was a significant association between acute postoperative seizures and failure of repeat surgery (P = 0.0083). In 17 of 30 patients, at least one complication was reported (57%) after the second invasive evaluation compared with a complication rate of 23% after the first invasive evaluation.

CONCLUSIONS

A second invasive evaluation may lead to seizure freedom in one-third of patients. However, this must be weighed against the increased complication rate with reoperation.

Utility of diffusion tensor imaging tractography in decision making for extratemporal resective epilepsy surgery

PURPOSE

To assess the utility of diffusion tensor imaging tractography (DTIT) in decision making in patients considered for extratemporal resective epilepsy surgery.

METHODS

We subjected 49 patients with drug-resistant focal seizures due to lesions located in frontal, parietal and occipital lobes to DTIT to map the white matter fiber anatomy in relation to the planned resection zone, in addition to routine presurgical evaluation. We stratified our patients preoperatively into different grades of risk for anticipated neurological deficits as judged by the distance of the white matter tracts from the resection zones and functional cortical areas.

RESULTS

Thirty-seven patients underwent surgery; surgery was abandoned in 12 (24.5%) patients because of the high risk of postoperative neurological deficit. DTIT helped us to modify the surgical procedures in one-fourth of occipital, one-third of frontal, and two-thirds of parietal and multilobar resections. Overall, DTIT assisted us in surgical decision making in two-thirds of our patients.

CONCLUSIONS

DTIT is a noninvasive imaging strategy that can be used effectively in planning resection of epileptogenic lesions at or close to eloquent cortical areas. DTIT helps in predicting postoperative neurological outcome and thereby assists in surgical decision making and in preoperative counseling of patients with extratemporal focal epilepsies.

Genomic microdeletions associated with epilepsy: not a contraindication to resective surgery

PURPOSE

Several recent reports of genomic microdeletions in epilepsy will generate further research; discovery of more microdeletions and other important classes of variants may follow. Detection of such genetic abnormalities in patients being evaluated for surgical treatment might raise concern that a genetic defect, possibly widely expressed in the brain, will affect surgical outcome.

METHODS

A reevaluation was undertaken of clinical presurgical data, histopathology of surgical specimen, and postsurgical outcome in patients with mesial temporal lobe epilepsy (MTLE) who have had surgical treatment for their drug-resistant seizures, and who have been found to have particular genomic microdeletions.

KEY FINDINGS

Three thousand eight hundred twelve patients with epilepsy were genotyped and had a genome-wide screen to identify copy number variation. Ten patients with MTLE, who had resective epilepsy surgery, were found to have 16p13.11 microdeletions or other microdeletions >1 Mb. On histopathology, eight had classical hippocampal sclerosis (HS), one had nonspecific findings, and one had a hamartoma. Median postsurgical follow-up time was 48 months (range 10-156 months). All patients with HS were seizure-free after surgery, International League Against Epilepsy (ILAE) outcome class 1, at last follow-up; the patient with nonspecific pathology had recurrence of infrequent seizures after 7 years of seizure freedom. The patient with a hamartoma never became seizure-free.

SIGNIFICANCE

  Large microdeletions can be found in patients with "typical" MTLE. In this small series, patients with MTLE who meet criteria for resective surgery and harbor large microdeletions, at least those we have detected, can have a good postsurgical outcome. Our findings add to the spectrum of causal heterogeneity of MTLE + HS.

The value of intraoperative electrocorticography in surgical decision making for temporal lobe epilepsy with normal MRI

PURPOSE

We hypothesized that acute intraoperative electrocorticography (ECoG) might identify a subset of patients with magnetic resonance imaging (MRI)-negative temporal lobe epilepsy (TLE) who could proceed directly to standard anteromesial resection (SAMR), obviating the need for chronic electrode implantation to guide resection.

METHODS

Patients with TLE and a normal MRI who underwent acute ECoG prior to chronic electrode recording of ictal onsets were evaluated. Intraoperative interictal spikes were classified as mesial (M), lateral (L), or mesial/lateral (ML). Results of the acute ECoG were correlated with the ictal-onset zone following chronic ECoG. Onsets were also classified as "M,""L," or "ML." Positron emission tomography (PET), scalp-EEG (electroencephalography), and Wada were evaluated as adjuncts.

KEY FINDINGS

Sixteen patients fit criteria for inclusion. Outcomes were Engel class I in nine patients, Engel II in two, Engel III in four, and Engel IV in one. Mean postoperative follow-up was 45.2 months. Scalp EEG and PET correlated with ictal onsets in 69% and 64% of patients, respectively. Wada correlated with onsets in 47% of patients. Acute intraoperative ECoG correlated with seizure onsets on chronic ECoG in all 16 patients. All eight patients with "M" pattern ECoG underwent SAMR, and six (75%) experienced Engel class I outcomes. Three of eight patients with "L" or "ML" onsets (38%) had Engel class I outcomes.

SIGNIFICANCE

Intraoperative ECoG may be useful in identifying a subset of patients with MRI-negative TLE who will benefit from SAMR without chronic implantation of electrodes. These patients have uniquely mesial interictal spikes and can go on to have improved postoperative seizure-free outcomes.

Epilepsy surgery in Argentina: long-term results in a comprehensive epilepsy centre

RATIONALE

Epilepsy surgery procedures started in Argentina more than 50 years ago. This is the first comprehensive and systematic survey of epilepsy surgery long-term outcome from our country.

METHODS

A descriptive cohort study was conducted between 1998 and 2008 for drug-resistant epilepsy surgery with a minimum of 12 months follow-up (n=110). In 84 cases (76.36%) resective surgery was performed, and outcome periodically assessed using the Engel score. Patients were stratified into groups: 12, 13-36, 37-60 and over than 60 months of follow-up. Video-EEG with and without intracranial electrode implants, intraoperative electrocorticograms, Wada tests, pathology reports, use of antiepileptic drugs (AEDs), and surgical complication rates were evaluated.

RESULTS

Surgical techniques included: 69 lobectomies (62.7%), 15 lesionectomies (13.6%), 6 callosotomies (5.4%), 6 multiple subpial transection (5.4%), 11 vagus nerve stimulations (10%), 3 hemispherectomies (2.7%). Male: female ratio: 1/1.44. Mean age at time of surgery: 26.2 years. Mean duration of epilepsy: 14 years. Age at seizure onset: 11.5 years. Mean follow-up: 46 months. Pathology findings: mesial temporal sclerosis 32 (35.1%); dual pathology 17 (18.7%); cortical dysplasia 15 (16.4%); non-specific inflammatory changes 11 (12.1%); tumors 7 (7.7%); other 6 (6.8%). Engel scores at 12 months follow-up: 72.6% (61) class I, 16.6% (14) class II and 15.5% (13) class III-IV; 13-36 months after surgery: 68.1% of cases were class I, 15.9% class II and 15.5% class III-IV. After 37-60 months, 74% class I, 14% class II, 14% class III-IV. Over 60 months (n=45) 78% class I, 13.5% class II and 8.1% class III-IV.

CONCLUSION

Conducting a successful epilepsy surgery program in a developing country is challenging. These results should encourage specialists in these countries. Long-term outcome results comparable to centres in developed countries can be achieved.

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.

Identifying epilepsy surgery candidates in the outpatient clinic

Epilepsy is the most prevalent disabling neurological disorder across the life span, and is not controlled by medications in more than one-third of patients. Epilepsy surgery is an accepted treatment, with guidelines supporting utilization in patients with recurrent temporal lobe seizures after two or more trials of antiepileptic medications. Unfortunately, the average delay in presurgical evaluation of appropriate candidates is more than 20 years, and this delay has not improved in recent decades. This offers the international neurological community the opportunity to improve disability, mortality, and quality of life by more effective application of epilepsy surgery and earlier identification of potential candidates. Optimal use of MRI and video/EEG monitoring should allow cost-effective screening of persons with recurrent seizures prior to more detailed presurgical evaluation when indicated.

Selecting patients for epilepsy surgery: synthesis of data

The consideration of epilepsy surgery for those with medically refractory seizure disorders requires a well-functioning multidisciplinary team and a systematic approach to investigations, with the aim of advising patients of their chances of being seizure free following surgery, and the risks of any procedure. Investigatory pathways may be outlined that cover most clinical situations, and the indications for invasive EEG studies. It is crucial that patients and their families are given realistic expectations of what may, and may not, be achieved with surgical treatment, and that long-term follow-up is maintained post-operatively.

Is it necessary to define the ictal onset zone with EEG prior to performing resective epilepsy surgery?

When evaluating candidates for neurosurgical treatment for medically intractable epilepsy, is it always necessary to define the region of seizure onset with EEG? A simple answer to this question is not possible. There are specific situations where surgery is commonly performed without clear EEG ictal localization, and other situations where electrical localization is mandatory. However, opinions differ in many other situations. What are the core issues for determining when EEG localization is necessary? Neuroimaging is imperfect. It does not always accurately identify the site of seizure origination, because seizures do not always arise from visible structural lesions. EEG localization is also imperfect, as well as expensive and time consuming. Sometimes the site of origin is not identified, or a region of spread is misidentified as site of origin. False localization and lateralization can occur. Finally, epilepsy surgery is imperfect. It can produce life-changing results, but it carries risk, and surgical failure is not rare. The limitations of these methods, and the high stakes of epilepsy surgery imply that we should be very cautious to omit EEG studies. The desire to improve access to epilepsy surgery, and to minimize the expense and risk from inpatient EEG studies, must be weighed against the possibility of an ineffective resection. To improve outcomes, improvements in both neuroimaging and EEG techniques are needed.

AES 2009 Annual Course: Reoperation for medically refractory epilepsy

A significant percentage of patients undergoing resective surgery for medically refractory epilepsy have persistent or recurrent disabling seizures. In these patients, the objective of seizure freedom justifies the consideration of repeat resective surgery. In this report, the available published experience with repeat resective surgery is analyzed. The reoperated patients are subdivided into three categories: patients with residual medial temporal structures, patients with an unresected or partially resected structural/mass (non-glioma) lesion and patients with non-lesional neocortical epilepsy. This analysis indicates that the chance of achieving seizure freedom is significant, although lower than with the initial surgery. The chance of significant morbidity (particularly significant neurologic deficit) is low, although higher than with the initial surgery. A proper evaluation can identify appropriate candidates for a resective reoperation. Palliative surgical options should be strongly considered for all patients, especially for those with lower chance of seizure freedom and/or elevated risk of morbidity.

Temporal lobe epilepsy surgery failures: predictors of seizure recurrence, yield of reevaluation, and outcome following reoperation

Object

The authors provide a systematic analysis of electroclinical characteristics in patients with persistent seizures following temporal lobe epilepsy (TLE) surgery and identify ideal candidates for reoperation.

Methods

The authors retrospectively reviewed the records of 68 adult patients (mean follow-up 8.7 years) who underwent a video electroencephalography evaluation and high-resolution imaging after failed TLE surgery performed between 1990 and 2004 at The Cleveland Clinic. Multivariate logistic regression analyses were performed to identify predictors of the yield of a repeat evaluation, location of the recurrence focus, and outcome following reoperation.

Results

Although a focus of recurrence was identified in 44 patients, only 15 underwent reoperation, and only 6 of these became seizure free. Localized foci of recurrence were successfully identified in patients with early (within 1 postoperative year) and frequent (≥ 4 per month) recurrent seizures (yield of 100% if both conditions were fulfilled). Predictors of contiguity of the focus of recurrence to the initial surgical bed were variable depending on the type of the initial surgery: patients with baseline contralateral temporal spiking were 6 times (OR 6.34, p < 0.05) more likely to experience seizure recurrence from the contralateral temporal lobe after a “standard” temporal lobectomy, while the need to use subdural electrodes and the timing of recurrence were more significant following limited temporal resections. The focus of recurrence was distant to the original surgical bed when subdural electrodes were used prior to first surgery (OR 28.0, p = 0.01) or when seizures recurred early (within < 6 postoperative months; OR 12.5, p = 0.04). With reoperation, only patients with mesial and basal extension of the temporal resections became seizure free. Interestingly, seizure freedom was achieved with medical therapy alone in 42% of patients with a nonidentifiable recurrence focus as opposed to 4% of those with an unoperated identifiable focus.

Conclusions

The timing and frequency of recurrent seizures following unsuccessful TLE surgery provide useful guidelines for the yield of a surgical reevaluation, and potentially for the mechanisms of surgical failure.

Epilepsy surgery: recommendations for India

The following article recommends guidelines for epilepsy surgery for India. This article reviews the indications, the various surgical options available and the outcome of surgery for drug resistant epilepsy based on current evidence. Epilepsy surgery is a well-established option for patients who have been diagnosed to have drug resistant epilepsy (DRE) (on at least two appropriate, adequate anti-epileptic drugs (AEDs) (either in monotherapy or in combination) with continuing seizures), where the presurgical work-up has shown concordance of structural imaging (magnetic resonance imaging) and electrical mapping data (electroencephalography (EEG), video EEG). There may be a requirement of functional imaging techniques in a certain number of DRE like positron emission tomography (PET), single photon emission tomography, (SPECT)). Invasive monitoring should be restricted to a few when all noninvasive investigations are inconclusive, there is a dual pathology or there is a discordance of noninvasive data. The types of surgery could be curative (resective surgeries: amygdalo hippocampectomy, lesionectomy and multilobar resections; functional surgeries: hemispherotomy) and palliative (multiple subpial transaction, corpus callosotomy, vagal nerve stimulation). Epilepsy surgery in indicated cases has a success range from 50 to 86% in achieving seizure freedom as compared with <5% success rate with AEDs only in persons with DRE. Centers performing surgery should be categorized into Level I and Level II.

Mesial temporal lobe epilepsy: How do we improve surgical outcome?

Surgery has become the standard of care for patients with intractable temporal lobe epilepsy, with anterior temporal lobe resection the most common operation performed for adults with hippocampal sclerosis. This procedure leads to significant improvement in the lives of the overwhelming majority of patients. Despite improved techniques in neuroimaging that have facilitated the identification of potential surgical candidates, the short-term and long-term success of epilepsy surgery has not changed substantially in recent decades. The basic surgical goal, removal of the amygdala, hippocampus, and parahippocampal gyrus, is based on the hypothesis that these structures represent a uniform and contiguous source of seizures in the mesial temporal lobe epilepsy (MTLE) syndrome. Recent observations from the histopathology of resected tissue, preoperative neuroimaging, and the basic science laboratory suggest that the syndrome is not always a uniform entity. Despite clinical similarity, not all patients become seizure-free. Improving surgical outcomes requires a re-examination of why patients fail surgery. This review examines recent findings from the clinic and laboratory. Historically, we have considered MTLE a single disorder, but it may be time to view it as a group of closely related syndromes with variable type and extent of histopathology. That recognition may lead to identifying the appropriate subgroups that will require different diagnostic and surgical approaches to improve surgical outcomes.

Anterior temporal lobectomy combined with anterior corpus callosotomy in patients with temporal lobe epilepsy and mental retardation

AIMS

To investigate the surgical outcomes of anterior corpus callosotomy (aCCT) combined with anterior temporal lobectomy (ATL) in patients with intractable temporal lobe epilepsy (TLE) and mental retardation (MR).

METHODS

Sixty patients with TLE and MR were carefully selected and randomly divided into two equal groups: ATL and aCCT, in which they were treated with ATL or ATL combined with aCCT, respectively. Surgical outcomes, including seizure control, IQ and quality of life (QOL) changes, as well as complications were recorded and analyzed 2 years after operation.

RESULTS

Seizure-free status had been achieved in 66.7% of all patients. The aCCT group had higher percentage in Engle Classes I-II than the ATL group (96.7% vs. 80.0%, P<0.05). 56.7% of patients in ATL group and 63.3% in aCCT group had improved full scale IQ (FIQ) after surgery, while the decline of FIQ in aCCT group was less than that of ATL group (3.3% vs. 30.0%). Compared with pre-operative score, the mean post-operative score of performance IQ in aCCT group had improved. Significant difference in QOL change had been found between two groups (P<0.001). 73.7% of patients in aCCT group had their QOL improved with no long-term complications.

CONCLUSIONS

ATL combined with aCCT can improve QOL and performance IQ in patients with TLE and MR.

Outcome after cortico-amygdalo-hippocampectomy in patients with temporal lobe epilepsy and normal MRI

RATIONALE

We describe seizure and neuropsychological outcome obtained after CAH in patients with TLE and normal MRI evaluated in the modern imaging era.

METHODS

Forty-five adult consecutive patients with TLE and normal MRI were studied. All patients had neuropsychological testing, interictal and ictal EEG recordings and MRI. They were divided into two groups: Group 1 (n=18), included patients in whom non-invasive neurophysiological evaluation was lateralizing and Group 2 (n=27) included patients with non-lateralizing neurophysiological data who were submitted to invasive recordings.

RESULTS

Seventy-seven percent of the Group 1 patients were rated as Engel I; 11% were rated as Engel II and 11% as Engel III. In Group 2, there were 57% of patients seizure-free, 26% in Engel II and 14% in Engel III. Pre-operatively, mean general IQ was 82 and 78 in Groups 1 and 2, respectively; post-operatively, mean general IQ was respectively 86 and 71. Some degree of verbal memory decline was noted in all patients submitted to dominant temporal lobe resection in both Groups 1 and 2. At last follow-up visit, 22% of Group 1 and 11% of Group 2 patients were receiving no antiepileptic drugs (AED).

CONCLUSIONS

Our data showed that patients with TLE and normal MRI could get good surgical results after CAH although 60% of them would need invasive recordings and their results regarding seizure control and cognition were worse than those obtained in patients with MRI defined temporal lobe lesions. Caution should be taken in offering dominant temporal lobe resection to this subset of patients.

Association between temporal lobe P-glycoprotein expression and seizure recurrence after surgery for pharmacoresistant temporal lobe epilepsy

Surgery is recommended for pharmacoresistant temporal lobe epilepsy (TLE), but seizures recur in approximately one third of patients postsurgery. P-glycoprotein is an efflux multidrug transporter that is overexpressed in a range of epileptogenic pathologies. We hypothesized that increased expression of P-glycoprotein in the epileptogenic temporal lobe might be a marker for recurrence of pharmacoresistant seizures postsurgery. We performed immunohistochemistry on temporal lobe tissues resected from 69 patients who underwent anterior temporal lobectomy for pharmacoresistant TLE with histopathological proven hippocampal sclerosis. P-glycoprotein expression was rated by three pathologists independently. Patients with seizure recurrence (n=22) had greater number of positively stained capillaries (p=0.001) and higher P-glycoprotein immunoreactive score in capillaries (p=0.002) in the white matter of resected temporal lobe. The differences remained significant in multivariate analysis (p=0.002 and 0.006, respectively). The results suggest that P-glycoprotein expression in temporal lobe may be associated with seizure recurrence after surgery for pharmacoresistant TLE.

Surgical outcomes in lesional and non-lesional epilepsy: a systematic review and meta-analysis

PURPOSES

To provide evidence-based quantitative summary estimates of seizure outcomes in patients with non-lesional and lesional epilepsy treated with surgery, and to assess the consistency of results among published studies.

METHODS

An exhaustive literature search identified articles published since 1995, describing outcomes according to lesional status in patients of any age who underwent resective epilepsy surgery. Two reviewers independently assessed study eligibility and extracted the data. Disagreements were resolved through discussion. Random effects meta-analyses were used after assessing the dataset for heterogeneity.

RESULTS

Forty articles fulfilled eligibility criteria and described outcomes in 697 patients with non-lesional epilepsy and 2860 patients with lesional epilepsy. Overall, the odds of being seizure-free after surgery were 2.5 times higher in patients with lesions on MRI or histopathology (OR 2.5, 95%CI 2.1, 3.0, p<0.001). In patients with temporal lobe epilepsy surgery the odds were 2.7 times higher in those with lesions (OR 2.7, 95%CI 2.1, 3.5, p<0.001). In patients with extratemporal epilepsy surgery the odds were 2.9 higher in those with lesions (OR 2.9, 95%CI 1.6, 5.1, p<0.001). Outcomes were similar in children, adults, and studies that used MRI or histopathology to identify lesions.

DISCUSSION

Overall, the odds of seizure freedom after surgery are two to three times higher in the presence of a lesion on histopathology or MRI. The results are clinically and statistically significant, consistent across various subgroups, and quite homogeneous across studies.

Failure of temporal lobe resection for epilepsy in patients with mesial temporal sclerosis: results and treatment options

OBJECT

The purpose of this study was to identify the causes of failed temporal lobe resection in patients with mesial temporal sclerosis (MTS) and the role of repeat surgery for seizure control.

METHODS

This is a retrospective study of 105 patients who underwent temporal lobe resection for MTS with unilateral electroencephalographic findings. The mean follow-up duration was 36 months (range 24-84 months). Surgeries were all performed by the senior author (F.L.V.).

RESULTS

Following initial surgical intervention, 97 patients (92%) improved to Engel Class I or II (Group A), and 8 (8%) did not have significant improvement (Engel Class III or IV; Group B). These 8 patients were restudied using video-electroencephalography (EEG) and MR imaging. All major surgical failures occurred within 1 year after initial intervention. Reevaluation demonstrated 3 patients (37.5%) with contralateral temporal EEG findings. Five patients (62.5%) had evidence of ipsilateral recurrent discharges. Four patients underwent extended neocortical resection along the previous resection cavity. Their outcomes ranged from Engel Class I to Class III. Only 1 patient (12.5%) who failed to improve after initial surgery was found to have incomplete resection of mesial structures. This last patient underwent reoperation to complete the resection and improved to Engel Class I.

CONCLUSIONS

Failure of temporal lobe resection for MTS is multifactorial. The cause of failure lies in the pathological substrate of the epileptogenic area. Complete seizure control cannot be predicted solely by conventional preoperative workup. Initial surgical failures from temporal lobe resection often benefit from reevaluation, because reoperation may be beneficial in selected patients. Based on this work, the authors have proposed a management and treatment algorithm for these patients.

Outcome of extratemporal epilepsy surgery experience of a single center

OBJECTIVE

Our aim was to determine the surgical outcome in adult patients with intractable extratemporal epilepsy and follow it over time.

METHODS

We retrospectively studied the operative outcome in 218 consecutive adult patients with extratemporal lesions who underwent resective surgical treatment for intractable partial epilepsy in the Bethel Epilepsy Center, Bielefeld, Germany, between 1991 and 2005. Patients were divided into three groups according to the 5-year period in which the surgical procedure took place.

RESULTS

Group I (1991-1995) consisted of 64 patients. The postoperative Engel Class I outcome was 50% at 6 months, 44.4% at 2 years, and 45.2% at 5 years. Group II (1996-2000) included 91 patients. Engel Class I outcome was 57.1% at 6 months, 53.8% at 2 years, and 53.5% at 5 years. In Group III (2001-2005), there were 63 patients. Engel Class I outcome was 65.1% at 6 months, 61.3% at 2 years, and 60.6% at 5 years. Short duration of epilepsy, surgery before 30 years of age, pathological findings of neoplasm, and well-circumscribed lesions on the preoperative magnetic resonance imaging scan were good prognostic factors. Poor prognostic factors were one or more of the following: psychic aura, generalized tonic-clonic seizure, versive seizure, history of previous surgery, and focal cortical dysplasia. On multivariate analysis, only the presence of well-circumscribed lesions on preoperative magnetic resonance imaging predicted a positive outcome (P = 0.001).

CONCLUSION

Our results indicate that extratemporal epilepsy surgery at the Bethel Epilepsy Center has become more effective in the treatment of extratemporal epilepsy patients over the years, ensuring continuous improvement in outcome. This improvement can be attributed mainly to more restrictive patient selection.

Selective amygdalohippocampectomy via the transsylvian approach

Surgery is an established treatment for temporal lobe epilepsy refractory to medication. Several surgical approaches have been used to treat this condition including temporal lobectomy, transcortical selective amygdalohippocampectomy, subtemporal amygdalohippocampectomy, and transsylvian amygdalohippocampectomy. In this article the author reviews the transsylvian amygdalohyppocampectomy and pertinent anatomy. He also discusses the procedure's results with regard to seizure control, neuropsychological outcome, and visual field preservation.

Role of subdural electrocorticography in prediction of long-term seizure outcome in epilepsy surgery

Since prediction of long-term seizure outcome using preoperative diagnostic modalities remains suboptimal in epilepsy surgery, we evaluated whether interictal spike frequency measures obtained from extraoperative subdural electrocorticography (ECoG) recording could predict long-term seizure outcome. This study included 61 young patients (age 0.4-23.0 years), who underwent extraoperative ECoG recording prior to cortical resection for alleviation of uncontrolled focal seizures. Patient age, frequency of preoperative seizures, neuroimaging findings, ictal and interictal ECoG measures were preoperatively obtained. The seizure outcome was prospectively measured [follow-up period: 2.5-6.4 years (mean 4.6 years)]. Univariate and multivariate logistic regression analyses determined how well preoperative demographic and diagnostic measures predicted long-term seizure outcome. Following the initial cortical resection, Engel Class I, II, III and IV outcomes were noted in 35, 6, 12 and 7 patients, respectively. One child died due to disseminated intravascular coagulation associated with pseudomonas sepsis 2 days after surgery. Univariate regression analyses revealed that incomplete removal of seizure onset zone, higher interictal spike-frequency in the preserved cortex and incomplete removal of cortical abnormalities on neuroimaging were associated with a greater risk of failing to obtain Class I outcome. Multivariate logistic regression analysis revealed that incomplete removal of seizure onset zone was the only independent predictor of failure to obtain Class I outcome. The goodness of regression model fit and the predictive ability of regression model were greatest in the full regression model incorporating both ictal and interictal measures [R(2) 0.44; Area under the receiver operating characteristic (ROC) curve: 0.81], slightly smaller in the reduced model incorporating ictal but not interictal measures (R(2) 0.40; Area under the ROC curve: 0.79) and slightly smaller again in the reduced model incorporating interictal but not ictal measures (R(2) 0.27; Area under the ROC curve: 0.77). Seizure onset zone and interictal spike frequency measures on subdural ECoG recording may both be useful in predicting the long-term seizure outcome of epilepsy surgery. Yet, the additive clinical impact of interictal spike frequency measures to predict long-term surgical outcome may be modest in the presence of ictal ECoG and neuroimaging data.

Ictal EEG remains the prominent predictor of seizure-free outcome after temporal lobectomy in epileptic patients with normal brain MRI

PURPOSE

While an abnormal pre-operative high-resolution brain MRI portends a favorable outcome in patients undergoing resective epilepsy surgery for medically intractable localization-related epilepsy (LRE), a normal MRI is less favorable. Ascertaining desirable pre-operative predictors for successful anterior temporal lobectomy (ATL) in LRE patients with a normal brain MRI is essential to better anticipate surgical outcome.

METHODS

Patients with LRE and normal temporal structures on MRI underwent ATL at two epilepsy centers in the southeastern US (FL and NC). Outcome was separated into those patients that were seizure free (SF), and those that were not seizure free (NSF), and those NSF were stratified in accordance with the Engel classification system. Those with a pre-operative history of clinical risk factors, unilateral anterior temporal interictal epileptiform discharges (IEDs), well localized scalp ictal EEG with rhythmic temporal theta at onset, localized PET/ictal SPECT, and Wada asymmetry with >2.5/8, were evaluated for the purpose of predicting outcome. Where appropriate, data is presented as a median (mean +/- S.D.).

RESULTS

Thirty-nine patients, median age 33 years, were followed up 2 years (3+/-1.2) after ATL. Overall, 22/39 (56.4%) patients were identified as SF, and 17/39 (43.6%) patients were NSF. Ictal EEG with rhythmic temporal theta at onset was the only predictive measure of seizure-free outcome (p=0.001, Fisher's exact test), and also favorably correlated with seizure reduction (p=0.0001, r(2)=0.34, multiple regression analysis). None of the other predictors examined added greater predictive value.

CONCLUSIONS

ATL is a favorable option for patients with LRE even when high-resolution brain MRI reveals normal temporal structures. Normal brain MRI patients with localizing pre-operative scalp ictal EEG, have better outcomes following ATL.

Predictors of outcome after temporal lobectomy for refractory temporal lobe epilepsy

OBJECTIVE

To identify predictors of outcome after epilepsy surgery in patients with temporal lobe epilepsy (TLE).

METHODS

Seventy-six patients with normal magnetic resonance imaging (MRI) or hippocampal sclerosis on MRI who underwent anterior temporal lobe resections were included. Outcome 2 years after surgery was classified as good (Engel I and II) or poor (Engel III and IV). Gender, age at onset and duration of epilepsy, history of febrile convulsions, auras, right- or left-sided TLE, memory ipsilateral to seizure onset (Wada test), hippocampal asymmetry (HA) and T2 relaxation time, amygdala, temporal lobe and hemispheral volume were tested for associations with outcome.

RESULTS

Sixty-seven percent had a good outcome. Of all parameters tested, only a history of febrile convulsions and HA on quantitative MRI were significantly associated with a good seizure outcome. The absence of these parameters did not exclude a good outcome, but only five of 18 patients (28%) without HA and without a history of febrile convulsions had a good outcome.

CONCLUSION

Febrile convulsions and HA were predictors of outcome after epilepsy surgery in TLE. Subtle volume loss in amygdala, temporal lobe or hemispheres and the memory ipsilateral to the side of resection were not associated with outcome.

Expectations prior to epilepsy surgery: an exploratory comparison of men and women

Although the clinical goal of resective epilepsy surgery is seizure freedom, patients have a wide set of expectations for this invasive procedure. The goal of this study was to evaluate potential gender differences in expectations among patients undergoing resective epilepsy surgery. Ratings of the importance of 12 potential impacts ("expectations") of resective surgery were analyzed in a seven-center cohort study including 389 adults aged 16 and older who underwent resective epilepsy surgery. Men and women both ranked anticipated changes in driving and memory as the most important presurgical expectations. Women rated driving, physical activity limitations, and economic worries as less important, and fatigue and pregnancy concerns as more important than did men (p's< or =0.05). Exploratory factor analysis indicated a different pattern of associations among the 12 importance items for men and women. Whether gender differences in presurgical values are associated with outcomes needs exploration.