Temporal neocorticectomy in management of intractable epilepsy: long-term outcome and predictive factors

Surgery procedures in temporal lobe epilepsies

Temporal lobe epilepsy (TLE) is the most common cause of refractory epilepsy amenable for surgical treatment and seizure control. Surgery for TLE is a safe and effective strategy. The seizure-free rate after surgical resection in patients with mesial or neocortical TLE is about 70%. Resective surgery has an advantage over stereotactic radiosurgery in terms of seizure outcomes for mesial TLE patients. Both techniques have similar results for safety, cognitive outcomes, and associated costs. Stereotactic radiosurgery should therefore be seen as an alternative to open surgery for patients with contraindications for or with reluctance to undergo open surgery. Laser interstitial thermal therapy (LITT) has also shown promising results as a curative technique in mesial TLE but needs to be more deeply evaluated. Brain-responsive stimulation represents a palliative treatment option for patients with unilateral or bilateral MTLE who are not candidates for temporal lobectomy or who have failed a prior mesial temporal lobe resection. Overall, despite the expansion of innovative techniques in recent years, resective surgery remains the reference treatment for TLE and should be proposed as the first-line surgical modality. In the future, ultrasound therapies could become a credible therapeutic option for refractory TLE patients.

Consequences of mesial temporal sparing temporal lobe surgery in medically refractory epilepsy

OBJECTIVE

We compared long-term seizure outcome, neuropsychological outcome, and occupational outcome of anterior temporal lobectomy (ATL) with and without sparing of mesial structures to determine whether mesial sparing temporal lobectomy prevents memory decline and thus disability, with acceptable seizure outcome.

METHODS

We studied patients (n = 21) and controls (n = 21) with no evidence of mesial temporal sclerosis (MTS) on MRI who had surgery to treat drug-resistant epilepsy. Demographic and pre- and postsurgical clinical characteristics were compared. Patients had neuropsychological assessment before and after surgery. Neuropsychological analyses were limited to patients with left-sided surgery and available data (n = 14 in each group) as they were at risk of verbal memory impairment. The California Verbal Learning Test II (CVLT-II) (sum of trials 1-5, delayed free recall) and the Logical Memory subtest of the Wechsler Memory Scale III or IV (WMS-III or WMS-IV) (learning and delayed recall of prose passages) were used to assess verbal episodic learning and memory. Seizure and occupational outcomes were assessed.

RESULTS

The chance of attaining seizure freedom was similar in the two groups, so sparing mesial temporal structures did not lessen the chance of stopping seizures. Sparing mesial temporal structures mitigated the extent of postoperative verbal memory impairment, though some of these individuals suffered decline as a consequence of surgery. Occupational outcome was similar in both groups.

SIGNIFICANCE

Mesial temporal sparing resections provide a similar seizure outcome as ATL, while producing a better memory outcome. Anterior temporal lobectomy including mesial structure resection did not increase the risk of postoperative disability.

Outcomes of hippocampus-sparing lesionectomy for temporal lobe epilepsy and the significance of intraoperative hippocampography

OBJECTIVES

We investigated hippocampal-sparing lesionectomy (HSL) outcomes in temporal lobe epilepsy (TLE) and the significance of high-frequency oscillations (HFOs) detected by hippocampography in HSL.

METHODS

We retrospectively reviewed data from patients who underwent HSL for lesional TLE. Patients were included when MRI confirmed (i) a lesion limited to the temporal lobe with normal hippocampi preoperatively and (ii) hippocampal integrity postoperatively. Factors possibly related to outcomes were collected. Intraoperative hippocampography was reviewed, and spikes, ripples, and fast ripples were marked. Seizure outcomes were tracked ≥ 2 years. Postoperative neuropsychological tests were performed and analyzed.

RESULTS

We included 67 patients (35 males/32 females, median age at surgery 28 years, 57 seizure-free). Complete resection was significantly associated with being seizure-free without aura, an outcome achieved by 32 (69.6%) patients with complete resection vs 1 (12.5%) with incomplete resection (p = 0.004). Spikes/ripples/fast ripples appeared frequently in the hippocampus, occurring in 86.4%/82.4%/75.0% of cases before resection and 76.7%/78.1%/63.0% after resection. The presence and rate were unconnected to seizure outcome. Postoperative neuropsychological outcomes in intelligence and visual memory improved overall.

CONCLUSIONS

HSL in lesional TLE can produce satisfactory seizure and cognitive outcomes. Intraoperative hippocampography-guided resection of apparently normal hippocampi should be performed cautiously and might not be necessary.

SIGNIFICANCE

This study provided evidence in decision making for patients with lesional TLE with a radiologically normal hippocampus.

Health-related quality of life after epilepsy surgery: A prospective, controlled follow-up on the Iranian population

Quality of life is affected by factors such as regional differences in access to treatment choices, and rehabilitation. This study aims to assess the result of epilepsy surgery and its impact on QoL in Iran. The data for 60 patients who underwent epilepsy surgery in Loghman-Hakim hospital between 2003 to 2017 were analyzed prospectively through clinical observation. Clinical variables of interest and the WHOQOL-BREF scale to assess QoL were applied. Scores of operated patients were compared to their preoperative scores as well as epileptic patients controlled with antiepileptic drugs (AEDs) and healthy individuals. The mean age of surgery group patients was 33.78 (34 male; 26 female). Twenty seven patients underwent temporal mesial lobectomy, 20 anterior callosotomy, and 13 neocortical resections. The average QoL score in healthy group was 72.48, in AEDs controls was 56.16, and in operated patients was 65.61. In addition, analysis showed a significant increase in postoperative QoL of the surgical group compared to the AEDs controls. Epilepsy surgery could be the best approach in patients suffering from drug-resistant epilepsy even in developing countries, which can result in seizure relief and a reduction in the frequency of disabling seizures.

Prospects for Applying Xenon Curative Properties in Pediatrics

The review discusses experimental and clinical trials on applying noble gas Xenon to treat therapeutic conditions in adults, as well as the prospects for its applying in children. Xenon therapeutic effects on the body are based on the healing properties of a noble gas. Xenon is close to the ‘ideal anesthetic’ by its anesthetic properties; but in addition, it possesses organoand neuroprotective as well as anti-stress properties which have been proved in experiment and clinically. Xenon in pediatric practice is an attractive agent because it is non-toxic, effective for the treatment of posthypoxic and traumatic impairments of the central nervous system, pain syndromes and stress conditions at its therapeutic concentration up to 30%.

Neocortical temporal lobe epilepsy

Complex partial seizures (CPSs) can present with various semiologies, while mesial temporal lobe epilepsy (mTLE) is a well-recognized cause of CPS, neocortical temporal lobe epilepsy (nTLE) albeit being less common is increasingly recognized as separate disease entity. Differentiating the two remains a challenge for epileptologists as many symptoms overlap due to reciprocal connections between the neocortical and the mesial temporal regions. Various studies have attempted to correctly localize the seizure focus in nTLE as patients with this disorder may benefit from surgery. While earlier work predicted poor outcomes in this population, recent work challenges those ideas yielding good outcomes in part due to better localization using improved anatomical and functional techniques. This paper provides a comprehensive review of the diagnostic workup, particularly the application of recent advances in electroencephalography and functional brain imaging, in neocortical temporal lobe epilepsy.

Long-term seizure and psychosocial outcomes of epilepsy surgery

Most results reported in studies focusing on long-term outcomes of epilepsy surgery resemble those reported in studies with shorter follow-up, indicating that many of the surgical results are enduring. In general, about 60% of patients with temporal epilepsy and 25% to 40% of those with extratemporal epilepsy achieve long-term seizure freedom after epilepsy surgery. Over a long term, about 20% of patients discontinue antiepileptic drugs, whereas 41% continue monotherapy and 31% use polytherapy. Evidence concerning the impact of epilepsy surgery on mortality is inconclusive, but some data support a reduction in the risk of death if patients become seizure-free. The information regarding long-term cognitive outcomes is limited but is similar to that derived from short-term studies. Decline in verbal memory occurs frequently after resections of the left temporal lobe; better memory outcomes are reported in seizure-free patients, and memory decline has been documented in patients with intractable epilepsy who do not undergo surgery. However, important confounders such as the effects of antiepileptic drugs, practice effects, and regression to the mean have not been adequately accounted for in these studies. All uncontrolled long-term studies report improved psychosocial outcomes with epilepsy surgery, including employment, education, driving status, satisfaction, and quality of life, but the results of the few existing controlled studies are less persuasive.

Intelligence quotient is not affected by epilepsy surgery in childhood

Epilepsy surgery is known to help children with intractable seizures. The effect of epilepsy surgery itself on cognition in childhood is less well studied. We report our experience at the University of Alberta Hospital on the effects of epilepsy surgery on cognition. All children undergoing epilepsy surgery at the Comprehensive Epilepsy Program from 1990-2005 were examined. Sixty-seven patients received both preoperative and postoperative neuropsychologic evaluations. We compared verbal, performance, and full scale intelligent quotients and the Child Behavioral Checklist preoperatively and postoperatively. Forty-eight patients demonstrated excellent surgical outcomes, with significant reductions in disabling seizures. Overall, no significant change occurred in neuropsychologic parameters examined after surgery. Epilepsy surgery in childhood offers excellent surgical outcomes for seizure control, and does not adversely affect intelligence quotient.

Randomized controlled trial of 2.5-cm versus 3.5-cm mesial temporal resection in temporal lobe epilepsy--Part 1: intent-to-treat analysis

BACKGROUND

Only one prospective randomized study on the extent of mesial resection in surgery for temporal lobe epilepsy (TLE) exists. This randomized controlled trial (RCT) examines whether 3.5-cm mesial resection is leading to a better seizure outcome than a 2.5-cm resection.

METHODS

Three epilepsy surgery centers using similar MRI protocols, neuropsychological tests, and resection types for TLE surgery included 207 patients in a RCT with pre- and postoperative volumetrics. One hundred and four patients were randomized into a 2.5-cm resection group and 103 patients into a 3.5-cm resection group, i.e., an intended minimum resection length of 25 versus 35 mm for the hippocampus and parahippocampus. Primary outcome measure was seizure freedom Engel class I throughout the first year. The study was powered to detect a 20% difference in class I outcome. Seizure outcome was available for 207 patients, complete volumetric results for 179 patients. Outcome analysis was restricted to control of successful randomization and an intent-to-treat analysis of seizure outcome.

RESULTS

The mean true resection volumes were significantly different for the 2.5-cm and 3.5-cm resection groups; thus, the randomization was successful. Median resection volume in the 2.5-cm group was 72.86% of initial volume and 83.44% in the 3.5-cm group. At 1 year, seizure outcome Engel class I was 74% in the 2.5-cm and 72.8% in the 3.5-cm resection group.

CONCLUSIONS

The primary intent-to-treat analysis did not show a different seizure freedom rate for the more posteriorly reaching 3.5-cm resection group. It appears possible that not maximal volume resection but adequate volume resection leads to good seizure freedom.

Analysis of Reoperation in Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis

BACKGROUND:

Most patients do well after epilepsy surgery for mesial temporal lobe sclerosis, and in only 8 to 12% of all operations, the outcome is classified as not improved.

OBJECTIVE:

To analyze the outcome of reoperation in cases of incomplete resection of mesial temporal lobe structures in patients with mesial temporal lobe sclerosis in temporal lobe epilepsy.

METHODS:

We analyzed 22 consecutive patients who underwent reoperation for mesial temporal lobe sclerosis (follow-up, 23-112 months; mean, 43.18 months) by evaluating noninvasive electroencephalographic/video monitoring before the first and second surgeries (semiology, interictal epileptiform discharges, ictal electroencephalography with special attention to the secondary contralateral evolution of the electroencephalographic seizure pattern after the initial regionalization), and magnetic resonance imaging (resection indices after the first and second surgeries on the amygdala, hippocampus, lateral temporal lobe). In 18 of 22 patients T2 relaxometry of the contralateral hippocampus was performed.

RESULTS:

Nine of 22 patients became seizure free; another 4 patients had a decrease in seizures and eventually became seizure free (range, 16-51 months; mean, 30.3). Recurrence of seizures is associated with (1) ictal electroencephalography with later evolution of an independent pattern over the contralateral temporal lobe (0 of 5 patients seizure free vs 5 of 7 patients non–seizure free; P = .046) and (2) a smaller amount of lateral temporal lobe resection in the second surgery (1.06 ± 0.59 cm vs 2.18 ± 1.37 cm; P = .019). No significant correlation with outcome was found for lateralization of interictal epileptiform discharges, change in semiology, other resection indices, T2 relaxometry, onset and duration of epilepsy, duration of follow-up, and side of surgery.

CONCLUSION:

Patients have a less favorable outcome with a reoperation if they show ictal scalp electroencephalography with secondary contralateral propagation and if only a small second resection of the lateral temporal lobe is performed.

The Irish epilepsy surgery experience: Long-term follow-up

AIM

To assess the long-term seizure outcome of Irish patients who underwent resective surgery for refractory epilepsy since 1975. We also wished to determine the impact of pathology and surgical technique (with particular reference to neocorticectomy) on seizure outcome.

METHODS

A retrospective review of medical notes, radiological and histopathological records, was undertaken between 1975 and 2005. Missing data was supplemented by telephone calls to patients. One hundred and ninety-nine patients suited the criteria for inclusion and had at least 1-year follow-up (1-24 years, mean 7.0 years). Engel's criteria were used to classify seizure outcome at 1, 2, 5, 10, 15 and >15 years follow-up.

RESULTS

The percentage of patients seizure free at 2, 5, 10, 15 and >15 years were, 56.6%, 41.4%, 44%, 25% and 31.3%, respectively. Of patients with a pathologically confirmed diagnosis of mesial temporal sclerosis, 55.6% were seizure free at 10 years. Equivalent figures for tumour were 62.5%, for cortical dysplasia, 34.8%, for those without any demonstrable pathologic abnormality, 50%, for dual pathology, 50% and for all others, 33.3%. Of those with 10 years or greater follow-up only 20% of neocorticectomy patients were in Engel class 1, compared with an average of 58.5% for the other surgical techniques.

CONCLUSION

Seizure freedom rates for Irish Patients were comparable to other large retrospective studies. Patients who underwent selective procedures tended to do better than those undergoing lobar resections, in keeping with international trends. The surgical technique unique to the Irish cohort, temporal necocorticectomy, had the worst long-term outcome.

When should a resection sparing mesial structures be considered for temporal lobe epilepsy?

Anteromesial temporal lobectomy (AMTL) is an effective and safe treatment for refractory temporal lobe epilepsy (TLE) caused by hippocampal sclerosis (HS). It is possible that modifications to this procedure could offer improved seizure control or a reduction in functional consequences in some patients. Reviewed here is the issue of when it might be appropriate to perform a resection for TLE that spares the mesial structures, particularly the hippocampus and parahippocampal gyrus. This issue is particularly important for dominant hemipshere TLE and for patients without obvious HS, as these are the patients at greatest risk for verbal memory decline following AMTL. Current evidence suggests that mesial structure-sparing resections may be worth consideration for two types of patients: those with temporal lobe foreign tissue lesions outside the mesial structures, and those with temporal lobe hypometabolism on fluorodeoxyglucose positron emission tomography but a normal MRI. Patients with dual pathology (i.e., HS plus another epileptogenic lesion) are unlikely to benefit from a resection that spares the mesial temporal lobe. There is little evidence to state whether resections of this kind are worthwhile for cryptogenic TLE, or for mesial TLE with preserved memory function. There is a clear need to move beyond the field's present focus on the hippocampus and investigate new approaches to TLE that may minimize the risks of functional consequences in patients without HS.

Mapping seizure pathways in the temporal lobe

Interest in temporal lobe seizure pathways has a long history based initially on the human condition of temporal lobe epilepsy (TLE). This interest in TLE has extended more recently into explorations of experimental models. In this review, the network structures in the temporal lobe that are recruited in animal models during various forms of limbic seizures and status epilepticus are described. Common to all of the various models is recruitment of the parahippocampal cortices, including the piriform, perirhinal, and entorhinal areas. This cortical involvement is seen in in vitro and in vivo electrophysiological recordings throughout the network, in trans-synaptic neuroplastic changes in associated network structures manifest at the molecular level, in network energy utilization visualized by 14C2-deoxyglucose uptake, and finally, in the behavioral consequences of network lesions. The conclusions of the animal models reviewed here are very similar to those described for the human condition presented recently in the 2006 Lennox lecture by Warren Blume, and addressed 53 years ago in the quadrennial meeting of the ILAE in 1953 by Henri Gastaut.

Temporal lobe epilepsy surgery and the quest for optimal extent of resection: a review

The efficacy of surgery to treat drug-resistant temporal lobe epilepsy (TLE) has been demonstrated in a prospective randomized trial. It remains controversial which resection method gives best results for seizure freedom and neuropsychological function. This review of 53 studies addressing extent of resection in surgery for TLE identified seven prospective studies of which four were randomized. There is considerable variability between the intended resection and the volumetrically assessed end result. Even leaving hippocampus or amygdalum behind can result in seizure freedom rates around 50%. Most authors found seizure outcome in selective amygdalohippocampectomy (SAH) to be similar to that of lobectomy and there is considerable evidence for better neuropsychological outcome in SAH. Studies varied in the relationship between extent of mesial resection and seizure freedom, most authors finding no positive correlation to larger mesial resection. Electrophysiological tailoring saw no benefit from larger resection in 6 of 10 studies. It must be concluded that class I evidence concerning seizure outcome related to type and extent of resection of mesial temporal lobe structures is rare. Many studies are only retrospective and do not use MRI volumetry. SAH appears to have similar seizure outcome and a better cognitive outcome than TLR. It remains unclear whether a larger mesial resection extent leads to better seizure outcome.

Long-term outcome after temporal lobe surgery—Prediction of late worsening of seizure control

We analyzed possible predictors of late worsening of seizure control in 94 adult patients who had anterior temporal lobectomy (ATL) from the Epilepsy Center of the National Institute of Psychiatry and Neurology, Budapest between 1985 and 2001. We evaluated data regarding epilepsy, presurgical evaluation, pre- and postoperative EEG, structural imaging, histology and operative complications. The mean follow-up was 6.1 years (range: 2-17 years). The outcome was measured as Engel class, the time to the first seizure and the longest seizure free period. Multiple regression analysis was used to assess predictors. Seizure free outcome was achieved in 72% of the patients 1-year after surgery. Eighty-seven percent of them remained seizure free at the second year of follow-up, 74% at the fifth, and 67% at the tenth year of follow-up. After 2 years of follow-up improvement was present in 3%, worsening in 18% of the patients. Factors associated with long-term worsening were: postoperative ipsilateral EEG spikes over the resected side, preoperative bilateral interictal discharges, cortical dysplasia of Taylor's type, and ictal contralateral propagation. In these patients, even in seizure free state, therapy reduction might be inappropriate.

Long-term seizure outcomes following epilepsy surgery: a systematic review and meta-analysis

Assessment of long-term outcomes is essential in brain surgery for epilepsy, which is an irreversible intervention for a chronic condition. Excellent short-term results of resective epilepsy surgery have been established, but less is known about long-term outcomes. We performed a systematic review and meta-analysis of the evidence on this topic. To provide evidence-based estimates of long-term results of various types of epilepsy surgery and to identify sources of variation in results of published studies, we searched Medline, Index Medicus, the Cochrane database, bibliographies of reviews, original articles and book chapters to identify articles published since 1991 that contained > or =20 patients of any age, undergoing resective or non-resective epilepsy surgery, and followed for a mean/median of > or =5 years. Two reviewers independently assessed study eligibility and extracted data, resolving disagreements through discussion. Seventy-six articles fulfilled our eligibility criteria, of which 71 reported on resective surgery (93%) and five (7%) on non-resective surgery. There were no randomized trials and only six studies had a control group. Some articles contributed more than one study, yielding 83 studies of which 78 dealt with resective surgery and five with non-resective surgery. Forty studies (51%) of resective surgery referred to temporal lobe surgery, 25 (32%) to grouped temporal and extratemporal surgery, seven (9%) to frontal surgery, two (3%) to grouped extratemporal surgery, two (3%) to hemispherectomy, and one (1%) each to parietal and occipital surgery. In the non-resective category, three studies reported outcomes after callosotomy and two after multiple subpial transections. The median proportion of long-term seizure-free patients was 66% with temporal lobe resections, 46% with occipital and parietal resections, and 27% with frontal lobe resections. In the long term, only 35% of patients with callosotomy were free of most disabling seizures, and 16% with multiple subpial transections remained free of all seizures. The year of operation, duration of follow-up and outcome classification system were most strongly associated with outcomes. Almost all long-term outcome studies describe patient cohorts without controls. Although there is substantial variation in outcome definition and methodology among the studies, consistent patterns of results emerge for various surgical interventions after adjusting for sources of heterogeneity. The long-term (> or =5 years) seizure free rate following temporal lobe resective surgery was similar to that reported in short-term controlled studies. On the other hand, long-term seizure freedom was consistently lower after extratemporal surgery and palliative procedures.

Predictors of seizure outcome after temporal lobectomy for intractable epilepsy

OBJECTIVES

To assess predictors of outcome of temporal lobectomy for intractable epilepsy.

MATERIAL AND METHODS

In 63 adult patients operated with anterior temporal lobectomy during 198892, we used logistic regression analysis to assess predictors of being seizure-free (Engel's class I) 2 years after surgery. As potential predictors, we included the following variables: gender, age at operation, age at onset of seizures, epilepsy duration, etiology, generalized vs not generalized seizures, seizure frequency, intelligence quotient, ictal electroencephalography, magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), side of resection, and extent of the resection.

RESULTS

About 44% of the surgery patients were seizure-free (Engel's class I) 2 years after surgery. In multivariate analysis (n = 55), MRI pathology defined as atrophy in the temporal lobe, angioma, tumor or mesial temporal sclerosis (odds ratio, OR 7.4, 95%CI: 1.7-32.9) and extent of the hippocampal resection (increase of 1 cm) (OR 2.2, 95%CI: 1.1-4.6) predicted being seizure-free.

CONCLUSION

Focal pathology in preoperative MRI and the extent of the hippocampal resection were the only significant predictors of being seizure-free after 2 years.

Rapid stereological quantitation of temporal neocortex in TLE

To determine the extent of neocortical atrophy in the temporal lobe using rapid stereological analysis of magnetic resonance slices in patients with temporal lobe epilepsy and to compare the findings to those obtained by visual analysis of high-resolution magnetic resonance images. 25 patients with temporal lobe epilepsy, along with 25 age-matched controls were scanned using a 1.5 Tesla magnetic resonance imaging machine (GE signa systems Paris). Visual analysis was performed on standard high-resolution images. Volumetric analysis of hippocampus and temporal neocortex was performed using computer-aided stereology (MEASURE program, Patrick Barta, Johns Hopkins, Baltimore, USA). Stereological volumetric analysis demonstrated isolated hippocampal atrophy in only nine (36%) cases including three (12%) with bilateral disease. However, eight (32%) cases had combined hippocampal and neocortical atrophy and three (12%) had isolated neocortical atrophy. All volumetric measurements took less than 10 min. On the other hand, visual analysis suggested that 17 (68%) had hippocampal atrophy alone with only two (8%) having combined neocortical atrophy and a further two (8%) having isolated neocortical atrophy. Nearly half of the patients had temporal neocortical atrophy with or without hippocampal atrophy. This rapid, accurate and non-biased quantitative technique has wide clinical utility and is significantly more valuable in detecting neocortical atrophy than visual analysis alone. The results support the notion that abnormalities may be overlooked by current standards of routine magnetic resonance imaging.

Standardization of amygdalohippocampectomy with intraoperative magnetic resonance imaging: preliminary experience

PURPOSE

Intraoperative magnetic resonance imaging (IMRI) is an extremely useful neurosurgical tool in surgeries in which the extent of resection is known to have a significant impact on outcome. Residual hippocampus is the most common cause of recurrent seizures after temporal lobectomy for medial temporal lobe epilepsy. Although the risk/benefit ratio of a policy of universal radical hippocampal resection is not known, we hypothesized that IMRI would aid in the intraoperative assessment of the extent of hippocampal resection and assist in accomplishing a complete hippocampectomy.

METHODS

Five consecutive patients with medically intractable medial temporal lobe epilepsy underwent a radical amygdalohippocampectomy as part of the their surgery for epilepsy. IMRI was used before surgery and after an initial resection. The quality of images was assessed. Postoperative MR images were evaluated by a radiologist to determine the extent of resection of the amygdala, hippocampus, and parahippocampal gyrus.

RESULTS

There were no perioperative infections. After a mean follow-up of 10 months, all patients are seizure free. T(1)-weighted coronal intraoperative images were judged adequate at visualizing the medial structures in all patients. T(2) and fluid-attenuated inversion recovery (FLAIR) images did not provide useful information. Postoperative MR images indicated that a complete hippocampectomy had been achieved in all patients.

CONCLUSIONS

IMRI is a useful adjunct in the surgical treatment of medial temporal lobe epilepsy and perhaps the most reliable method of standardizing a complete hippocampectomy. T(1)-weighted coronal images are the most helpful sequence.

Seizure outcome after temporal lobectomy: current research practice and findings

PURPOSE

The literature regarding seizure outcome and prognostic factors for outcome after temporal lobectomy is often contradictory. This is problematic, as these data are the basis on which surgical decisions and counseling are founded. We sought to clarify inconsistencies in the literature by critically examining the methods and findings of recent research.

METHODS

A systematic review of the 126 articles concerning temporal lobectomy outcome published from 1991 was conducted.

RESULTS

Major methodologic issues in the literature were heterogeneous definitions of seizure outcome, a predominance of cross-sectional analyses (83% of studies), and relatively short follow-up in many studies. The range of seizure freedom was wide (33-93%; median, 70%); there was a tendency for better outcome in more recent studies. Of 63 factors analyzed, good outcome appeared to be associated with several factors including preoperative hippocampal sclerosis, anterior temporal localization of interictal epileptiform activity, absence of preoperative generalized seizures, and absence of seizures in the first postoperative week. A number of factors had no association with outcome (e.g., age at onset, preoperative seizure frequency, and extent of lateral resection).

CONCLUSIONS

Apparently conflicting results in the literature may be explained by the methodologic issues identified here (e.g., sample size, selection criteria and method of analysis). To obtain a better understanding of patterns of long-term outcome, increased emphasis on longitudinal analytic methods is required. The systematic review of possible risk factors for seizure recurrence provides a basis for planning further research.

Neocortical temporal lobe epilepsy: intracranial EEG features and surgical outcome

Patients with neocortical temporal lobe epilepsy (NTLE) may have less favorable outcome with anterior temporal lobectomy than those with mesial temporal foci. The authors analyzed ictal intracranial electroencephalograms (EEGs) in patients with NTLE to identify features that predict surgical outcome. The following intracranial ictal EEG features in 31 consecutive medically intractable NTLE patients were studied: Frequency (i.e., low-voltage fast [>20 Hz], recruiting ictal-onset spikes, ictal-onset rhythms less than 5 Hz, ictal-onset rhythms with repetitive sharp waves between 5 and 20 Hz); extent of ictal onset (focal, sublobar, and lobar); localization within the temporal lobe (anterior, posterior, or regional); and the time to seizure spread outside the temporal lobe (rapid, intermediate, and slow). The average follow-up period was 36.7 months (range, 18 to 60 months). Findings between two outcome groups were compared: class I group (seizure-free) and class II to IV group (persistent seizures). Twenty-one (66.7%) of 31 patients with NTLE were seizure-free. Intracranial EEG features which were significantly associated with seizure-free outcome were focal or sublobar onset, anterior temporal onset, and slow propagation time (P < 0.05). There was a trend for patients with ictal onset morphologies of slow ictal-onset rhythm and repetitive sharp waves to be seizure-free (P = 0.07). Intracranial EEG is helpful in predicting surgical outcome in NTLE patients.

Factors associated with work outcome after anterior temporal lobectomy for intractable epilepsy

PURPOSE

Whereas the effect of anterior temporal lobectomy on seizure frequency is well recognized, less is known about its impact on work status.

METHODS

One hundred thirty-four of 190 consecutive patients with temporal lobectomy participated in this study. Eligibility criteria were developed to ensure that only patients with the potential of achieving specific outcomes were included in the corresponding analyses.

RESULTS

After surgery, significantly more patients were independent in activities of daily living (p < 0.001) or able to drive (p < 0.001). Income from work also increased (p < 0.01). Nearly one fifth of the patients who were eligible for analysis had either a gain (8%) or a loss (11%) of full- or of part-time work. Univariate analyses revealed the following factors to be associated with full-time work after surgery: student or full-time work within a year before surgery, full-time work experience before surgery, full- or part-time employment experience before surgery, no disability benefits before surgery, low postsurgical seizure frequency, improved postsurgical seizure control, excellent postsurgical seizure control, driving after surgery, and further education after surgery (p < 0.05). Significant factors on multivariate analysis were being a student or having full-time work within a year before surgery [odds ratio, 16.2 (95% CI, 4.3-60.5)], driving after surgery [15.2 (3.2-72.0)], and obtaining further education after surgery [9.2 (2.2-53.0)].

CONCLUSIONS

Anterior temporal lobectomy for intractable epilepsy improves activities of daily living and the ability to drive. Work outcome of this surgery is influenced by presurgical work experience, successful postsurgical seizure control especially to allow driving, and obtaining further education after surgery.

Surgical treatments for seizure. Adaptability for dogs

Surgical treatments are often used for human epileptics who are refractory to more conventional anticonvulsant therapies. The goals of surgery are to decrease seizure morbidity or, ideally, bring about a cure to the seizure disorder. As a sizable subpopulation of dogs with seizures are also refractory to currently available anticonvulsant therapies, consideration has been given to evaluating alternative treatments for seizures in dogs. This article discusses the adaptability of surgical treatments used in humans for use in seizure control in affected dogs.

Significance of spikes at temporal lobe electrocorticography

Among 87 consecutive patients operated on under local anesthesia, few aspects of pre- and posttemporal lobe resection electrocorticograms (ECoG) yielded prognostic data. Preresection spikes were most common in the hippocampus, followed in order of frequency by the anterior temporal convexity and the inferior temporal surface. Moderately frequent (>10 spikes/100 s) preresection spikes appeared beyond the subsequent resection line in the posterior temporal region in 16 of 87 (18%) and in orbital frontal cortex in 12 of 87 (14%). Although many hippocampus spikes portended a favorable outcome and rare spikes an unfavorable one, preresection spike quantity otherwise failed to distinguish outcome groups. Absolute quantity of postresection spikes and change from preresectrion quantity in any region did not correlate with outcome except for the insula, where relatively abundant spikes portended favorable outcomes. Postresection electrographic seizures were rare but occurred equally in all outcome groups. No significant change in spike incidence occurred between the first and last 10-min epoch of the 30-min postresection recording.

Extent of medial temporal resection on outcome from anterior temporal lobectomy: a randomized prospective study

WE REPORT A prospective, randomized, blinded clinical trial comparing seizure and neuropsychological outcomes from anterior temporal lobectomies between two groups of patients. One group (n = 34) underwent hippocampal resection posteriorly to the anterior edge of the cerebral peduncle (partial hippocampectomy). In the other group (n = 36), the hippocampus was removed further to the level of the superior colliculus (total hippocampectomy). The amount of lateral cortical resection was the same between groups. Patients were and neuropsychological morbidity. At 1 year postoperatively, the total hippocampectomy group had a statistically superior seizure outcome compared with the partial hippocampectomy group (69 versus 38% seizure-free), and examination of time to first seizure (survival analysis) revealed significantly superior outcomes associated with total hippocampectomy. There was no increased neuropsychological morbidity associated with the more extensive hippocampal resection.

Seizure control and extent of mesial temporal resection

Controversy exists about the extent of mesial temporal lobe resection that improves seizure control in patients with temporal lobe epilepsy. In this retrospective study, 70 patients with mesial temporal seizure activity (without evidence of tumor or vascular malformation) were surgically treated and followed for at least 2 years. The extent of mesial temporal resection was based on the findings of interictal and ictal discharges using depth electrodes, which were inserted preoperatively or intraoperatively by the orthogonal approach to the amygdaloid and hippocampal regions. Only the amygdala was resected along with the limited lateral neocortex if no epileptiform activity involved the hippocampus. The amount of hippocampal excision was determined by the extent of interictal seizure activity. The following groups became seizure free: all 8 patients with only amygdalar resection; 6 of 10 patients with amygdalar and < or = 1 cm hippocampal resection; 23 of 38 with 1-2 cm hippocampal removal, and 11 of 14 with > 2 cm hippocampal excision. In cases where there was no hippocampal resection, neuropsychological outcome compared favorably with controls. Our results suggest that although most patients with temporal lobe epilepsy require hippocampal resection of varying degrees, there is a subset in whom the amygdala may be the crucial element of a mesial temporal epileptogenic network. These patients can undergo a surgical resection sparing the hippocampus without compromising seizure outcome.