Quantitative analysis of seizure frequency 1 week and 6, 12, and 24 months after surgery of epilepsy

Seizure outcomes of large volume temporo-parieto-occipital and frontal surgery in children with drug-resistant epilepsy

OBJECTIVE

In this study, we investigate the seizure outcomes of temporo-parieto-occipital (TPO) and frontal disconnections or resections in children with drug-resistant epilepsy (DRE) in order to determine factors which may predict surgical results.

METHODS

Children with DRE, who underwent either TPO or frontal disconnection or resection at Great Ormond Street Hospital for Children between 2000 and 2017, were identified from a prospectively collated operative database. Demographic data, age at surgery, type of surgery, scalp EEGs and operative histopathology were collected. Magnetic resonance imaging (MRI) was assessed to determine completeness of disconnection and presence of radiological lesion beyond the disconnection margins. Seizure outcome at 6, 12, and 24 months post-surgery was assessed using the Engel Scale (ES). Logistic regression was used to identify relationships between data variables and seizure outcome.

RESULTS

46 children (males = 28, females = 18; age range 0.5-16.6 years) who underwent TPO (n = 32, including a re-do disconnection) or frontal disconnection or resection (n = 15) were identified. Patients in the TPO treatment group had more favourable seizure outcomes than those in the frontal treatment group (ES I-II in 56 %vs 47 % at 6 months, 52 % vs 46 % at 12 months). Presence of the lesion beyond disconnection boundaries and older age at the time of surgery were associated with poorer seizure outcome. Gender, surgery type, completeness of disconnection, scalp EEG findings and underlying pathology were not related to seizure outcome, but subgroup numbers were small.

CONCLUSIONS

Both TPO and frontal disconnection are effective treatments for selected children with posterior multi-lobar or diffuse frontal lobe epilepsy. Confinement of the MRI lesion within the disconnection margins and a younger age at surgery are associated with favourable seizure outcomes. Further studies are required to elucidate these findings.

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 < .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.

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.

Epilepsy surgery and tuberous sclerosis complex: special considerations

Epilepsy surgery for medically refractory seizures among patients with tuberous sclerosis complex (TSC) is a well-accepted treatment option. Many epilepsy centers around the world have published their experience over the past several years, supporting the idea that the best seizure control is obtained when a single tuber and associated epileptogenic zone is documented and targeted surgically. Recent advances in imaging and physiological techniques that reveal the epileptogenic zone have been used successfully in children with TSC who are being evaluated for surgery. As a result, a number of different surgical strategies have emerged, each reflecting the experience, strengths, and referral biases of the individual treating teams. Experience suggests that some patients with TSC who present with seizures that are difficult to localize and do not meet the classic selection criteria for epilepsy surgery may, nevertheless, benefit from surgery. Tuberectomy alone is often not sufficient for obtaining seizure control. Intracranial electrode recordings performed in a large number of children with TSC undergoing epilepsy surgery have raised new questions about the relationship of the cortical tuber to the epileptogenic zone in TSC. A careful assessment of the risks and benefits of any surgical strategy, compared with those associated with continued refractory epilepsy, should be considered by the treating team in conjunction with the patient's family. Epilepsy surgery has not only benefited many children with TSC, but it also facilitates the understanding of epileptogenesis in TSC.

Long-term seizure control after resection of supratentorial cavernomas: a retrospective single-center study in 53 patients

OBJECTIVE

The goal of this study was to examine the long-term outcomes of 53 epilepsy patients who were surgically treated for supratentorial cavernomas in a single-center study and to assess both the duration of epilepsy and the resection of the hemosiderin rim for their prognostic relevance during extended follow-up.

METHODS

Fifty-three patients underwent microsurgical resection of radiologically diagnosed supratentorial cavernomas. For the outcome analysis, they were divided into 2 groups: Group A (33 patients) with a preoperative duration of epilepsy of less than 2 years, and Group B (20 patients) with a preoperative duration of epilepsy of 2 years or more. The natural history of the cavernomas, localization and size of the lesions, use of antiepileptic drugs, surgery timing, and technique (removal or not of the surrounding gliosis) were evaluated retrospectively. The outcome of epilepsy was based on Engel's classification and the International League Against Epilepsy classification.

RESULTS

After a mean follow-up period of 8.1 years, 45 (84.9%) of the 53 patients were free from disabling seizures (Engel Class I), including 37 patients (69.8%) who were completely free of postoperative seizures (Engel Class IA); 43 patients (81.1%) were categorized as International League Against Epilepsy Class 1. Outcome was statistically significantly improved in the patient subgroup of our study in which patients underwent a resection of the surrounding gliosis after a preoperative duration of epilepsy of less than 2 years (Group A). There was no mortality, and only minor postoperative neurological deficits occurred in 7.5% of patients.

CONCLUSION

In a long-term follow-up period, 84.9% of the patients in the study could be evaluated as Engel Class I. The analysis of outcome showed that patients benefited significantly from early surgery and excision of the hemosiderin rim.

Trans-Sylvian selective amygdalohippocampectomy for medically intractable temporal lobe epilepsy: a single-centre experience

Selective amygdalohippocampectomy (SelAH) is now widely used in the surgical treatment of patients with medically intractable medial temporal lobe epilepsy (MTLE). We present our single-centre experience of a uniform series of drug-resistant MTLE patients treated exclusively with SelAH. A retrospective study of 50 adult patients (25 males, 25 females, mean age 34 years) suffering from medically intractable MTLE was conducted. All patients has been investigated under the same protocol and operated by SelAH performed by one surgeon. Immediate and long-term follow-up was also available and is presented. Forty-two patients (84%) became seizure free (Engel's I); eight of them (16%) were classified as Engel's II; four (8%) as Engel's III; and one as Engel's IV (2%). In 42 of them the final result has been achieved after a single operation, while in the rest eight after a second or third surgical procedure. The mean follow-up period was 6.2 years. Two permanent complications (4%) with no treatment-related mortality have been detected. SelAH performed in well selected cases, where concordance between electrophysiological and MR findings exists, can be a safe and effective surgical treatment method for medically intractable MTLE.

Long-term Seizure Outcome in Reoperation after Failure of Epilepsy Surgery

OBJECTIVE

Treatment of patients who fail epilepsy surgery is problematic. Selected patients may be candidates for further surgery, potentially leading to a significant decrease in the frequency and severity of seizures. We present our long-term outcome series of highly investigated patients who failed resective epilepsy surgery and subsequently underwent reoperative resective procedures.

METHODS

We performed a retrospective consecutive analysis of patients who underwent reoperative procedures because of medically intractable epilepsy at our institution from 1990 to 2001. Seventy patients underwent reoperative epilepsy surgery, with 57 patients having a minimum follow-up period of 2 years. We assessed the relationship between seizure outcome and categorical variables using χ2 and Fisher's exact tests, and the relationship between outcome and continuous variables using a Wilcoxon rank-sum test. Statistical significance was set at a P value of 0.05.

RESULTS

Of the 57 patients (29 male and 28 female patients), the age of seizure onset ranged from 3 months to 39 years (mean, 10.7 ± 10.3 yr; median, 7 yr). The mean age at reoperation was 24.7 ± 12 years (range, 4–50 yr). The interval between first and second resection was 7 days to 16 years. The follow-up period ranged from 24 to 228 months (mean, 128 mo; mode, 132 mo). Seizure outcome was classified according to Engel's classification. Fifty-two percent of the patients had a favorable outcome (38.6% were Class I and 14.0% were Class II). Patients with tumors as their initial pathology had better outcome compared with patients with focal cortical dysplasia and mesial temporal sclerosis (P < 0.05).

CONCLUSION

Reoperation should be considered in selected patients failing epilepsy resective surgery because approximately 50% of patients may have benefit. Patients with cortical dysplasia and mesial temporal sclerosis are less likely to improve after reoperation.

Quality of life related to surgical treatment in patients with temporal lobe epilepsy due to mesial temporal sclerosis

INTRODUCTION: Surgery is widely accepted as a modality of treatment for medically intractable seizures and the main goals of surgery as reduction or elimination of seizures without significant compromise in neurological function and improving QOL. PURPOSE: To assess QOL pre- and post-surgery in a sample of patients with temporal lobe epilepsy (TLE) due to mesial temporal sclerosis (MTS). METHODS: Thirty-five consenting subjects who had undergone corticoamygdalo-hipocampetomy were included in this study. They answered the ESI-55 before and six months after surgical treatment. Analyses of Variance (ANOVA) was used to study the changes in QOL and we also determined the effect-size of the sample. RESULTS: After surgical treatment 18 (51%) subjects were seizure free, 10 (29%) had only auras and seven (20%) had partial seizures. The post-operative mean scores were higher than pre-operative scores, except for Cognitive Function and Limitation due to Cognitive Problems in the group with seizures. A significant improvement in QOL post-surgery was observed in the domains Health-Perception (1.24), Emotional-Well-being (1.32) and Energy/Fatigue (1.43). CONCLUSION: A long-term follow-up is necessary to identify meanigful changes after the surgery.

Seizure outcome after surgery for epilepsy due to focal cortical dysplastic lesions

Neocortical development is a highly complex process encompassing cellular proliferation, neuronal migration and cortical organization. At any time this process can be interrupted or modified by genetic or acquired factors causing malformations of cortical development (MCD). Epileptic seizures are the most common type of clinical manifestation, besides developmental delay and focal neurological deficits. Seizures due to MCD are frequently pharmacoresistant, especially those associated to focal cortical dysplasia (FCD). Surgical therapy results have been reported since 1971, however, currently available data from surgical series are still limited, mainly due to small number of patients, distinct selection of candidates and surgical strategies, variable pathological diagnosis and inadequate follow-up. This study addresses the possibilities of seizure relief following resection of focal cortical dysplasia, and the impact of presurgical evaluation, extent of resection and pathological findings on surgical outcome. We included 41 patients, 22 adults and 19 children and adolescents, with medically intractable seizures operated on from 1996 to 2002. All were submitted to standardized presurgical evaluation including high-resolution MRI, Video-EEG monitoring and ictal SPECT. Post-surgical seizure outcome was classified according to Engel's schema. Univariate and multivariate analysis were performed. Fifteen patients had temporal and 26 extratemporal epilepsies. Of the total 26 patients (63.4%) reached seizure-free status post-operatively. There was no correlation between outcome and age at surgery, duration of epilepsy, frequency of seizures, and pathological findings. There was, however, a clear correlation with topography of FCD (temporal versus extratemporal) and regional ictal EEG onset, on univariate as well as multivariate analysis.

Long-term outcome of epilepsy surgery among 399 patients with nonlesional seizure foci including mesial temporal lobe sclerosis

OBJECT

The authors reviewed the long-term outcome of focal resection in a large group of patients who had intractable partial nonlesional epilepsy, including mesial temporal lobe sclerosis (MTS), and who were treated consecutively at a single institution. The goal of this study was to evaluate the long-term efficacy of epilepsy surgery and the preoperative factors associated with seizure outcome.

METHODS

This retrospective analysis included 399 consecutive patients who underwent epilepsy surgery at Mayo Clinic in Rochester, Minnesota, between 1988 and 1996. The mean age of the patients at surgery was 32 +/- 12 years (range 3-69 years), and the mean age at seizure onset was 12 +/- 11 years (range 0-55 years). There were 214 female (54%) and 185 male (46%) patients. The mean duration of epilepsy was 20 +/- 12 years (range 1-56 years). The preceding values are given as the mean +/- standard deviation. Of the 399 patients, 237 (59%) had a history of complex partial seizures, 119 (30%) had generalized seizures, 26 (6%) had simple partial seizures, and 17 (4%) had experienced a combination of these. Preoperative evaluation included a routine and video-electroencephalography recordings, magnetic resonance imaging of the head according to the seizure protocol, neuropsychological testing, and a sodium amobarbital study. Patients with an undefined epileptogenic focus and discordant preoperative studies underwent an intracranial study. The mean duration of follow up was 6.2 +/- 4.5 years (range 0.6-15.7 years). Seizure outcome was categorized based on the modified Engel classification. Time-to-event analysis was performed using Kaplan-Meier curves and Cox regression models to evaluate the risk factors associated with outcomes. Among these patients, 372 (93%) underwent temporal and 27 (7%) had extratemporal resection of their epileptogenic focus. Histopathological examination of the resected specimens revealed MTS in 113 patients (28%), gliosis in 237 (59%), and normal findings in 49 (12%). Based on the Kaplan-Meier analysis, the probability of an Engel Class I outcome (seizure free, auras, or seizures related only to medication withdrawal) for the overall patient group was 81% (95% confidence interval [CI] 77-85%) at 6 months, 78% (CI 74-82%) at 1 year, 76% (CI 72-80%) at 2 years, 74% (CI 69-78%) at 5 years, and 72% (CI 67-77%) at 10 years postoperatively. The rate of Class I outcomes remained 72% for 73 patients with more than 10 years of follow up. If a patient was in Class I at 1 year postoperatively, the probability of seizure remission at 10 years postoperatively was 92% (95% CI 89-96%); almost all seizures occurred during the 1st year after surgery. Factors predictive of poor outcome from surgery were normal pathological findings in resected tissue (p = 0.038), male sex (p = 0.035), previous surgery (p < 0.001), and an extratemporal origin of seizures (p < 0.001).

CONCLUSIONS

The response to epilepsy surgery during the 1st follow-up year is a reliable indicator of the long-term Engel Class I postoperative outcome. This finding may have important implications for patient counseling and postoperative discontinuation of anticonvulsant medications.

Postoperative routine EEG correlates with long-term seizure outcome after epilepsy surgery

We investigated the correlation of interictal epileptiform discharges (IED) in routine EEG 6 and 24 months after epilepsy surgery with regard to long-term seizure outcome. In 148 patients (74% temporal lobe epilepsy (TLE), 26% extratemporal epilepsy) EEG results (IED present or absent) were correlated with the postoperative outcome using the Engel classification 6 and 24 months after resection (PO6m and PO2y, respectively). Self-evaluation was conducted 3 and 5 years after resection (PO3y and PO5y, respectively). Ninety-one patients (62%) were seizure-free 5 years after resection; 88% of them showed no IED in PO6m. Twenty-eight patients (19%) displayed IED in routine EEG 6 months after resection; 61% of them had recurrent seizures at PO5y, whereas of 120 patients without IED only 33% had recurrent seizures at PO5y; p=0.01. Absence of IED in PO6m and PO2y correlated with good outcome: 71% without IED remained seizure-free, whereas only 25% with IED at PO6m and PO2y remained seizure-free; p=0.001. Seizure-free patients (Engel 1) and patients with less favourable outcome (Engel 3-4) at PO6m and PO2y rarely changed categories of outcome during the following years (p<0.001). Half of the patients with favourable seizure reduction (Engel 2) changed to seizure-free (Engel 1) or to a worse outcome category (Engel 3-4). Postoperative routine EEG is a good prognostic instrument for the prediction of long-term seizure outcome, especially for TLE. It predicts the running up and down of fits in patients with rare seizures (Engel 2).

Multistage Epilepsy Surgery: Safety, Efficacy, and Utility of a Novel Approach in Pediatric Extratemporal Epilepsy

OBJECTIVE:

To evaluate the safety, efficacy, and utility of a novel surgical strategy consisting of multiple (more than two) operative stages performed during the same hospital admission with subdural grid and strip electrodes in selected pediatric extratemporal epilepsy.

METHODS:

Subdural grid and strip electrodes were used for multistage chronic electroencephalographic monitoring in 15 pediatric patients (age, &lt;19 yr) with refractory localization-related epilepsy and poor surgical prognostic factors. Initial resective surgery and/or multiple subpial transections were performed, followed by further monitoring and additional resection and/or multiple subpial transections.

RESULTS:

Mean patient age was 9.7 years. Mean duration of total invasive monitoring was 10.5 days (range, 8–14 d). The first monitoring period averaged 6.5 days, and the second averaged 3.9 days. Additional surgery was performed in 13 of 15 patients. Two patients who did not undergo additional surgery had a Class I outcome. Rationales for reinvestigation included incomplete localization, multifocality, and proximity to eloquent cortex. Complications were minimal, including two transfusions. There were no cases of wound infection, cerebral edema, hemorrhage, or major permanent neurological deficit. Minimum duration of follow-up was 31 months. Outcomes were 60% Engel Class I (9 of 15 patients), 27% Class III (4 of 15 patients), and 13% Class IV (2 of 15 patients).

CONCLUSION:

In a very select group of pediatric patients with poor surgical prognostic factors, the multistage approach can be beneficial. After failed epilepsy surgery, subsequent reoperation with additional intracranial investigation traditionally is used when a single residual focus is suspected. Our results, however, support the contention that multistage epilepsy surgery is safe, effective, and useful in a challenging and select pediatric population with extratemporal medically refractory epilepsy.

Early seizures after temporal lobectomy predict subsequent seizure recurrence

Patients are understandably anxious if seizures occur immediately after temporal lobectomy. Such "neighborhood" seizures are commonly regarded as irrelevant to seizure outcome and discounted in outcome measurement. We conducted an in-depth examination of early postoperative seizures (<28 days) and outcome. The risk of recurrence at one postoperative year was calculated using Poisson regression, and statistical adjustments were made for preoperative pathology. Of 321 patients, 69 (22%) experienced early postoperative seizures. These early seizures were associated with subsequent seizure recurrence (rate ratio [RR] 5.9; 95% confidence interval [CI], 4.1-8.4). Among patients with early seizures, the only significant factor was the presence of seizure precipitants, which was associated with a lower recurrence risk. However, when compared with patients with no early seizures, those with precipitants to early seizures had a higher risk of recurrence (RR, 3.0; 95% CI, 1.8-5.2). The risk was higher again for patients without precipitants to early seizures (RR, 7.6; 95% CI, 5.0-11.5). Early seizures and other seizure recurrences in the first postoperative year did not differ in their effect on subsequent outcome (X(2) [3] = 3.4, p = 0.33). We conclude that early postoperative seizures are associated with subsequent seizure recurrence. These findings have implications for patient counseling and the measurement of outcome.

Postoperative EEG and seizure outcome in temporal lobe epilepsy surgery

OBJECTIVE

To assess the prognostic value of scalp electroencephalogram (EEG) after epilepsy surgery, we investigated whether postoperative EEG abnormalities (interictal epileptiform discharges, IED; interictal slow activity, ISA) were associated with seizure outcome and other patient characteristics after resective surgery in patients with temporal lobe epilepsy (TLE).

METHODS

Sixty-two patients with medically refractory TLE who underwent surgery were studied. Patients were categorized according to etiology (mesiotemporal sclerosis vs. tumors/cortical dysplasias); extent of surgical resection (extensive vs. limited); and amount of preoperative IED on wake EEG (oligospikers, <1 IED/h, vs. spikers). Patients were also classified as seizure-free (SF) or having persistent seizures/auras (not-SF) during follow up visits 1 month and 1 year after surgery. Preoperative 60-min interictal EEGs were evaluated for IED and ISA, and compared to postoperative wake EEGs.

RESULTS

Seizures/auras persisted in 16/62 (25.8%) patients at 1 month and in 8/62 (12.9%) at 1 year follow up. ISA was not significantly related to outcome. Of 42 patients with EEG negative for IED at 1 month, 4 were not-SF; at 1 year, one of 44 such patients was not-SF. IED was significantly associated with seizure/aura persistence in patients categorized as mesiotemporal sclerosis and with extensive surgery. Oligospikers and spikers on preoperative EEG showed no differences in the postoperative seizure outcome, excellent in both cases; moreover, the presence of postoperative IEDs indicated auras/seizures persistence apart from the preoperative EEG spike frequency.

CONCLUSIONS

Our study showed that the presence of IED of postoperatve EEG strongly indicates seizure/aura persistence. Therefore, serial EEGs should be included in postoperative follow up schedules as a crucial tool in evaluating seizure outcome.

Five or More Acute Postoperative Seizures Predict Hospital Course and Long-term Seizure Control after Hemispherectomy

PURPOSE

Acute postoperative seizures (APOSs) are those that occur in the first 7 to 10 days after surgery, and previous studies in temporal lobe epilepsy patients support the notion that APOSs may foretell failure of long-term seizure control. It is unknown whether APOSs also predict seizure outcome or hospital course after hemispherectomy.

METHODS

Hemispherectomy patients (n = 114) were studied retrospectively and subdivided into the following groups: No APOSs, 1 to 5 APOSs, or >5 APOSs. Intensive care unit (ICU) nursing staff or family members reported and described the APOS events. APOS categories were compared with pre- and postsurgery clinical variables abstracted from the medical record.

RESULTS

APOSs occurred in 22.6% of hemispherectomy patients. Compared with the 0 and 1 to 5 APOS groups, patients with >5 APOS showed (a) longer seizure durations before surgery, (b) longer hospitalizations, (c) later oral food intake, (d) more frequent lumbar punctures, (e) worse seizure control at 0.5 and 1 year after surgery, (f) more antiepileptic drug (AED) use at 2 and 5 years after surgery, and (g) higher reoperation rate. No similar differences were found between the 0 and 1 to 5 APOS groups. The day of the APOS, whether the APOS was typical of preoperative seizures, and postsurgery scalp EEG did not predict long-term seizure control. APOS patients in the 1 to 5 and >5 groups had lower pre- and postsurgery Vineland developmental quotients compared with those without an APOS.

CONCLUSIONS

Hemispherectomy patients with >5 APOSs had a more prolonged and complicated hospital course and worse postsurgery seizure control, more AED use, and higher reoperation rate than did patients with 0 or 1 to 5 APOSs. Thus the number of APOSs was a predictor of postsurgery seizure control and can be used to counsel patients and families about prognosis after hemispherectomy.

Seizures after epilepsy surgery

This article reviews types and prognostic significance of seizures that occur after epilepsy surgery, so-called postsurgical seizures.

Antiepileptic drug treatment before and after selective amygdalohippocampectomy

Retrospectively, we analyzed pre and postoperative (po) AED treatment in relation to long-term annual seizure outcome in the Zurich selective amygdalohippocampectomy (AHE) series. In 376 patients (hippocampal sclerosis ("HS"), n:185; other lesions ("lesional"), n:191) with a follow-up of more than 1 year, in the last available outcome (lao), 60% were seizure- and aura-free (ILAE Class 1). During the year prior to surgery, in the "HS" group a mean of 2.3 +/- 0.8 AEDs were taken. The percentage of patients without AEDs increases to 36.1% in the po years 1-5 (po year 5: "HS" (n:133) 27.8%; "lesional" (n:111) 45.9%). In po years 7-11 this percentage is between 40 and 43% (po year 10: "HS" (n:75) 29.3%; "lesional" (n:65) 55.4%). In the ILAE Class 1a, at po year 5 63/85 (74.1%) patients have discontinued AED intake. At lao 36.2% of patients were off AEDs and additional 18.9% had a "substantial" reduction (i.e. from polytherapy to monotherapy, or a reduction of the existing monotherapy by at least 66% compared to the year before AHE). The relapse rate is similar for patients who were free of disabling seizures (a) for > or =1 year and without AEDs (17.1%), (b) immediately after surgery with or without AEDs (18.4%), and (c) had a "substantial" AED reduction over the entire follow-up period (18.9%). The rate of re-gained full seizure control, however, is significantly better for group (b) compared to (c) (77% versus 53%). 10.9% of patients showed the "running down phenomenon," i.e. had seizures during the first po year, but then became seizure-free for 1 or more years. The percentage of patients free of "disabling" seizures, who did not follow the medical advice to discontinue/reduce AEDs, is about 30% after the 10th po year. In the 15th po year this figure is 4.2 times higher for "HS" versus "lesional" patients. We conclude that the time of discontinuation of AEDs after AHE should be tailored based on the results of the presurgical evaluation, the early po seizure outcome, the histopathological findings, the intraoperative ECoG findings and the po EEG. In an optimal constellation, "substantial" AED reduction with the goal of a monotherapy can be advised 1 year and discontinuation 2 years after surgery.

Long-term seizure outcomes following amygdalohippocampectomy

OBJECT

Analyses of the results of surgery for epilepsy are hindered by inconsistent classifications of seizure outcome, small numbers of patients, and short postoperative follow-up periods. The authors conducted a retrospective study with a reassessment of the long-term seizure outcomes in patients who underwent selective amygdalohippocampectomy (SelAH) for pharmacotherapy-resistant mesial temporal lobe epilepsy (MTLE) at the Zurich University Hospital from 1975 to 1999.

METHODS

Year-by-year data and the last available data on seizure outcomes were retrospectively assessed for 369 consecutively surgically treated patients who had participated in a follow-up period longer than 1 year as of 1999 and whose outcomes were classified according to the Engel scale and the proposed new International League Against Epilepsy (ILAE) scale. Patients were grouped into nonlesional and lesional MTLE groups depending on whether they harbored a gross anatomical lesion that caused the MTLE. Differentiation was made between curative and palliative operations. Complications related to surgery are reported for 453 patients who underwent SelAH and participated in more than 3 months of follow-up review. The last available outcome data according to the Engel scale were found to be generally similar to those of the new ILAE classification, with 66.9% of patients free from disabling seizures (Engel Class I) compared with 57.1% who were completely seizure and aura free (ILAE Class 1). The last available data on seizure outcome were not significantly different between patients in the lesional and nonlesional MTLE groups. In the lesional group, seizure outcomes were significantly better when patients underwent surgery early in the course of the disease. Overall, 70% of the patients received reductions in their antiepileptic drug treatment at the time of the last available follow-up review. Complications related to the surgical procedures were rare.

CONCLUSIONS

The authors conclude that SelAH is a safe and effective surgical procedure for MTLE.

Prognostic implications of seizure recurrence in the first year after anterior temporal lobectomy

PURPOSE

Seizure recurrence after anterior temporal lobectomy (ATL) incites concerns of whether seizures will eventually be successfully controlled. Our study evaluated the prognostic significance of seizure recurrence in the first year after ATL.

METHODS

The postoperative courses of 175 consecutive patients who had undergone ATL and had > or =2 years of follow-up were studied. Recurrence was considered early if the first seizure occurred within 7 days after ATL and late if it occurred >7 days after ATL. Recurrent seizures were considered provoked when precipitating factors were present, such as interruption of antiepileptic drug (AED) intake. Subsequent outcome was determined at terminal follow-up.

RESULTS

Percentage of excellent outcome was comparable between patients whose initial recurrent seizures were auras or simple partial seizures and patients without seizure recurrence in the first year (86.7 vs. 93.1%; p > or = 0.05). However, percentage of excellent outcome was less when the initial recurrent seizure was complex partial, either with or without secondary generalization (44.8%; p < or = 0.01). Outcome was not different between early and late seizure recurrence (excellent in 41.7 vs. 55.7%; p > or = 0.05). Nonetheless, patients with either early or late seizure recurrence were less likely to have excellent outcome than were patients with no seizure recurrence in the first year (p < or = 0.001). Percentage of excellent outcome was best when patients were seizure free in the first year (93.1%), intermediate when initial recurrent seizure was provoked (72.0%), and worst when unprovoked (27.8%) (p < or = 0.001).

CONCLUSIONS

In the first postoperative year, the type of initial recurrent seizure, whether aura or complex partial and whether provoked or unprovoked, is associated with long-term prognosis in seizure control after ATL. The timing of the initial seizure recurrence is not as important.

Localization of ictal and interictal bursting epileptogenic activity in focal cortical dysplasia: agreement of magnetoencephalography and electrocorticography

Focal cortical dysplasia (FCD) is often associated with severe partial epilepsy. In such cases, interictal frequent rhythmic bursting epileptiform activity (FBREA) on both scalp electroencephalography (EEG) and electrocorticography (ECoG) is generally accepted to be identical to the ictal epileptiform activity. We used magnetoencephalography (or Magnetic Source Imaging (MSI)) to determine the epileptogenic zone in a 6-year-old patient with histopathologically proven FCD and normal magnetic resonance imaging (MRI). MSI was used to localize the sources of both ictal activity and FRBEA, which was then compared with ECoG findings. The intracranial sources of both types of activity co-localized in the left inferior frontal and superior temporal gyri. The location and extent of the epileptogenic area determined by MSI was essentially identical to that determined directly through extra-operative ECoG. In the absence of structural abnormalities detectable on MRI, the noninvasive method of MSI provided valuable information regarding the location and extent of the primary epileptogenic area. This was critical for pre-surgical planning regarding placement of intracranial electrodes and for risk-benefit evaluation.

Frequency and significance of acute postoperative seizures following epilepsy surgery in children and adolescents

PURPOSE

To determine the frequency and prognostic features of acute postoperative seizures (APOSs), within the first postoperative week, in a group of children undergoing surgery for the treatment of medically refractory epilepsy.

METHODS

Patients younger than 18 years who underwent surgery for the relief of medically intractable epilepsy at the Mayo Clinic between 1985 and 1998 with a minimum of 12 months of follow-up were eligible. A retrospective chart review was conducted to abstract information regarding demographics, epilepsy history, and preoperative, intraoperative, and postoperative risk factors, APOSs, and outcome. A multivariate analysis was conducted to control for confounding variables.

RESULTS

The study group was composed of 148 patients (mean age at surgery, 13 years; range, 5 months to 18 years). Twenty-five percent of patients experienced APOSs. Risk factors associated with a statistically significant (p < 0.05) greater likelihood of experiencing APOS were non-complex partial seizure type, extratemporal surgery, postoperative fever, non-temporal lobe epilepsy, and postoperative interictal epileptiform activity. At last follow-up, patients who did not experience APOSs had a significantly greater chance of being seizure free (80 vs. 51%; p < 0.001). With a multivariate analysis, APOS was found to be an independent predictor of outcome.

CONCLUSIONS

This study indicates that APOSs are predictive of a less favorable outcome in the pediatric postsurgical patient; however, 51% remained seizure free at last follow-up. Finally, the effects of APOSs on outcome were shown to be stable over a 12-month follow-up period.

Detection and significance of focal, interictal, slow-wave activity visualized by magnetoencephalography for localization of a primary epileptogenic region

OBJECT

Magnetoencephalography (MEG) is a novel noninvasive diagnostic tool used to determine preoperatively the location of the epileptogenic zone in patients with epilepsy. The presence of focal slowing of activity recorded by electroencephalography (EEG) is an additional indicator of an underlying pathological condition in cases of intractable mesial temporal lobe epilepsy (MTLE). In the present study the authors examined the significance of focal, slow-wave and interictal spike activity detected using MEG in 29 patients who suffered from MTLE that was not associated with structural brain lesions.

METHODS

All patients underwent resective surgery after MEG and EEG monitoring. Equivalent single-dipole modeling was applied to focal low-frequency magnetic activity (LFMA) and interictal paroxysmal activity. Lateralized LFMA was defined as trains of rhythmic activity over the temporal area, with frequencies lower than 7 Hz, which were easily distinguished from background activity. Lateralized LFMA was found in 17 patients (58.6%); it always occurred on the side ipsilateral to the side of resection and displayed a maximum amplitude over the temporal area. Dipolar sources of magnetic flux computed during slow-wave trains were found in the majority of cases in the posterior superior temporal region and, occasionally, in mesial temporal structures that were subsequently resected. With respect to lateralization there was never disagreement between LFMA and MEG interictal spike sources. Thus, in patients with MTLE that is not associated with a mass lesion LFMA is topographically related to the epileptogenic area and, therefore, has value for reliable determination of the side and, possibly, the location of this area.

CONCLUSIONS

Although focal slowing of EEG background activity is generally considered to be a nonspecific sign of functional disturbance, interictal LFMA in patients with MTLE should be conceptualized as a distinct electrographic phenomenon that is directly related to the epileptogenic abnormality. Analyzing the interictal MEG distribution of LFMA and sharp activity improves the diagnostic utility of MEG in patients with suspected TLE who are undergoing surgical evaluation.

Verbal retention lateralizes patients with unilateral temporal lobe epilepsy and bilateral hippocampal atrophy

PURPOSE

To examine the lateralization utility of preoperative verbal retention in patients with and without bilateral hippocampal atrophy.

METHODS

The sample consisted of 74 patients with EEG-defined unilateral temporal lobe epilepsy (TLE) who had also undergone volumetric magnetic resonance imaging (MRI). Verbal retention was operationalized by the Logical Memory percentage retention subtest (LM%) of the Wechsler Memory Scale. Patients were divided into groups with (a) bilaterally normal hippocampal volumes, (b) unilateral atrophy, or (c) bilateral atrophy. Two different thresholds (empirically derived vs. normative) were used to lateralize on the basis of LM%. LM% lateralization was then examined by group using chi2, sensitivity, positive predictive values, and odds ratios. Analyses were also conducted separately in the subset of patients who were seizure free after surgery.

RESULTS

Mean LM% performance was significantly lower in patients with left versus right TLE in the subset with bilateral hippocampal atrophy (p = 0.018), but not in patients with a normal MRI (p = 0.918) or unilateral atrophy (p = 0.087). The odds of a correct lateralization by LM% increased from 1.67 in patients with normal MRI to 36.11 in patients with bilateral hippocampal atrophy. The power of a right and left lateralization prediction by LM% was 100% and 75%, respectively, in patients with bilateral hippocampal atrophy. Similar results were obtained when analysis was restricted to patients who were seizure free after surgery.

CONCLUSIONS

Preoperative verbal retention as measured by LM% may provide meaningful lateralization information in patients who are difficult to lateralize via MRI.

Surgical treatment for intractable epilepsy caused by cavernous angioma in the temporal lobe of the dominant hemisphere--three case reports

The surgical treatment modality for intractable epilepsy with cavernous angioma in the dominant hemisphere is still unclear. Three patients with medically intractable seizures associated with cavernous angioma in the dominant hemispheric temporal lobe underwent tailored resection based on magnetic resonance (MR) imaging, single photon emission computed tomography (SPECT), electroencephalography monitoring (from scalp and sphenoidal electrodes), and neuropsychologic assessment. Epileptogenic zones were located in the area surrounding the angioma in all patients and mesial temporal dysfunction in two patients. The adjacent cortex and gliotic tissues containing hemosiderin were resected, in conjunction with either total or partial resection of the nidus. Intraoperative electrocorticography (ECoG) was then performed. Additional resection of the mesial temporal structures or multiple subpial transection was performed as indicated by the ECoG findings. All three patients have been seizure free and showed no language or cognitive deterioration for 30, 18, and 14 postoperative months, respectively, while receiving tapered antiepileptic medication. Tailored resection based on electrophysiological data, MR imaging, SPECT, and intraoperative ECoG is effective for the treatment of medically intractable seizure associated with cavernous angioma in the temporal lobe of the dominant hemisphere.

Seizure outcome after epilepsy surgery in children and adolescents

Few epilepsy surgery outcome data are available from series of pediatric patients. We studied seizure outcome in 136 pediatric patients who had surgery for intractable epilepsy at The Cleveland Clinic between January 1990 and June 1996, with a postoperative follow-up of 1 to 7.5 years (mean, 3.6 years). Sixty-two children (3 months to 12 years old at time of surgery) were compared with 74 adolescents (13-20 years old). Extratemporal or multilobar resections and hemispherectomies were similarly frequent among children (50%) and adolescents (44%), but these procedures strongly predominated in infancy (90% of patients 0-2 years of age). The remaining patients had temporal resection. Cortical dysplasia and low-grade tumor were the most common causes and hippocampal sclerosis was rare. Seizure-free outcome was achieved for 69% of adolescents, 68% of children, and 60% of the infant subgroup, overall; for 23 (74%) of 31 children and 33 (80%) of 41 adolescents after temporal resection; for 11 (58%) of 19 children and 15 (52%) of 29 adolescents after extratemporal or multilobar resection; and for 8 (67%) of 12 children and 3 (75%) of 4 adolescents after functional hemispherectomy. Seizure-free outcome was more frequent after temporal resection (56 of 72, 78%) than after extratemporal or multilobar resection (26 of 48, 54%; 41 of 48 with a focal lesion on magnetic resonance imaging), and among patients with tumor (36 of 44, 82%) versus cortical dysplasia (16 of 31, 52%). The frequency of seizure-free outcome after epilepsy surgery was similar for infants, children, and adolescents, and comparable with results from adult series. Most patients in each age, surgery type, and causal group were free from seizures after surgery. These results suggest that children should be considered for surgical evaluation at whatever age they manifest with severe, intractable, disabling localization-related epilepsy.

Presurgery expectations, postsurgery satisfaction, and psychosocial adjustment after epilepsy surgery

PURPOSE

The medical benefits of epilepsy surgery are well documented, but the psychosocial consequences of surgery have received less attention. This is especially true of the roles of expectations and satisfaction in postsurgery functioning. The present study was designed to examine the relationships between expectation, satisfaction with surgery, and psychosocial functioning in patients and their significant others before and after epilepsy surgery.

METHODS

The neuropsychology findings of 79 patients undergoing epilepsy surgery were examined from assessments made before, 2 months after, and 1 year after anterior temporal lobectomy (ATL) was performed. The Minnesota Multiphasic Personality Inventory (MMPI) and the Washington Psychosocial Seizure Inventory (WPSI) were used to assess psychosocial functioning. A subset of 32 patients and their significant others were followed prospectively with an additional semistructured interview to assess expectations for and satisfaction with surgery outcome.

RESULTS

Before surgery, patients showed considerable problems with psychosocial adjustment. After surgery, patients in the seizure-free group showed improvements on the psychosocial measures at both follow-ups, whereas patients with continued seizures showed improvement at the 2-month follow-up and then a decline to baseline or worse at the time of the 1-year follow-up. Subjects who were studied prospectively had high presurgery expectations for seizure elimination. After surgery, subjects whose expectations were met reported high satisfaction whereas subjects whose expectations were not met reported low satisfaction. Satisfaction with surgery was associated with better psychosocial functioning.

CONCLUSIONS

Such data help elucidate the ways in which successful epilepsy surgery results in improved psychosocial functioning. The results identify ways to increase the likelihood that both patients who are seizure-free and those with reduced seizure frequency may benefit from surgery.

Contribution of neuropsychological data to the prediction of temporal lobe epilepsy surgery outcome

PURPOSE

We empirically examined the contribution of neuropsychological data to the prediction of postoperative seizure control relative to base rate information in an existing series of patients undergoing anterior temporal lobectomy (ATL).

METHODS

A discriminant function predicting surgery outcome (seizure-free vs. non-seizure-free) was computed separately for samples of patients with left (n = 79) and right (n = 62) temporal lobectomy (LATL, RATL). Predictor variables included 14 measures tapping five neurocognitive domains. The predicted base rates were compared with the actual base rates in the two samples. Finally, overall predictive accuracy was examined in optimal versus suboptimal ATL patients.

RESULTS

The base rate of seizure freedom in the LATL group was 74.70%; that in the RATL group was 66.10%. The predictive function for the LATL group achieved a hit rate of 80.00% and a positive predictive power of 92.11%. The function for the RATL group achieved a hit rate of 83.33% and a positive predictive power (PPP) of 89.66%. The overall predictive accuracy for the optimal group was only 55%, but that in the suboptimal group was 72%.

CONCLUSIONS

Neuropsychological data used in a multivariate statistical fashion may be able to offer an incremental increase in the prediction of postoperative seizure freedom relative to existing base rates of surgery success in patients with ATL epilepsy. The use of neuropsychological data may be of greatest predictive value in a population of ATL candidates with suboptimal findings with a lower base rate of postoperative seizure freedom, but may actually reduce predictive accuracy in a group of ATL candidates from an optimal population with an already high base rate of surgical success.

Supratentorial cavernous angiomas and epileptic seizures: preoperative course and postoperative outcome

OBJECTIVE

Patients operated on for supratentorial cavernous angiomas were studied to define the incidence and the course of seizures in their clinical history. Electroclinical and neuroradiological data were correlated with the location of cavernomas. The impact of lesionectomy on the outcome of seizures was evaluated.

METHODS

Preoperative clinical data on the history of the seizures, semeiology, incidence, severity, and response to antiepileptic drugs were analyzed. The location of the cavernomas, revealed by magnetic resonance imaging, was correlated with electroencephalographic and clinical data. Postoperative clinical and neuroradiological data were evaluated, with particular consideration to the outcome of the seizures, antiepileptic drug withdrawal, and the completeness of the lesion excision.

RESULTS

A higher incidence of severe epilepsy was observed in the patients with mesiotemporal and cortical angiomas. In most of the patients (78.7%), a good concordance between the site of the lesion and the electroclinical data was found. The complete removal of the lesion led to a favorable outcome, with discontinuation of antiepileptic drugs achieved in one-quarter of the patients.

CONCLUSION

A high percentage of patients with cortical cavernomas had epileptic seizures. They often presented with chronic intractable epilepsy (44.7% in our series). In cases of good concordance between the electroclinical data and the location of the angioma, complete lesionectomy led to the disappearance of seizures. Removal of the hemosiderin ring did not correlate with better outcome. Preoperative ictal scalp recordings to assess the topographic relationship between the cavernoma and the epileptic seizures could improve outcome, which suggests different surgical strategies (lesionectomy versus enlarged resection) in patients without a clear-cut concordance between the site of the lesion and the ictal semeiology.