Postoperative EEG and seizure outcome in temporal lobe epilepsy surgery

Earlier Age at Surgery for Brain Cavernous Angioma-Related Epilepsy May Achieve Complete Seizure Freedom without Aid of Anti-Seizure Medication

Background: The present study hypothesized that some factors may distinguish between patients with a brain cavernous angioma (BCA), who were free from anti-seizure medication (ASM), and patients who still required ASMs postoperatively. The purpose of the study was thus to identify factors associated with ceasing ASMs for patients with drug-resistant epilepsy secondary to BCA, who underwent BCA removal surgery. Methods: We divided patients into those with drug-resistant epilepsy secondary to BCA who achieved complete seizure freedom without ASMs a year after surgery (No-ASM group) (International League Against Epilepsy (ILAE) classification class I with no epileptiform discharges), and others (ASM group) (ILAE classification ≤ II and/or epileptiform discharges). We statistically compared groups in terms of: (1) age at operation; (2) history of epilepsy; (3) size of BCA; and (4) location of BCA. Results: Overall, a year after the surgery, the No-ASM group comprised 12 patients (48%), and the ASM group comprised 13 patients (52%). In both multi- and univariate logistic regression analyses, age at BCA removal surgery correlated significantly with the No-ASM group (p = 0.043, p = 0.019), but history of epilepsy did not (p = 0.581, p = 0.585). Conclusions: Earlier age at surgery for patients with drug-resistant epilepsy is encouraged to achieve complete seizure freedom without the need for ASMs when the cause of epilepsy is BCA.

MEG Node Degree Differences in Patients with Focal Epilepsy vs. Controls-Influence of Experimental Conditions

Drug-resistant epilepsy can be most limiting for patients, and surgery represents a viable therapy option. With the growing research on the human connectome and the evidence of epilepsy being a network disorder, connectivity analysis may be able to contribute to our understanding of epilepsy and may be potentially developed into clinical applications. In this magnetoencephalographic study, we determined the whole-brain node degree of connectivity levels in patients and controls. Resting-state activity was measured at five frequency bands in 15 healthy controls and 15 patients with focal epilepsy of different etiologies. The whole-brain all-to-all imaginary part of coherence in source space was then calculated. Node degree was determined and parcellated and was used for further statistical evaluation. In comparison to controls, we found a significantly higher overall node degree in patients with lesional and non-lesional epilepsy. Furthermore, we examined the conditions of high/reduced vigilance and open/closed eyes in controls, to analyze whether patient node degree levels can be achieved. We evaluated intraclass-correlation statistics (ICC) to evaluate the reproducibility. Connectivity and specifically node degree analysis could present new tools for one of the most common neurological diseases, with potential applications in epilepsy diagnostics.

Improving the prediction of epilepsy surgery outcomes using basic scalp EEG findings

OBJECTIVE

This study aims to evaluate the role of scalp electroencephalography (EEG; ictal and interictal patterns) in predicting resective epilepsy surgery outcomes. We use the data to further develop a nomogram to predict seizure freedom.

METHODS

We retrospectively reviewed the scalp EEG findings and clinical data of patients who underwent surgical resection at three epilepsy centers. Using both EEG and clinical variables categorized into 13 isolated candidate predictors and 6 interaction terms, we built a multivariable Cox proportional hazards model to predict seizure freedom 2 years after surgery. Harrell's step-down procedure was used to sequentially eliminate the least-informative variables from the model until the change in the concordance index (c-index) with variable removal was less than 0.01. We created a separate model using only clinical variables. Discrimination of the two models was compared to evaluate the role of scalp EEG in seizure-freedom prediction.

RESULTS

Four hundred seventy patient records were analyzed. Following internal validation, the full Clinical + EEG model achieved an optimism-corrected c-index of 0.65, whereas the c-index of the model without EEG data was 0.59. The presence of focal to bilateral tonic-clonic seizures (FBTCS), high preoperative seizure frequency, absence of hippocampal sclerosis, and presence of nonlocalizable seizures predicted worse outcome. The presence of FBTCS had the largest impact for predicting outcome. The analysis of the models' interactions showed that in patients with unilateral interictal epileptiform discharges (IEDs), temporal lobe surgery cases had a better outcome. In cases with bilateral IEDs, abnormal magnetic resonance imaging (MRI) predicted worse outcomes, and in cases without IEDs, patients with extratemporal epilepsy and abnormal MRI had better outcomes.

SIGNIFICANCE

This study highlights the value of scalp EEG, particularly the significance of IEDs, in predicting surgical outcome. The nomogram delivers an individualized prediction of postoperative outcome, and provides a unique assessment of the relationship between the outcome and preoperative findings.

Outcome of epilepsy surgery in lesional epilepsy: Experiences from a developing country

BACKGROUND

Our aim was to report the postoperative seizure outcome and associated factors in patients with lesional epilepsy, in a low-income setting.

METHODS

This longitudinal prospective study included patients who underwent epilepsy surgery at Kashani Comprehensive Epilepsy Center between 2014 and 2019. Post-surgical outcomes were reported according to the Engel score, and patients were classified into two groups of seizure free (SF) and not-seizure free (NSF).

RESULTS

A total of 148 adult patients, with a mean age of 30.45 ± 9.23 years were included. The SF outcome was reported in 86.5% of patients and antiepileptic drugs (AEDs) were reduced or discontinued in 45.9%. The mean follow-up duration was 26.7 ± 14.9 months. Temporal lobe lesions (76.3%) and mesial temporal sclerosis (MTS) (56.7%) were the most frequent etiologies. Temporal lesion (Incidence relative risk (IRR): 1.76, 95% CI [1.08-2.87], p = 0.023), prior history of CNS infection (IRR:1.18, 95% CI [1.03-1.35], p = 0.019), use of intra-operative ECoG (IRR:1.73, 95% CI [1.06-2.81], p = 0.028), and absence of IEDs in postoperative EEG (IRR: 1.41, 95% CI [1.18-1.70], p < 0.001) were positive predictors for a favorable outcome.

CONCLUSION

Many patients with drug-resistant lesional epilepsy showed a favorable response to surgery. We believe that resective epilepsy surgery in low-income settings is a major treatment option. The high frequency of patients with drug-resistant epilepsy in developing countries is associated with high rates of morbidity and mortality. Hence, strategies to increase access to epilepsy surgery in these settings are urgently needed.

Focal Cortical Dysplasia IIIa in Hippocampal Sclerosis-Associated Epilepsy: Anatomo-Electro-Clinical Profile and Surgical Results From a Multicentric Retrospective Study

BACKGROUND

Hippocampal sclerosis (HS) may be associated with focal cortical dysplasia IIIa (FCD IIIa) in patients undergoing surgery for temporal lobe epilepsy (TLE).

OBJECTIVE

To investigate whether the anatomo-electro-clinical profile and surgical outcome in patients with HS-related TLE are affected by coexisting FCD IIIa.

METHODS

A total of 220 patients, operated in 5 centers, with at least 24 mo follow-up (FU), were retrospectively studied. Preliminary univariate and subsequent multivariate analyses were performed to investigate possible associations between several potential presurgical, surgical, and postsurgical predictors and different variables (Engel's class I and Engel's class Ia, co-occurrence of FCD IIIa).

RESULTS

At last available postoperative control (FU: range 24-95 mo, median 47 mo), 182 (82.7%) patients were classified as Engel's class I and 142 (64.5%) as Engel's class Ia. At multivariate analysis, extension of neocortical resection and postoperative electroencephalogram were significantly associated with Engel's class I, whereas length of FU had a significant impact on class Ia in the whole cohort and in isolated HS (iHS) patients, but not in the FCD IIIa group. No differences emerged in the anatomo-electro-clinical profile and surgical results between patients with FCD IIIa and with iHS.

CONCLUSION

Coexistence of FCD IIIa did not confer a distinct anatomo-electro-clinical profile to patients with HS-related epilepsy. Postoperative seizure outcome was similar in FCD IIIa and iHS cases. These findings indicate limited clinical relevance of FCD IIIa in HS-related epilepsy and might be useful for refining future FCD classifications. Further studies are needed to clarify the correlation of class Ia outcome with the duration of FU.

Cost-effectiveness of surgery for drug-resistant temporal lobe epilepsy in the US

OBJECTIVE

Surgery is an effective but costly treatment for many patients with drug-resistant temporal lobe epilepsy (DR-TLE). We aim to evaluate whether, in the United States, surgery is cost-effective compared to medical management for patients deemed surgical candidates and whether surgical evaluation is cost-effective for patients with DR-TLE in general.

METHODS

We use a semi-Markov model to assess the cost-effectiveness of surgery and surgical evaluation over a lifetime horizon. We use second-order Monte Carlo simulations to conduct probabilistic sensitivity analyses to estimate variation in model output. We adopt both health care and societal perspectives, including direct health care costs (e.g., surgery, antiepileptic drugs) and indirect costs (e.g., lost earnings by patients and care providers.) We compare the incremental cost-effectiveness ratio to societal willingness to pay (∼$100,000 per quality-adjusted life-year [QALY]) to determine whether surgery is cost-effective.

RESULTS

Epilepsy surgery is cost-effective compared to medical management in surgically eligible patients by virtue of being cost-saving ($328,000 vs $423,000) and more effective (16.6 vs 13.6 QALY) than medical management in the long run. Surgical evaluation is cost-effective in patients with DR-TLE even if the probability of being deemed a surgical candidate is only 5%. From a societal perspective, surgery becomes cost-effective within 3 years, and 89% of simulations favor surgery over the lifetime horizon.

CONCLUSION

For surgically eligible patients with DR-TLE, surgery is cost-effective. For patients with DR-TLE in general, referral for surgical evaluation (and possible subsequent surgery) is cost-effective. Patients with DR-TLE should be referred for surgical evaluation without hesitation on cost-effectiveness grounds.

Association Between Quantitative Electroencephalogram Frequency Composition and Post-Surgical Evolution in Pharmacoresistant Temporal Lobe Epilepsy Patients

The purpose of this paper is to estimate the association between quantitative electroencephalogram frequency composition (QEEGC) and post-surgical evolution in patients with pharmacoresistant temporal lobe epilepsy (TLE) and to evaluate the predictive value of QEEGC before and after surgery. A prospective, longitudinal study was made at International Neurological Restoration Center, Havana, Cuba. Twenty-nine patients with TLE submitted to epilepsy surgery were evaluated before surgery, and six months and two years after. They were classified as unsatisfactory and satisfactory post-surgical clinical evolution using the Modified Engels Scale. Eighty-seven electroencephalograms with quantitative narrow- and broad-band measures were analyzed. A Mann Whitney test (p > 0.05) showed that QEEGC before surgery was similar between groups independently of two years post-surgical evolution. A Mann Whitney test (p ˂ 0.05) showed that subjects with two years satisfactory post-surgical evolution had greater alpha power compared to subjects with two years unsatisfactory post-surgical evolution that showed greater theta power. A Wilcoxon test (p ˂ 0.05) showed that alpha and theta power increased for two groups from pre-surgical state to post-surgical state. Logit regression (p ˂ 0.05) showed that six months after surgery, quantitative electroencephalogram frequency value with the greatest power at occipital regions shows predictive value for two years evolution. QEEGC can be a tool to predict the outcome of epilepsy surgery.

Postoperative EEG association with seizure recurrence: Analysis of the NIH epilepsy surgery database

The epilepsy surgery database from 1984 to 2012 at the National Institutes of Health (NIH) was reviewed to determine the association of postoperative electroencephalography (EEG) with seizure recurrence. Eighty‐three patients were analyzed, with 41 having at least 5 years of follow‐up. The relationship between epileptiform postoperative EEG findings and seizure recurrence at 1, 2, and 5 years was not significant, despite a significant decrease in abnormal EEG recordings after surgery. Clinicians use a variety of tools to predict seizure recurrence following epilepsy surgery to guide medication management and to modulate patient expectations. EEG is but one tool for assessing the likelihood of seizure recurrence following epilepsy surgery.

Long-Term Electroclinical and Employment Follow up in Temporal Lobe Epilepsy Surgery. A Cuban Comprehensive Epilepsy Surgery Program

The purpose of this paper is to present a long- term electroclinical and employment follow up in temporal lobe epilepsy (TLE) patients in a comprehensive epilepsy surgery program. Forty adult patients with pharmacoresistant TLE underwent detailed presurgical evaluation. Electroencephalogram (EEG) and clinical follow up assessment for each patient were carried out. The occurrence of interictal epileptiform activity (IEA) and absolute spike frequency (ASF) were tabulated before and after 1, 6, 12, 24 and 72 months surgical treatment. Employment status pre- to post-surgery at the last evaluated period was also examined. Engel scores follow-up was described as follows: at 12 months 70% (28) class I, 10% (4) class II and 19% (8) class III-IV; at 24 months after surgery 55.2% (21) of the patients were class I, 28.9% (11) class II and 15.1% (6) class III-IV. After one- year follow up 23 (57.7%) patients were seizure and aura-free (Engel class IA). These figures changed to 47.3%, and 48.6% respectively two and five years following surgery whereas 50% maintained this condition in the last follow up period. A decline in the ASF was observed from the first year until the sixth year after surgery in relation to the preoperative EEG. The ASF one year after surgery allowed to distinguish “satisfactory” from “unsatisfactory” seizure relief outcome at the last follow up. An adequate social functioning in terms of education and employment in more than 50% of the patients was also found. Results revealed the feasibility of conducting a successful epilepsy surgery program with favorable long term electroclinical and psychosocial functioning outcomes in a developing country as well.

Prognostic significance of postoperative spikes varied in different surgical procedures for mesial temporal sclerosis

PURPOSE

We conducted this study to compare the occurrence and prognostic significance of early postoperative interictal epileptiform discharges (IEDs) on seizure outcomes between corticoamygdalohippocampectomy (CAH) and selective amygdalohippocampectomy (SAH).

METHODS

We reviewed our database of patients who had epilepsy surgery with hippocampus atrophy or signal changes on brain MRIs and pathology of mesial temporal sclerosis. One hundred and seventy-seven CAH and 39 SAH patients were enrolled. Postoperative EEG within 30days, other preoperative variables and seizure outcome 2years after surgery were obtained for analysis. Engel's IA and IB were defined as seizure-free.

RESULTS

There was no significant difference in the seizure-free rate between the two procedures (127 (71.8%) of CAH vs 30 (76.9%) of SAH, p=0.51). Postoperative IEDs were more frequently seen in the SAH group (64.1%) than in the CAH group (29.9%), p<0.001. The IEDs in the SAH group did not show correlation with the seizure outcome 2 years after surgery. In the CAH group, patients who had no postoperative IEDs showed a higher seizure-free rate compared to those with IEDs (78.2% vs 56.6%, p=0.003; OR 2.267, 95% CI 1.09-4.73, p=0.029 in multivariate logistic regression).

CONCLUSIONS

Early postoperative IEDs are more frequently seen in SAH than in CAH. Unlike in patients with CAH, the presence of IEDs after SAH was not a predictor of seizure recurrence. The type of surgery should be considered while utilizing postoperative IEDs for evaluating the prognosis.

The delta between postoperative seizure freedom and persistence: Automatically detected focal slow waves after epilepsy surgery

OBJECTIVE

In this study, we use a novel automated method for localization and quantitative comparison of magnetoencephalographic (MEG) delta activity in patients with and without recurrent seizures after epilepsy surgery as well as healthy controls.

METHODS

We identified the generators of delta activity by source location in frequency domain between 1 and 4 Hz in spontaneous MEG data. Comparison with healthy control subjects by z-transform emphasized relative changes of activation in patients. The individual results were compared to spike localizations and statistical group analysis was performed. Additionally, MEG results were compared to 1-4 Hz activity in invasive EEG (iEEG) in two patients, in whom this data was available.

RESULTS

Patients with recurrent seizures exhibited significantly increased focal MEG delta activity both in comparison to healthy controls and seizure free patients. This slow activity showed a correlation to interictal epileptic activity and was not explained by consequences of the resection alone. In two patients with iEEG, iEEG analysis was concordant with the MEG findings.

SIGNIFICANCE

The quantity of delta activity could be used as a diagnostic marker for recurrent seizures. The close relation to epileptic spike localizations and the resection volume of patients with successful second surgery imply involvement in seizure recurrence. This initial evidence suggests a potential application in the planning of second epilepsy surgery.

Surgical outcomes in patients with intraoperative Electrocorticography (EcoG) guided epilepsy surgery-experiences of a tertiary care centre in India

INTRODUCTION

The Comprehensive Epilepsy Surgery Program was started in 2001 at K.E.M. Hospital, Mumbai with the aim of performing epilepsy surgeries at highly concessional rates. We have started using intraoperative Electrocorticography (EcoG) since 2009 in patients with tumors, Mesial Temporal Sclerosis (MTS) plus and focal cortical dysplasia (FCD). This study highlights our experience with EcoG and it's utility in epilepsy surgery.introduction METHODS: 51 patients with drug resistant epilepsy due to temporal and extra-temporal tumors, MTS plus and FCD underwent pre-surgical evaluation and ECoG guided epilepsy surgery through our program. The surgical procedures employed included intraoperative EcoG guided lesionectomy or a lesionectomy with Anterior Temporal Lobectomy (ATL). Postoperative MRI and EEG were done. Seizure freedom was categorized as per Engel's classification.

RESULTS

At a mean follow up of 33 months (range: 14-69 months), 43 out of 51(84.31%) patients were completely seizure free post-surgery (Engel's Class I). Among the patients who were not seizure free, 3 patients were in Engel's Class II and 5 patients were in Engel's Class III. Presence of a residual lesion on postoperative MRI (p < 0.001), abnormal postoperative EEG (p < 0.001) and persistent spikes on post-resection EcoG (p < 0.05) had a significant statistical association with poor seizure freedom post-surgery.

CONCLUSION

The success of epilepsy surgery depends upon accurate localization and complete resection of the epileptogenic tissue, both of which are aided by intraoperative EcoG.Thus, intraoperative EcoG is a useful adjunct in epilepsy surgery to achieve optimal seizure freedom in cases of MTS plus, focal cortical dysplasia and tumors. Even the patients who are not seizure free can achieve worthwhile improvement post surgery.

Surgical management of cavernous malformations presenting with drug-resistant epilepsy

Cerebral cavernous malformations (CMs) are dynamic lesions characterized by continuous size changes and repeated bleeding. When involving cortical tissue, CMs pose a significant risk for the development of drug-resistant epilepsy, which is thought to be result of an altered neuronal network caused by the lesion itself and its blood degradation products. Preoperative evaluation should comprise a complete seizure history, neurological examination, epilepsy-oriented MRI, EEG, video-EEG, completed with SPECT, PET, functional MRI, and/or invasive monitoring as needed. Radiosurgery shows variable rates of seizure freedom and a high incidence of complications, thus microsurgical resection remains the optimal treatment for CMs presenting with drug-resistant epilepsy. Two thirds of patients reach Engel I class at 3-year follow-up, regardless of lobar location. Those with secondarily generalized seizures, a higher seizure frequency, and generalized abnormalities on preoperative or postoperative EEG, show poorer outcomes, while factors such as gender, duration of epilepsy, lesion size, age, bleeding at the time of surgery, do not correlate consistently with seizure outcome. Electrocorticography and a meticulous removal of all cortical hemosiderin - beyond pure lesionectomy - reduce the risk of symptomatic recurrences.

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.

Microsurgical treatment of temporal lobe cavernomas

BACKGROUND

Cavernomas of the temporal lobe occur in 10-20% of patients with cerebral cavernomas. They frequently cause epileptic seizures, some of which tend to become refractory to medical therapy. Surgical removal of safely achievable symptomatic lesions has been frequently consistent with good long-term outcome. In the present study, a postoperative outcome is assessed.

METHODS

Of our 360 consecutive patients with cerebral cavernomas, 53 (15%) had a single cavernoma in the temporal lobe. Forty-nine patients were treated surgically and were included in the study. All data were analyzed retrospectively. The cavernomas were allocated into three groups based on the temporal lobe site: medial, anterolateral, and posterolateral. To collect follow-up data, all available patients were interviewed by phone. Seizure outcome was assessed using the Engel classification and general outcome using the Glasgow Outcome Scale (GOS).

RESULTS

Patients' median age at presentation was 37 (range, 7-64) years, with a female/male ratio of 2.5:1. Epileptic seizures occurred in 40 patients (82%). Median duration of seizures preoperatively was 3 (range, 0.1-23) years. In addition, four patients (10%) had memory disorder. Three patients without history of seizures (6%) complained of headache and two (4%) had memory problems. Three patients (6%) had an incidental cavernoma. Hemorrhage occurred in nine patients (18%) preoperatively. Median postoperative follow-up time was 6 (range, 0.2-26) years. Favorable seizure outcome (Engel class I and II) was registered in 35 patients (90%). Ten patients (25%) who had only a single seizure before surgery were seizure free during postoperative follow-up. Good general outcome (GOS, 4.5) was detected in 46 patients (96%). Two patients (4%) developed a new mild memory deficit after surgery, and in two patients existing memory deficits worsened.

CONCLUSIONS

Microsurgical removal of temporal lobe cavernomas is a safe and effective method to improve seizure outcome in patients with medically intractable epilepsy and to prevent deterioration caused by hemorrhage.

Long-term Prognosis and Psychosocial Outcomes after Surgery for MTLE

PURPOSE

To assess the seizure-freedom rates and self-perceived psychosocial changes associated with the long-term outcome of epilepsy surgery in patients with refractory medial temporal lobe epilepsy associated with hippocampal sclerosis.

METHODS

A standard questionnaire was given to 183 patients who underwent surgery between 1988 and 2004, and 110 were completed.

RESULTS

The mean duration of follow-up after surgery was 7 years, with a maximum of 17 years. The probability that patients were seizure-free after surgery was dependent on the definition of the seizure freedom. For the patients who were seizure-free since surgery (Engel's class Ia), the probability was 97.6% at 1 year after surgery, 85.2% at 2 years after surgery, 59.5% at 5 years after surgery, and 42.6% at 10 years after surgery. For the patients who still experienced rare disabling seizures after surgery but were seizure-free at least 1 year before the time of assessment, the probability was of 97.6% at 1 year after surgery, 95% at 2 years after surgery, 82.8% at 5 years after surgery, and 71.1% at 10 years after surgery. The psychosocial long-term outcome, as measured by indices of driving, employment, familial and social relationships, and marital status, was similar to the psychosocial short-term outcome. It did not depend on seizure freedom or on follow-up time interval and was not influenced statistically by seizure frequency in cases of persisting seizures. Most but not all patients noticed a substantial overall improvement in their psychosocial condition; 48% drove (increased by 7%), 47% improved (14% worsened) in their employment status, and 68% improved (5% worsened) in their familial and social relationships. Overall, 91% of patients were satisfied with the surgery, and 92% did not regret their decision.

CONCLUSIONS

The results of this study suggest that temporal lobe surgery has real long-term benefits. Two specific conclusions emerge: (a) the long-term rates of freedom from seizure depend on how seizure freedom is defined, and (b) the psychosocial long-term outcome does not change dramatically over years and does not depend on seizure freedom.

Drug-resistant temporal lobe epilepsy due to cavernous malformations

Object

Supratentorial cavernous angiomas may be associated with drug-resistant focal epilepsy. Surgical removal of the malformation may result in seizure control in a number of patients, although in most studies a long history and high frequency of attacks have been recognized as indicators of unfavorable seizure outcome. In the literature, there are no clear indications regarding the optimal diagnostic presurgical workup and the surgical strategy for this particular subgroup of patients with symptomatic epilepsy. In this paper the authors focus on the preoperative workup and the surgical management of the disease in eight consecutive patients undergoing surgery for drug-resistant temporal lobe epilepsy (TLE) due to cavernous malformations (CMs), and the relevant literature on this issue is also reviewed.

Methods

Preoperatively, all patients were assessed using a noninvasive protocol aimed at localizing the epileptogenic zone on the basis of anatomical, electrical, and clinical criteria. The presurgical assessment yielded an indication for lesionectomy in two cases, lesionectomy plus anteromesial temporal lobectomy in four cases, and lesionectomy plus extended temporal lobectomy in two cases. At follow-up examinations, seizure, neuropsychological, and psychiatric outcomes were all evaluated. Seven patients were categorized in Engel Class IA (seizure free), and one was categorized in Engel Class IB (occasional auras only). No adverse effects on neuropsychological or psychosocial functioning were observed.

Conclusions

Epilepsy surgery can be performed with excellent results in patients with intractable TLE caused by CMs. Noninvasive presurgical evaluation of these patients may enable a tailored approach, providing complete seizure relief in most cases.

Temporal lobe epilepsy surgery: different surgical strategies after a non-invasive diagnostic protocol

AIM

To test a non-invasive presurgical protocol for temporal lobe epilepsy (TLE) based on "anatomo-electro-clinical correlations".

METHODS

All consecutive patients with suspected TLE and seizure history <2 years were entered into the protocol, which included video-electroencephalographic (EEG) monitoring and magnetic resonance imaging (MRI). Three different TLE subsyndromes (mesial, lateral, mesiolateral) were identified by combined anatomical, electrical, and clinical criteria. "Tailored" surgery for each subsyndrome was offered. Patients with seizure history <2 years, MRI evidence of temporal mass lesion, and concordant interictal EEG and clinical data bypassed video-EEG monitoring and were directly scheduled for surgery.

RESULTS

Lesionectomy was performed without video-EEG recording in 11 patients with tumorous TLE. Of 146 patients studied with video-EEG, 133 received a TLE diagnosis. Four were excluded for neuropsychological risks, eight refused surgery, and 121 underwent surgery. Of 132 consecutive patients who underwent surgery, 101 had at least one year of follow up. They were divided into a "hippocampal sclerosis/cryptogenic" group (n = 57) and a "tumours/cortical organisation disorders" group (n = 44). In the first group, extensive temporal lobectomy (ETL) was performed in 40 patients, anteromesial temporal lobectomy (AMTL) in 17 patients. At follow up, 47 patients were seizure free. In the second group, lesionectomy plus ETL was performed in 23 patients, lesionectomy plus AMTL in six patients, and lesionectomy alone in 15 patients. Thirty nine patients were seizure free.

CONCLUSIONS

These findings suggest that different TLE subsyndromes can be identified accurately using non-invasive anatomo-electro-clinical data and can be treated effectively and safely with tailored surgery.