Frontal Lobe Epilepsy Surgery Research Articles

The correlation between ictal semiology and magnetoencephalographic localization in frontal lobe epilepsy

ObjectiveThe aim of this study was to investigate the correlation of ictal semiology with localization and/or lateralization by magnetoencephalography (MEG). MethodsSeven patients from the Neurology Department of the University Hospital Erlangen who underwent resective surgery for frontal lobe epilepsy (FLE) with an Engel 1a outcome were investigated retrospectively. MEG localizations were classified according to five compartments (separate or combined) of the frontal lobe: frontal basal (FB), frontal lateral (FL), frontal polar (FP), frontal mesial (FM), and frontal precentral (FPr). On the basis of previous studies that investigated the value of ictal semiology in localization and lateralization, we compared the experiential localization and/or lateralization of the epileptogenic region deduced from ictal semiology, that is, both seizure history and ictal video/EEG monitoring, with MEG localization. ResultsIt is easier to determine lateralization than localization from ictal semiology because of the variety of signs and fast propagation in FLE. All of the patients had specific MEG localizations according to favorable postoperative outcome. Three patients had MEG foci associated with ictal semiology; in another four, the MEG localization was adjacent to the estimated area suggested by ictal semiology. Head version signs could be observed in all compartments of the frontal lobe: clonic in FB and FP areas; postural in FPr, FL, and FM areas; hypermotor in FB, FP, FPr, and FM areas; sensation aura in FB, FL, and FM areas; and automatisms in FP, FPr, and FL areas. All patients had concordant lateralizing and limited valuable locating information from ictal semiology, but no complete correlation with MEG foci. ConclusionIctal semiology may indicate the involvement of a symptomatogenic brain region during a seizure, but extent of seizure onset in central motor or sensorimotor area is not reliable enough to indicate the seizure onset zone and favorable postoperative outcome in FLE. MEG provided specific localization of epileptic activity in a FLE compartment, and indicated the relationship between epileptogenic region and lesion. MEG can complement ictal semiology in establishing a noninvasive focal localization hypothesis.

Longitudinal Change in Outcome of Frontal Lobe Epilepsy Surgery

Although the outcome of epilepsy surgery changes with time, few studies have considered longitudinal changes after frontal lobe epilepsy (FLE) surgery. To assess the longitudinal changes after FLE surgery. Resection of the seizure onset zone was performed in 76 patients with FLE. Invasive monitoring was performed in 56 of these 76. Awake craniotomy was performed in 43 of the 76 patients. More than 50% of patients were followed up for at least 7 years. The mean follow-up was 81 months. For all patients, the seizure-free rate was 79% at 6 months, 64% at 1 year, 55% at 2 years, and 55% at 7 years. For patients with cortical dysplasia, the seizure-free rate was 72% at 6 months, 53% at 1 year, 51% at 2 years, and 46% at 7 years. For patients with tumor, the seizure-free rate was 89% at 6 months, 83% at 1 year, 83% at 2 years, and 74% at 7 years. Patients with tumor showed better outcome than those with cortical dysplasia (P = .04). Although the overall seizure-free rate became stable after 2 years, individual status changed for up to 5 years. Seizures recurred in 11 patients within 1 year (early recurrence) and in 12 patients by 1 to 5 years (late recurrence). Antiepileptic drug (AED) medication was adjusted in all patients with recurrence. Patients with late recurrence had a more favorable response (Engel class I or II) than early recurrence (P < .01). The overall seizure outcome changes mostly during the first year. However, individual seizure status changes for up to 5 years. The outcome of late recurrence is favorable to AED adjustment.

Outcome of frontal lobe epilepsy surgery in adults

Our aim is to investigate seizure outcome and prognostic factors after pure frontal lobe epilepsy (FLE) surgery. We retrospectively studied the operative outcome in 97 consecutive adult patients who underwent resective surgery for intractable partial epilepsy between 1991 and 2005. Based on Kaplan-Meier, the probability of an Engel Class I outcome was found to be 54.6% (95% CI 44-64) at 6 months, 49.5% (95% CI 39.3-59.6) at 2 years, 47% (CI 34-59) at 5 years and 41.9% (CI 23.5-60.3) at 10 years. If the patient was seizure free at 2-year follow-up, the probability of remaining seizure free up to 10 years was 86% (95% CI 76-98). For 13.6% of the patients a running down of seizures could be shown. Factors predictive of poor long-term outcome were incomplete resection, using of subdural grids, IED in follow-up EEG, tonic seizures and an unspecific aura or a postoperative aura. Factors predictive of good long-term outcome were the presence of a well-circumscribed lesion in preoperative MRI, ipsilateral IED in preoperative EEG, surgery before age of 30 and short epilepsy duration prior to surgery. In the multivariate analysis, preoperative well-circumscribed lesion in MRI predicts seizure remission whereas persistent postoperative auras predict seizure relapse. FLE surgery should depend on restrictive patient selection to assure favorable outcome.

Quelles stratégies pour quels résultats dans la chirurgie des épilepsies partielles frontales ?

Frontal lobe epilepsy surgery is the second most common surgery performed for drug-resistant partial epilepsy. We investigated the longitudinal outcome in a cohort of patients investigated since 1990 with SEEG and modern diagnostic techniques. We reviewed 105 patients who underwent surgery between 1990 and 2005 (mean follow-up, six years; range: one to 17 years) and analyzed the year-per-year follow-up according to Engel's classification. Favorable outcome (Class I) was observed for 70% and this result was stable at least five years after surgery. More than 90% of patients with lesion-related epilepsies (focal cortical dysplasia and dysembryoplastic neuroepithelial tumors) became seizure-free. Less than 50% of patients classified as having cryptogenic epilepsy (defined as normal imaging and neuropathology on surgical specimen) had a favorable outcome. Permanent neurological sequelae were subtle and rare, especially after surgery for dysplasia in eloquent cortex (primary motor cortex). Our data indicate that frontal surgery is a successful treatment in patients when electrophysiological and morphological investigations demonstrate a well-defined epileptogenic zone or lesion to be surgically resected. Progress in electrophysiological and brain-imaging techniques will further improve the selection of frontal lobe epilepsy surgery candidates.

Epilepsy Surgery in the Frontal Lobe: Terra Incognita or New Frontier?

Surgical Outcome and Prognostic Factors of Frontal Lobe Epilepsy Surgery. Jeha LE, Najm I, Bingaman W, Dinner D, Widdess-Walsh P, Luders H. Brain 2007;130(Pt 2):574–584. Epub 2007 Jan 5. Frontal lobe epilepsy (FLE) surgery is the second most common surgery performed to treat pharmacoresistant epilepsy. Yet, little is known about long-term seizure outcome following frontal lobectomy. The aim of this study is to investigate the trends in longitudinal outcome and identify potential prognostic indicators in a cohort of FLE patients investigated using modern diagnostic techniques. We reviewed 70 patients who underwent a frontal lobectomy between 1995 and 2003 (mean follow-up 4.1 ± 3 years). Data were analysed using survival analysis and multivariate regression with Cox proportional hazard models. A favourable outcome was defined as complete seizure-freedom, allowing for auras and seizures restricted to the first post-operative week. The estimated probability of complete seizure-freedom was 55.7% [95% confidence interval (CI) = 50–62] at 1 post-operative year, 45.1% (95% CI = 39–51) at 3 years, and 30.1% (95% CI = 21–39) at 5 years. Eighty per cent of seizure recurrences occurred within the first 6 post-operative months. Late remissions and relapses occurred, but were rare. After multivariate analysis, the following variables retained their significance as independent predictors of seizure recurrence: MRI-negative malformation of cortical development as disease aetiology [risk ratio (RR) = 2.22, 95% CI = 1.40–3.47], any extrafrontal MRI abnormality (RR = 1.75, 95% CI = 1.12–2.69), generalized/non-localized ictal EEG patterns (RR = 1.83, 95% CI = 1.15–2.87), occurrence of acute post-operative seizures (RR = 2.17, 95% CI = 1.50–3.14) and incomplete surgical resection (RR = 2.56, 95% CI = 1.66–4.05) (log likelihood-ratio test P-value &lt; 0.0001). More than half of patients in favourable prognostic categories were seizure-free at 3 years, and up to 40% were seizure-free at 5 years, compared to &lt;15% in those with unfavourable outcome predictors. These data underscore the importance of appropriate selection of potential surgical candidates.

Surgical outcome and prognostic factors of frontal lobe epilepsy surgery

Frontal lobe epilepsy (FLE) surgery is the second most common surgery performed to treat pharmacoresistant epilepsy. Yet, little is known about long-term seizure outcome following frontal lobectomy. The aim of this study is to investigate the trends in longitudinal outcome and identify potential prognostic indicators in a cohort of FLE patients investigated using modern diagnostic techniques. We reviewed 70 patients who underwent a frontal lobectomy between 1995 and 2003 (mean follow-up 4.1 +/- 3 years). Data were analysed using survival analysis and multivariate regression with Cox proportional hazard models. A favourable outcome was defined as complete seizure-freedom, allowing for auras and seizures restricted to the first post-operative week. The estimated probability of complete seizure-freedom was 55.7% [95% confidence interval (CI) = 50-62] at 1 post-operative year, 45.1% (95% CI = 39-51) at 3 years, and 30.1% (95% CI = 21-39) at 5 years. Eighty per cent of seizure recurrences occurred within the first 6 post-operative months. Late remissions and relapses occurred, but were rare. After multivariate analysis, the following variables retained their significance as independent predictors of seizure recurrence: MRI-negative malformation of cortical development as disease aetiology [risk ratio (RR) = 2.22, 95% CI = 1.40-3.47], any extrafrontal MRI abnormality (RR = 1.75, 95% CI = 1.12-2.69), generalized/non-localized ictal EEG patterns (RR = 1.83, 95% CI = 1.15-2.87), occurrence of acute post-operative seizures (RR = 2.17, 95% CI = 1.50-3.14) and incomplete surgical resection (RR = 2.56, 95% CI = 1.66-4.05) (log likelihood-ratio test P-value < 0.0001). More than half of patients in favourable prognostic categories were seizure-free at 3 years, and up to 40% were seizure-free at 5 years, compared to <15% in those with unfavourable outcome predictors. These data underscore the importance of appropriate selection of potential surgical candidates.

Ipsilateral Head Deviation in Frontal Lobe Seizures

The lateralizing value of ictal head deviation (HD) in frontal lobe epilepsy (FLE) is a matter of debate. Although FLE is typically associated with tonic or clonic HD contralateral to seizure onset, ipsilateral HD has been noted in numerous reports. Whether both types of HD can be distinguished according to their clinical patterns has not yet been specifically investigated. We studied the clinical pattern and time of occurrence of HD of 129 seizures in 13 consecutive patients, who underwent successful surgery for FLE, including 12 investigated with an intracerebral stereotactic EEG procedure. Ictal HD was ipsilateral to the epileptogenic zone (EZ) in four (30%) patients and 27 (20.9%) seizures and contralateral in five (38%) patients and 15 (11.6%) seizures. Ipsilateral HD was rarely tonic and never associated with clonic manifestation. Contralateral HD was always tonic, unnatural, and associated with hemifacial clonic movements in 86% of seizures. Ipsilateral HD occurred earlier than contralateral HD (p < 0.03), with a mean delay of 1 +/- 2 s after the first detectable ictal sign, as compared with a delay of 17 +/- 11 s for contralateral HD. Moreover, ipsilateral HD always occurred before contralateral HD when both signs coexisted in the same seizure. Our patients with ipsilateral HD demonstrated either an anterior or dorsolateral frontal EZ. Ipsilateral HD is a common ictal sign during FLE and can be distinguished from contralateral HD by its time of occurrence at or immediately after seizure onset and its lacking association with clonic movements.

Factors underlying scalp‐EEG interictal epileptiform discharges in intractable frontal lobe epilepsy

ABSTRACT Aims Scalp‐EEG interictal epileptiform discharges (IEDs) may be less predictive of the outcome of frontal lobe epilepsy surgery than of temporal lobe epilepsy surgery. We identified factors associated with the location of scalp‐EEG IEDs in intractable frontal lobe epilepsy. Methods Ten factors were assessed in a retrospective review of 53 patients with either concordant (frontal lobe seizure focus) or discordant (generalized or outside frontal seizure focus) IED or both, who had excellent surgical outcomes. The Fisher exact test and the Wilcoxon rank sum test determined statistically significant associations. Results Thirty‐six patients (68%) had concordant IED, 24 (45%) discordant IED, and 17 (32%) both. Younger age at onset was significantly associated with discordant IED (mean, 7.5 years versus 17 years for patients without discordant IED; P &lt; 0.01), whereas duration of epilepsy was not. Seizure foci at the frontal convexity were associated with concordant IED. About 72% of patients with a convexity seizure focus had concordant IED, compared with only 33% of patients with mesial frontal foci having concordant IED ( P = 0.06). Conclusions Early seizure onset in intractable frontal lobe epilepsy is associated with IEDs discordant with seizure focus. Frontal convexity seizure foci are more likely than mesial frontal seizure foci to be associated with concordant discharges.

Do Immediate Postoperative Seizures Predict Surgical Failure after Frontal Lobe Epilepsy Surgery?

Do Immediate Postoperative Seizures Predict Surgical Failure after Frontal Lobe Epilepsy Surgery?

3. 前頭葉てんかん手術の解剖と手技(M3-C 難治性てんかんの治療)

3. 前頭葉てんかん手術の解剖と手技(M3-C 難治性てんかんの治療)

Surgery for frontal lobe epilepsy

Frontal lobe epilepsy makes up between 20 and 30% of all partial epilepsies and is the biggest subgroup of the extratemporal lobe epilepsies. Of the patients who undergo surgery for epilepsy up to 18% have a frontal lobe focus. The aetiology of frontal lobe epilepsy is varied, clinical semiology is diverse and seizures are often frequent, disabling and refractory to treatment. Imaging and EEG findings are often non-localising therefore patients who undergo surgical evaluation for frontal lobe epilepsy require extensive and often-invasive diagnostic investigations1–7.

Focal ictal beta discharge on scalp EEG predicts excellent outcome of frontal lobe epilepsy surgery.

To determine whether a focal beta-frequency discharge at seizure onset on scalp EEG predicts outcome of frontal lobe epilepsy (FLE) surgery. We identified 54 consecutive patients with intractable FLE who underwent epilepsy surgery between December 1987 and December 1996. A blind review of EEGs and magnetic resonance images (MRIs) was performed. Lesional epilepsy is defined as presence of an underlying structural abnormality on MRI. Overall, 28 (52%) patients were seizure free, with a mean follow-up of 46.5 months. Presence of a focal beta-frequency discharge at seizure onset on scalp EEG predicted seizure-free outcome in lesional (p = 0.02) and non-lesional (p = 0.01) epilepsy patients. At least 90% of patients who had either lesional or non-lesional epilepsy were seizure free if scalp EEG revealed a focal beta discharge at ictal onset. Moreover, logistic regression analysis showed that focal ictal beta pattern and completeness of lesion resection were independently predictive of seizure-free outcome. Ictal onset with lateralized EEG activity of any kind and postresection electrocorticographic spikes did not predict surgical outcome (p > 0.05). Only about 25% of FLE surgical patients have a focal beta-frequency discharge at seizure onset on scalp EEG. However, its presence is highly predictive of excellent postsurgical seizure control in either lesional or non-lesional FLE surgical patients.

Neuropsychological Outcome in Children after Frontal Lobe Epilepsy Surgery

We investigated the neuropsychological performance of children with frontal lobe epilepsy (FLE, n = 12) before and 1 year after surgery. Children with temporal lobe epilepsy (TLE, n = 12) were included as control group. Preoperatively, children with FLE had a significantly higher IQ than children with TLE, but were significantly more often impaired in manual motor coordination. Postoperatively, both groups improved in attention, short-term and long-term memory, and manual coordination, although the latter was not significant. Neuropsychological outcome in FLE patients was not better in seizure-free patients than in patients with continuing seizures. To avoid deterioration in language functions of patients in whom surgery involved left area 44, correspondence of results in cortical stimulation and intracarotid amytal test may be essential. All in all, our data indicate a favorable cognitive outcome in children 1 year after frontal lobe surgery.

Postsurgical outcome of children and adolescents with medically refractory frontal lobe epilepsies.

In the adult population surgical treatment is generally less favorable for refractory frontal lobe epilepsy (FLE) than for temporal lobe epilepsy (TLE). Predictive factors and outcome of FLE surgery had not previously been described for the pediatric and adolescent population. Therefore, 32 children and adolescents who underwent FLE surgery were analyzed in this study. Medical records were reviewed for demographic data, presurgical evaluation procedures, surgical procedures, pathological findings and follow-up. Mean age at operation was 10.8 years, with seizure onset at 4.6 years. Excellent outcomes were observed in 21 of the 32 patients following evaluation a mean of 34.5 months after surgery. Nineteen of 22 patients became seizure free after tailored resections, versus 2 out of 10 after lobectomy. Transient neurological and surgical complications occurred in 4 patients. Focal neoplastic lesions detectable by MRI were associated with a favorable outcome. As seen in adult FLE series, the detection of a resectable ictal neoplastic lesion on preoperative MRI is associated with an excellent outcome comparable to that of TLE surgery.

Relevance of residual histologic and electrocorticographic abnormalities for surgical outcome in frontal lobe epilepsy.

To estimate the significance of residual electrocorticographic and neuropathologic abnormalities on seizure control after surgery for frontal lobe epilepsy with the purpose of determining their relevance in deciding the extent of the surgical procedure. The presence of epileptiform discharges in intraoperative electrocorticograms (ECoGs) and the nature and extent of neuropathologic abnormalities were reviewed for 35 patients who underwent frontal lobe resections for the treatment of epilepsy at our institution. The relations between surgical outcome and presence of the following features were studied: (a) presence of abnormal tissue at the limits of the resection; (b) presence of sporadic spikes and seizure patterns in the preresection ECoG; (c) their abolition in the postresection ECoG; and (d) the topography of residual discharges with respect to the margins of the resection. On neuropathologic examination, 18 patients showed focal cortical dysplasia (CD), and 17 showed other abnormalities (non-CD). Ten CD patients and 11 non-CD patients experienced a favourable outcome. Seizure patterns were significantly more common in patients with focal cortical dysplasia than in those without, with a sensitivity of 94% and a specificity of 75%. Abolition of seizure patterns was associated with a favourable surgical outcome (p = 0.031). Abolition of sporadic spikes or their presence in the postresection ECoG did not influence outcome. There was no clear relation between outcome and location of residual sporadic discharges. Seizure patterns persisted in the postresection ECoG in three CD patients, were located at the margins of the resection in all three, and these patients had a poor outcome. Incomplete removal of abnormal tissue was not associated with a poorer outcome in either patient group or in the complete sample. Seizure patterns were significantly more common in patients with cortical dysplasia, and their abolition on postresection ECoG recordings was associated with a favourable surgical outcome. Persistence of sporadic ECoG spikes and incomplete removal of histologic abnormalities did not affect outcome significantly.

Factors predictive of the outcome of frontal lobe epilepsy surgery.

To identify factors that predict the outcome in seizure control after frontal lobe epilepsy surgery (FLES). FLES is the second most frequent type of epilepsy surgery, but the results are generally not as good as those after anterior temporal lobectomy. Our cohort consisted of 68 consecutive patients whose first epilepsy surgery involving the frontal lobe occurred between 1987 and 1994. Clinical history and results of imaging and electroencephalographic studies were reviewed in detail. Excellent outcome was defined as being seizure free or having only nondisabling seizures at last follow up. Forty of the 68 patients (58.8%) had an excellent outcome; none of the patients with a history of childhood febrile seizures had an excellent outcome, whereas outcome was excellent in 63% of those without that history (p </= 0.01). The other significant presurgical factor was the presence of a potentially epileptogenic lesion in the frontal lobe on neuroimaging (excellent outcome in 72% when present versus 41% when absent, p </= 0.001). The only significant postsurgical factor was early postoperative seizure control in the first year (excellent outcome in 96% with early control versus 25% without, p </= 0.01). History of childhood febrile seizures is a poor prognostic factor in FLES patients. It may suggest that the structural basis of all or some of the patients' intractable seizures is mesial temporal sclerosis. On the other hand, neuroimaging detection of a potentially epileptogenic frontal lobe lesion and early postoperative seizure control are associated with subsequent excellent outcome.

Results of lesional vs. nonlesional frontal lobe epilepsy surgery.

Fifty-three seizure focus resections limited to the frontal lobe were performed. Forty-nine had adequate follow-up. Five of 17 (29%) nonlesional (NL) cases and 21 of 32 (66%) lesional (L) cases were seizure free (SF) at 1 year postoperatively. Eight of 9 (89%) L cases < or = 18 years old vs. 13 of 23 (57%) > 18 years old were SF. Eight of 10 (80%) tumor vs. 13 of 22 (59%) nontumor L cases were SF. Sixteen NL cases were localized by invasive recording. Five (31%) were SF. Ictal localization was obtained in 4 of 32 L cases. Three of 4 (75%) were SF. Eighteen of 24 (64%) L cases without ictal localization were SF. Nine of 12 (75%) lateral resections, 7 of 12 (58%) lobectomies, and 2 of 13 (15%) mesial resections were SF. Three of 20 cases with at least 90% reduction in seizures became SD > or = 2 years postresection. No case with < 90% seizure reduction at one year showed improvement with longer follow-up.

Surgical treatment of children with medically intractable frontal or temporal lobe epilepsy: results and highlights of 40 years' experience.

Etiologic, pathologic, and clinical features of possible prognostic significance were studied in 118 children who underwent frontal or temporal lobe epilepsy surgery at the Montreal Neurological Institute (MNI) between 1940 and 1980 (excluding tumor cases). Mean age of seizure onset was 5.1 years (range 0-12 years), mean age at operation was 11.7 years (range 0.6-15 years), and median duration of follow-up was 15 years (range 2-31 years). Thirteen of 45 frontal surgery patients and 43 of 73 temporal surgery patients had an excellent outcome. In the frontal surgery group, this was restricted almost entirely to patients with an established etiology, particularly if this included a circumscribed resectable structural abnormality. In the temporal surgery group, a history of early, prolonged febrile seizures was usually associated with good outcome, unless there was additional evidence of extratemporal epilepsy. In the entire series, the presence of a nonresectable structural lesion or secondarily generalized seizures was associated with a poor outcome.