Predictive factors of postoperative outcome in the elderly after resective epilepsy surgery.

OBJECTIVE: To evaluate the efficiency of resective epilepsy surgery (RES) in patients over 50 years and determine prognostic factors. RESULTS: Over the 147 patients over 50 years (54.9±3.8 years [50-69]) coming from 8 specialized French centres for epilepsy surgery, 72.1%, patients were seizure-free and 91.2% had a good outcome 12 months after RES. Seizure freedom was not associated with the age at surgery or duration of epilepsy. In multivariate analysis, seizure freedom was associated with MRI and neuropathological hippocampal sclerosis (HS) (P=0.009 and P=0.028 respectively), PET hypometabolism (P=0.013), temporal epilepsy (P=0.01). On the contrary, the need for intracranial exploration was associated with a poorer prognosis (P=0.001). Postoperative number of antiepileptic drugs was significantly lower in the seizure-free group (P=0.001). Neurological adverse event rate after surgery was 21.1% and 11.7% of patients had neuropsychological adverse effects overall transient. CONCLUSIONS: RES is effective procedure in the elderly. Even safe it remains at higher risk of complication and population should be carefully selected. Nevertheless, age should not be considered as a limiting factor, especially when good prognostic factors are identified.

Transient symptomatic vasospasm following antero-mesial temporal lobectomy for refractory epilepsy.

RATIONALE: Arterial vasospasm has rarely been reported following temporal lobectomy for intractable epilepsy. CASE PRESENTATION: A 31-year-old patient presented with a global aphasia 2 days after a left dominant anteromesial temporal lobectomy for intractable epilepsy. Magnetic resonance imaging on 5th post-operative day revealed severe narrowing of M1 segment of the left middle cerebral artery (MCA) and Transcranial Doppler (TCD) ultrasonography an increased velocity of the MCA that suggested a severe vasospasm. The patient received continuous intravenous hyperhydratation and nimodipine; aphasia improved within 24 h and resolved completely within 6 weeks, associated with velocity reduction on control TCD. CONCLUSION: Transient vasospasm is a likely underestimated cause of focal deficit following temporomesial resection that deserves appropriate treatment.

[Malformation of cortical development: which strategy is best?]. / Malformations du développement cortical: quelles stratégies ?

Malformations of cortical development (MCD) correspond to a broad spectrum of cerebral lesions resulting from cortical development abnormalities during embryogenesis. They are frequently associated with drug-resistant epilepsy as well as more or less severe neurological and cognitive deficits. Diagnosis of MCD has greatly improved with the progress in contemporary imaging techniques, and patients with cryptogenic epilepsy are increasingly recognized as having MCD. Current classifications based on the combination of clinical, imaging, genetic and pathological data allow analysis of homogeneous patient series and optimal therapeutic strategies. Successful surgical treatment can be proposed to patients with focal lesions such as focal cortical dysplasia or tumors associated with cortical dysplasia (dysembryoplastic neuroepithelial tumors and gangliogliomas). Favorable outcome can also be obtained in some diffuse cases such as tuberous sclerosis, periventricular heterotopia and polymicrogyria. Invasive monitoring, especially stereoelectroencephalography (SEEG), has proved to be useful in determining the organization of the epileptogenic zone in each MCD type and planning cortical resections. Moreover, establishing correlations between neurophysiological data, imaging and pathological findings has allowed surgery without previous invasive procedures in the majority of focal MCD types; however, intracranial recordings remain necessary in case of more diffuse MCD.

[Positron emission tomography: which indications, which benefits?]. / Tomographie par émission de positons (TEP): quelles indications, quels bénéfices ?

Positron emission tomography (PET) is currently used in the presurgical workup for drug-resistant partial epilepsies in addition to MRI. Interictal metabolism is studied in clinical practice using (18)fluoro-desoxy-glucose ((18)FDG). In medial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis, hypometabolism ipsilateral to the epileptogenic focus is found in 70-90% of cases. However, hypometabolism is larger than the structural lesion observed on MRI and includes the epileptogenic zone and ictal discharge spread areas. Hypometabolism is related to surgical outcome and cognitive disturbances in MTLE. Although the usefulness of PET appears less well-established in extratemporal lobe epilepsy and in children, its sensitivity may be improved by coregistration and superimposition of PET on MRI at any age. Focal hypometabolism can be easily detected by visual analysis, allowing detection of minor gyral abnormalities that may correspond to focal cortical dysplasias. Moreover, in cases of negative MRI, focal hypometabolism findings may help invasive monitoring planning and deep electrode placement for SEEG, and finally improve surgical outcome.

[Healthcare networks in epilepsy: situation in the greater Paris region]. / Réseaux de santé et épilepsie: état des lieux en Ile-de-France.

The goal of healthcare networks is to provide global care for patients and to coordinate the actions of the different healthcare professionals to provide the most appropriate treatment based on patient needs. Such networks have been created in Ile-de-France for some neurological diseases but not epilepsy. However, the needs of the population are significant, with 55,000 to 70,000 epilepsy patients in the geographic area. Contacts between the three main adult epilepsy centers, although not formal, form the basis of a dedicated epilepsy network so that the quality of care can be improved and surgical treatment made easier if indicated.

[Surgical resection of focal cortical dysplasias in the central region]. / Chirurgie des dysplasies corticales focales en région centrale.

BACKGROUND AND PURPOSE: Taylor-type focal cortical dysplasias (TTFCD) represent a particular pathological entity responsible for severe drug-resistant epilepsy of extratemporal location. Epilepsy can be surgically cured if complete removal of the lesion can be performed. However, identification on imaging may be difficult and negative standard MRIs are not rare. The frequent location of TTFCD in the central region restrains the possibilities of complete resection. We report a series of patients operated on for intractable epilepsy associated with TTFCD in the central area. PATIENTS AND METHODS: Between 2000 and 2006, of 34 consecutive patients with TTFCD, 17 had a lesion located in the central area. MRI was considered normal in eight, although in five a subtle gyral abnormality was disclosed on further analysis. A (18)FDG PET scan performed in 16 cases demonstrated focal hypometabolism in 15 that correlated with abnormalities on MRI when visible. SEEG performed in 13 cases revealed typical abnormalities for TTFCD in 10 cases. At resection, cortical and subcortical stimulations of the dysplastic cortex did not elicit a motor response. RESULTS: Postoperative motor or sensory deficit was observed in 13 patients--severe in four--which subsequently resolved completely in seven. Six patients had a minor permanent, motor or sensory deficit. Four patients were reoperated for seizure recurrence and residual dysplastic tissue was found at reoperation in three cases. Average postoperative follow-up was 3.7 years. Sixteen patients (94%) were in Engel Class I (65% in Class IA). CONCLUSION: This study suggests that surgical resection of central region TTFCD may be associated with favorable seizure outcome and no or minor functional permanent disability. In cases of seizure relapse, reoperation can be performed without further permanent deficit and lead to seizure-free outcome. Future techniques for intraoperative detection of these lesions could optimize their complete resection in functional areas.

[On the best strategies on the best results for surgery of frontal epilepsy]. / 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.

[Surgical resections in functional areas: report of 89 cases]. / Résections en région fonctionnelle: étude d'une série de 89 cas.

Surgical resections for intractable epilepsy are generally associated with a high risk of permanent neurological deficit and a poor rate of seizure control. We present a series of 89 patients operated on from 1992 through 2007 for drug-resistant partial epilepsy, in whom surgery was performed in a functional area of the brain: the central (sensorimotor and supplementary motor areas) region in 48 cases, posterior regions (parietal and occipital) in 27, the insula in eight, and the language areas in six. Epilepsy was cryptogenic in 12 patients, and lesion-related in 77: malformation of cortical development in 43, tumor in 17, perinatal cicatrix in 13, vascular lesion in three, and another prenatal lesion in one. Seventy patients underwent stereoelectroencephalographic (SEEG) exploration. The surgical procedure was resective (lesionectomy or SEEG-guided corticectomy) in 83 patients and multiple stereotactic thermocoagulations in six. Ten patients were reoperated because of early seizure recurrence. A postoperative complication was observed in 12 patients. Postoperative deficits were observed in 54 patients (61%) and resolved completely in 29. In 25, a permanent deficit persisted, minor in 19 and moderate to severe in six, which did not correlate with localization or etiology. With a one-year follow-up in 74 patients (mean, 3.6 years), 53 (72%) were in Engel's class I, including 38 (51%) in class IA. Seizure outcome was significantly associated with etiology: 93% of Taylor-type focal cortical dysplasia, whereas only 40% of cryptogenic epilepsies were in class I (p<0.05). This suggests that resective or disconnective surgery for intractable partial epilepsy in functional areas of the brain may be followed by excellent results on seizures and a moderate risk of permanent neurological sequelae.

[Medicoeconomic assessment of epilepsy surgery in adults with medically intractable partial epilepsy. Three-year outcomes from a multicenter French cohort]. / Evaluation médicoéconomique de la chirurgie des épilepsies partielles pharmacorésistantes de l'adulte. Résultats à trois ans d'une étude prospective multicentrique française.

PURPOSE: To compare resective surgery and medical therapy in a cost-effectiveness analysis in a multicenter cohort of adult patients with partial intractable epilepsy. POPULATION AND METHODS: Adult patients with partial, medically intractable, potentially operable epilepsy were eligible and followed every year over five years. Effectiveness was defined as one year without seizure. The long-term costs and effectiveness were extrapolated over the patients' lifetime with a Markov model. Productivity (indirect costs) and quality of life (QOLIE-31, SEALS) were also assessed. Changes before and after surgery were compared between the two groups. RESULTS: Two hundred and eighty-nine patients were included (119 with surgery, 161 medically treated, six not eligible, three lost to follow-up). One year after surgery, 81% of the patients were seizure-free; at two and three years, this rate was 78%. In the medical group, these rates were 10, 18, and 15%, respectively. The cost of the explorations was euro 8464; including surgery, it was euro 19,700. In the medical group, the average annual direct costs were between 3500 and euro 6000. At two years after surgery, the annual direct cost decreased to euro 2768, at three years, it was euro 1233, predominately antiepileptic drug costs. Surgery became cost-effective between seven and eight years. In the surgical group, all the quality-of-life scores improved at one year after surgery and were stable during the second and third years. CONCLUSION: Surgical therapy was cost-effective at the middle term even though indirect costs were not considered.

[Epilepsy surgery in France]. / La chirurgie de l'épilepsie en France Evaluation de l'activité

We report here the results of the first survey on epilepsy surgery activity in France. Data from a questionnaire sent to 17 centers practicing epilepsy surgery were analyzed. All centers responded; however, all items were not completely documented. Over 50 years, more than 5000 patients have been operated on for drug-resistant epilepsy and more than 3000 patients underwent some invasive monitoring, most often SEEG. Currently, nearly 400 patients (including more than 100 children) are operated on yearly for epilepsy in France. Over a study period varying among centers (from two to 20 years; mean, 9.5 years), results from more than 2000 patients including one-third children were analyzed. Important differences between adults and children, respectively, were observed in terms of location (temporal: 72% versus 4.3%; frontal: 12% versus 28%; central: 2% versus 11%), etiology (hippocampal sclerosis: 41% versus 2%; tumors 20% versus 61%); and procedures (cortectomy: 50% versus 23%; lesionectomy: 8% versus 59%), although overall results were identical (seizure-free rates following temporal lobe surgery: 80.6% versus 79%; following extratemporal surgery: 65.9% versus 65%). In adults, the best results were observed following temporomesial (TM) resection associated with hippocampal sclerosis or other lesions (class I: 83% and 79%, respectively), temporal neocortical (TNC) lesional (82%), while resections for cryptogenic temporal resections were followed by 69% (TM) and 63% (TNC) class I outcome. Extratemporal lesional resections were associated with 71% class I outcome and cryptogenic 43%. In children, the best results were obtained in tumor-associated epilepsy regardless of location (class I: 80%). A surgical complication occurred in 8% after resective surgery - with only 2.5% permanent morbidity - and 4.3% after invasive monitoring (mostly hemorrhagic). Overall results obtained by epilepsy surgery centers were in the higher range of those reported in the literature, along with a low rate of major surgical complications. Growing interest for epilepsy surgery is clearly demonstrated in this survey and supports further development to better satisfy the population's needs, particularly children. Activity should be further evaluated, while existing epilepsy surgery centers as well as healthcare networks should be expanded.

Prevention and management of postoperative seizures in neuro-oncology.

INTRODUCTION: Epilepsy related to brain tumors is often difficult to treat and may impact the quality of life. We performed a review of current recommendations for the prevention of postoperative seizures and optimizing the anti-epileptic treatment. MATERIAL AND METHODS: Based on studies performed since 2000 we conducted the review by (1) analyzing the incidence of tumoral epilepsy and mechanisms of epileptogenicity; (2) describing the current medical and surgical strategy according to oncologic treatments; (3) discussing the management of postoperative seizures; (4) considering the drug withdrawal after oncologic therapy. RESULTS: Epilepsy related to supra-tentorial brain tumors is frequent (40-60%) especially in low-grade gliomas, glioneuronal tumors, fronto-temporal and eloquent cortex locations. Seizures can occur as a presenting symptom or during the course of the tumor, including after surgery and oncological treatments. Maximal safe surgical resection is the more effective therapy, alone or combined with adjuvant therapy (chemotherapy, radiotherapy). Anti-epileptic drugs are not indicated for epilepsy prophylaxis in patients without seizures but only after the first seizure due to high risk of recurrence. As they may generate adverse effects and interfere with oncological treatments, the choice is based on efficacy, tolerability and potential interactions. New anti-epileptic non-enzyme-inducing drugs are recommended in first-line monotherapy in association with adjuvant oncological therapies. Enzyme-inhibiting drugs could have a favorable effect on survival. Late seizures are often related to tumor progression or recurrence. Discontinuation of anti-epileptic drugs could be considered after successful oncological treatment and a stable medical condition. CONCLUSION: These guidelines are helpful for a rational therapy in tumoral epilepsy.

Surgery for dysembryoplastic neuroepithelial tumors and gangliogliomas in eloquent areas. Functional results and seizure control.

INTRODUCTION: Dysembryoplastic neuroepithelial tumors and gangliogliomas are developmental glioneuronal tumors usually revealed by partial epilepsy. High epileptogenicity, childhood epilepsy onset, drug-resistance, temporal location, and seizure freedom after complete resection are common characteristics of both tumors. We report the specificity of surgical management, functional results and seizure outcome in cases of a tumor location in eloquent areas. METHODS: Among 150 patients (88 males, 3-55 years) operated on for refractory epilepsy due to a glioneuronal tumor (1990-2015), 30 (20%, dysembryoplastic neuroepithelial tumors=21; gangliogliomas=9) had a tumor located in an eloquent cortex (sensory-motor, insular or language areas). Surgery was performed after a preoperative work-up, including stereo-electroencephalography in 48 patients (26%) and functional MRI in 100 (67%). MRI-guided lesionectomy was mainly performed in extra-temporal location, whereas an additional corticectomy was performed in a temporal location. Tumor microsurgical resections were guided using neuronavigation and cortical/subcortical electrical stimulations. Multiple stereotactic thermocoagulations were performed in two insular tumors. RESULTS: New motor/language deficits related to eloquent areas occurred postoperatively in 6/30 patients (20%) without any major permanent disability. Minor sensorimotor (n=2) and moderate language disturbance (n=1) persisted in three of them. Postoperative seizure-free outcome (mean follow-up>5 years) was obtained in 81% of the entire series, but significantly decreased to 60% in eloquent areas. Incomplete tumor resection was the main cause of surgical failure. However, unfavorable seizure outcome was also observed despite complete tumor resection. Malignant transformation occurred in one ganglioglioma. CONCLUSION: Epilepsy surgery for benign glioneuronal tumors in eloquent areas provides acceptable results regarding the functional risks. Complete tumor resection is crucial for long-term favorable outcome.

Inter-ictal brain SPET in frontal epilepsy: correlations with stereo-electroencephalography.

Single photon emission tomography (SPET) imaging holds promise for localization of the site of extratemporal seizures, but limited data currently exist; in particular, correlations with stereo-electroencephalography (S-EEG) have not been made. Ten patients aged 14-44 years (mean 25 years) with a proven frontal or central epilepsy by S-EEG and post-surgical follow-up were studied retrospectively: 7 patients had frontal cortectomy and one patient had a callosotomy for bifrontal epilepsy. All patients underwent clinical, inter-ictal and ictal video-EEG, computed tomography scan and/or magnetic resonance imaging, SPET and S-EEG examinations. SPET was performed inter-ictally, while on usual epileptic medications, using 99Tcm-HMPAO (n = 4) or 123I-IMP (n = 6) as the perfusion tracer. The SPET images were evaluated independently by two observers, blind to any data other than the diagnosis of frontral or central epilepsy. Localization of inter-ictal SPET hypoperfusion was compared with the epileptogenic (EZ), irritative (IZ) and lesional (LZ) zones, as defined by S-EEG. Six patients showed structural frontal abnormalities. One patient had normal SPET and one had a contralateral hypoperfusion. Therefore, concordance of sides was found in 8 of 10 patients (including one with bilateral SPET and S-EEG abnormalities). The hypoperfusion was equal to or larger than the EZ + IZ + LZ in 6 patients (5 had a frontal lesion). SPET hypoperfusion was smaller than the EZ in one patient, and different from the EZ, IZ and LZ in two patients. Although this was a retrospective study, it provides qualitative data regarding the significance of inter-ictal SPET abnormalities in frontal or central epilepsy.(ABSTRACT TRUNCATED AT 250 WORDS)

[Eclampsia in the late postpartum. Contribution of x-ray computed tomography and magnetic resonance imaging]. / Eclampsie du post-partum tardif. Apport du scanner X et de l'imagerie par résonance magnétique.

A 28-year-old woman developed late post-partum eclampsia. CT scan showed focal cortical hypodensities and diffuse and bilateral hypodensity of the hemispheric white matter. These lesions were hypointense on T1-weighted sequences and hyperintense on T2-weighted sequences. The CT and MRI abnormalities resolved completely within a few weeks. These changes are similar to those which occur with the more common prepartum eclampsia.

[Cost-effectiveness of epilepsy surgery in a cohort of patients with medically intractable partial epilepsy--preliminary results]. / Evaluation médico-économique de la chirurgie des épilepsies partielles pharmaco-résistantes de l'adulte. Etude coût-efficacité--résultats préliminaires.

OBJECTIVE: Patients with medically intractable epilepsy are potential candidates for surgery if the epileptogenic tissue is localized and resectable. Surgical therapy can eliminate seizures but is very expensive. We followed a prospective adult cohort of intractable epileptic patients in order to perform a cost-effectiveness analysis. POPULATION AND METHODS: Adult patients with a suspected partial medically intractable and operable epilepsy were eligible for evaluation, explorations and/or surgery. Clinical and economical data were collected at the inclusion and every 6 months over at least two years. Two patient groups were analyzed: some underwent a surgery, others did not. Clinical data were compared between both groups. As the data collection was not yet complete, we compared the surgery to a continuation of the preoperative medical management in a cost-effectiveness analysis. Direct medical and nonmedical costs were evaluated according to a societal perspective. The effectiveness was defined as one year without seizure. We assessed the incremental cost-effectiveness ratio (ICER) for the first two years after the surgery. We also modeled long-term costs and effectiveness and extrapolated the results over the patients' lifetime with a Markov model. We computed the ICER and performed a sensitivity analysis. Indirect costs were measured in physical units and intangible costs were assessed with quality-of-life measures (QOLIE-31, SEALS). Data were compared before and after surgery. RESULTS: Among the 286 patients included, 119 did not enter in the analysis: 7 were not eligible, 44 not operable, 31 did not present a follow-up, 37 still underwent exams. Finally, 89 underwent a surgical treatment, and 78 were medically treated. Disease was more severe in surgical patients than in medical patients: seizures frequency, depressive disorders and cognitive impairment were greater. One year after the surgery, 83% patients were seizure free. During the year before inclusion and the year after surgery, direct costs were mainly due to hospitalization. During the second year after surgery, the cost of antiepileptic drugs predominated. One additional year without seizure costs 23 531 euro one year after surgery and 9533 euro two years after surgery. In a long-term perspective, the surgery became cost-effective between 7 and 8 years after the surgery. CONCLUSION: Surgical therapy is a cost-effective treatment in a middle-term even without indirect costs consideration.

Dysembryoplastic neuroepithelial tumors: CT, MR findings and imaging follow-up: a study of 53 cases.

PURPOSE: To evaluate CT and MRI features and long term imaging follow-up of a large series of dysembryoplastic neuroepithelial tumors (DNTS). PATIENTS AND METHODS: We retrospectively analyzed CT (100%) and MR imaging (83%) findings of 53 patients with complex (n = 14), simple (n = 6) or non specific histological forms (n = 33) of DNTS. All patients underwent epilepsy surgery for the treatment of drug resistant partial seizures. Preoperative radiological follow-up from two to 10 years (81%) and a post-operative follow-up from one to 13 years (92%) were available. RESULTS: DNTs are intracortical tumors with no mass effect and no peritumoral edema. An associated deformity of the overlying skull was observed in 44% of the 34 patients with a cortical lesion of the convexity. We found a contrast enhancement of the lesion in 21% of cases, a calcic hyperdensity in 36% of cases and a cystic part in 7.5% of cases. DNTs were hypodense (82%) on CT examinations and had a decreased signal on the T1 Weighted Images (95%) and a hypersignal in T2 Weighted Images (100%) on MR imaging. Eighty-one percent of patients had a mean preoperative radiological follow-up of four years and the tumor was stable in size in all cases; 92% of patients had a mean post-operative radiological follow-up of 4.5 years and no recurrence was seen. CONCLUSION: Three radiological features of DNTs are helpful for the diagnosis: cortical location, absence of mass effect and no surrounding edema. Clinical, radiological and histopathological findings have to be considered together in order to assess the diagnosis and to differentiate DNTs, which are stable lesions from gliomas.

[Functional neurosurgery for epilepsy]. / La chirurgie fonctionnelle de l'épilepsie.

Introduced at the end of the last century, epilepsy surgery is indicated in patients with intractable partial seizures and based on the resection of the epileptogenic cerebral tissue from which ictal discharges originate. Palliative procedures include seizure spread pathways interruption (callosotomy, multiple subpial transections) and chronic stimulation of the vagus nerve. Complete preoperative investigations including seizure observation, clinical tests, video-EEG, MRI and functional MRI, and PET-scan are performed in order to identify the epileptogenic zone. In difficult cases, invasive seizure monitoring through depth electrode implantation (SEEG) is performed. Resections for temporal lobe seizures are associated with favorable outcome: 60 to 90% of patients will be seizure-free after surgery. A less favorable outcome is observed after extra-temporal resections: 40 to 60% seizure-free patients. A better outcome is observed after surgery for epilepsy associated with an image-defined lesion, most often a tumor, rather than for cryptogenic epilepsy. Tumors associated with chronic partial epilepsy are indolent, most of them are dysembryoplastic neuroepithelial tumors (DNET). Outcome after palliative procedures are more variable, depending on the etiology of epilepsy.

Optimizing MR imaging detection of type 2 focal cortical dysplasia: best criteria for clinical practice.

BACKGROUND AND PURPOSE: Type 2 FCD is one of the main causes of drug-resistant partial epilepsy. Its detection by MR imaging has greatly improved surgical outcomes, but it often remains overlooked. Our objective was to determine the prevalence of typical MR imaging criteria for type 2 FCD, to provide a precise MR imaging pattern, and to optimize its detection. MATERIALS AND METHODS: We retrospectively reviewed 1.5T MR imaging of 71 consecutive patients with histologically proved type 2 FCD. The protocol included millimetric 3D T1-weighted, 2D coronal and axial T2-weighted, and 2D or 3D FLAIR images. Two experienced neuroradiologists looked for 6 criteria: cortex thickening, cortical and subcortical signal changes, blurring of the GWM interface, the "transmantle" sign, and gyral abnormalities. The frequency of each sign and their combination were assessed. We compared the delay between epilepsy onset and surgery, taking into account the time of type 2 FCD detection by MR imaging. RESULTS: Only 42 patients (59%) had positive MR imaging findings. In this group, a combination of at least 3 criteria was always found. Subcortical signal changes were constant. Three characteristic signs (cortical thickening, GWM blurring, and transmantle sign) were combined in 64% of patients, indicating that MR imaging can be highly suggestive. However, typical features of type 2 FCD were overlooked on initial imaging in 40% of patients, contributing to a delay in referral for surgical consideration (17 versus 11.5 years when initial MR imaging findings were positive). CONCLUSIONS: A combination of 3 major MR imaging signs allows type 2 FCD to be recognized in clinical practice, thereby enabling early identification of candidates for surgery.

FDG-PET improves surgical outcome in negative MRI Taylor-type focal cortical dysplasias.

OBJECTIVE: To determine the diagnostic accuracy and prognostic value of ¹8FDG-PET in a recent series of patients operated for intractable partial epilepsy associated with histologically proven Taylor-type focal cortical dysplasia (TTFCD) and negative MRI. METHODS: Of 23 consecutive patients (12 male, 7-38 years old) with negative 1.5-Tesla MRI, 10 exhibited subtle nonspecific abnormalities (e.g., unusual sulcus depth or gyral pattern) and the 13 others had strictly normal MRI. FDG-PET was analyzed both visually after coregistration on MRI and using SPM5 software. Metabolic data were compared with the epileptogenic zone (EZ) determined by stereo-EEG (SEEG) and surgical outcome. RESULTS: Visual PET analysis disclosed a focal or regional hypometabolism in 18 cases (78%) corresponding to a single gyrus (n = 9) or a larger cortical region (n = 9). PET/MRI coregistration detected a partially hypometabolic gyrus in 4 additional cases. SPM5 PET analysis (n = 18) was concordant with visual analysis in 13 cases. Location of PET abnormalities was extratemporal in all cases, involving eloquent cortex in 15 (65%). Correlations between SEEG, PET/MRI, and histologic findings (n = 20) demonstrated that single hypometabolic gyri (n = 11) corresponded to EZ and TTFCD, which was localized at the bottom of the sulcus. Larger hypometabolic areas (n = 9) also included the EZ and the dysplastic cortex but were more extensive. Following limited cortical resection (mean follow-up 4 years), seizure freedom without permanent motor deficit was obtained in 20/23 patients (87%). CONCLUSIONS: ¹8FDG-PET coregistered with MRI is highly sensitive to detect TTFCD and greatly improves diagnosis and surgical prognosis of patients with negative MRI.