Search

Objective: Completeness as a predictor of seizure freedom is broadly accepted in epilepsy surgery. We focused on the requirements for a complete hemispherotomy and hypothesized that the disconnection of the insula contributes to a favorable postoperative seizure outcome. We analyzed surgical and nonsurgical predictors influencing long-term seizure outcome before and after a modification of our hemispherotomy technique., Methods: We retrospectively studied surgical procedures, electroclinical parameters, magnetic resonance imaging (MRI) results, and follow-up data in all children who had undergone hemispherotomy between 2001 and 2018 at our institution. We used logistic regression models to analyze the influence of different factors on seizure outcome., Results: A total of 152 patients were eligible for seizure outcome analysis only. Of these, 140 cases had complete follow-up data for ≥24 months and provide the basis for the following results. The median age at surgery was 4.3 years (range = .3-17.9 years). Complete disconnection (including the insular tissue) was achieved in 63.6% (89/140). At 2-year follow-up, seizure freedom (Engel class IA) was observed in 34.8% (8/23) with incomplete insular disconnection, whereas this was achieved in 88.8% (79/89) with complete surgical disconnection (p < .001, odds ratio [OR] = 10.41). In the latter group (n = 89), a potentially epileptogenic contralateral MRI lesion was the strongest predictor for postoperative seizure recurrence (OR = 22.20)., Significance: Complete surgical disconnection is the most important predictor of seizure freedom following hemispherotomy and requires disconnection of the insular tissue at the basal ganglia level. Even if the hemispherotomy is performed surgically completely, a potentially epileptogenic contralateral lesion on preoperative MRI significantly reduces the chances of postoperative seizure freedom., (© 2023 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Objective: We describe for the first time clinical characteristics in a series of 20 pre-surgically investigated patients with mild malformation of cortical development with oligodendroglial hyperplasia (MOGHE) who were operated on in our epilepsy center. We aimed to better diagnose this entity and help surgical planning., Methods: Data on 20 patients with histologically confirmed MOGHE were retrospectively evaluated as to age at epilepsy onset and operation, seizure semiology, magnetic resonance imaging (MRI) localization, electroencephalography (EEG) patterns, extent of the operative resection, and postoperative seizure outcome., Results: Epilepsy began mainly in early childhood; however, symptoms did not manifest until adolescence or adulthood in 30% of patients. All patients had pathologic MRI findings. In 45% of patients the lesion was initially overlooked. Most commonly, the lesion was seen in the frontal lobe. Seizure semiology was characterized as follows: (1) epileptic spasms at epilepsy onset were common and (2) nocturnal hyperkinetic seizures during the course of the disease were rare. EEG always showed frequent interictal epileptic discharges. Two peculiar patterns were observed: (1) during sleep stage I-II, sub-continuous repetitive (0.5-1.5/s) unilateral plump spike/polyspike slow waves were seen and (2) during wakefulness, unilateral paroxysms of 2-2.5/s spike-wave complexes occurred. In total, 60% of patients were seizure-free 1 year postoperatively. Postoperative seizure outcome was positively correlated with the extent of resection, age at epilepsy onset, and age at operation. Postoperative long-term outcomes remained stable in patients undergoing larger operations., Significance: MRI, EEG, and semiology already contribute to the diagnosis of probable MOGHE preoperatively. Because postoperative seizure outcomes depend on the extent of the resection, prior knowledge of a probable MOGHE helps to plan the resection and balance the risks and benefits of such an intervention. In patients undergoing larger operations, epilepsy surgery achieved good postoperative results; the first long-term outcome data were stable in these patients., (© 2021 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Objective: Surgical volumes at large epilepsy centers are decreasing. Pediatric cohorts, however, show a trend toward more resections and superior outcome. Differences in pediatric and adult epilepsy surgery were investigated in our cohort., Methods: The Bethel database between 1990 and 2014 was retrospectively analyzed., Results: A total of 1916 adults and 1300 children underwent presurgical workup. The most common etiologies were medial temporal sclerosis (35.4%) in adults, and focal cortical dysplasias (21.1%) and diffuse hemispheric pathologies (14.7%) in children. Only 1.4% of the total cohort had normal histopathology. A total of 1357 adults (70.8%) and 751 children (57.8%) underwent resections. Surgery types for children were more diverse and showed a higher proportion of extratemporal resections (32.8%) and functional hemispherectomies (20.8%). Presurgical evaluations increased in both groups; surgical numbers remained stable for children, but decreased in the adult group from 2007 on. The patients' decision against surgery in the adult nonoperated cohort increased over time (total = 44.9%, 27.4% in 1995-1998 up to 53.2% in 2011-2014; for comparison, in children, total = 22.1%, stable over time). Postsurgical follow-up data were available for 1305 adults (96.2%) and 690 children (91.9%) 24 months after surgery. The seizure freedom rate was significantly higher in children than in adults (57.8% vs 47.5%, P < 0.001) and significantly improved over time (P = 0.016)., Significance: Pediatric epilepsy surgery has stable surgical volumes and renders more patients seizure-free than epilepsy surgery in adults. A relative decrease in hippocampal sclerosis, the traditional substrate of epilepsy surgery, changes the focus of epilepsy surgery toward other pathologies., (Wiley Periodicals, Inc. © 2018 International League Against Epilepsy.)

We report the clinical presentation, neuroradiologic characteristics, and detailed histopathologic findings in a unique case of drug-resistant focal epilepsy due to sublobar dysplasia (SLD), treated successfully by resection of the malformed cortex. Histopathology with leptomeningeal and subcortical heterotopia, disturbance of cortical lamination and marked cortical and subcortical astrocytosis, but absence of balloon cells, points to a disorder of neuronal migration and organization rather than proliferation in SLD. The additional presence of a lateral proboscis and meningocele in our case as well as further associated callosal and cerebellar anomalies may suggest an etiologic unknown damage of pathways controlling the embryogenesis of craniofacial field processes.

Purpose: By using speech-activated functional MRI (fMRI), we investigated whether the frequency of left-sided interictal epileptic activity (IED: spikes or sharp waves on the EEG) is associated with atypical speech lateralization., Methods: We investigated 28 patients (13 men, aged 17-59 years) with left-sided mesial temporal lobe epilepsy (MTLE) and 11 patients with right-sided MTLE as a control population. Only patients with unilateral hippocampal sclerosis with unilateral IED were included. For fMRI of individual patients, we contrasted images sampled during covert word generation with a low-level rest condition. With SPM99, an individual comparison for the contrast "word generation versus resting inactivity" was conducted. To characterize speech lateralization in individual patients, we calculated asymmetry indexes (AIs): the difference between activated left-sided and right-sided voxels was divided by all activated voxels. Analyzing long-term EEG, the first 2 min of each hour were evaluated for the frequency of IED. Univariate associations with AIs were assessed by Pearson's correlation and by t test. When testing the independent associations, multivariate linear regression was performed., Results: The AIs in patients with left-sided MTLE were 0.40 +/- 0.53 on average (range, -0.83 to +1.0), whereas in right-sided MTLE, they were 0.78 +/- 0.15 (p = 0.029). For the further investigations, we included left-sided MTLE patients only. The median frequency of IED was six per hour (range, 0-240). Higher IED frequency was correlated with left-right shift of lateralization of speech fMRI activity (p = 0.002)., Conclusions: Higher left-sided spike frequency in MTLE was associated with a left-right shift of speech representation, suggesting that chronic frequent interictal activity may induce a reorganization of speech lateralization.

Purpose: Anterior temporal lobe resection (ATR) is a treatment option in drug-resistant epilepsy. An important risk of ATR is loss of memory because mesiotemporal structures contribute substantially to memory function. We investigated whether memory-activated functional MRI (fMRI) can predict postoperative memory loss after anterior temporal lobectomy in right-sided medial temporal lobe epilepsy (MTLE)., Methods: We included 16 patients (10 women) aged 16-54 years. The mean age at epilepsy onset was 12.5 years (range, 1-26 years). The patients' mean Wechsler IQ score was 95.2 (range, 62-125). The activation condition of fMRI consisted of retrieval from long-term memory induced by self-paced performance of an imaginative walk. All but one patient had left-sided speech dominance according to speech-activated fMRI. Outside the scanner, we evaluated the pre- and postoperative visual memory retention by using Rey Visual Design Learning Test., Results: We found a correlation between the preoperative asymmetry index of memory-fMRI and the change between pre- and postsurgical measures of memory retention. Reduced activation of the mesiotemporal region ipsilateral to the epileptogenic region correlated with a favorable memory outcome after right-sided ATR., Conclusions: In light of the postoperative results, the theoretical implication of our study is that fMRI based on a simple introspective retrieval task measures memory functions. The main clinical implication of our study is that memory-fMRI might replace the invasive Wada test in MTLE by using a simple fMRI paradigm. Predictive power, however, will be studied in larger patient samples. Other studies are required for left-sided MTLE and neocortical epilepsies to assess the clinical usefulness of memory-fMRI.

Purpose: We used short-echo-time proton magnetic resonance spectroscopy imaging (MRSI) to study metabolite concentration variation through the temporal lobe in patients with temporal lobe epilepsy (TLE) with and without abnormal MRI., Methods: MRSI was performed at TE = 30 ms to study 10 control subjects, 10 patients with TLE and unilateral hippocampal sclerosis, and 10 patients with TLE and unremarkable MRI (MRI negative). We measured the concentrations of N-acetyl aspartate +N-acetyl aspartyl-glutamate (NAAt), creatine (Cr), choline (Cho), glutamate + glutamine (Glx), and myoinositol, in the anterior, middle, and posterior medial temporal lobe (MTL), and in the posterior lateral temporal lobe. Segmented volumetric T1-weighted MRIs gave the tissue composition of each MRSI voxel. Normal ranges were defined as the control mean +/- 3 SD., Results: In the hippocampal sclerosis group, seven of 10 had abnormally low NAAt in the ipsilateral anterior MTL. In the MRI-negative group, four of 10 had low NAAt in the middle MTL voxel ipsilateral to seizure onset. Metabolite ratios were less sensitive to abnormality than was the NAAt concentration. Group analysis showed low NAAt, Cr, and Cho in the anterior MTL in hippocampal sclerosis. Glx was elevated in the anterior voxel contralateral to seizure onset in the MRI-negative group. Metabolite concentrations were influenced by voxel position and tissue composition., Conclusions: (a) Low NAAt, Cr, and Cho were features of the anterior sclerotic hippocampus, whereas low NAAt was observed in the MRI-negative group in the middle MTL region. The posterior temporal lobe regions were not associated with significant metabolite abnormality; (b) The two patient groups demonstrated different metabolite profiles across the temporal lobe, with elevated Glx a feature of the MRI-negative group; and (c) Voxel tissue composition and position influenced obtained metabolite concentrations.

Purpose: To demonstrate the integration of complementary functional and structural data acquired with magnetic resonance imaging (MRI) in a patient with localization-related epilepsy., Methods: We studied a patient with partial and secondarily generalized seizures and a hemiparesis due to a malformation of cortical development (MCD) in the right hemisphere by using EEG-triggered functional MRI (fMRI), diffusion tensor imaging (DTI), and chemical shift imaging (CSI)., Results: fMRI revealed significant changes in regional blood oxygenation associated with interictal epileptiform discharges within the MCD. DTI showed a heterogeneous microstructure of the MCD with reduced fractional anisotropy, a high mean diffusivity, and displacement of myelinated tracts. CSI demonstrated low N-acetyl aspartate (NAA) concentrations in parts of the MCD., Conclusions: The applied MR methods described functional, microstructural, and biochemical characteristics of the epileptogenic tissue that cannot be obtained with other noninvasive means and thus improve the understanding of the pathophysiology of epilepsy.

Purpose: To investigate changes in hippocampal volume., Methods: We used serial magnetic resonance imaging (MRI) in a patient who developed chronic epilepsy after having generalized tonic-clonic status epilepticus (SE). Five MRI investigations were performed during SE and a 58-month follow-up period. Hippocampal volumetric measurements and coregistration of scans were performed to detect hippocampal atrophy., Results: During status both mesiotemporal regions returned a high signal on T2-weighted images. Two months after the onset of SE, bilateral hippocampal atrophy was detected. Further progressive hippocampal atrophy was detected in the subsequent 58 months by both hippocampal volumetric measurements and coregistration of scans., Conclusions: Our findings suggest that hippocampal atrophy is a process that may continue after the end of the SE.