Comparing the determination of language dominance using fMRI with results of the Wada test in 100 patients with different localization-related epilepsies, the authors found 91% concordance between both tests. The overall rate of false categorization by fMRI was 9%, ranging from 3% in left-sided temporal lobe epilepsy (TLE) to 25% in left-sided extratemporal epilepsy. Language fMRI might reduce the necessity of the Wada test for language lateralization, especially in TLE.

MRI scans of patients with idiopathic generalized epilepsy (IGE) are normal on visual assessment. Using an interactive anatomical segmentation technique and volume-of-interest measurements of MRI, we showed recently that patients with IGE had significantly larger cortical grey matter than control subjects. Further, 40% of individual patients with juvenile myoclonic epilepsy (JME), a syndrome of IGE in adolescence, had significant abnormalities of cerebral structure. In this study, we applied the automated and objective technique of statistical parametric mapping (SPM) to the analysis of structural MRI from 20 patients with JME and 30 control subjects. The cortical grey matter of each individual JME patient and the group of JME patients was contrasted with that of the group of 30 normal subjects. The voxel-based SPM comparison between the group of JME patients and the control subjects showed an increase in cortical grey matter in the mesial frontal lobes of the patients. Analysis of individual patients revealed significant abnormalities of cortical grey matter in five out of 20 JME patients, four of whom had been shown to have widespread abnormalities using the previous volume of interest technique. These findings indicate a structural cerebral abnormality in JME, with involvement of mesiofrontal cortical structures.

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The histopathological spectrum of human epileptogenic brain lesions is widespread including common and rare variants of cortical malformations. However, 2-26% of epilepsy surgery specimens are histopathologically classified as nonlesional. We hypothesized that these specimens include also new diagnostic entities, in particular when presurgical magnetic resonance imaging (MRI) can identify abnormal signal intensities within the anatomical region of seizure onset. In our series of 1381 en bloc resected epilepsy surgery brain specimens, 52 cases could not be histopathologically classified and were considered nonlesional (3.7%). An increase of Olig2-, and PDGFR-alpha-immunoreactive oligodendroglia was observed in white matter and deep cortical layers in 22 of these patients (42%). Increased proliferation activity as well as heterotopic neurons in white matter were additional histopathological hallmarks. All patients suffered from frontal lobe epilepsy (FLE) with a median age of epilepsy onset at 4 years and 16 years at epilepsy surgery. Presurgical MRI suggested focal cortical dysplasia (FCD) in all patients. We suggest to classify this characteristic histopathology pattern as "mild malformation of cortical development with oligodendroglial hyperplasia (MOGHE)." Further insights into pathomechanisms of MOGHE may help to bridge the diagnostic gap in children and young adults with difficult-to-treat FLE.