Abstracts

To analyze metabolic data according to electro-clinical features in seizures of mesio-temporal lobe (MTL) origin associated with dystonic posturing (DP).
Thirty-six 36 patients (17 males, 19 females, mean age: 34 years, range 14 - 49) had presurgical investigations for MTLE. Inclusion criteria consisted of at least one usual seizure recorded during surface or depth EEG and no early secondary generalization during the recorded seizure. All patients had 1) isolated unilateral hippocampal sclerosis demonstrated by MRI, 2) mesio-temporal origin of their seizures confirmed by video-EEG recordings and 3) interictal ¹⁸FDG-PET scan. In addition, 11 patients underwent a stereo-EEG. Thirty-one patients were operated with favourable outcome in most cases (out of 26 patients with a follow-up of at least 2 years, 21 were in class I, 4 in class II and 1 in class III according to Engel[rsquo]s classification. ¹⁸FDG-PET scans were performed using a high-resolution head dedicated PET camera (ECAT 953/31B Siemens) with 5.8-mm in-plane and 5-mm axial resolution, allowing 31 transverse sections of the brain, spaced 3,37mm apart. We analyzed electro-clinical findings in patients presenting with DP or without, and compared interictal hypometabolism in each group with 10 control subjects using SPM99 software (The Wellcome Trust, UK).
DP was found in 20 patients (55%) of this series (group A), and 16 had no DP (group B). In group A, we observed 3 types of DP characterized by a gradual increase in duration and complexity : DP type 1 corresponded to the most subtle and brief DP, type 2 corresponded to the most typical DP pattern, while bilateral but asymetrical DP was found in DP type 3. DP was contralateral to the epileptogenic focus in 95% of the cases. Group A patients had significantly higher frequency of head deviation, salivation, somato-motor manifestations, secondary generalization, severe consciousness clouding and prolonged post-ictal confusion when compared with group B patients. Ictal discharge patterns in group A mainly consisted of fast rhythmic activity involving frontal or suprasylvian areas, whereas slow rhythmic activity restricted to the temporal areas was observed in group B. A large temporal and extratemporal hypometabolism including basal ganglia was found in group A, while it was restricted to the antero-mesial part of the temporal lobe and anterior part of insula in group B. Hypometabolism involved the lateral part of the putamen in DP type 1, a larger putaminal area associated with frontal cortex involvement in DP type 2 ; the most severe hypometabolism involving the putamen associated with perisylvian and parietal cortex involvement was observed in DP type 3.
Our data suggest that DP results from involvement of both sub-cortical and cortical areas implied in motor functions. Moreover, different networks may be involved according to the DP type.