WIDESPREAD FUNCTIONAL DEFICITS IN PERCEPTION-RELATED NETWORKS DEMONSTRATED BY PET IN A CASE WITH SIMPLE VISUAL SEIZURES

Purpose: To study benzodiazepine receptor (BZR) density and functional deficits in occipital lobe epilepsy. Methods: A 39-year-old man who h ad simple partial visual seizures after neurosurgical transtentorial e xtirpation of a pinealoma was studied by EEG, magnetic resonance imagi ng (MRI), and positron emission tomography (PET) of [F-18]2-fluoro-2-d eoxy-D-glucose (FDG) at rest and during visual activation task and [C- 11]flumazenil (FMZ). Results: Electroencephalographic recordings were nonspecific, and MRI did not reveal any morphologic anomaly in the occ ipital lobe. Flumazenil-PET demonstrated a small epileptogenic region in the right visual association cortex and FDG-PET showed hypometaboli sm in a corresponding location and thalamic diaschisis. Stimulation of occipital metabolism by a continuous visual recognition task improved significantly the contrast between the dysfunctional zone and its sur round. Conclusions: As BZR deficits are restricted to a small region, widespread hypometabolism in networks involved in visual information p rocessing indicates an extensive functional deactivation by the epilep togenic focus.