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Widespread functional deficits in perception-related networks demonstrated by PET in a case with simple visual
R Mielke1, G Weber-Luxenburger, J Kessler
1Max-Planck-Institut für Neurologische Forschung und Universitätsklinik für Neurologie, Köln, Germany.
Purpose:
To study benzodiazepine receptor (BZR) density and functional deficits in occipital lobe epilepsy.
Methods:
A 39-year-old man who had simple partial visual seizures after neurosurgical transtentorial extirpation of a pinealoma was studied by EEG, magnetic resonance imaging (MRI), and positron emission tomography (PET) of [18F]2-fluoro-2-deoxy-D-glucose (FDG) at rest and during visual activation task and[11C]flumazenil (FMZ).
Results:
Electroencephalographic recordings were nonspecific, and MRI did not reveal any morphologic anomaly in the occipital lobe. Flumazenil-PET demonstrated a small epileptogenic region in the right visual association cortex and FDG-PET showed hypometabolism 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 surround.
Conclusions:
As BZR deficits are restricted to a small region, widespread hypometabolism in networks involved in visual information processing indicates an extensive functional deactivation by the epileptogenic focus.