Diazepam-enhanced β activity in Sturge Weber syndrome: its diagnostic significance in comparison with MRI

Objectives: This study was performed to assess the extent of functional involvement of the affected hemisphere in Sturge Weber syndrome in comparison with the uninvolved hemisphere. To this end β activity in the electroencephalogram (EEG) was measured, both before and after administration of diazepam intravenously (i.v.). Methods: In 9 patients asymmetry in β band activity was studied before and after diazepam administration. Several β bands and asymmetry parameters were calculated. β band asymmetries were compared with structural abnormalities (magnetic resonance imaging, MRI). Results: Total β activity was reduced in the involved hemisphere in all patients after diazepam administration. In 3 patients functional abnormalities were found in brain regions that were structurally intact. Conclusions: Decreased diazepam-enhanced β activity in the EEG is a sensitive criterion of functional abnormality. In patients with subtle structural abnormalities diazepam-enhanced EEG may have added value in diagnosing functional involvement and in monitoring disease progression in patients.