EEG PRIOR TO HEMISPHERECTOMY - CORRELATION WITH OUTCOME AND PATHOLOGY

Hemispherectomy, for the treatment of seizures, is highly successful b ut has a significant morbidity rate. The procedure is usually restrict ed to patients with an intractable seizure disorder and hemiparesis. B ecause of the inherent risk of surgery, patient selection is a critica l issue. This report describes the evaluation of background activity a nd ictal patterns on surface and invasive EEG in 12 children who under went both anatomical (7) and functional (5) hemispherectomy in order t o determine the role of electroencephalography in the selection of pat ients for hemispherectomy, and to correlate EEG findings with underlyi ng pathology and outcome. A favorable outcome was predicted by an inte rictal EEG with two or more of the following: suppression over the abn ormal hemisphere, absence of contralateral slowing, absence of general ized discharges and absence of bilateral independent spiking; or by un ilateral onset of ictal discharges on invasive intracerebral EEG recor ding. Outcome did not correlate with the underlying pathology. Hemisph erectomy can be successful in patients with a variety of predominantly unilateral pathologic entities.