Electroencephalographic features of moyamoya in adults.

ABSTRACT

OBJECTIVE: Electroencephalography is useful for evaluating transient neurological events in the setting of moyamoya disease. METHODS: EEG findings of adults with moyamoya seen at a large moyamoya referral center are summarized. Patients were identified by retrospective chart review. RESULTS: EEGs were ordered after cerebral revascularization for altered mental status, aphasia, limb shaking, or facial twitching. Among the study population of 103 patients having EEGs, 24% of adults with moyamoya had a history of clinical seizures. Ischemic or hemorrhagic strokes were associated with a twofold relative risk of seizures. Overall, 90% of EEGs were abnormal, most commonly focally (78%), or diffusely slow (68%). Epileptiform EEG discharges were seen in 24%. Whereas hemispheres with an ischemic stroke had a 19% risk of epileptiform discharges and an 8% risk of seizures on EEG, hemispheres with hemorrhagic stroke had a 35% risk of epileptiform discharges and 19% risk of seizures on EEG. Focal amplitude attenuation was seen in 19%, breach rhythm in 15%, rhythmic delta in 14%, and electrographic seizures in 12%. CONCLUSIONS: Seizures and epileptiform EEG changes are common in patients with moyamoya disease. SIGNIFICANCE: Transient events in patients with moyamoya can result from seizures as well as ischemia.