The background EEG may be normal, or may show focal slowing or attenuation over the region of the cerebral angioma(s).
Focal interictal spikes or sharp waves may be seen, at the location of the cerebral angioma(s).
EEG abnormality may be enhanced by sleep deprivation and in sleep.
CAUTION hyperventilation causes cerebral vasoconstriction, which may, in certain circumstances, impair critical cerebral perfusion and cause neurological symptoms. Hyperventilation is best avoided in the presence of intracranial vascular malformations.
Focal rhythmic epileptiform discharges occur during focal seizures, with spatial correlation with the cerebral angioma(s).