Symptomatic hydrocephalus due to an elongated and ectatic basilar artery.

A patient with symptomatic hydrocephalus, due to an elongated and ectatic basilar artery and involving the third ventricle, is described. Characteristic CT scan features are outlined and were sufficient to confirm the diagnosis without resort to pneumoencephalography or angiography. The intraventricular CSF pressure was normal and a ventriculoperitoneal shunt resulted in significant sustained improvement of her balance and higher mental functions, coincident with CT scan evidence of return of ventricular size to normal. Other neurological presentations of an elongated and ectatic basilar artery include single or multiple cranial nerve involvement, a cerebellopontine-angle syndrome or chiasmal compression with visual failure.