Bitemporal hemianopsia in basilar artery aneurysm.

A 10-year-old boy had a 4-month history of blurred vision and severe occipital headaches. Visual acuity was diminished bilaterally, but ophthalmoscopy was normal, and the correct diagnosis was delayed until inferior bitemporal defects were found. Cranial CT scans and vertebral angiograms demonstrated a giant aneurysm at the bifurcation of the basilar artery. Bitemporal hemianopsia occurring in children is usually due to craniopharyngioma or chiasmal glioma. To the best of our knowledge, this is the first report of a patient whose chiasmal syndrome was due to a basilar artery aneurysm and whose visual deficit improved after occlusion of the aneurysm.