Chiasmal apoplexy: hemorrhage from a cryptic vascular malformation in the optic chiasm.

We describe three patients with acute chiasmal visual field loss caused by hemorrhage within an intrachiasmal arteriovenous malformation. One patient had five episodes; vision improved three times without treatment and twice after surgical decompression. Surgical intervention restored vision in two of the three patients. The role for surgery is indefinite, but may be indicated if the visual defect remains static for 1 week or progresses. Decompression is likely to be most effective if done early. The approach to the optic chiasm should be transcranial, not transsphenoidal. A radiologically normal sella turcica favors the diagnosis of chiasmal apoplexy in the acute chiasmal syndrome.