Cerebral ischemia as an apparent complication of anterior cervical discectomy in a patient with an incomplete circle of Willis.

A 58-yr-old patient sustained a cerebral ischemic injury in the distribution of the carotid artery ipsilateral to retraction during an anterior cervical discectomy. Relative hypotension was permitted during the anesthetic. Angiography revealed an anatomic variant of the circle of Willis that resulted in minimal collateralizaton of the left internal carotid artery territory. The combination of that vascular variant with relative hypotension and some degree of carotid compression appears to have resulted in clinically significant cerebral ischemia.