Consecutive oculomotor nerve palsy from a de novo cerebral aneurysm.

A 26-year-old woman presented with a partial left oculomotor nerve palsy and an acute subarachnoid hemorrhage. Bilateral angiography showed a left posterior communicating artery aneurysm and a normal right anterior circulation. The aneurysm was successfully clipped. At 4 1/2 years later, she had an acute, nearly complete, right oculomotor nerve palsy. Repeat bilateral angiography showed a right posterior communicating artery aneurysm, in a previously angiographically normal region, and continued closure of the original left-sided aneurysm. New aneurysms may develop from angiographically normal locations. It is possible that certain patients are more susceptible than average to aneurysm formation or that aneurysm repair leads to a higher rate of new aneurysm occurrence. The previous cases of de novo aneurysms are summarized and the implications for repeat aneurysm screening, using current technology, are discussed.