Recurrence of cerebral aneurysm after initial neck clipping.

Neck clipping has generally been believed to be among the most reliable of the operative modalities for cerebral aneurysm. However, recurrences with catastrophic outcome have been known to occur. We recently treated two patients who each had a new aneurysm at the site of the initial clipping. In both cases, the recurrence was found several years after the aneurysm neck had been closed successfully with a silver clip, which had been confirmed by intraoperative inspection and by postoperative angiographic studies demonstrating disappearance of the aneurysm. Histological examination of the recurrent aneurysm showed that the arterial wall had apparently been damaged by the clip edge, which resulted in thinning and disruption of both the muscle layer and the internal elastic lamina. Therefore, local fragility of the arterial wall adjacent to the aneurysm seems to have been the cause of the formation of a new aneurysm. The need to reinforce the thin-walled parent artery and the usefulness of high resolution computed tomography for the early detection of recurrent aneurysms are emphasized.