Background and Purpose--Many studies have reported frequent cognitive deficits associated with subarachnoid hemorrhage (SAH) and aneurysm repair. One study found more severe cognitive deficits after clipping than coiling of aneurysms, raising the possibility that deficits are due to surgery instead of SAH itself. This possibility was directly addressed by evaluating the cognitive effects of surgery without SAH. The goal of this study was to identify changes in cognitive function associated with surgical clipping of unruptured intracerebral aneurysms.

Methods--A consecutive series of 25 patients who underwent surgical clipping of 1 unruptured intracerebral aneurysm were tested within 1 week preoperatively and again postoperatively (before hospital discharge and at 3-month follow-up if they had deficits at discharge) on a neuropsychological battery. Different forms of each test were used preoperatively and postoperatively to reduce practice effects. Paired t tests were used to examine differences between preoperative and postoperative test scores across individuals.

Results--On most tests, there was no significant change between preoperative and postoperative scores. A significant decline in accuracy before hospital discharge was found only in figure copying (P<0.04) and associative learning (P<0.01), and significant slowing was found on 1 test (P<0.01). Even on these tests, only 3 of 25 patients showed significant deterioration. All but 1 patient returned to baseline by the 3-month follow-up.

Conclusions--We found no evidence of subtle cognitive deficits resulting from aneurysm clipping alone, suggesting that the common impairments after surgery for ruptured aneurysms are due to SAH itself, complications of SAH such as vasospasm or hydrocephalus, or perioperative stroke.