Cognitive functions in surgically treated cases of unruptured intracranial aneurysms

Abstract

We evaluated the cognitive outcome in 40 consecutive patients who underwent surgery for unruptured intracranial aneurysms affecting the anterior circulation in the Willis ring to ascertain whether or not these patients were completely cured without any neuropsychological deficit from the surgery. We examined patients using the mini mental state examinations (MMSE) and a kana recognition test before and 3 months after surgery. We also used a simplified dementia diagnostic scale based on the Hamamatsu method, which contains the MMSE and kana recognition test. Prognostic factors were analyzed using a logistic regression test. There were no mortality cases, however there were 2 transient morbidity cases (transient morbidity rate 5.0%). The postoperative neuropsychological status of 38 patients was the same as or improving on the patients preoperative status for both the MMSE and kana recognition tests. The postoperative MMSE score for 2 patients was significantly lower than the preoperative score, and one of them showed a deterioration in her neuropsychological status by the Hamamatsu method (cognitive morbidity rate 2.5∼5.0%). The other 3 patients showed transient disorientation for several weeks after surgery (transient cognitive morbidity rate 7.5%). Factors found to be significant in relation to permanent or transient impairment of cognitive function included an age over 70 years old (p<0.05), a subnormal score in the kana recognition test, a subnormal score in the Hamamatsu method, having ischemic cerebrovascular disease (p<0.10). These results indicated that cognitive functions, including frontal lobe function, should be carefully examined to make a favorable treatment plan for unruptured aneurysms.