We evaluated the neuropsychological functions of 105 patients who underwent 108 surgeries for unruptured cerebral aneurysms. All patients completed the Wechsler Adult Intelligence Scale-Revised (WAIS-R) before and one month after surgery. The aneurysms were located mainly in the anterior cerebral artery, middle cerebral artery, or internal cerebral artery. Deep white matter hyper-intensities (DWMH), brain atrophy and cerebral infarction were evaluated using preoperative magnetic resonance imaging (MRI). Brain contusion (large: 10 mm or more in largest diameter; small: smaller than 10 mm), subdural fluid collection (thick: midline shift observed; thin: mass effect observed without midline shift) and cerebral infarction were evaluated on postoperative MRI and/or computed tomography. A decrease of four points or more in the WAIS-R score postoperatively was interpreted as deterioration.
Although there was no statistical difference between the preoperative and postoperative WAIS-R scores, 25 of 108 surgeries (23%) showed deterioration of the WAIS-R score postoperatively. Brain contusion on MRI was observed in 15 surgeries (large: 7; small: 8), and six of those surgeries (40%) showed deterioration of the WAIS-R score. Deterioration of the WAIS-R score was observed more frequently in patients with large brain contusion (4 of 7, 57%) than in those without brain contusion (19 of 93, 20%) (p<0.05). Brain contusion occurred more frequently in patients with moderate or severe DWMH (5 of 23, 22%) than in those without DWMH (2 of 43, 5%) (p<0.05), and in patients with ACoA aneurysm (5 of 26, 19%) than in those with MCA aneurysm (1 of 33, 3%) (p<0.05). Although large brain contusion was observed postoperatively in patients with aneurysms localized to the ACoA operated through the pterional approach, damage was not apparent in patients operated with an interhemispheric approach. Subdural fluid collection was observed after 14 surgeries (thick: 5; thin: 9), and four of those patients (29%) showed deterioration of the WAIS-R score. Deterioration of the WAIS-R score was observed more frequently in patients with thick subdural fluid collection (2 of 5, 40%) than in those without subdural fluid collection (21 of 94, 22%), though the difference was not significant. The occurrence of subdural fluid collection was more frequent in patients with brain atrophy (11 of 36, 31%) than in those without brain atrophy (3 of 72, 4%) (p<0.01). Although thick subdural fluid collection was observed in five of 91 surgeries and deterioration of the WAIS-R score was recognized in four of 91 surgeries using physiological saline solution, they were not observed using artificial cerebrospinal fluid. Cerebral infarction was observed in five surgeries, but deterioration of the WAIS-R score was not detected in those patients.
Neuropsychological dysfunction due to brain damage or subdural fluid collection was observed after clipping unruptured cerebral aneurysms. The aneurysm location, presence of DWMH or brain atrophy were related to the occurrence of brain contusion or subdural fluid collection.
Our findings suggest that results may be improved by selection of a surgical approach to reduce brain contusion or by usage of artificial cerebrospinal fluid instead of physiological saline solution during surgery.