[Aneurysm surgery using temporary occlusion under SEP monitoring].

Premature rupture of a cerebral aneurysm during operation is a serious hazard. Temporary occlusion of intracranial arteries has emerged as a valuable technical adjunct in the management of intracranial aneurysms. Twenty-five patients (from a group of 43 consecutive aneurysm patients treated during a 13-month period) underwent elective temporary arterial occlusion under somatosensory evoked potential (SEP) monitoring. Median nerve SEPs were used during 19 ICA and MCA aneurysm operations, while posterior tibial SEPs only were used in 7 patients with aneurysm of the ACA. Amplitude of the N20 or P40 was evaluated. A decrease in amplitude more than 50% when compared to baseline value was defined as a significant SEP change. In 11 patients of the 25 cases, SEP changes were observed. Temporary occlusion was applied to the proximal portion of the internal carotid artery 10 times, to the M1 portion of the middle cerebral artery 5 times, to the M1-M2 complex 5 times, to the A1 portion of the anterior cerebral artery 9 times, and to the A2 - A3 once. Of the 26 clipping (25 patients), 12 had SEP alterations, 14 had no SEP changes. Temporary occlusion was released within 3 minutes after disappearance of N20 (or P40) in all the patients with SEP changes except one. Nine of these 11 patients showed complete recovery of SEP and two showed partial recovery. Patients with partial recovery of SEP were associated with postoperative new neurological deficit, which was transient in one of them. There was a correlation between changes in SEP and post operative outcome.(ABSTRACT TRUNCATED AT 250 WORDS)