We evaluated the usefulness of medullary trigeminal evoked potential monitoring (M-TEP) and fluorescence cerebral angiography using fluorescein sodium (fluorescein-FCAG) for detecting the blood flow insufficiency in the posterior inferior cerebellar artery (PICA) during aneurysm surgery.
The study population consisted of 3 patients with PICA aneurysm (2 cases) and vertebral artery aneurysm (1 case). In 2 cases, after aneurysm clipping and/or trapping, M-TEP disappeared and the fluorescence of the PICA was not seen. After clip replacement (Case 1) and occipital artery (OA) - PICA anastomosis (Case 2), M-TEP returned to the control level and blood flow of PICAs were confirmed by fluorescein-FCAG. Postoperatively, incomplete Wallenberg syndrome appeared in Case 2. In Case 3, OA-PICA anastomosis was performed, and the aneurysm was trapped. Intraoperative findings of M-TEP and fluorescein-FCAG did not change. No neurological deficits appeared postoperatively.
Based on our findings, we suggest that M-TEP and fluorescein-FCAG are useful to prevent unexpected postoperative Wallenberg syndrome and to improve the surgical outcome.