1995 Volume 17 Issue 2 Pages 181-187
Two cases of unruptured giant vertebro-basilar aneurysm presenting with marked brain-stem compression are reported. The first patient with a partially thrombosed saccular aneurysm of the left vertebral artery underwent aneurysmal trapping through a suboccipital craniectomy. The second patient with a vertebro-basilar fusiform aneurysm was treated with proximal ballon occlusion of the right vertebral artery by intravascular surgery. Preoperative evaluation with balloon test occlusion and intraoperative monitoring of brain stem responses suggested that the parent artery occlusion was safe in both patients. Postoperatively, however, they fatally continued to suffer from progressive brain-stem insufficiency. Postmortem examinations revealed significant atrophy of the brainstem and its distortion by aneurysmal compression. Histopathological studies demonstrated extensive necrosis of the brain stem in both cases, resulting from compression and/or ischemia. The possible factors causing the neurological deterioration in these two cases are speculated to involve the following :
1) ischemia in the territory of the parent artery and its perforators (hemodynamic ischemia);
2) thrombosis and/or embolism from the distal site of the artery occlusion (thromboembolic ischemia);
3) progressive enlargement of the aneurysm even after trapping or parent artery occlusion; and
4) mechanical trauma due to the surgery.
Our experience with these two cases suggests that successful treatment of such glant aneurysms of the posterior circulation with marked brain-stem compression is extremely difficult.
