Abstract
We report a transcallosal interfornicial approach to a high position basilar bifurcation aneurysm considered to be unapproachable by conventional pterional or subtemporal techniques.A 68-year-old female suffered from headache followed by loss of consciousness. On admission, her Glasgow Coma Scale (GCS) was 6 and a CT scan revealed massive intraventricular and subarachnoid hemorrhage. Right vertebral angiography showed a high position basilar bifurcation aneurysm with a neck located 18mm above the posterior clinoid process. Six days after the emergent external ventricular drainage, the patient was operated on via a transcallosal interfornicial approach. On inspection of the third ventricle base, the aneurysm appeared to have gradually grown into the third ventricle. Following careful identification of perforating arteries, the aneurysm was successfully clipped with two Sugita clips. Postoperatively, consciousness disturbance persisted with serum electrolyte imbalance, which had been present even before the operation. Finally the patient remained in a severely disabled condition.
Despite the advent of microsurgical techniques, surgery for basilar bifurcation aneurysms, especially for high position aneurysms, remains a challenge. Compared with conventional techniques, the transcallosal interfornicial approach offers a spacious surgical field, an excellent view of perforating arteries, and less retraction of frontal or temporal lobe. On the other hand, this approach may possibly damage the peculiar neural or vascular structures including cortical bridging veins, corpus callosum, fornix and the third ventricular floor. We conclude that this special technique can be a surgical option for high position basilar bifurcation aneurysms if the following criteria from radiographical findings are met. (1) The neck of aneurysm is about 20mm above the posterior clinoid process. (2) The aneurysm seems to reside within the third ventricle or damage the third ventricular floor. (3) Sufficient interhemispheric space can be obtained without damaging cortical bridging veins.
