Basilar Artery Trunk Aneurysms-Eight Operative Experiences and 2 Autopsy Findings-

Over the past 10 years we have experienced 8 operative cases of basilar artery trunk aneurysm. Among the operative cases, 3 were males and 5 were females. Their ages ranged from 20 to 73, with a mean age of 53.3 years. Preoperative grade of Hunt and Kosnik included 5 cases of Grade II, 2 cases of Grade III, and 1 case of Grade IV. The maximum diameter of the aneurysms ranged from 5 mm to 18mm, with a mean of 11mm. Two cases were operated on by the pterional approach, 5 cases by subtemporal approach, and 1 by subtemporal approach without successful clipping and finally treated by presigmoid approach. Concerning the Glasgow Outcome Scale, 6 cases had good recovery (75%) and 1 case was severely disabled. One patient died due to uremia caused by severe bilateral renal tuberculosis. Autopsy findings of this case showed successful obliteration of the ruptured aneurysm, but the other small unruptured aneurysm was left unclipped due to narrow operative space. There was no definite temporal contusion on the approached side. The other autopsied case was a 74-year-old male who was DOA at the emergency center. Autopsy revealed the presence of 2 aneurysms between the SCA and AICA, of which the smaller one facing the brain stem had ruptured fatally. From the operative and autopy findings, the following can be concluded: 1) Preoperative angiography should focus on the possibility of the presence of multiple aneurysms, and if any are found, any ruptures should be determined. Angiography without subtraction should be performed in reveal the relationship between the (proximal) neck of the aneurysm and bony landmarks.2) If the proximal neck of the aneurysm is below the posterior crinoid process and above the upper margin of the pyramis, the procedure of choice might be subtemporal approach without drilling of the pyramis. If it situated below the upper margin of the pyramis, small drilling of the pyramis might be necessary. If it is at the same level or below the external auditory meatus, some modified suboccipital approach should be selected for successful clipping.3) For successful in clipping, meticulous knowledge of the microsurgical anatomy should be obtained, and some special clips or clip applicator should be prepared. Our preference is the use of fenestrated clip to secure the aneurysmal neck with good visibility and without untoward manipulation of the surrounding structures.