[Posterior subtemporal transtentorial approach for a lower basilar trunk aneurysm (author's transl)].

A lower basilar trunk aneurysm is rare and it has been difficult to operate on this kind of aneurysm which is located in so-called "no man's land". We have recently operated on the aneurysm which was located between the vertebrobasilar junction and the origin of AICA. The aneurysm was approached posterior-subtemporal-transtentorially and wrapped with a muscle piece because of its broad neck. After the operation the patient developed amnestic aphasia which, however, disappeared 4 months postoperatively. The advantage of this approach is that it enables a better visualization of the lower basilar trunk, the lateroventral portion of the pons, the distal part (5 mm) of both vertebral arteries and the upper portion of the medulla oblongata than any other approaches hitherto reported. The retraction of the temporal lobe and subsequent brain damage may be minimized by using intraoperative ventricular drainage and microtechnical maneuver.