[Surgery of vertebral aneurysms at the origin of PICA (author's transl)]

Abstract

Thirteen cases of vertebral aneurysm at the origin of PICA (VA-PICA aneurysm) were operated on at the Department of Neurological Surgery of Kitano Hospital from March, 1970 through July, 1975. Those included 9 cases of saccular aneurysm and 5 cases of fusiform aneurysm (Table 1). The incidence of VA-PICA aneurysms among our whole series of intracranial aneurysms was 4.2%. Patients with subarachnoid hemorrhage were subjected to our routine 4 vessel angiography. For those with suspected vertebral aneurysm vertebral angiography was performed in a transoral projection. In this method, when the angle between the film and the horizontal plain of Frankfurt is fixed at 50 degrees, the origin of PICA is projected on the film between the upper and lower teeth line. Since X-ray beam falls vertically on the origin of PICA, the resultant vascular shadow is free from shortening, elongation and distortion, leading to precise demonstration of anatomical arrangement of the vessels. At surgery a lateral suboccipital incision was made. With the position of VA-PICA junction the surgical approach was slightly different. When the junction was located higher than the line between the lowest point of the occipital bone and the basion by 1 cm or more, the approach was made through the middle of the sigmoid sinus which was exposed by suboccipital osteoclastic craniectomy (mid-lateral cerebellar approach). When the VA-PICA junction was situated lower than the line by 1 cm or more, the operation was initiated at the upper limit of the lower one-third of the sigmoid sinus (lower-lateral cerebellar approach). Since VA-PICA junction is ventrally situated to the lower cranial nerves, surgical attack to the junction can be attained only through the space among the nerves. Two spaces are available for this direct attack. One is the space between the facial nerve, acoustic nerve and the group of vagal nerves. The other is between accessory nerve bundles or between the group of accessory nerves and the hypoglossal nerves. The former procedure is employed for reaching the aneurysm by mid-lateral cerebellar approach and the latter by lower-lateral cerebellar approach. In the patients in acute stage of ruptured VA-PICA aneurysm, hemisuboccipital craniectomy and laminectomy of the atlas were carried out for the purpose of decompression. Surgical procedures used included coating in 2 cases, trapping in 2, proximal ligation of the vertebral artery in 2 and neck clipping in 6. Two patients died due to grastrointestinal bleeding. Surgical complications noted were hypoglossal nerve palsy in 1 case mild sensory disturbance contralateral to the aneurysm in 3 cases. Those symptoms were thought to be caused either by direct injury to the lower cranial nerves or circulatory disturbance in the medullary branches of the vertebral artery. To eliminate those postoperative complications it is desirable to devise smaller aneurysm clips and smaller clip foreceps.