傍正中VA Aneurysmに対する (Trans-) Condylar Approach

Abstract

The surgical technique of the transcondylar approach (TCA) for midline vertebral aneurysms is presented, and the differences in the surgical fields between TCA and the lateral suboccipital approach (LSA) are highlighted. Extradural resection of the lateral wall of the foramen magnum, from the occipital condyle to the jugular tubercule, was the most important element for exposure of the aneurysm in this area. Effective bone resection using the TCA enlarged the subarachnoid space around the lower cranial nerves, and offered more surgical space than that of LSA for aneurysm clipping between the nerves. The total length of the vertebral artery was observed with minimal retraction on those nerves. Resection of the JT was necessary when the aneurysm was located close to the vertebro-basilar junction (VBJ), in the area less than 10 mm from the midline on the A-P view of the angiogram, and closer than 12 mm to the internal auditory meatus on the lateral X-ray. One of the shortcomings of the TCA was the necessity of sacrificing or exposing the cervical venous plexus, which continues from the jugular bulb through the supracondylar emissary vein. A preoperative thin-slice bone CT scan offered important information about the variation of the venous system and the size of the JT in each case.