Six adults with spontaneous dissection of the vertebrobasilar system are reported. Clinically, 2 patients presented with subarachnoid hemorrhage and 4 with brain-stem ischemia. In all patients, angiography demonstrated fusiform dilatation and constrictions of the involved vessel, which were called “pearl and string”sign. Among these, 2 patients of subarachnoid hemorrhage and one patient with definite dissecting aneurysm that did not improve in spite of angiographic monitoring were surgically treated. Three other patients were treated conservatively with rather good clinical results. Ischemic type of vertebrobasilar dissection must be angiographically monitored, because of spontaneous healing of dissection. In dealing with dissection of vertebrobasilar arteries, because only severe headache develops before ischemic symptoms appear, great care must be taken for these patients. MRI is one of the most reliable neuroimaging methods for detecting dissection.
