DISSECTING ANEURYSMS OF THE VERTEBROBASILAR SYSTEM - STUDY OF 16 CASES

In the last 14 years we have encountered 16 patients with spontaneous intracranial dissections of the vertebrobasilar (VB) system (mean age was 46 years and male/female ratio was 10/6). VB dissections presented in eight cases with subarachnoid bleeding and in eight with brainstem , cerebellar, or cerebral ischemia. Three patients had multiple dissec tions. Ten dissections occurred in the vertebral artery (two extended to the basilar artery), three in the posterior cerebral artery (one bi lateral), two in the basilar artery, and one in the posterior inferior cerebellar artery. The angiographic configuration included ''string'' sign, ''pearl and string'' sign, fusiform dilation, and double lumen. The following angiographic evolution (available in 11 cases) was that of complete healing (three cases), partial resolution (five cases), p rogression (one case), and unimproving (two cases). Three patients die d (two due to recurrent subarachnoid hemorrhage): two patients were ex plored surgically (one had further intravascular therapeutic embolizat ion), and the rest were treated conservatively. Not all dissecting ane urysms fared in the same manner, depending either on the location in t he VB circulation or on the variable vascular configuration: treatment should be fitted to the timing of diagnosis.