Fifteen patients with ruptured dissecting vertebral aneurysm were treated by intravascular neurosurgery. Twelve of them were treated in the acute stage (within 80 hours after the last rupture) and three were in the chronic stage. They were divided into 3 types according to location of the posterior inferior cerebellar artery (PICA) and the aneurysm: Type A, the PICA originated distal to the aneurysm; Type B, the PICA originated proximal to the aneurysm; Type C, the PICA was absent or uncertain. A parent vertebral artery was occluded as proximal to the aneurysm as possible in Types A and C. A vertebral artery was occluded between the PICA and the aneurysm, if possible, in Type B (Type B-1). Because that procedure is, in practice, difficult, especially if a detachable balloon is used, a parent vertebral artery was occluded at C₄ or C₅ level, proximal to the segmental arteries, in most Type B_s (Type B-2). The parent vertebral artery was occluded with detachable balloons in 14 patients. In all the patients treated with detachable balloon, parent arterial occlusion followed 15 minutes after test occlusion. If the patient's neurological symptoms or conscious conditions were not changed, the balloon was detached just as it was. The most recent case was treated with electrically detachable coils. Three patients developed cranial nerve palsies and three patients developed hemiparesis or sensory disturbance. Those symptoms were thought to be caused by gradual thrombotic formation, since the symptoms appeared not immediately after arterial occlusion but in the next day. Cranial nerve palsies disappeared in a few months in all the patients. Minimal hemiparesis or sensory disturebance remained. Seven patients suffered from symptomatic vasospasm. Transluminal angioplasty was performed on four of them, and one of them soon recovered. The remaining three and another one died of severe vasospasm in spite of angioplasty.
In conclusion, intravascular neurosugery is an effective and less invasive way to treat a ruptured dissecting vertebral aneurysm. Several kinds of platinum coils, including electrically detachable coils are a useful alternative. Attention should be paid to delayed neurological deficits caused by gradual thrombotic formation. Transluminal angioplasty is also an effective way to treat severe vasospasm.