We present a patient with unruptured vertebral dissection whose angiograph showed further enlargement of the aneurysm, after a transient reduction in the size of the fusiform dilatation. Tolerance of parent artery occlusion was first confirmed by a balloon occlusion test. Both proximal and distal portions of the vertebral artery, including the dissected site, were occluded using Guglielmi electrolytically detachable coils; there were no complications. No new symptoms occurred during a 9-month follow-up period. For cases presenting with angiographic aneurysmal enlargement, embolization of the lesion using electrolytically detachable coils may be effective.
