Gradual Growth of Spontaneous Dissecting Aneurysm of the Extracranial Internal Carotid Artery After Aneurysmal Subarachnoid Hemorrhage.

Spontaneous dissecting aneurysm of the extracranial internal carotid artery is uncommon, and simultaneous onset of multiple dissecting aneurysms is rare in patients without congenital or traumatic risk factors. A few reports suggest that extracranial internal carotid artery dissecting aneurysms can grow after SAH due to another intracranial dissecting aneurysm. The present report describes two cases in which gradual growth of unruptured dissecting aneurysm of extracranial internal carotid artery occurred after SAH due to ruptured dissecting aneurysm of the vertebral artery and in which carotid artery stenting was subsequently performed. A 42-year-old man was admitted to our hospital with SAH due to ruptured left vertebral artery dissecting aneurysm and was managed surgically. Dissecting aneurysm of the right extracranial internal carotid artery was found and showed gradual growth. The aneurysm was treated with a stent at 7 weeks after onset. In another case, a 47-year-old woman presented with SAH due to ruptured right vertebral artery dissecting aneurysm and was managed surgically. Concomitant left extracranial internal carotid artery dissecting aneurysm was found and showed gradual growth. The aneurysm was treated with stent and coils. These are rare cases of multiple dissecting aneurysms that originated from different arteries simultaneously and that showed growth after SAH.