Dissecting aneurysm of the vertebral artery developed after microvascular decompression for hemifacial spasm

We report a rare case of a ruptured de novo dissecting aneurysm induced by ethyl 2-cyanoacrylate. A 39-year-old woman underwent microvascular decompression for left hemifacial spasm. The offending vessel was left posterior inferior cerebellar artery (PICA). Left vertebral artery (VA) was mobilized and affixed to the dura mater with cyanoacrylate to remove pressure of PICA to the root exit zone of the facial nerve. The left VA was found to be intact at the time of the operation. One year later, th e patient sufferd subarachnoid haemorrhage (SAH) caused by rupture of a newly-developed dissecting aneurysm of the left VA. Endovascular occlusion of the dissecting site was performed using Guglielmi detachable coils. We suppose mechanical injury and chemical reaction of ethyl 2-cyanoacrylate induced dissecting aneurysm.