Hearing loss after surgery of ruptured cerebral aneurysm

Only a few cases have been reported of hearing impairment after various procedures that result in loss of cerebrospinal fluid (CSF). We experienced eight cases of hearing loss following surgery for ruptured cerebral aneurysm. Angiography revealed that the aneurysm was located at the middle cerebral artery bifurcation in two cases, anterior communicating artery in four cases, posterior communicating artery in one case, and superior hypophyseal artery in one case. All of them were relatively far from the hearing structures. The aneurysm was clipped easily after drainage of CSF for slack brain. Pure-tone audiometry revealed unilateral or bilateral hearing loss that not only affected the low, but all frequencies. Completely normalized hearing was found in five patients at 3-6 months follow-up, whereas two cases noticed a partial loss and one made no recovery. We speculate that the explanation of hearing loss following aneurysm surgery results directly from diminished CSF pressure by the loss of CSF during operation. This decrease is transmitted to the perilymph via a patent cochlear aqueduct (CA) producing the release of perilymphatic fluid in the subarachnoid space. It is possible that a haemolabyrinth caused by an inflow of subarachnoid haemorrhage through CA could be an additional factor in the induced impaired hearing.