Anosmia after perimesencephalic nonaneurysmal hemorrhage.

BACKGROUND AND PURPOSE Anosmia frequently occurs after aneurysmal subarachnoid hemorrhage not only after clipping, but also after endovascular coiling. Thus, at least in part, anosmia is caused by the hemorrhage itself and not only by surgical treatment. However, it is unknown whether anosmia is related to rupture of the aneurysm with sudden increase in intracranial pressure or to the presence of blood in the basal cisterns. Therefore, we studied the prevalence of anosmia in patients with nonaneurysmal perimesencephalic hemorrhage. METHODS We included all patients admitted to our hospital with perimesencephalic hemorrhage between 1983 and 2005. Patients were interviewed with a structured questionnaire. We calculated the proportion of patients with anosmia with corresponding 95% CIs. RESULTS Nine of 148 patients (6.1%; 95% CI, 2.8% to 11%) had noticed anosmia shortly after the perimesencephalic hemorrhage. In 2, the anosmia had disappeared after 8 to12 weeks; in the other 7, it still persisted after a mean period of follow-up of 9 years. CONCLUSIONS Anosmia occurs in one of every 16 patients with perimesencephalic hemorrhage, which is lower than previously reported rates after coiling in patients with subarachnoid hemorrhage but higher than rates after coiling for unruptured aneurysms. These data suggest that blood in the vicinity of the olfactory nerves plays a role in the development of anosmia.