Olfactory bulb volume in patients with idiopathic normal pressure hydrocephalus

Abstract

An important pathological feature of idiopathic normal pressure hydrocephalus (iNPH) is a dysfunction of cerebrospinal fluid dynamics. Considering the delicate olfactory structures it appears possible that the olfactory bulb (OB) is compromised by this disease. Reports on the anatomy of the olfactory bulb and smell function in patients with idiopathic normal pressure hydrocephalus are absent in the literature. The main purpose of the present study was to evaluate the olfactory bulb (OB) volume and smell function in iNPH. The study comprised 17 patients with iNPH (seven women and ten men, mean age = 66years); they were compared to a group of 24 healthy people (11 women and 13 men, mean age = 62years). Comprehensive assessment of olfactory function was conducted with the "Sniffin' Sticks" test kit. In an additional pilot study, in a small subgroup of eight patients, measurements were performed before and approximately 7months after surgical treatment of the hydrocephalus. The OB volume in patients with iNPH was significantly smaller compared to healthy controls. In our small postoperative patient population (n = 8), there was no significant change of the OB volume. In conclusion our results suggest that iNPH significantly affects OB volumes.