Lateralized Differences in Olfactory Function and Olfactory Bulb Volume Relate to Nasal Septum Deviation

Abstract: One of the most common reasons for partial nasal ob-struction is nasal septal deviation (NSD). The effect of a partiallateralized nasal obstruction on olfactory bulb (OB) volume remainsunclear. Thus, the aim of this study was to investigate the side dif-ferences in olfactory function and OB in patients with serious NSD.Sixty-five volunteers were included: 22 patients with serious rightNSD and 43 patients with left NSD. The patients’ mean age was22 years. All participants received volumetric magnetic resonanceimaging scans of the entire brain and detailed lateralized olfactorytests. The majority of the patients exhibited an overall decreasedolfactory function (as judged for the better nostril: functional an-osmiain3%,hyposmiain72%,normosmiain25%),whichseemstobe mostly due to the overall severe changes in nasal anatomy. Asexpected, olfactory function was significantly lower at the narrowerside as indicated for odor thresholds, odor discrimination, and odoridentification (P e 0.005). When correlating relative scores andvolumes (wider minus narrower side), a significantly positive cor-relation between the relative measures emerged for OB volume andodor identification, odor discrimination, and odor thresholds. Ourstudy clearly highlights that septal deviation results in decreasedolfactory function at the narrower side.Key Words: Olfactory bulb, nasal septal deviation, olfaction,magnetic resonance imaging, psychophysiology(J Craniofac Surg 2014;25: 359Y362)