Olfactory dysfunction and olfactory bulb volume reduction in patients with leprosy

To ascertain the level and rate of olfactory dysfunction in patients with leprosy and to determine whether olfactory bulb volume is affected by the pathophysiology. Olfactory bulb (OB) volume, measured using magnetic resonance imaging (MRI), was compared in 15 patients with leprosy and 15 healthy controls. All of the participants were evaluated using a detailed history to identify the probable causes of the smell dysfunction. Those who had a disease other than leprosy that may have caused the smell dysfunction were excluded from the study. OB volumes were calculated by manually tracing the OB on coronal sections. Orthonasal olfaction testing was used to assess smell function. The orthonasal olfaction testing indicated that all patients with leprosy were anosmic or severely hyposmic. The smell function test indicated that the OB volume of the patient group was significantly lower than that of the control group. No within-group difference was detected between right and left OB volume in either group. The patients in the leprosy group were severely hyposmic or anosmic and their olfactory bulb volume was significantly lower than that of the control group. To our knowledge, this study is the first to show a reduction in olfactory bulb volume among leprosy patients.