OBJECTIVETo analyze the correlation between olfactory bulb (OB) volume with depth of olfactory sulcus (OS) and olfactory function in patients with idiopathic rapid eye movement sleep behavior disorder (iRBD).

METHODSFifty patients with iRBD and fifty controls were assessed with polysomnography (PSG). The results of olfactory function T & T testing, OB volume and depth of OS assessed with magnetic resonance imaging (MRI) were compared. SPSS 11.0 software was used to analyze the data.

RESULTST & T olfactory testing revealed that iRBD patients had higher scores (3.1 ± 0.5) than those in controls (0.6 ± 0.1), and the difference was significant (t = 7.913, P < 0.05). Both men and women with iRBD were affected by the same extent of olfactory loss (t = 1.015, P > 0.05). OB volume of left side in iRBD patients was (33.75 ± 4.11) mm(3), right side was (34.57 ± 4.21) mm(3), average OB volume was (33.94 ± 4.15) mm(3); OB volume of left side in controls was (51.68 ± 7.71) mm(3), right side was (52.31 ± 7.77) mm(3), average OB volume was (51.94 ± 7.74) mm(3); OB volume were lower in iRBD patients as compared to controls (t value were 9.013, 8.889 and 8.923, all P < 0.01). OS depth study revealed no statistical difference between iRBD patients and controls (t value were 0.923, 0.897 and 0.904, all P > 0.05). Olfactory discriminate threshold was negatively correlated with OB volume in iRBD patients (r = -0.61, P < 0.05), but no correlated with depth of OS (r = -0.24, P > 0.05).

CONCLUSIONSThe OB volume was lower in iRBD patients as compared to controls. The depth of OS showed no significant changes in iRBD patients. The OB volume was correlated with olfactory function, while the depth of OS was no correlated with olfactory function.