OBJECTIVETo analyze the correlation between olfactory bulb(OB) volume with depth of olfactory sulcus (OS) and olfactory function in patients with idiopathic olfactory loss (IOL).

METHODSForty patients with IOL and forty normal controls were compared in terms of olfactory function T&T testing and magnetic resonance imaging (MRI, observation of OB volume and depth of OS). T&T testing and MRI were performed again after a year in 40 IOL patients, the results were compared with the first time.

RESULTSOB volume of left side in IOL patients was (30.31 ± 4.07) mm(3), right side was (30.82 ± 4.14) mm(3), average OB volume was (30.53 ± 4.10) mm(3); OB volume of left side in normal controls was (49.56 ± 7.19) mm(3), right side was (49.84 ± 7.25) mm(3), average OB volume was (49.73 ± 7.21) mm(3). OB volume was lower in IOL patients as compared to controls (t value were 8.122, 8.274, 8.231, all P < 0.01). OS depth study revealed no statistical different between IOL patients and controls (t value were 0.998, 1.017, 1.001, all P > 0.05). Olfactory discriminate threshold was negatively correlated with OB volume in IOL patients (r = -0.53, P < 0.05). There was no correlation with the depth of OS (r = -0.19, P > 0.05). Among 40 IOL patients, when followed-up, 12 showed increased in OB volume and olfactory function after a year, but no statistical difference was found with the first time (t value were 0.831, 0.864, 0.826, all P > 0.05). The other 28 patients showed no significant changes of OB volume and olfactory function.

CONCLUSIONSThe OB volume was lower in IOL patients as compared to normal controls. The depth of OS showed no significant changes in IOL patients. The OB volume was correlated with olfactory function. The depth of OS did not correlated with the olfactory function. Some IOL patients showed increased OB volume and improved olfactory function with the development of the disease.