[Assessment of the brain volume alterations in patients with hyposmia based on voxel-based morphometry]

Objective: To investigate the brain volume alterations in patients with hyposmia using voxel-based morphometry (VBM) and to correlate these alterations with the degree and duration of hyposmia. Methods: Forty patients with hyposmia from Department of Otorhinolaryngology Head and Neck Surgery, Beijing Anzhen Hospital since 2013 to 2016 and forty age and sex matched normal subjects were recruited in this study. Sniffin' Sticks olfactory test was performed to evaluate the olfactory function of all subjects. We acquired T1-weighted magnetic resonance images from all subject on a 3T scanner. VBM was performed using VBM8 toolbox and SPM8 in a Matlab environment. Independent sample t test analysis was used to compare the volume of gray and white matter between the controls and patients. In addition, the Pearson or Spearman correlation analysis was used for the correlation between the voxel value of cerebral volume alterations area and the degree and duration of hyposmia on patients (threshold discrimination identification, TDI). Results: Compared with the controls, patients showed significantly decreased volume in the gray matter of right orbitofrontal cortex (number of voxel in clusters was 226, t=-4.46, P<0.001, uncorrected). There was negative correlation between decreased gray matter volume of the right orbitofrontal cortex with significantly decreased area and the TDI results (r=-0.40, P=0.01), but positive correlation with duration of hyposmia (r=0.37, P=0.02). Conclusions: The patients with hyposmia show gray matter atrophy of the right orbitofrontal cortex. The duration may be an important risk factor for decreased gray matter in patients with hyposmia.