To investigate the gray matter volumes (GMV) alterations in the patients with obstructive sleep apnea hypopnea syndrome (OSAHS) by using voxel-based morphometry (VBM) of magnetic resonance imaging (MRI).

A total of 55 OSAHS patients who were diagnosed by polysomnography (PSG) in the Affiliated Hospital of Qinghai University from January 2016 to December 2017 were enrolled for this study. According to the apnea hypopnea index (AHI), they were divided into a mild group, a moderate group and a severe group. These groups were matched with the altitude, age, gender and residential elevation. Then we used the VBM to compare the whole brain GMV among the mild group, moderate group and severe group.

①No significant difference was found in the altitude, age, gender and residential elevation among the groups (P>0.05). The mean oxygen saturation in the mild group was higher than those of the moderate group and the severe group (P<0.05) and the AHI in the severe group was higher than those of the mild group and the moderate group (P=0.000). ②The volumes of the left amygdala, left hippocampal and left insular gray matter in the patients with moderate OSAHS were decreased compared with those in the mild patients. ③The volume of the right parahippocampal gray matter was decreased in the severe OSAHS patients compared with the mild patients. ④The volumes of the left caudate nucleus and left-sided putamen gray matter in the patients with severe OSAHS were increased, and bilateral thalamic volume was reduced compared with the moderate group.

The changes of brain regions of different degrees of OSAHS patients′gray matter volumes were different, which indicates that different degrees of OSAHS may affect different brain structures.