Evaluation of Brain Volume Changes by Magnetic Resonance Imaging in Obstructive Sleep Apnea Syndrome

Background and objectives: The objective of this study was to evaluate potential morphological changes in the brain tissue of patients with severe obstructive sleep apnea syndrome (OSAS) in comparison with normal subjects by using T1-weighted magnetic resonance imaging (MRI) technique.

Material and methods: This study comprised subjects with severe OSAS with an apnea-hypopnea index (AHI) more than 30 and normal subjects with AHI less than 5 according to polysomnography findings. The study subjects were evaluated using Three Dimensional Magnetization Prepared Rapid Acquisition Gradient Echo sequence on T1-weighted MRI. FreeSurfer morphometric procedure was used as the automated segmentation method and in both cerebral and cerebellar hemsipheres and segmental volumes of brain were analyzed.

Results: Of the 22 patients with severe OSAS, 19 were male, three were female and their ages ranged between 40 and 60 years (mean age 50.27 ± 5.3 years). Of the 22 control subjects 19 were male, three were female and their ages ranged between 40 and 60 years (mean age 49.36 ± 6.95 years). There were no statistically significant differences in terms of age and sex properties between the groups. There was a statistically significant difference in BMI between the OSAS patients and the control group. There were statistically significant differences in polysomnographic features (time elapsed below 90% SaO₂ (min), Epworth Sleepiness Scale, AHI, mean minimum SaO₂ (%), mean O₂ desaturation (%), and arousal index values) between the OSAS patients and the control group.

Conclusions: The findings of our study indicated that even if severe, no structural changes occur in the course of mild, moderate, and severe OSAS.