Journal of Magnetic Resonance Imaging (JMRI)Brain White Matter Changes in CPAP-Treated Obstructive Sleep Apnea Patients with Residual Sleepiness

⚠️ Small Study / Early Comparative Evidence

This study examined whether brain white-matter microstructure differed between CPAP-adherent patients with severe obstructive sleep apnea who remained sleepy and those without residual sleepiness. Diffusion tensor imaging distinguished the groups, particularly through increased mean and radial diffusivity, but the small, male-only, cross-sectional cohort makes the findings hypothesis-generating rather than clinically actionable.

Clinical Considerations

• The study compared 12 sleepy and 17 nonsleepy men, all reporting at least six hours of nightly CPAP use.
• Residual sleepiness was defined objectively by more than five Psychomotor Vigilance Task lapses, not solely by self-reported symptoms.
• The sleepy group had higher mean diffusivity across 17.8% of evaluated white-matter tracts.
• Elevated radial diffusivity, rather than axial diffusivity, drove most differences, suggesting possible myelin-related alterations.
• Regional findings involved the corpus callosum, internal and external capsules, corona radiata, and sagittal stratum.
• Cross-sectional imaging cannot determine whether abnormalities preceded OSA, resulted from hypoxemia, or contributed directly to persistent symptoms.

Practice Applications

• Recognize residual sleepiness despite documented CPAP adherence as a clinical problem requiring further evaluation.
• Review residual respiratory events, sleep duration, medication effects, comorbid sleep disorders, and other contributors.
• Interpret DTI findings as research signals, not validated biomarkers for routine monitoring or treatment selection.
• Avoid attributing persistent sleepiness to irreversible white-matter injury based on this study alone.