Medulla oblongata damage and cardiac autonomic dysfunction in Parkinson disease.

OBJECTIVE: To characterize medulla oblongata damage using diffusion tensor imaging (DTI) in Parkinson disease (PD) and correlate it with dysfunction of the cardiac sympathetic/vagal balance.

METHODS: Fifty-two patients with PD and 24 healthy controls were included in the study. All participants underwent clinical examination and 3T MRI using 3D T1-weighted imaging and DTI. DTI metrics were calculated within manually drawn regions of interest. Heart rate variability was evaluated using spectral analysis of the R-R cardiac interval during REM and slow-wave sleep based on continuous overnight electrocardiographic monitoring. Respiratory frequency was measured in 30-second contiguous epochs of REM and slow-wave sleep. The relationships between imaging and cardiac variables were calculated using partial correlations followed by the multiple comparisons permutation approach.

RESULTS: The changes in heart rate and respiratory frequency variability from slow-wave sleep to REM sleep in healthy controls were no longer detectable in patients with PD. There were significant increases in the mean (p = 0.006), axial (p = 0.006), and radial diffusivities (p = 0.005) in the medulla oblongata of patients with PD. In PD, diffusion changes were specifically correlated with a lower heart rate and respiratory frequency variability during REM sleep.

CONCLUSIONS: This study provides evidence that medulla oblongata damage underlies cardiac sympathetic/vagal balance and respiratory dysfunction in patients with PD.