Metabolic abnormality of pontine tegmentum in patients with REM sleep behavior disorder analyzed using magnetic resonance spectroscopy

• NAA/Cr ratio in pontine tegmentum significantly decreased in the sRBD group.
• Cho/Cr and NAA/Cho ratios were decreased compared with control group.
• NAA/Cr ratio had an adverse correlation with age in all participants.
• There was no correlation between participant age and Cho/Cr or NAA/Cho ratios.

ObjectivesWe aimed to evaluate the metabolism differences in pontine tegmentum among patients with idiopathic RBD (iRBD), secondary RBD (sRBD) and healthy control groups using magnetic resonance spectroscopy (1H-MRS) and whether metabolic changes are correlated with age in patients with RBD.Patients and methodsThe iRBD, sRBD, and control groups were composed of 18, 26, and 29 patients, respectively. All participants underwent magnetic resonance imaging (MRI) and 1H-MRS detection at 17:00 for approximately 15 min. All NAA/Cr, Cho/Cr and NAA/Cho ratios were automatically generated using FuncTool and the correlation between metabolism and age was analyzed by Pearson’s correlation analysis.ResultsSignificant difference in NAA/Cr ratio was found between the sRBD group and the other groups (p < 0.05). Significant difference in NAA/Cho ratio was found among all groups (p < 0.05). Cho/Cr ratio remarkably increased in the control group (p < 0.05) compared with the other groups. NAA/Cr ratio had an adverse correlation with age in the control, iRBD, and sRBD groups (r = −0.822, p = 0.000 vs r = −0.663, p = 0.003 vs r = −0.583, p = 0.002). However, there was no correlation between participants age and Cho/Cr (r = −0.054, p = 0.651) or NAA/Cho (r = 0.029, p = 0.805).ConclusionNeurons in the sRBD group were lost or damaged; however, this damage was not obvious in the iRBD group. Nevertheless, NAA and Cho levels were reduced in the local nerve cells of both RBD groups; these changes might indicate the sensitive pathogenic areas among patients with RBD.