Brainstem Proton Magnetic Resonance Spectroscopy in Idopathic REM Sleep Behavior Disorder

STUDY OBJECTIVESRapid-eye-movement (REM) sleep behavior disorder (RBD) is thought to result from a dysfunction of the brainstem structures that regulate physiologic REM sleep muscle atonia. Proton magnetic resonance spectroscopy (1H-MRS) is a noninvasive method that allows detection of in vivo neuronal dysfunction in localized brain areas. The aim of our study was to investigate whether 1H-MRS can detect brainstem abnormalities in patients with idiopathic RBD.DESIGN1H-MRS centered on the midbrain and the pontine tegmentum was acquired in 15 patients with idiopathic RBD and 15 control subjects matched for age and sex.SETTINGUniversity hospital sleep laboratory center.PARTICIPANTSFifteen untreated patients with chronic RBD diagnosed by history and video-polysomnography, normal neurologic examination, and normal cranial MRI. Fifteen healthy controls with no sleep complaints and normal polysomnography and brain MRI.INTERVENTIONSN/A.MEASUREMENTS AND RESULTSThe metabolic peaks detectable with 1H-MRS, N-acetylaspartate (NAA), creatine-phosphocreatine (Cr), choline-containing compounds (Cho) and myoinositol (mI), and the ratios of NAA, Cho and ml to Cr were evaluated both in the midbrain and pontine tegmentum. No significant differences in N-acetylaspartate/creatine, choline/creatine and myoinosito/creatine ratios were found between patients and controls.CONCLUSIONSThe results do not suggest that marked mesopontine neuronal loss or 1H-MRS detectable metabolic disturbances occur in idiopathic RBD.