Study on transcranial sonography in patients with idiopathic rapid eye movement sleep behavior disorder

Objective To investigate the changes of transcranial sonography (TCS) in patients with rapid eye movement sleep behavior disorder (RBD).  Methods Fifteen patients fulfilled the diagnostic criteria of RBD according to International Classification of Sleep Disorders (ICSD, 2nd edition). Under the monitor of polysomnography (PSG), the sleep architectures of all RBD cases were evaluated by Polysmith software and visual analysis. Furthermore, all RBD patients and 15 normal controls underwent TCS. Cases with substantia nigra echo intensity over Ⅲ grade and substantia nigra area over 0.20 cm 2 were supposed to be hyperechogenicity. Additionally, the width of the third ventricle was measured and whether there was hyperechogenicity in basal ganglia was evaluated. The cognitive functions were evaluated by Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA).  Results RBD patients presented typical clinical manifestations and electrophysiologic changes. No significant difference ( P = 0.080, 0.109) was found in the comparison of hyperechogenicity rate on substantia nigra (6/15) and basal ganglia (7/15) in RBD patients and normal controls (1/15, 2/15). No significant difference in the comparison of MoCA was found in RBD patients with or without substantia nigra hyperechogenicity ( P = 0.075). The RBD patients with hyperechogenicity on basal ganglia had higher MMSE scores than those without hyperechogenicity on basal ganglia, and the difference was significant ( P = 0.021).  Conclusions RBD which is suggested as the prodromal period of synucleinopathy may present hyperechogenicity in substantia nigra and basal ganglia on TCS. TCS could detect subclinical changes of brain and evaluate the risk of synucleinopathy. DOI: 10.3969/j.issn.1672-6731.2016.04.010