Neurophysiological examination of functional integrity and excitability of brainstem pathways in patients diagnosed with idiopathic REM sleep behavior disorder and REM sleep without atonia

In recent years, the interest in the physiology of pedunculopontine nucleus and pedunculopontine arousal system has increased. The functions of PPN can be evaluated by the prepulse inhibition (PPI) method by the blink reflex (BR) and auditory startle reflex (ASR). The study includes REM sleep without atony and idiopathic RDD patients diagnosed with polysomnography in the Neurology Sleep Disorders Unit of Cerrahpaşa Medical Faculty and matched healthy control subjects. In order to investigate the presence of increased excitability, the study examined ASR, BR, BR PPI, BR R2 -RC in brain stem reflexes. Main findings are: In ASR analysis with ASR probabilities; in the SCM muscle, iRBD patient group were increased. Total ASR probabilities were increased in the iRBD patient group compared to other groups. In BR analyzes, R1 amplitude, latency, duration, R2k latency, R2k area were normal in groups; when R2 area increased in the iRDB patient group compared to the other groups. According to the results obtained in BR-PPI, with 100 ms excitation intervals; R2-PPM and R2k- PPM were increased in iRDB the patient group and REM sleep without atony compared to control subject. In BR-R2 RC, the conditioning/test percentages (recovery) in the R2 field were increased significantly at 200 ms stimulation interval compared to patient control groups in REM sleep atony and iRDB patients.These findings are thought to be due to abnormal behaviors resulting from an inability to suppress RDB, disruption of REM atony pathway and/or disinhibition of brain stem motor structure generators.In our study, pathological findings could be used as early markers that can be used to show the presence of neurodegeneration.