Autonomic Nervous System and Rem Behavior Sleep Disorder: a new tool to identify Idiopathic or Parkinsonians patients through Heart Rate Variability Polysomnography Analysis

Objective: RBD is a sleep disorder known to be associated in a very high percentage of cases with alfa-synucleopathies. During rapid eye movement (REM) sleep, the cardiovascular system is unstable and greatly influenced by sympathetic activity. Heart Rate Variability (HRV) indirectly tests functions and activities of the ANS during sleep. We evaluate whether HRV and Hypnogram Indices are polysomnographic valid biomarkers to distinguish subjects with idiopathic RBD from those with Parkinson's Disease. METHODS: Our study examines HRV linear and non-linear indices of 37 patients aged 53 years and older (median 72.7; mean 72.3 ± 7.4; range 53-84), 7 women (18.9%) and 30 men (81.1%). 22 pts were idiopathic REM sleep behavior disorder (59.5%; age: median 72.5; mean 74.5 ± 5.2; range 68 83), of which 3 women (13.6%) and 19 men (86.4%); 15 pts had REM Sleep Behavior Disorder secondary to Parkinson's disease (40.5%; a ge: median 73; mean 69.5 ± 9 ; range 53 84), including 4 women (26.7%) and 11 men (73.3%). A parallel Analysis was made on Hypnogram Parameters. RESULTS: The REM sleep phase allowed to record the greatest number of significant differences in HRV Index between the two groups of patients. Among the Frequency HRV Linear Indices, VLF signal band recorded the highest number of significant results suggesting that the sympathetic component may be the one most compromised in the autonomic neurodegeneration process of RBD. HRV Complexity Non-Linear Indices (LZC and KC) have the highest number of statistically significant results so that could be the right parameter to use to distinguish our two RBD populations. Hypnogram Indices Analysis showed no significant value for not even a parameter. CONCLUSIONS: HRV can be a valid biomarker to distinguish the two populations of patients affected by RBD, both idiopathic and affected by Parkinson's disease. It could represent a new and easy tool to identify, among the REM Behavior Sleep Disorder, patients affected or not by Parkinson’s desease or could be even useful when an early diagnosis is needed or it is necessary monitoring a probable conversion from idiopathic form to PD or evaluate the effectiveness of RBD therapies.