Probable REM-Sleep Behavior Disorder and Dysautonomic Symptoms in Essential Tremor.

Background: Non-motor symptoms can be present in essential tremor (ET). We intend to assess the frequency of rapid eye movement (REM) sleep behavior disorder (RBD) and dysautonomic symptoms in ET patients and evaluate the differences between patients with ET and RBD (ET-RBD and ET without RBD [ET-nonRBD]).

Methods: All ET patients were contacted by telephone. Autonomic symptoms were assessed using the Scales for Outcomes in Parkinson's Disease-Autonomic (SCOPA-AUT) questionnaire, and RBD symptoms with the RBD screening questionnaire (RBDSQ) using ≥5 as a cut-off for probable RBD (pRBD).

Results: From 92 ET patients contacted, 53 (55% female) were included. The mean age at assessment was 73.6±19 years, and the average disease duration was 19.9±17.3 years. Fourteen patients (26.4%) had pRBD and 52 (98.1%) reported at least one autonomic symptom, the most prevalent being urinary symptoms (96%). The ET-RBD group had higher SCOPA-total and thermoregulatory scores than ET-nonRBD patients (13.9±9.6 vs. 7.7±5.1, p=0.017 and 2.5±2.0 vs. 0.9±1.6, p=0.001). There were no other differences between groups.

Discussion: Our results suggest that pRBD is common in ET, and its presence is associated with dysautonomic symptoms. As these symptoms are known to be prodromal symptoms of Parkinson's disease (PD), we question if this patient subgroup has a higher risk of developing a synucleinopathy.