Polysomnographic Findings into Sleep Disorders in Essential Tremor and Essential Tremor Plus: A Comparison with Healthy Controls

Objective: To explore sleep patterns in individuals with Essential Tremor (ET) and Essential Tremor Plus (ET-Plus), compared to healthy controls, and assess differences between ET and ET-Plus, given the lack of established polysomnography (PSG) data on these groups and the potential for sleep disturbances to serve as clinical markers.

Methods: We conducted a prospective cross-sectional study at NIMHANS, Bengaluru, from November 2021 to August 2023 on 45 patients (26 ET, 19 ET-Plus) and 45 controls. Tremor severity was assessed using TETRAS and FTMTRS, and sleep symptoms with ESS, PSQI, Mayo Sleep Questionnaire, RLS-Q, BQ, GAD-7 and PHQ-9. All cases and controls underwent overnight video PSG. Sleep scoring was manually done by a technically adequate sleep researcher and the first author following AASM (2022) guidelines with data analysed using R studio.

Results: ET patients exhibited younger onset age (30.8 ± 16.7 years) compared to ET-Plus patients (46.8 ± 11.1 years). ET-Plus had higher TETRAS and FTMRS scores (P < 0.001) than ET. Both ET and ET-Plus patients exhibited poorer sleep quality, excessive daytime sleepiness, REM sleep behavior disorder (RBD), and Restless Legs Syndrome (RLS) symptoms compared to controls. PSG findings supported these clinical observations, showing elevated Apnea-Hypopnea Index (AHI), reduced Total Sleep Time (TST), prolonged REM latency, decreased sleep efficiency, increased N1 stage duration, and reduced N2/N3 durations and percentages in patients versus controls.

Conclusion: The study highlights significant sleep architecture abnormalities in both ET and ET-Plus patients as compared to healthy controls, with no differences between the ET groups.