Polysomnographic Evaluation of 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 with 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 National Institute of Mental Health and Neurosciences, Bengaluru, from November 2021 to August 2023 on 45 patients (26 ET, 19 ET-Plus) and 45 controls. Tremor severity was assessed using The Essential Tremor Rating Assessment Scale (TETRAS) and Fahn-Tolosa-Marin Clinical Rating Scale (FTMRS). Sleep symptoms were assessed via the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Mayo Sleep Questionnaire, restless legs syndrome questionnaire, Berlin questionnaire, Generalized Anxiety Disorder Scale 7, and Patient Health Questionnaire-9. All patients and controls underwent overnight video PSG. Sleep scoring was manually performed by a trained sleep research technician and the first author following the American Academy of Sleep Medicine (2017) guidelines, with data analyzed using R studio. Results Compared with ET-Plus patients, ET patients had a younger onset age (46.8 +/- 11.1 years versus 30.8 +/- 16.7 years, respectively). Compared with ET patients, ET-Plus patients had higher TETRAS and FTMRS scores (p<0.005). Compared with controls, both ET patients and ET-Plus patients presented poorer sleep quality, excessive daytime sleepiness, rapid eye movement (REM) sleep behavior disorder, and restless legs syndrome symptoms. PSG findings supported these clinical observations, showing an elevated apnea-hypopnea index, reduced total sleep time, 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 compared with healthy controls, with no differences between the ET groups.