Non-motor symptoms are associated with midline tremor in essential tremor

Essential tremor (ET) patients presenting tremor in the midline structures may be a distinct subtype of the syndrome. Therefore, we sought to explore the clinical manifestations, especially non-motor symptoms (NMS) of Chinese ET patients with midline tremor (MT).

In the cross-sectional study, we grouped 290 definite or probable ET patients based on their MT conditions. The NMS in ET patients were evaluated using the NMS scale (NMSS). NMS and other clinical correlates were then compared among subgroups with, and without MT.

We revealed that 39.0%, 27.6%, and 6.9% of the patients respectively had neck, voice, and facial tremors. With the accumulation of tremor in midline structures, NMS became more severe and prevalent. Logistic regression analyses revealed that factors such as: female gender (OR = 2.164, 95% CI: 1.307-3.583), having least or highest action arm tremor (OR = 2.512, 95% CI: 1.520-4.151), having higher score of sleep/fatigue domain (OR = 1.692, 95% CI: 1.004-2.850) and mood/apathy (OR = 1.926, 95% CI: 1.143-3.246) domain, to be independently associated with MT manifestation.

Our study demonstrates the heterogeneity of symptoms in ET patients with MT, especially in prominent NMS. In addition, the discrepancy of NMS between patients with, and without MT provides novel insight into the underlying pathophysiology and therapeutic of ET.