Clinical Features of Essential Tremor and its Impact on Quality of Life in Japan

Background: Essential tremor (ET) is primarily characterized by action tremor, but is also associated with various non-motor symptoms (NMS). However, the diagnostic relevance of NMS in ET remains unclear. This study aimed to compare NMS and motor symptoms of ET with those of Parkinson’s disease-tremor dominant type (PD-TDT) and healthy controls (HCs) and to identify the presence and diagnostic relevance of NMS.

Methods: Twenty-three ET patients, 23 PD-TDT patients, and 22 HCs were enrolled. Diagnoses of ET and PD were confirmed using Movement Disorder Society (MDS) criteria and Dopamine transporter single-photon emission computed tomography. Motor symptoms, NMS and quality of life (QOL) were evaluated using validated scales, including the Clinical Rating Scale for Tremor (CRST), MDS-Unified Parkinson’s Disease Rating Scale (UPDRS), Non-Motor Symptoms Scale for Parkinson’s Disease (NMSS), Odor Stick Identification Test for Japanese (OSIT-J), and Quality of Life in Essential Tremor Questionnaire (QUEST).

Results: ET patients had significantly higher NMSS total scores and MDS-UPDRS part IB scores than HCs, with more severe sleep disturbances, fatigue, and urinary problems. CRST scores were significantly correlated with QUEST scores. Logistic regression identified CRST Part B and OSIT-J as key factors distinguishing ET from PD-TDT, with 87% sensitivity and 90% specificity.

Discussion: ET patients showed more severe NMS than HCs. Differentiating ET from PD-TDT requires motor and sensory assessments, highlighting the diagnostic relevance of NMS. Comprehensive evaluation is essential for accurate diagnosis and management of ET.