Essential tremor-Parkinson's disease syndrome: clinical characteristics and subtypes using cluster analysis

• Published in: Chinese medical journal Vol. 136; no. 4; pp. 446 - 450
• Main Authors: Hou, Yanbing, Han, Qin, Ou, Ruwei, Liu, Kuncheng, Lin, Junyu, Yang, Tianmi, Shang, Huifang
• Format: Journal Article
• Language: English
• Published: China Lippincott Williams & Wilkins Ovid Technologies 20.02.2023; Lippincott Williams & Wilkins; Wolters Kluwer
• Subjects: Cluster Analysis; Education; Essential Tremor - classification; Essential Tremor - diagnosis; Family medical history; Humans; Medical records; Mental Status and Dementia Tests; Movement disorders; Olfaction disorders; Original; Parkinson Disease - classification; Parkinson Disease - diagnosis; Parkinson's disease; Sleep; Syndrome; Tremor (Muscular contraction); Variables; China
• ISSN: 0366-6999; 2542-5641
• DOI: 10.1097/CM9.0000000000002229

Essential tremor (ET) and Parkinson's disease (PD) are common movement disorders. ET-PD syndrome is characterized by the occurrence of PD in patients with a previous history of ET, which may be an independent phenotype distinct from PD. This study aims to identify clinical characteristics and subtypes in ET-PD. A total of 93 newly diagnosed ET-PD patients and 93 newly diagnosed PD patients matched for age, sex, education, and disease duration of PD were selected using propensity score matching analysis. The K-means cluster analysis was performed for 11 variables derived from the ET-PD group, and cluster profiles were established through statistical analysis of demographic and clinical variables. The ET-PD group consisted of a high number of patients with a family history of ET exhibiting evident tremor with milder hypokinesia and postural instability symptoms, as compared to the PD group. Through the cluster analysis, two clusters of ET-PD patients were identified. The ET-PD cluster 1 ( n  = 34) had a shorter ET duration before PD onset, lower number of patients with a family history of ET, higher unified PD rating scale instability scores, higher non-motor symptoms scores (non-motor symptoms scale D1 scores, Hamilton depression scale scores, Hamilton anxiety scale scores, and PD sleep scale-2 scores), and higher Chinese version of the PD questionnaire-39 scores relative to the ET-PD cluster 2 ( n  = 59). ET-PD patients had significantly different characteristics for motor symptoms as compared to PD patients, and may be distinctly divided into two clinical subtypes, namely, the ET-PD complex type and the ET-PD simple type.