The Spectrum of Non-Parkinsonian Tremor: A Registry at a Tertiary Care Teaching Institute

Background: Tremors other than those associated with Parkinson's disease (non-parkinsonian tremor) are commonly observed in clinical settings. However, their frequency and clinical characteristics have rarely been reported. Objectives: To classify non-parkinsonian tremors based on the consensus statement on the classification of tremors, from the task force of the International Parkinson and Movement Disorder Society published in 2018. Methods: A prospective registry at a tertiary care teaching institute. Results: A total of 475 patients with non-parkinsonian tremors were recruited for the study. 67.57% (n = 321) of our patients were male and a family history of tremor was present in 20.84% (n = 99) of patients. Dystonic tremor (DT) was the most common non-parkinsonian tremor (33.26%). 27.78% of patients fulfilled the new classification criteria for essential tremor, with 13.47% classified as pure ET (ET) and 14.31% exhibiting neurological soft signs, leading to the classification of ET plus (ETP). Patients with ETP had more family history (57.35%) [vs DT (26.48%, p = 0.00004) and ET (10.93%, p = 0.00003], longer duration of disease [mean +/- standard deviation (SD) = 9.53 +/- 8.64 years] [vs DT (5.60 +/- 5.93, p = 0.0003) and ET (6.38 +/- 5.97, p = 0.01) years], and more severe tremor as measured by the essential tremor rating assessment scale total score [mean +/- SD = 27.42 +/- 11.70] [vs DT (23.50 +/- 8.62, p = 0.007) and ET (22.12 +/- 8.19, p = 0.007)] compared with patients with DT and ET. Conclusions: DT was the most common cause of non-parkinsonian tremor in our registry followed by essential tremor syndrome. ETP was more common than ET.