Objective: This study was designed to determine the relationship between age of onset and age at clinical diagnosis of Essential Tremor (ET).

Background: ET is the most common movement disorder, with a prevalence of about 5 % in the general population, rising to over 20% in the elderly. Recently the International Parkinson and Movement Disorder Society tremor task force issued a consensus statement on tremor classification. Determination of accurate age of onset and rough categorization of patients was proposed based on age groups. Different clinical features, mode of progression, co-morbidities and mortality have been reported for early and late onset ET. We studied the association between age of onset and age when a diagnosis of ET was established.

Method: The Movement Disorders Clinical Case Registry (MD-CCR) is an application that works within a specific US Veterans Health Administration medical center’s electronic medical record (EMR) to query and export information. The MD-CCR in Houston was queried for all patients with ICD-9/10 codes of 333.1 and/or G25.0 seen in a movement disorder center’s outpatient clinics during the time period September 1, 2001 – March 31, 2018. Each patient’s EMR was reviewed to verify the diagnosis of ET and to find information on the age at onset of symptoms and age at diagnosis. Those with available information on both ages were divided into age groups based on the MDS Consensus Statement on the Classification of Tremors[1].

Results: Of 1468 patients with at least one of the codes, 1181 (80.4%) had evidence of ET in the EMR, and 1148 had information for both ages. For the age-onset categories, the totals and percentages were: [Childhood n=10, 1%], [Adolescence 110, 10%], [Early adulthood 232, 20%], [Middle adulthood 371, 32%], and [Late adulthood 425, 37%]. The mean age at the time of diagnosis and latent period (LP) to seek medical attention for ET was: childhood group; 58.70 years, LP: 49.40 years, adolescence group; 55.65 years, LP: 37.76 years, early adulthood group; 56.72 years, LP: 22.47 years, middle adulthood; 62.53 years, LP: 7.32 years, and late adulthood; 72.32 years, LP: 4.11 years.

Conclusion: Late adulthood constituted the largest group in this ET cohort. They were also diagnosed with ET within the shortest time frame as compared to other groups. This could be due to faster progression of tremor or increasing concern among patients and referring physicians for an underlying neurodegenerative disorder.

References: Deuschl G, Bain P, Brin M. Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee. Mov Disord 1998;13(Suppl 3):2-23.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/age-of-onset-and-diagnosis-of-essential-tremor/