Similar association between objective and subjective symptoms in functional and organic tremor

• Published in: Parkinsonism & related disorders 2019-07, Vol.64, p.2-7
• Main Authors: Kramer, Gerrit, Dominguez-Vega, Zeus T., Laarhoven, Heleen SA, Brandsma, Rick, Smit, Marenka, van der Stouwe, AM Madelein, Elting, Jan Willem J, Maurits, Natasha M., Rosmalen, Judith GM, Tijssen, Marina AJ
• Format: Article
• Language: English
• Subjects: Actigraphy; Ambulatory assessment; Functional movement disorder; Self-report; Tremor
• ISSN: 1353-8020; 1873-5126
• DOI: 10.1016/j.parkreldis.2019.05.026

A previous study reported a dramatic mismatch in objectively detected and self-reported tremor duration in patients with functional tremor. As these findings have an important and widespread impact in both clinical care and research, we conducted a validation study with a longer study duration and a larger sample of patients. Fourteen patients with functional tremor and 19 with organic tremor completed a 30 day study period. Objective tremor duration was recorded using a wrist-worn accelerometer. Simultaneously, participants completed a web-based diary five times a day, each time rating their symptom burden since the previous diary entry. Patients with functional tremor had shorter objective tremor duration compared to patients with organic tremor (21.6% vs 30.7%, P = 0.034). A post-hoc analysis revealed the difference in objective duration was mainly due to patients with essential tremor (37.2%). Subjective symptom burden was not significantly different between functional and organic tremors (38.7 vs 28.7 on a 0–100 VAS scale, P = 0.138). Finally, a mixed model analysis did not reveal significant differences in the association between subjective and objective tremor symptoms (P = 0.168). patients with functional tremor do have an objectively detectable, persistent tremor during daily life activities. Furthermore, they have a similar symptom burden and a similar association between subjective and objective tremor symptoms as patients with organic tremor. •Few studies tried to objectively quantify functional tremor in the home environment.•We found a considerable level of objective tremor duration in functional tremor.•Subjective symptom burden was similar in functional and organic tremor patients.•Objective and subjective tremor symptoms had a similar association in both groups.