Abstract
Functional tremor is the most common presentation of functional movement disorders and can occur in isolation or together with other functional symptoms, including other abnormal movements. The diagnosis of functional tremor is based on positive features on history, examination, and, if necessary, neurophysiological studies. Historical features include: sudden onset, a preceding physical event or injury, variability in severity with or without remission, variability in affected body parts, the presence of other somatic symptoms, and a history of failed therapeutic trials. Positive signs on examination include: variability in the frequency, direction, and distribution of the tremor; clear coherence in the different body parts affected; reduction or elimination of the tremor with distraction; and tremor amplification with attention, entrainability, suggestibility, and the presence of co‐contraction. Neurophysiological studies include electromyography and accelerometry and can be helpful to make a laboratory‐supported diagnosis when the clinical picture is less clear.
Keywords: functional tremor, functional movement disorder, functional neurological disorder
Author Roles
(1) Research Project: A. Conception, B. Organization, C. Execution; (2) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique.
S.C.L.: 1B, 1C, 2A
A.E.L.: 1A, 1C, 2B
Disclosures
Ethical Compliance Statement
The authors confirm that the approval of an institutional review board was not required for this work. Informed consent was separately obtained for all videotapes taken as part of the routine clinical evaluation as per standard policy in the Toronto Western Hospital Movement Disorders Clinic. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.
Funding Sources and Conflicts of Interest
The authors report no sources of funding and no conflicts of interest.
Financial Disclosures for previous 12 months
A.E.L. reports consultancy support from AbbVie, AFFiRis, Biogen, Janssen, Lilly, Lundbeck, Merck, Paladin, Roche, Sun Pharma, Theravance, and Corticobasal Degeneration Solutions; advisory board support form Jazz Pharma, PhotoPharmics, and Sunovion; other honoraria from Sun Pharma, AbbVie, Sunovion, American Academy of Neurology, and the International Parkinson and Movement Disorder Society; grants from Brain Canada, Canadian Institutes of Health Research, Corticobasal Degeneration Solutions, Edmond J. Safra Philanthropic Foundation, Michael J. Fox Foundation, the Ontario Brain Institute, Parkinson Foundation, Parkinson Canada, and W. Garfield Weston Foundation; and royalties from Elsevier, Saunders, Wiley‐Blackwell, Johns Hopkins Press, and Cambridge University Press.
Supporting information
Video 1: Examination of patients with functional tremor.
Relevant disclosures and conflicts of interest are listed at the end of this article
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Video 1: Examination of patients with functional tremor.