Article Text

Download PDFPDF
How to use the entrainment test in the diagnosis of functional tremor
  1. Louise S Roper1,
  2. Tabish A Saifee2,
  3. Isabel Parees2,
  4. Hugh Rickards3,
  5. Mark J Edwards2
  1. 1University of Birmingham, Birmingham, West Midlands, UK
  2. 2Sobell Department of Motor Neuroscience, Institute of Neurology, Queen Square, London, UK
  3. 3Department of Neuropsychiatry, University of Birmingham and Barberry National Centre for Mental Health, Birmingham, UK
  1. Correspondence to Dr Mark J Edwards, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; m.j.edwards{at}

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


Functional (psychogenic) tremor is the commonest functional movement disorder.1 As with other functional neurological symptoms, a key diagnostic component is to search for positive physical signs.1 ,2

A key positive sign in a patient with functional tremor is a change in the tremor with distraction of attention.1 There are several potential distraction tasks, but the ‘entrainment test’ is the most important.2 ,3 Here, the clinician asks the patient to tap another limb at a different frequency to the tremor. We present a method of performing and interpreting the entrainment test.

What are we looking for?

The term ‘entrainment test’ suggests that we are looking for ‘pure’ entrainment. This is where the tremor frequency switches to match exactly the frequency of a voluntary rhythmical movement performed by the unaffected limb. In reality, this is not that common—tremor recordings found pure entrainment in only 5 of 13 patients2 and 2 of 6 patients.3 In practice, therefore, we are looking for three broader responses to the entrainment (see online supplementary videos):

  1. a shift in the tremor frequency, with pauses or other disruption to the tremor when tapping at a different frequency with the other limb;

  2. poor task performance—a paradoxical and inexplicable difficulty to tap at a different frequency to the tremor with the other (usually unaffected) limb;

  3. pure entrainment, when the tremor frequency shifts to match the frequency of tapping.

How to do it

This technique is for the most common clinical situation: asymmetric or unilateral tremor of the arm or hand. (see online supplementary videos and box 1).

Box 1

Aide Mémoire for Performing and Interpreting the ‘Entrainment Test’.

  • What to do

  • Place the patient in the position in which there are the most tremors (usually arms out in front).

  • Move the least tremoring or …

View Full Text


  • Competing interests None.

  • Provenance and peer review Commissioned; externally peer reviewed. This paper was reviewed by Jon Stone, Edinburgh, UK

Linked Articles

  • Editors' Choice
    Phil Smith Geraint N Fuller

Other content recommended for you