Computer vision of smartphone video has potential to detect functional tremor

Published:April 12, 2019DOI:https://doi.org/10.1016/j.jns.2019.04.016
      Functional neurological disorders (FND) constitute more than 15% of referrals to neurology clinics [
      • Stone J.
      • Carson A.
      • Duncan R.
      • et al.
      Who is referred to neurology clinics?—the diagnoses made in 3781 new patients.
      ], and functional tremor is the most common functional movement disorder [
      • Factor S.A.
      • Podskalny G.D.
      • Molho E.S.
      Psychogenic movement disorders: frequency, clinical profile, and characteristics.
      ]. Physical features of a functional tremor include: tremor present at rest, posture and action; variability in frequency and direction; and reduction or abolition of tremor with distraction [
      • Factor S.A.
      • Podskalny G.D.
      • Molho E.S.
      Psychogenic movement disorders: frequency, clinical profile, and characteristics.
      ]. Tremor judgement by eye is inherently subjective and imprecise [
      • Bajaj N.P.S.
      • Gontu V.
      • Birchall J.
      • Patterson J.
      • Grosset D.G.
      • Lees A.J.
      Accuracy of clinical diagnosis in tremulous parkinsonian patients: a blinded video study.
      ], and a need for objective tests is recognised [
      • Schwingenschuh P.
      • Katschnig P.
      • Seiler S.
      • et al.
      Moving toward “laboratory-supported” criteria for psychogenic tremor.
      ]. Although laboratory accelerometery can distinguish functional tremor from other tremors [
      • Schwingenschuh P.
      • Katschnig P.
      • Seiler S.
      • et al.
      Moving toward “laboratory-supported” criteria for psychogenic tremor.
      ], it is a limited resource. Smartphone accelerometers can measure tremor frequency and discriminate tremor type [
      • Barrantes S.
      • Sánchez Egea A.J.
      • González Rojas H.A.
      • et al.
      Differential diagnosis between Parkinson's disease and essential tremor using the smartphone's accelerometer.
      ], but a clinical test whereby patients hold a smartphone is not one that has entered routine practice. An alternative ubiquitous item of hardware that could be used to assess tremor is the camera (present in smartphones, personal computers, CCTV). Computer vision technology uses algorithms to detect and interpret the contents of camera images [
      • Xie X.
      • Jones M.
      • Tam G.
      Recognition, tracking, and optimisation.
      ]. It is widely used commercially, e.g. facial recognition, but there are only a few reports of its application within neurology. Here we describe early results for computer vision of functional tremor.

      Keywords

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