Letter to the Editor. Clinical Rating Scale for Tremor: a needed clarification

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  • 1 Toronto Western Hospital, University of Toronto, ON, Canada
  • | 2 Université de Sherbrooke, QC, Canada
  • | 3 Henan University School of Medicine, Zhengzhou, China
  • | 4 University of Louisville, School of Medicine, Louisville, KY
  • | 5 School of Medicine, University of Tartu, Estonia
  • | 6 Krembil Brain Institute, Toronto, ON, Canada
  • | 7 Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, UHN, Toronto, ON, Canada
  • | 8 University of Toronto, ON, Canada
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TO THE EDITOR: We read with great interest the article of Sinai and colleagues1 and we would like to clarify some issues related to the Clinical Rating Scale for Tremor (CRST), one of the most commonly used tremor assessment scales (Sinai A, Nassar M, Eran A, et al. Magnetic resonance–guided focused ultrasound thalamotomy for essential tremor: a 5-year single-center experience. J Neurosurg. 2020;133[2]:417-424).

First published in 1988, the CRST was developed by Fahn, Tolosa, and Marin, and contains three parts.2 Part A quantifies tremor at rest (R) and/or on action (postural [P] or kinetic [K]) of the following body sites: 1) face (R); 2) tongue (R/P); 3) voice (K); 4) head (R/P); 5) trunk (R/P); 6 and 7) right and left upper limbs (R/P/K); and 8 and 9) right and left lower limbs (R/P/K). Part B assesses kinetic tremor of the upper limbs during writing (only dominant hand), three drawing tasks, and water pouring (both hands). Part C assesses the functional disability and includes speaking, eating, drinking, hygiene, dressing, writing, and working.

Each item is rated on a scale from 0 to 4. The maximum possible scores of the first version of CRST are 80, 36, and 28 for Parts A, B, and C, respectively; thus the maximum possible total score is 144.2 In 1993, a revised version of the CRST was published adding two items to part A (face postural and orthostatic tremor) and social activities to Part C, thus resulting in a maximum possible score of 156.3

There are several noteworthy inaccuracies in the original CRST papers.2,3 The first version2 did not contain the "face (P)" item either in the description or in the calculations part; however, a scoring box was provided for it in the scorecard. In the second version,3 the "face (P)" score was written in the text but the assessment method while posture holding was not specified. Another inaccuracy of this version is the presence of a box for the "voice (P)" item in the scorecard, although it was not referred to in the text and calculations. In fact, face tremor cannot be assessed while holding a posture. In our clinical practice we have been using a modified version of the CRST omitting the "face (P)" item with a maximum score of 152 instead of 156. However, to keep in line with the existing literature, we have been forced to use the original 156-point scale in our prospective trials.

A version of the CRST with a 160-point maximum score as stated by Sinai and colleagues1 and Xiong and colleagues in their response letter4 has never existed. The confusion may result from two scoring boxes placed near the handwriting section (scored only for the dominant hand) in the original article.3 A similar error exists in a Neurosurgical Focus article,5 in which the maximum CRST and Part A score was noted as 160 and 32, instead of 156 and 88, respectively.

Although available digitally,6 the original CRST forms may be challenging to access. We note that unreviewed web sources exist that share problematic forms. To avoid such misuse, herein we share the CRST form designed for the Bilateral focused ultrasound thalamotomy for essential tremor (BEST-FUS) trial in a sequence optimized for video-recorded physical examinations.7,8

References

  • 1

    Sinai A, Nassar M, Eran A, et al. Magnetic resonance–guided focused ultrasound thalamotomy for essential tremor: a 5-year single-center experience. J Neurosurg. 2020;133(2):417424.

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  • 2

    Fahn S, Tolosa E, Marin C. Clinical rating scale for tremor. In: Jankovic J, Tolosa E, eds. Parkinson’s Disease and Movement Disorders. Urban & Schwarzenberg;1988:225234.

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  • 3

    Fahn S, Tolosa E, Marin C. Clinical rating scale for tremor. In: Jankovic J, Tolosa E, ed. Parkinson’s Disease and Movement Disorders. 2nd ed.Williams & Wilkins;1993:271280.

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  • 4

    Xiong Y, He J, Lou X. Errors about the use of the Clinical Rating Scale for Tremor score. Letter. J Neurosurg. 2020;133(2):605.

  • 5

    Mohammed N, Patra D, Nanda A. A meta-analysis of outcomes and complications of magnetic resonance–guided focused ultrasound in the treatment of essential tremor. Neurosurg Focus. 2018;44(2):E4.

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  • 6

    University Consortium. Hathitrust Digital Library. Accessed September 17, 2021.https://www.hathitrust.org

  • 7

    Iorio-Morin C, Yamamoto K, Sarica C, et al. Bilateral focused ultrasound thalamotomy for essential tremor (BEST-FUS phase II trial). Mov Disord. Published online July 20, 2021. doi:10.1002/mds.28716

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  • 8

    Iorio-Morin C, Yamamoto K, Sarica C, et al. Bilateral focused ultrasound thalamotomy for essential tremor (BEST-FUS phase II trial). Scorecard. July 2021.Accessed September 17, 2021. https://www.researchgate.net/publication/353437520_CRST_scorecardpdf

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Response

No response was received from the authors of the original article.

  • 1

    Sinai A, Nassar M, Eran A, et al. Magnetic resonance–guided focused ultrasound thalamotomy for essential tremor: a 5-year single-center experience. J Neurosurg. 2020;133(2):417424.

    • Search Google Scholar
    • Export Citation
  • 2

    Fahn S, Tolosa E, Marin C. Clinical rating scale for tremor. In: Jankovic J, Tolosa E, eds. Parkinson’s Disease and Movement Disorders. Urban & Schwarzenberg;1988:225234.

    • Search Google Scholar
    • Export Citation
  • 3

    Fahn S, Tolosa E, Marin C. Clinical rating scale for tremor. In: Jankovic J, Tolosa E, ed. Parkinson’s Disease and Movement Disorders. 2nd ed.Williams & Wilkins;1993:271280.

    • Search Google Scholar
    • Export Citation
  • 4

    Xiong Y, He J, Lou X. Errors about the use of the Clinical Rating Scale for Tremor score. Letter. J Neurosurg. 2020;133(2):605.

  • 5

    Mohammed N, Patra D, Nanda A. A meta-analysis of outcomes and complications of magnetic resonance–guided focused ultrasound in the treatment of essential tremor. Neurosurg Focus. 2018;44(2):E4.

    • Search Google Scholar
    • Export Citation
  • 6

    University Consortium. Hathitrust Digital Library. Accessed September 17, 2021.https://www.hathitrust.org

  • 7

    Iorio-Morin C, Yamamoto K, Sarica C, et al. Bilateral focused ultrasound thalamotomy for essential tremor (BEST-FUS phase II trial). Mov Disord. Published online July 20, 2021. doi:10.1002/mds.28716

    • Search Google Scholar
    • Export Citation
  • 8

    Iorio-Morin C, Yamamoto K, Sarica C, et al. Bilateral focused ultrasound thalamotomy for essential tremor (BEST-FUS phase II trial). Scorecard. July 2021.Accessed September 17, 2021. https://www.researchgate.net/publication/353437520_CRST_scorecardpdf

    • Search Google Scholar
    • Export Citation

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