Objective: To compare patient and clinician assessments of head tremor (HT) presence and severity in isolated cervical dystonia (CD).

Background: Over 50% of people with CD have HT that may respond to treatment with botulinum neurotoxin (BoNT) injections. However, efficacy trials of BoNT in CD have not assessed changes in HT.

Method: First, we compared patient and clinician reports of HT presence at trough periods just prior to receiving BoNT injections and at times of expected peak BoNT effectiveness.  Then, among the patients who reported HT at trough, we compared patient-reported and clinician-reported assessments of HT severity at trough and peak.  The patient-reported metric was rated on a Likert-scale of 0 to 10 in response to the question, “How much shaking or tremor do you have in your neck or head?”  Patients were asked to consider the prior week.  The clinician-reported metric was assessed using a global severity scale (0-10) based on video recording of the patient maintaining a midline head posture and at the null point.

Results: At trough, patient and clinician agreed on the presence of HT 50% of the time (8 of 16 patients).  At peak, patient and clinician agreed on the presence of HT 44% of the time (7 of 16 patients).  Of the 12 patients who reported HT at trough, 7 reported less HT, 3 no change, and 2 more HT at time of expected peak benefit from BoNT.  The change in patient-reported HT severity from trough to peak reached statistical significance based on 1-sided Wilcoxon signed rank test (S= -23 p=0.041).  For those same 12 patients, clinician-reported HT severity decreased in 1, did not change in 6, and increased in 5 after BoNT.  This was not a statistically significant change (S=16.5, p=0.781).

Conclusion: There was a significant improvement in HT based on patient report but not based on clinician report.  Patient and clinician reports are not equivalent when assessing HT in CD.  The differences may be due to internal tremors, varying observation times, and random fluctuation.  More research is needed to determine which is useful in assessing treatment response, or whether they are complementary.

An abstract reporting more preliminary results from this study was presented at the annual meeting of the American Academy of Neurology on April 8, 2025.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/do-we-agree-patient-and-clinician-ratings-of-head-tremor-in-isolated-cervical-dystonia/