To assess whether 3D motion capture data can differentiate Holmes tremor (HT) from more common tremors.

HT is a rare complex, irregular tremor consisting of rest, postural, and action components. This typically arises from neurologic insult to the brainstem, thalamus, or cerebellum.

We performed a cross-sectional study of N=436 patients assessed with quantitative motion capture between 2014 and 2020 (N=436). Patients with HT (N=11), Parkinson’s disease (PD), and essential tremor (ET) were identified. After aggregating data for analysis and excluding cases with incomplete kinematic data, N=193 patients (N=10 Holmes, N=110 PD, N=73 ET) were available.

Standard ~1-hour full body motion capture session protocols generated data including peak tremor amplitude (TA), tremor frequency (TF), and tremor constancy (TC) during rest, posture, or action.  ANOVA analyses assessed differences across HT, PD, and ET.

HT patients were predominantly female (63.6%) with an average age of 60 ± 11 y.  Comparison patients were closely matched on sex (P=0.99) and age (P=0.66).

Among HT patients, most tremor occurred at rest (40%), followed by action (36%) and postural tasks (24%). Both PD and ET patients trended towards more postural and less action tremor (41% and 18%, respectively, P=0.07). Among HT patients, average TF was 3.2 ± 0.9 Hz, average TA was 62 ± 37 mm, and average TC was 66 ± 23 %. ANOVAs identified significant differences across groups in TA (P<0.001) and TF (P<0.001). Both PD and ET exhibited smaller TAs (11 ± 18 mm, PD; 16 ± 13 mm, ET), and faster TFs (3.3 ± 1.3 Hz, PD; 4.2 ± 1.1 Hz, ET).

Quantitative description of tremor characteristics may be useful in the differential diagnosis and management of tremor disorders including HT.