Objective: To determine the prevalence of tremor in patients with oromandibular dystonia, characterise its anatomical distribution relative to dystonic regions, and assess the relationship between tremor severity and dystonia severity using the Global Dystonia Rating Scale (GDRS).

Background: Dystonia is defined by the Movement Disorder Society as a movement disorder characterised by sustained or intermittent abnormal movements or postures that are often patterned and repetitive.¹ Oromandibular dystonia (OMD), a focal cranial dystonia involving the jaw, tongue, and lower facial muscles, can significantly impair speech and mastication. OMD accounts for approximately 3–5% of dystonia cases and shows marked phenotypic heterogeneity.² Tremor in dystonia is classified as dystonic tremor (DT) or tremor associated with dystonia (TAWD), but its prevalence and distribution in OMD remain poorly characterised.³

Method: A retrospective observational study included 57 patients with clinically diagnosed oromandibular dystonia at a tertiary movement disorders centre. Clinical records and archived videos were reviewed. Dystonia severity was assessed using the Global Dystonia Rating Scale. Tremor distribution was evaluated and classified as dystonic tremor (DT) or tremor associated with dystonia (TAWD). Descriptive statistics and Pearson correlation were used for analysis.

Results: The mean GDRS score was 16.93 ± 9.68. Tremor was present in 34 of 57 patients (59.6%). Among these, tremor predominantly occurred within dystonic regions, consistent with dystonic tremor in 23 (67.64%) patients, while TAWD was observed in 6 (17.6%) patients, and overlap was seen in 5 (14.7%). The mean tremor score was 3.74 ± 4.38. A moderate positive correlation was observed between dystonia severity and tremor severity (r = 0.515), with p = 0.00004. Tremor was most frequently distributed in the jaw and tongue (49.1%), followed by the lower face (24.6%) and bilateral distal upper limbs (14.0% each).

Conclusion: Tremor is a common but underecognished feature of Oromandibular Dystonia, affecting nearly 60% of patients in this cohort. The predominance of dystonic tremor supports its role as an intrinsic component of the OMD motor phenotype and highlights the importance of systematic tremor assessment in cranial dystonia.

References: 1. Albanese, Alberto et al. “Definition and Classification of Dystonia.” Movement disorders: official journal of the Movement Disorder Society vol. 40,7 (2025): 1248-1259. doi:10.1002/mds.30220
2. Scorr, Laura M et al. “Oromandibular Dystonia: A Clinical Examination of 2,020 Cases.” Frontiers in neurology vol. 12, 700714. 16 Sep. 2021
3. Bhatia, Kailash P et al. “Consensus Statement on the classification of tremors. from the task force on tremor of the International Parkinson and Movement Disorder Society.” Movement disorders: official journal of the Movement Disorder Society vol. 33,1 (2018): 75-87.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tremor-in-oromandibular-dystonia/