Objective: Our study aimed to evaluate the clinical outcome of patients with upper-limb dystonic tremor (UL-DTs) treated at a tertiary hospital in London.

Background: Tremor is part of the motor phenomenology of dystonia. Treatments available are oral medication (OM), botulinum neurotoxin (BoNT) and brain surgery (deep brain stimulation or thalamotomy). Few studies have analyzed the outcome with the different treatment options, and evidence is especially scarce in the UL-DTs (1,2).

Method: Subjects assessed between August 2016 and October 2021 were retrospectively included. Demographic, clinical and treatment data were analyzed. Outcome measures considered were drop-out rates, side effects, and the 7-points patient-based clinical global impression scale (p-CGI-S, 1: very much improved, 7: very much worse).

Results: Forty-seven subjects (46.8% female) were included with a median age at onset of 58 yrs [7-86]. Thirty-one subjects were treated with OM, 31 with BoNT and 7 with surgery. The drop-out rate with OM was 74.2% due to either inefficacy (N=10) or side effects (N=13). Seven patients treated with BoNT (22.6%) had a mild weakness determining drop-out only in 1. P-CGI-S was ≤ 3 (improvement) in 39% with OM, compared to 92 % with BoNT and 100% with surgery. Abo-botulinum toxin (mean ± SD Units, 250 ± 164.1) and Inco-botulinum toxin (mean ± SD Units, 68.6 ± 35.7) were equally used. Muscles more injected were pronator teres, longus supinator and biceps braquialis as the pattern of tremor functionally disabling was more frequently prono-supination and arm flexion.

Conclusion: Our findings suggest an excellent response of the UL-DTs to BoNT and surgery with higher rates of drop-out and side effects with OM. Further studies are needed to provide more evidence, but BoNT injections seem effective and safe to be considered the first-line therapeutic option for UL-DTs. Brain surgery should be reserved for the most disabling and resistant cases.

References: 1. Fasano A, Bove F, Lang AE. The treatment of dystonic tremor: a systematic review. J Neurol Neurosurg Psychiatry 2014;85(7):759-69. doi: 10.1136/jnnp-2013-305532 [published Online First: 2013/10/30]
2. Rajan R, Srivastava AK, Anandapadmanabhan R, et al. Assessment of Botulinum Neurotoxin Injection for Dystonic Hand Tremor: A Randomized Clinical Trial. JAMA Neurol 2021;78(3):302-11. doi: 10.1001/jamaneurol.2020.4766 [published Online First: 2020/12/22].

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MDS Abstracts - https://www.mdsabstracts.org/abstract/treatment-of-upper-limb-dystonic-tremors-a-retrospective-study/