Hand tremor in MS can be very debilitating leading to an inability to hold things, as well as leading to hand weakness. In many instances, this is due to involvement of the cerebellum (part of the brain dealing with coordination), rather than the basal ganglia that is involved in Parkinson’s.
MS-related tremors tend to respond poorly to oral medications used for tremor control (for example, propranolol, primidone, gabapentin etc.). Deep-brain stimulation (see diagram below) was popular as a treatment option when it came out, but outcomes have been variable especially when there is an ataxic (swaying side to side) component, suggesting it’s originating from the cerebellum.
However, all is not lost. It would seem that there may be place for botox in the treatment of tremor in MS.
In analysis of all publications for tremor Zheng and colleagues noted that botox into the forearms significantly ameliorated tremor (see Figure below); a similar response was not observed in Parkinson’s-related tremor.
The only draw back of using botox is the secondary weakness that occurs with muscle relaxation; with 30-70% of individuals experiencing hand weakness in the low-dose to high-dose botox group, respectively.
Neurol Neurochir Pol. 2020 Oct 13. doi: 10.5603/PJNNS.a2020.0079. Online ahead of print.
Botulinum toxin type A for hand tremor: a meta-analysis of randomised controlled trials
Background: Tremor is one of the most common movement disorders. It does not usually respond to first-line drug treatments (e.g. propranolol, primidone, anticholinergics, gabapentin and clonazepam) due to side effects and frequent dose limitations. Botulinum toxin type A (BoNT-A) has been widely used to treat tremor, but its efficacy and safety are uncertain.
Aims: To evaluate the efficacy and safety of BoNT-A in the treatment of hand tremor.
Methods: We searched the MEDLINE, EMBASE, PsycINFO and Cochrane Library databases for relevant randomised controlled trials of the effects of BoNT-A injections on tremors, up to 20 February 2020. A meta-analysis of comparative effects was performed using R studio software, and publication bias was examined using Egger’s test.
Results: Six studies examining a total of 245 participants with tremor were included in the meta-analysis. The primary outcome of meta-analysis showed no difference in clinical tremor scale scores between the BoNT-A group versus the placebo group (standardised mean difference (SMD): -0.42, 95% confidence interval (CI): -1.94 to 1.10; I2 = 96%). For clinical tremor scale scores, subgroup analyses suggested that the BoNT-A group may differ in terms of multiple sclerosis (MS) related tremor (SMD: -1.10; 95% CI: -2.17 to -0.04; I2 = 79%) compared to a placebo, but the difference did not exist in the outcome of essential tremor (ET) or hand tremor (MD: -1.31; 95% CI: -3.39; 1.31; I2 = 97%). Grip strength (MD: -1.25, 95% CI: -5.99 to 3.50, I2 = 97%) was slightly lower in the BoNT-A group, but the difference was not significant. The incidence of adverse events (AEs), including hand weakness (RR: 2.96, 95% CI: 1.40 to 6.24, I2 = 37%), was significantly greater in the BoNT-A group than in the placebo group. Two studies were assessed as having an overall low risk of bias.
Conclusions: Our study confirms that BoNT-A injections are unlikely to have an impact on patients with hand tremors. However, subgroup analysis suggested that BoNT-A injections could have possible benefits in MS-related tremor. While moderate to severe hand weakness AEs often limits their use in clinical practice, additional well-designed double-blind, placebo-controlled trials are needed to provide more robust conclusions.