[Experience of botulinum toxin in treatment of writer's cramp]

Efficacy and safety of botulinum toxin-A in writer’s cramp: a systematic review, meta-analysis, and meta-regression

Background

Botulinum toxin-A (BoNT) reduce over-firing of dystonic muscles, spasmodic contractions by enhancing function. We conducted a systematic review and random-effects meta-regression to investigate the efficacy and safety of BoNT in writer’s cramp (WC). Published electronic articles from inception till January 2022 were screened from four databases (Medline, Science Direct, Scopus, ProQuest). Effect sizes in the form of standardized mean differences were calculated for estimation of efficacy.

Results

Nineteen studies [six randomized control trials (RCTs) and 13 observational studies] involved 587 (514 experimental; 73 Controls) participants with mean age of 43.46 ± 8.84 years with mean duration of WC of 8.31 ± 5.35 years. Injection did not result in significant improvement in writing speed [standard mean difference (95% CI) 0.06 (− 0.35, 0.46)]. There was no significant difference in writing speed as compared to controls [standard mean difference (95% CI) − 0.51 (− 2.55, 1.52)]. The meta-analysis of observational studies showed a significant difference in the mean WC rating score [standard mean difference (95% CI) 0.54 (0.20, 0.88)]. Pooled analysis (observational studies and RCTs) demonstrated a significant difference in the mean Writer’s cramp rating score (WCRS) after BoNT [standard mean difference (95% CI) 0.75 (0.06, 1.44)]. No major safety concerns were reported in the included studies.

Conclusions

According to the meta-analysis of observational studies, BoNT injections are effective in WC for improving WCRS without major safety concerns. However, according to the meta-analysis of RCTs, there was no significant effect in efficacy with BoNT.

Botulinum neurotoxin a therapy efficacy and safety for oromandibular dystonia: a meta-analysis

Oromandibular dystonia (OMD) is a focal dystonia involving the mouth, jaw, and tongue. Botulinum neurotoxin (BoNT) therapy might be one form of treatment in OMD. Systematic pooling of BoNT studies in OMD remains wanting, as the derived data could provide useful information in regard to efficacy and safety issues. This meta-analysis determined the effects of botulinum neurotoxin type A (BoNT/A) on the reduction of dystonic movement and its safety among patients with OMD. A systematic search of the literature that met the following eligibility criteria were done: (1) patients treated with BoNT/A for OMD, (2) studies of high methodological quality and (3) outcome criteria specified as regard to efficacy. Risk of unresolved dystonia was computed before and after BoNT/A intervention. Random effect size (p < 0.05ɑ) and test of heterogeneity (< I2 50%) were computed as meta-analysis tool using REVMAN ver 5.3 program. Safety data, where available, were systematically reviewed. Nine studies involved 387 cases in total of OMD. The pooled risk ratio is 0.607 with a confidence interval of 0.371-0.783, a z value of 3.85, and a p value of 0.0001. Results indicate that risk of dystonic movements is lower by 39.30% in the treatment group than in the control group. A total of 105/387 patients (27.1%) experienced adverse events most commonly dysphagia. Whilst cited literatures have inherent weaknesses, results show that BoNT/A is efficacious in reducing dystonic movements of patients with OMD. Majority of studies employed electromyography (EMG) guidance in muscle targeting. Given the potential adverse event of dysphagia, one may take a cautious stand while delivering injections to target muscles. These findings are congruent with what has been published in regard to efficacy of BoNT/A in focal dystonia.