Objective: The aim of this study was to compare the severity of  pain and bruises between a microneedle (34-G) and standard needle (30-G) in patients with HFS with BoNT-A injections.

Background: Botulinum toxin type A (BoNT-A) injection is considered the first-line treatment in patients with hemifacial spasm (HFS), but therapeutic effects are temporarily, resulting in repeated injections that are associated with pain and discomfort. Although the use of microneedle is a common practice for facial aesthetic injections with evidence demonstrating minimal pain and bruises, the evidence in HFS is lacking.

Method: This was a cross-over, double-blind, randomised controlled trial involving 62 HFS patients to receive two,12-week interval, BoNT-A injections with either standard needle or microneedle. All subjects were treated with BoNT-A by the same investigator using the same injection technique. Primary outcomes were pain severity and characteristics, determined immediately after the injections with the Visual Analogue Scale (VAS) and Short-form McGill Pain Questionnaire (SF-MPQ-2). Secondary outcomes were bruised scores, complications, and the efficacy of BoNTA injections as rated by global rating and comprehensive scales at baseline, one week and one-month  following injections

Results: Clinical demographics  were included in Table 1. The majority of subjects female (72.6%), with a mean age of 60.18±11.12 years and a mean disease duration of 5.64±3.98 years. Compared to standard  needle injections, significant reductions of VAS (p<0.001), total SF-MPQ-2 (p<0.001), and bruise scores (p<0.001) were demonstrated with microneedle injections. Complication rates not significantly different between the two procedures (Table 2). Follow-up comparisons indicated a significant difference for a substantial decrease in scores of global rating and comprehensive scales, suggesting that both microneedle and standard needle injections improved patients’ outcomes. (Figure 2)

Conclusion: While clinical benefits were similar between standard and microneedle injections, our study demonstrated significant reductions of pain and bruises with microneedle injections in patients with HFS.

References: 1. Jankovic J, Albanese A, Atassi MZ, Dolly JO, Hallett M, Mayer NH. Botulinum toxin E-Book: Therapeutic clinical practice and science: Elsevier Health Sciences; 2009.
2. Price KM, Williams ZY, Woodward JA. Needle preference in patients receiving cosmetic botulinum toxin type A. Dermatol Surg. 2010;36(1):109-12.
3. Alam M, Geisler A, Sadhwani D, Goyal A, Poon E, Nodzenski M, et al. Effect of Needle Size on Pain Perception in Patients Treated With Botulinum Toxin Type A Injections: A Randomized Clinical Trial. JAMA Dermatol. 2015;151(11):1194-9.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/does-needle-size-matter-in-botulinum-toxin-injection-a-crossover-randomised-controlled-trial-of-microneedle-in-patients-with-hemifacial-spasm/