Is Vibration Anesthesia Effective and Safe for Pain Reduction in Botulinum Toxin Injection? A Randomized Split-Face Controlled Trial and Cadaver Experiment.

Background: Pain is an important issue in botulinum toxin injection. Vibration anesthesia is a noninvasive way for pain alleviation, but few study reported its use during botulinum toxin injection.

Objectives: To investigate whether vibration anesthesia is effective and safe for pain reduction during botulinum toxin injection for masseter reduction.

Methods: A randomized split-face controlled trial was performed in patients who required masseter reduction. Vibration anesthesia was randomly administered on either side. Study outcomes were pain scores on a visual analog scale, duration of effect, satisfaction, and complications. Intergroup comparison and linear regression analyses were performed.

Results: In a total of 216 patients, the pain score on the vibration side (2.97 ± 1.44) was significantly lower than that on the non-vibration side (4.72 ± 2.13) (p < 0.0001), with a higher proportion of mild pain. Linear regression showed that history of injection, more injection points and doses increased the pain, while 2 ml syringe reduced the pain compared to 1ml syringe. Side effects were found in 19 patients and 21 sides (7%), but were not associated with vibration. High satisfactions were reported. Cadaver experiment confirmed that vibration did not alter the diffusion radius and depth of injection.

Conclusions: Vibration anesthesia could significantly relieve the pain during botulinum toxin injection for masseter reduction, while did not affect adverse effect and effect duration. Therefore, we recommended the use of vibration anesthesia, larger syringe size, and less injection points to improve patient experience and satisfaction.