Effect of topical anesthetics on needle insertion pain during botulinum toxin type A injections for limb spasticity

Abstract

Objective: To compare pain perception using 3 anesthetics (eutectic mixture of local anesthetics [EMLA], vapocoolant spray, and ice) compared with a control (no anesthetic) during botulinum toxin type A (BTX-A) injections for lower limb spasticity.

Design: A placebo-controlled, single-blinded study where each study patient served as their own control.

Setting: Spasticity clinic.

Participants: Subjects (N=30) with ankle spasticity who visited the clinic for BTX-A injections in the gastrocnemius muscle were consecutively sampled.

Intervention: The gastrocnemius muscle was divided into 4 quadrants and 1 of the 3 different anesthetic agents was applied to each quadrant with 1 quadrant using no anesthetic, control.

Main outcome measures: Numerical Rating Scale (NRS) and the Wong-Baker FACES scale.

Results: Pain perception using the NRS and FACES scale was significantly lower using ice and EMLA compared with control and spray conditions (P<.05). Pain perception using EMLA and ice was similar. These results indicate that patients experience minimal to moderate pain during BTX-A injections.

Conclusions: Pain relief offered by EMLA and ice was comparable, suggesting that ice is a more convenient option because of brief application time (compared with EMLA). Spray may have made the patients more sensitive to pain and alternative approaches for using vapocoolant should be considered.