Effect of Topical Anesthetics on Needle Insertion Pain During Botulinum Toxin Type A Injections for Limb Spasticity

Fung S, Phadke CP, Kam A, Ismail F, Boulias C. Effect of topical anesthetics on needle insertion pain during botulinum toxin type A injections for limb spasticity.ObjectiveTo 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.DesignA placebo-controlled, single-blinded study where each study patient served as their own control.SettingSpasticity clinic.ParticipantsSubjects (N=30) with ankle spasticity who visited the clinic for BTX-A injections in the gastrocnemius muscle were consecutively sampled.InterventionThe 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 MeasuresNumerical Rating Scale (NRS) and the Wong-Baker FACES scale.ResultsPain 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.ConclusionsPain 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.