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Topical Anesthetics for Reducing Injection Pain in Open Carpal Tunnel Surgery : A Randomized Controlled Trial Comparing EMLA, Maxilene 5% and Placebo
December Olivia Joy Sampson, MD
Montreal University, Montreal, QC, Canada
IntroductionCarpal tunnel release (CTR) is among the most frequently performed hand surgeries. While outcomes are typically excellent, patients often report the local-regional anesthetic injection as the most painful and anxiety-inducing aspect of the perioperative experience.
ObjectiveTo evaluate whether topical anesthetic creams reduce pain during local-regional anesthesia for CTR.
Materials & MethodsThis was a prospective, randomized, double-blind, placebo-controlled trial conducted at our institution. Patients undergoing CTR between June 2024 to June 2025 were recruited. Patients were excluded if they were allergic to the anesthetic creams' contents, used regular analgesic medication, had a diagnosis of chronic pain, had previously undergone CTR on the ipsilateral hand (ie. reoperation), were to undergo concurrent procedures or if their study form was incomplete. Patients undergoing open CTR were randomized to receive one of three treatments: lidocaine-prilocaine 2.5%:2.5%, liposomal lidocaine 5%, or placebo. Creams were applied to the volar wrist at least 60 minutes prior to local-regional anesthesia. The primary outcome was pain during needle insertion and injection, assessed via a visual analog scale (VAS1). Secondary outcomes included daily postoperative pain scores and analgesic consumption (Acetaminophen, Celecoxib, Hydromorphone). Pain outcomes were additionally stratified by surgeon to assess the impact of individual injection techniques. Regression models were used in a subgroup analysis to identify predictors of pain.
ResultsA total of 117 wrists from 98 patients were analyzed. There were no significant differences in VAS1 scores among the three cream groups (p = 0.2313), nor in postoperative pain scores (VAS2: p = 0.9301; VAS3: p = 0.1947) or analgesic consumption (acetaminophen p = 0.9061; celecoxib p = 0.8373; hydromorphone p = 0.5010). However, the surgeon performing the injection significantly influenced pain scores (p = 0.0014). Univariate regression showed that male sex (p = 0.0018), lower anxiety scores (p < 0.0001), cream A (p = 0.0400) and injection by surgeon 2 (p = 0.0134) or surgeon 3 (p = 0.0022) were associated with lower pain scores. Multivariate regression modeling identified female sex and anxiety as the best predictors of higher pain scores during injection.
ConclusionsTopical anesthetic creams did not significantly reduce pain during local-regional anesthesia or reduce postoperative analgesic consumption compared to placebo in CTR surgery. Variability in pain experience was strongly associated with injector technique, sex, and pre-procedural anxiety. These findings suggest that provider training and addressing patient anxiety may be more impactful than topical agents in improving the perioperative experience for patients.
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