Does Addition of a Longer Acting Local Anesthetic Improve Postoperative Pain After Carpal Tunnel Release? A Randomized Controlled Trial

Purpose: Carpal tunnel release (CTR) is a simple and effective treatment for carpal tunnel syndrome in patients who have failed nonsurgical management. This surgery is often performed in the ambulatory clinic under local anesthesia, with lidocaine, a short-acting agent. Few studies have investigated the use of longer acting agents, such as bupivacaine, for outpatient CTR. Therefore, the aim of our study was to compare the postoperative pain experience after CTR with the use of either our standard lidocaine solution (control) or a mixture consisting of lidocaine and bupivacaine in equal amounts (intervention).

Methods: Patients undergoing CTR were randomized into control or intervention groups. Postoperative pain severity and numbness were recorded at several timepoints within the first 72 hours. The timing and quantity of postoperative analgesic use (acetaminophen and/or ibuprofen) was also documented. Both patients and assessor were blinded to allocation.

Results: Our study cohort included 139 patients: 67 in the control group and 72 in the intervention group. Postoperative pain scores were significantly lower in the intervention group at 6 hours (2.3 vs 3.2) and 8 hours (2.9 vs 3.9). Additionally, patients in the intervention group reported longer time to first analgesic use than those in the control group (5.2 hours vs 3.7 hours). A greater proportion of patients in the intervention group reported postoperative numbness at nearly all time points, compared to the control group.

Conclusions: Our study shows that a mixture of bupivacaine and lidocaine improves early postoperative pain but causes prolonged finger numbness when compared to lidocaine alone. As both medications are effective and feasible for outpatient CTR, surgeon and patient preference should guide local anesthetic choice.

Type of study/level of evidence: Therapeutic Ib.