Chronic pain after carpal tunnel surgery: epidemiology and associated factors.

Background: Chronic postoperative pain (CPOP) has been assessed after major orthopedic surgeries but not after carpal tunnel surgery (CTS). This study aimed at describing the evolution of nocturnal and diurnal pains during the year following CTS, and at looking for factors associated with CPOP.

Methods: Cohort of adult outpatients operated by one single surgeon, under regional anaesthesia (RA). Patients were questioned in the recovery room, and phoned 3 days and 12 months later. A multivariate analysis tested the association between CPOP and preoperative demographics, regional anaesthesia protocol, pain during RA, surgery and the first 3 postoperative days, postoperative complications.

Results: Between November 2006 and June 2010, 324 of 389 patients could be included. The nocturnal and diurnal pains disappeared on the evening of the procedure in 55% (180/324) and 50% (163/324) of patients respectively. At one year, 12% of patients (40/324) complained of pain which characteristic was similar to the preoperative one, and 22% (71/324) complained of a new pain (different from the preoperative one), which was therefore considered as CPOP. CPOP was associated with a decreased functional score (QuickDASH). After multivariate analysis, CPOP was associated with postoperative pain from D0 to D3 (p=0.02), minor postoperative complications (p<0.001) and absence of hypnotic approach during surgery (p=0.01).

Conclusion: One year after CTS, 22% of patients have CPOP. This incidence is similar to the one observed after major surgeries. This study suggests for the first time that a hypnotic approach during the surgical procedure might decrease the CPOP incidence.