In cases that do not respond well to conservative treatment, surgical decompression of the flexor retinaculum is recommended, which is the definitive therapy for CTS. Indications for surgical referral include failure to respond to conservative treatment, severe CTS based on NCS (prolonged distal motor latencies, slowed sensory conduction velocities) or EMG (denervation of the abductor pollicis brevis muscle).
In carpal tunnel release surgery, the goal is to divide the flexor retinaculum in two. The surgeon must be careful to avoid the superficial palmar vascular arch (branch of the ulnar artery), the superficial branch of the radial artery, and the palmar cutaneous branches of the median and ulnar nerves. Once divided the flexor retinaculum no longer presses down on the median nerve, relieving the pressure and subsequently symptoms.
The two major types of surgery are open carpal tunnel release (OCTR) and endoscopic carpal tunnel release (ECTR). Most surgeons historically have performed the open procedure, widely considered to be the gold standard. Both approaches are brief outpatient procedures and have similar efficacy both in the short term and long term. An article in the Cochrane Database of Systematic Reviews states that endoscopic surgery results in return to work or lifestyle activities six days earlier and fewer wound problems than OCTR, but possible disadvantages may be higher complication rates and cost1. The additional expense for such a small advantage over OCTR in terms of return to work is not justified to overturn OCTR as the gold standard in favor of ECTR. However, the decision to use ECTR instead of OCTR is still guided by the surgeon's and patient's preferences as well as available resources.
If no improvement in symptoms or function is evident following a sufficient post-operative recovery period to ensure that post-operative comlication are not responsible for the delayed improvement, than the first step would be to confirm the initial diagnosis. Following that it may be a case of inadequate or incomplete decompression or intra-operative trauma to the median nerve.
In general population cases, carpal tunnel release surgery is frequently reported to give excellent results. However, there are far fewer studies that evaluate the effectiveness of surgery among patients with WRCTS and those that have been done have not consistently demonstrated favourable outcomes. A study in Washingston state found that among worker's compensation claimants with WRCTS, 59% experienced no or only moderate relief of symptoms2. Another study found that 23% of worker's who had carpal tunnel release surgery were still out of work 6 months after surgery because of symptom persistence3. This study also found that one of the biggest prepoperative predictors for symptom persistence was exposure to hand intensive work3. This evidence indicates that occupational exposures must be controlled if adequate recovery is to be achieved. This is another reason why it is important to take an occupational history during the first medical encounter and flesh out any suspect occupational exposures.
1Scholten RJPM, Mink van der Molen A, Uitdehaag BMJ, Bouter LM, de Vet HCW. Surgical treatment options for carpal tunnel syndrome. Cochrane Database Systematic Review 2007, 4;CD003905.
2Adams ML, Franklin GM, Barnhart S. 1994. Outcomes of carpal tunnel surgery in Washington State workers' compensation. American Journal of Industrial Medicine 25:527-536.
3Katz JN, Keller RB, Fossel AH, Punnett L, Bessette L, Simmons BP, Mooney N. 1997. Predictors of return to work following carpal tunnel release. Am J Ind Med 32:85-91.
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