Treating carpal tunnel syndrome

BACKGROUND CTS is a common problem caused by compression of the median nerve at the wrist resulting in hand numbness, loss of dexterity, muscle wasting, and decreased functional ability at work. This study investigated the efficacy of a corticosteroid injection just proximal (not into) the carpal tunnel for CTS.

Study participants included 60 patients referred to a neurology clinic in Amsterdam, Netherlands, with CTS symptoms for longer than 3 months' duration and confirmed with electrophysiological tests. Patients in the intervention and control groups had symptoms for an average of 32 months and 25 months, respectively. In patients with bilateral symptoms, the arm with the most severe symptoms was chosen for randomization. Patients aged younger than 18 years and those who had previous treatment for CTS were excluded. STUDY DESIGN AND VALIDITY: Patients were randomized to receive an injection of either lignocaine (Lidocaine 10 mg) and methylprednisolone 40 mg or a lignocaine 10-mg injection only. The site of injection was proximal to the carpal tunnel on the volar side of the forearm 4 cm proximal to the wrist crease, between the tendon of the radial flexor muscle and the long palmar muscle. Injections were given at a 10 degrees to 20 degrees angle with a 3-cm needle. At baseline, there were no significant differences between the control group and the intervention group. The study was performed at one clinic where one neurologist performed all injections. Thus, we do not know if the results of this technique can be consistently reproduced. No patients were reported lost to follow-up at 1 year. To ensure blinding of the treatment assignment, a pharmacist wrapped the syringes in paper and a second neurologist performed outcomes assessment interviews. One month after the initial injection, patients were asked whether they had no symptoms or only minor symptoms that they considered so much improved that they felt no further treatment was necessary. Investigators broke the trial code at follow-up assessment visits to offer nonresponders an injection with methylprednisolone or surgery.

Patients were considered improved if they self-reported no symptoms or only minor symptoms needing no additional treatment. Other symptoms (weakness, nighttime pain) or impact on lifestyle and occupation were not reported.

At 1 month, 20% of the patients in the control group had improved compared with 77% of patients in the intervention group (P <.001; number needed to treat = 1.8). After 1 year, 8 of the 23 patients (35%) who initially responded to methylprednisolone required a second injection. A total of 86% of nonresponders in the control group improved after receiving a methylprednisolone injection, but 50% of these patients went on to need surgical treatment within 1 year. The investigators reported no side effects to the injection.