Local Steroid Injection vs Wrist Splinting for Carpal Tunnel Syndrome: A Randomized Clinical Trial

Carpal tunnel syndrome (CTS) is caused by the pressure and consequent compression on the median nerve within a confined anatomical area at the wrist referred to as the carpal tunnel. It is very common and has an important socio-economic impact. The prevalence of CTS in the UK is 7-16%. Its incidence has been estimated at 88-125 per 100,000 in USA. Economic consequences include the direct financial implications of treatment and the indirect cost of absenteeism from the workplace. The median number of days away from work for CTS is among the highest at 27 days. In the US in 1995, between 400,000 and 500,000 patients underwent surgical decompression. This equates to an economic cost of in excess of $2 billion. CTS and hearing loss was found to account for more morbidity, measured by cases and working days lost, than any other illness in the US working population. CTS may also occur as a work- related disorder leading to compensation claims.

Despite the vast burden of the disease, there is no consensus regarding its best management. Surgical treatment is generally preferred in severe cases of CTS. A Cochrane review investigating surgical treatment of CTS showed surgical treatment relieves symptoms significantly better than splinting, but no conclusion could be drawn in people with mild symptoms and if surgical treatment is better than steroid injection. On the other hand, surgical treatment is relatively costly and carries risks of significant complications that may last several months and give rise to further work absence. In addition, the waiting time for surgery is usually long.

For non-surgical interventions many modalities have been trialed but only a few have shown discernable benefits. Local steroid injection and wrist splinting are among the most popular options. They are commonly employed in mild to moderate cases of CTS. For severe cases, they can also offer relief of complaints during the waiting period for surgery or when there are contra-indications for surgery. Systematic reviews of randomized controlled trials have concluded that local steroid injection provides greater clinical improvement at one month compared with placebo and that there is weak evidence that a splint worn at night is more effective than no treatment in the short term. However, the number of studies that compare the two methods is limited, and they are mostly either retrospective in design or prospective but non-randomized. Two randomized controlled trials comparing local steroid injection and splinting found respectively that local steroid injection does not significantly improve clinical outcome compared to anti-inflammatory drugs and splinting and that injections of steroids are ineffective. However, the conclusions of these two studies are limited either by a small sample size or the lack of a validated outcome measure.

We would like to conduct a prospective randomized clinical trial comparing the efficacy of local steroid injection and splinting in patients with CTS using the Boston Carpal Tunnel Questionnaire as outcome measure with a 4-week follow-up.

Patients attending the medical clinic of a local hospital (Kwong Wah Hospital) complaining of finger or hand numbness are referred to the electro-neuro-diagnostic unit for nerve conduction test. Consecutive patients with clinical and electrophysiological features of CTS are invited to participate in the study. Clinical features are pain, paresthesia or weakness in the median nerve distribution for at least 3 months. The neurodiagnostic criteria are based on the American Academy of Neurology summary statement, which further classifies the abnormalities as follows: (1) mild abnormality, i.e., abnormal comparative tests or prolonged median distal sensory latency (DSL > 3.5 ms) but normal median distal motor latency (DML); (2) moderate abnormality, i.e., prolonged median DSL and DML (⩾4.2 ms); and (3) severe abnormality, i.e., absence of median sensory nerve action potential and prolonged median DML or absent compound muscle action potentials.