Carpal tunnel syndrome (CTS) is a condition where one of two main nerves in the wrist is compressed, which can lead to pain in the hand, wrist and sometimes arm, and numbness and tingling in the thumb, index and long finger. Splinting is usually offered to people with mild to moderate symptoms. However, the effectiveness and duration of the benefit of splinting for this condition remain unknown.
To compare the effectiveness of splinting for carpal tunnel syndrome with no treatment, placebo or another non-surgical intervention.
We searched the Cochrane Neuromuscular Disease Group Specialized Register (10 January 2011), CENTRAL, NHSEED and DARE (The Cochrane Library 2011, Issue 4), MEDLINE (January 1966 to December 2011), EMBASE (January 1980 to January 2012), AMED (January 1985 to January 2012), and CINAHL Plus (January 1937 to January 2012), using no time limits. We searched the reference lists of all included trials and relevant reviews for further relevant studies.
All randomised and quasi-randomised trials comparing splinting with no treatment (or a placebo) or with other non-surgical treatments were eligible for inclusion. We also included studies comparing one splint type or regimen versus another. We excluded studies comparing splinting with surgical treatment. There were no language restrictions. We included all patients diagnosed with carpal tunnel syndrome unless they had undergone surgical release.
Data collection and analysis
Two review authors independently selected trials for inclusion, and performed data extraction. Two authors also independently performed the assessment of risk of bias. We calculated measures of effect as risk ratios (RR) for dichotomous outcomes and mean differences (MD) for continuous outcomes, with 95% confidence intervals (CI) reported and statistical significance set at P < 0.05 for all outcome comparisons.
The review included 19 studies randomising 1190 participants with carpal tunnel syndrome. Two studies compared splinting with no treatment, five compared different splint designs, one compared different splint-wearing regimens, seven compared splint delivered as a single intervention with another non-surgical intervention, and five compared splint delivered alongside other non-surgical interventions with another non-surgical intervention. Only three studies reported concealing the allocation sequence, and only one reported blinding of participants. Three studies measured the primary outcome, short-term overall improvement at three months or less. One low quality study with 80 wrists found that compared to no treatment, splints worn at night more than tripled the likelihood of reporting overall improvement at the end of four weeks of treatment (RR 3.86, 95% CI 2.29 to 6.51). However, the lack of patient blinding and unclear allocation concealment suggests this result should be interpreted with caution. A very low quality quasi-randomised trial with 90 wrists found that wearing a neutral splint more than doubled the likelihood of reporting 'a lot or complete relief' at the end of two weeks of treatment compared with an extension splint (RR 2.43, 95% CI 1.12 to 5.28). The third study which measured short-term overall improvement did not report outcome data separately per group. Nine studies measured adverse effects of splinting and all found either no or few participants reporting discomfort or swelling due to splinting; however, the precision of all RRs was very low. Differences between groups in the secondary outcomes - symptoms, function, and neurophysiologic parameters - were most commonly small with 95% CIs incorporating effects in either direction.
Overall, there is limited evidence that a splint worn at night is more effective than no treatment in the short term, but there is insufficient evidence regarding the effectiveness and safety of one splint design or wearing regimen over others, and of splint over other non-surgical interventions for CTS. More research is needed on the long-term effects of this intervention for CTS.