Key messages
Corticosteroid injection into the wrist probably improves symptoms of carpal tunnel syndrome (compression of a nerve in the wrist) and function of the hand for up to six months. Quality of life assessments, and tests of nerve conduction measured up to three months after injection, may also improve. Corticosteroid injection may reduce the need for surgery, assessed at one-year follow-up. Side effects appear to be rare. However, spontaneous improvement without treatment can occur in up to a third of people.
What is carpal tunnel syndrome?
Carpal tunnel syndrome is very common worldwide, affects people's quality of life and has significant financial costs for health systems. Symptoms occur when the median nerve in the wrist becomes 'irritated', which causes pain, tingling, numbness, and sometimes weakness and loss of function, mainly in the hand and fingers.
How is carpal tunnel syndrome treated?
Corticosteroids are medicines that reduce inflammation and swelling. Corticosteroid injections into the carpal tunnel (a narrow passageway surrounded by bones and ligaments on the palm side of the hand) tends to be used for mild or moderate symptoms and is much cheaper than surgery, but its effectiveness and how long any effects last are disputed.
What did we want to do?
We wanted to find out if local corticosteroid ('steroid') injection into the carpal tunnel at the wrist benefits people with carpal tunnel syndrome. The review authors collected and analysed all relevant studies to answer this question and found 14.
What did we do?
We searched medical databases for studies assessing the effects of local corticosteroid injections on symptoms and function of the hands and on improvements in electrical tests for nerve damage (called nerve conduction studies) up to six months after injection. We also looked at requirement for surgery, quality of life and side effects for up to 12 months.
What did we find?
We found nine studies involving 639 people conducted in hospital-based clinics across North America, Europe, and the Middle East. The studies excluded people with underlying conditions that often occur with carpal tunnel syndrome, such as arthritis and diabetes, and all participants had 'mild' or 'moderate' disease at the carpal tunnel.
Local corticosteroid injection probably improves symptoms and function of the hand at up to three months. Local corticosteroid injection probably improves nerve conduction. Quality of life at up to three months may improve and there may be a reduced need for surgery at one year. Serious complication rates were very low but only 66% of the studies reported them.
What are the limitations of the evidence?
Corticosteroid injections might work better or worse in people with more severe disease or with other conditions such as diabetes. We cannot say because those people typically were not included in the studies.
How up to date is this review?
The review authors searched for studies that had been published up to 26 May 2022.
Local corticosteroid injection is effective for the treatment of mild and moderate CTS with benefits lasting up to six months and a reduced need for surgery up to 12 months. Where serious adverse events were reported, they were rare.
Carpal tunnel syndrome (CTS) is a very common clinical syndrome manifested by signs and symptoms of irritation of the median nerve at the carpal tunnel in the wrist. Direct and indirect costs of CTS are substantial, with estimated costs of two billion US dollars for CTS surgery in the USA in 1995 alone. Local corticosteroid injection has been used as a non-surgical treatment for CTS many years, but its effectiveness is still debated.
To evaluate the benefits and harms of corticosteroids injected in or around the carpal tunnel for the treatment of carpal tunnel syndrome compared to no treatment or a placebo injection.
We used standard, extensive Cochrane search Methods. The searches were 7 June 2020 and 26 May 2022.
We included randomised controlled trials (RCTs) or quasi-randomised trials of adults with CTS that included at least one comparison group of local injection of corticosteroid (LCI) into the wrist and one group that received a placebo or no treatment.
We used standard Cochrane methods. Our primary outcome was 1. improvement in symptoms at up to three months of follow-up. Our secondary outcomes were 2. functional improvement, 3. improvement in symptoms at greater than three months of follow-up, 4. improvement in neurophysiological parameters, 5. improvement in imaging parameters, 6. requirement for carpal tunnel surgery, 7. improvement in quality of life and 8. adverse events. We used GRADE to assess the certainty of evidence for each outcome.
We included 14 trials with 994 participants/hands with CTS. Only nine studies (639 participants/hands) had useable data quantitatively and in general, these studies were at low risk of bias except for one quite high-risk study. The trials were conducted in hospital-based clinics across North America, Europe, Asia and the Middle East. All trials used participant-reported outcome measures for symptoms, function and quality of life.
There is probably an improvement in symptoms measured at up to three months of follow-up favouring LCI (standardised mean difference (SMD) −0.77, 95% confidence interval (CI) −0.94 to −0.59; 8 RCTs, 579 participants; moderate-certainty evidence). Up to six months this was still evident favouring LCI (SMD −0.58, 95% CI −0.89 to −0.28; 4 RCTs, 234 participants/hands; moderate-certainty evidence).
There is probably an improvement in function measured at up to three months favouring LCI (SMD −0.62, 95% CI −0.87 to −0.38; 7 RCTs, 499 participants; moderate-certainty evidence). We are uncertain if there is a difference in median nerve DML at up to three months of follow-up (mean difference (MD) −0.37 ms, 95% CI −0.75 to 0.02; 6 RCTs, 359 participants/hands; very low-certainty evidence). The requirement for surgery probably reduces slightly in the LCI group at one year (risk ratio 0.84, 95% CI 0.72 to 0.98; 1 RCT, 111 participants, moderate-certainty evidence). Quality of life, measured at up to three months of follow-up using the Short-Form 6 Dimensions questionnaire (scale from 0.29 to 1.0; higher is better) probably improved slightly in the LCI group (MD 0.07, 95% CI 0.02 to 0.12; 1 RCT, 111 participants; moderate-certainty evidence). Adverse events were uncommon (low-certainty evidence). One study reported 2/364 injections resulted in severe pain which resolved over "several weeks" and 1/364 injections caused a "sympathetic reaction" with a cool, pale hand that completely resolved in 20 minutes. One study (111 participants) reported no serious adverse events, but 65% of LCI-injected and 16% of the placebo-injected participants experienced mild-to-moderate pain lasting less than two weeks. About 9% of participants experienced localised swelling lasting less than two weeks. Four studies (229 participants) reported that they experienced no adverse events in their studies. Three studies (220 participants) did not specifically report adverse events.