Key messages
– We found very uncertain evidence on improvements in symptoms, function and quality of life after treatment with corticosteroid injection or surgery for carpal tunnel syndrome, from which we could not draw conclusions.
– We could not assess differences in unwanted effects, although serious unwanted effects were infrequent.
– Electrical studies of nerve function may improve slightly more after surgery than after corticosteroid injection when measured at three months of follow-up (monitoring).
What is carpal tunnel syndrome?
Carpal tunnel syndrome is very common worldwide. Symptoms occur when the median nerve in the wrist becomes 'irritated'. This causes pain, tingling, numbness, and sometimes weakness and loss of function, mainly in the hand and fingers. It affects people's quality of life and has significant financial costs for health systems.
How is carpal tunnel syndrome treated?
Corticosteroids are medicines that reduce inflammation and swelling. Corticosteroid injections into the carpal tunnel (a narrow passageway in the wrist surrounded by bones and ligaments on the palm side of the hand) tend to be used for mild or moderate symptoms. While these injections are much cheaper than surgery, their effectiveness and how long the effects last are disputed. Surgery is typically a simple and quick procedure that is done using just local anaesthetic (only the area of the wrist is numbed).
What did we want to do?
We wanted to compare the benefits of local corticosteroid injection into the carpal tunnel at the wrist to the benefits of surgery.
What did we do?
We searched for studies assessing the effects of corticosteroid injections on symptoms and function of the hands and on improvements in electrical tests for nerve damage (called nerve conduction studies). We also looked at quality of life and unwanted effects up to 12 months.
What did we find?
We found seven studies involving 569 'hands' with mild to moderate carpal tunnel syndrome. The studies randomly put people into two groups. One group received one injection of corticosteroid and the other group received surgery.
In every study, all symptoms improved in both surgery and corticosteroid groups after treatment. The evidence comparing corticosteroid injection and surgery was too uncertain for any conclusions to be drawn about differences in symptoms or function, quality of life or unwanted effects. Surgery may improve nerve conduction at three months than after corticosteroid injection, based on electrical studies, but this evidence was also uncertain. Serious side effects were infrequent, but again the evidence was too uncertain for conclusions to be drawn.
What are the limitations of the evidence?
In all studies, the participants and healthcare providers were aware of treatment and expectations about the effects of surgery or corticosteroid injections could have influenced their judgements of how effective they were. Results varied greatly among the studies, possibly because the studies were small, and the doses and types of corticosteroid varied, as did the measures used.
How up to date is this review?
We searched for studies that had been published up to 26 May 2022.
The evidence comparing LCI to surgery for CTS, either in the short term or up to 12 months' follow-up, is too uncertain for any reliable conclusions to be drawn.
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 alone. Local corticosteroid injection has been used as a non-surgical treatment for CTS for 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 (CTS) compared to surgery.
We used standard, extensive Cochrane search methods. We searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, and WHO ICTRP. The latest search was 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 corticosteroid injection (LCI) into the wrist and one group of any surgical intervention.
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. improvement in quality of life and 7. adverse events. We used GRADE to assess the certainty of evidence for each outcome.
We included seven studies involving 569 'hands' (although two studies had unusable data for quantitative analyses). All studies used a one-time LCI as a comparator, using several different types and doses of corticosteroids. In every study, for both surgery and LCI groups, all our primary and secondary outcomes showed improvement from pre- to post-treatment. However, evidence from the combined analysis was too uncertain for us to draw reliable conclusions for the comparison of surgical treatment versus LCI with respect to our primary outcome of symptom relief at up to three months' follow-up (standardised mean difference (SMD) 0.63, 95% confidence interval (CI) −0.61 to 1.88; I2 = 95%; 5 trials, 305 participants; very low-certainty evidence).
Findings with respect to secondary outcome measures of symptom relief at greater than three months' follow-up (SMD 0.94, 95% CI −0.31 to 2.19; I2 = 93%; 4 trials, 235 participants), functional improvement at up to three months' follow-up (SMD −0.11, 95% CI −0.94 to 0.72; I2 = 84%; 3 trials, 215 participants) and functional improvement at greater than three months' follow-up (SMD 0.19, 95% CI −1.22 to 1.59; I2 = 93%; 3 trials, 185 participants) were also uncertain (very low-certainty evidence) and showed no clear advantage for surgery or LCI. Surgery may improve neurophysiology (median nerve distal motor latency) more than LCI (mean difference (MD) 0.87 ms, 95% CI 0.32 to 1.42; I2 = 72%; 3 trials, 162 participants; low-certainty evidence). Evidence for quality of life and adverse events was also uncertain; quality of life (EuroQol-5D-3L) may be slightly improved after LCI than after surgery (the difference may not be clinically important) (MD 0.07, 95% CI 0.02 to 0.12; 1 trial, 38 participants; very low-certainty evidence) and there may be fewer adverse events with LCI than with surgery (risk ratio (RR) 0.34, 95% CI 0.04 to 3.26; 3 trials, 112 participants; very low-certainty evidence).