Acupuncture for Carpal Tunnel Syndrome: A Systematic Review of Randomized Controlled Trials

This systematic review represents the first comprehensive analysis of randomized controlled trials on the effectiveness of acupuncture in the treatment of carpal tunnel syndrome (CTS). CTS is a common neuropathy caused by compression of the median nerve at the wrist, resulting in numbness, tingling, hand pain, and muscle dysfunction. It affects approximately 1 to 3 people per 1,000 per year in the United States, with a higher prevalence in women.

The investigators conducted systematic searches in 11 electronic databases without language restrictions, including Asian databases often overlooked in previous reviews. Of 159 articles initially identified, only 6 randomized controlled trials met the rigorous inclusion criteria, enrolling 442 patients with CTS confirmed by electrodiagnostic parameters or specific clinical criteria.

The methodology of the included studies was evaluated using the Cochrane risk-of-bias tool, revealing generally low methodological quality. Only 2 of the 6 studies used adequate methods for random sequence generation, and none reported details on allocation concealment. Only 1 study adequately implemented blinding procedures for patients and assessors, which is particularly problematic considering that subjective outcomes are susceptible to expectation bias.

Acupuncture treatments varied considerably across studies. Five studies evaluated manual needle acupuncture, while one tested laser acupuncture. A total of 21 acupuncture points were used, with 85.7% located in the upper extremity, especially the hand and wrist on the affected side. The most commonly used points were PC-6, PC-7, and PC-8.

All studies stated that they followed Traditional Chinese Medicine theory for point selection, but the prescription was not consistent across studies.

Treatment duration ranged from 2.8 to 6 weeks, with an average of 4.1 weeks. Three studies considered the deqi (得氣, arrival of qi) sensation, though its role in efficacy has not been determined. Only 2 studies reported acupuncture-related adverse events: one noted that 56 of 173 total adverse events were acupuncture-related in 24 patients, while another found a 5% rate of adverse events in the acupuncture group. Importantly, no serious adverse events were reported.

Results showed mixed patterns. Only one study compared real acupuncture versus sham acupuncture with penetrating needles, failing to demonstrate specific effects of real acupuncture. A laser acupuncture study showed a favorable effect over sham acupuncture for nocturnal pain, but with a very small sample (n=26) susceptible to type II error.

The most robust meta-analysis compared acupuncture versus steroid block therapy, including 2 studies with 144 patients. Results significantly favored acupuncture in terms of response rate (RR 1.28; 95% CI 1.08-1.52; P=0.005), with low heterogeneity between studies (I²=10%). This finding suggests that acupuncture may be more effective than steroid injections for some patients with CTS.

One study compared acupuncture with oral steroids, showing superiority only in distal motor latency on nerve conduction studies. Another study evaluated acupuncture combined with tuina massage versus massage alone, demonstrating a favorable effect of acupuncture on median nerve conduction velocity.

The limitations of this review are substantial and significantly affect the interpretation of results. The limited number of included studies (only 6) and their low methodological quality represent important obstacles. The heterogeneity in acupuncture prescriptions, treatment duration, and frequency makes it difficult to generalize the findings. There is only one sham-controlled trial for needle acupuncture, severely limiting the evidence on specific acupuncture effects.

Additionally, 4 of the 6 studies originated from China, where previous research has demonstrated that virtually all acupuncture studies report positive results, raising questions about publication bias and data reliability. The possibility of selective publication of small, negative studies represents another potential source of bias.

The clinical implications remain uncertain. Although the results are encouraging, especially when compared with steroid blocks, the evidence is not convincing enough to establish acupuncture as a first-line treatment for CTS. Safety appears acceptable based on the limited data available, but more information is needed.

This review highlights the urgent need for studies of higher methodological quality, with adequate randomization, allocation concealment, appropriate blinding, and larger samples. Future studies should also standardize acupuncture protocols and include adequate sham control groups to definitively establish whether acupuncture has specific therapeutic value for CTS beyond placebo or nonspecific effects.