Acupuncture for the treatment of trigeminal neuralgia: A systematic review and meta-analysis

This systematic review and meta-analysis examined the efficacy of acupuncture in the treatment of trigeminal neuralgia, a neurological condition characterized by severe and intermittent facial pain. Trigeminal neuralgia affects between 0.03% and 0.3% of the population, mainly women aged 37-67, causing electric-shock-like pain that can become chronic and resistant to treatment. Standard treatment with carbamazepine frequently produces significant side effects such as bone marrow suppression, memory loss, and cognitive impairment. The researchers conducted a comprehensive search of 11 databases through November 2022, including PubMed, Embase, Cochrane, and Asian databases.

Thirty randomized controlled trials involving 2,295 patients, all conducted in China, were included. Study quality was assessed using the Cochrane RoB 2 tool, and certainty of evidence was rated using the GRADE system. The intervention consisted of traditional manual acupuncture, with points selected based on traditional Chinese medicine theory. The most commonly used points included Hegu (LI-4), Xiaguan (ST-7), Taiyang (EX-HN5), and Fengchi (GB-20), followed by Yintang (EX-HN3), Shenting (GV-24), and Renzhong (GV-26).

Sessions lasted between 20-40 minutes, performed daily or 5-6 times per week, for periods of 4 weeks to 3 months. Results showed that acupuncture was superior to carbamazepine across multiple outcomes. For pain measured by visual analog scale (15 studies), there was a mean difference of -1.40 points favoring acupuncture (95% CI: -1.82 to -0.98). The response rate was higher with acupuncture in 29 studies (RR 1.20, 95% CI: 1.15-1.25).

Two studies reported reduction in pain attack frequency (MD -2.53, 95% CI: -4.11 to -0.96). Importantly, acupuncture resulted in significantly fewer adverse events compared to carbamazepine (RD -0.15, 95% CI: -0.19 to -0.11). Proposed mechanisms for acupuncture analgesia include activation of pain afferents in the dorsal horn of the spinal cord, stimulation of the descending pain suppression system, and modulation of the central nervous system through endogenous opioid receptors. The diffuse noxious inhibitory control (DNIC) theory suggests that noxious stimuli can immediately inhibit pain transmission in trigeminal neurons.

However, the quality of evidence was rated low to very low due to several limitations. Risk of bias assessment showed concerns in all studies, mainly due to lack of adequate blinding and unclear randomization methods. Only one study reported adequate allocation concealment. There was substantial heterogeneity between studies (I² = 96% for pain), and funnel plots suggested possible publication bias.

All studies were conducted in China, limiting the generalizability of findings. Clinical implications suggest that, although acupuncture may offer benefits for patients with trigeminal neuralgia, including fewer adverse effects than standard pharmacological therapy, current evidence is insufficient for definitive recommendations. Future studies should adhere to CONSORT and STRICTA standards, include appropriate blinding, adequate randomization, and be conducted in different countries and populations. Longitudinal studies are necessary to determine the long-term effects and safety of acupuncture for this debilitating condition.