Acupuncture and vitamin B12 injection for Bell's palsy: no high-quality evidence exists

This meta-analysis investigated the efficacy of combining acupuncture with vitamin B12 injection for the treatment of Bell's facial palsy, a condition that affects 20-30 people per 100,000 in the general population. Bell's palsy is an acute, idiopathic facial paralysis that results in unilateral facial weakness or paralysis, with about 71% of untreated patients recovering completely and 84% having complete or near-normal recovery within 6 months.

Investigators performed a comprehensive search of medical databases (Medline, Web of Science, CNKI, CBM) through April 2014, looking for randomized clinical trials that compared acupuncture alone with acupuncture combined with vitamin B12. Of 384 studies initially identified, only 5 met the rigorous inclusion criteria, totaling 344 patients (173 in the combined group and 171 in the acupuncture-only group).

The methodology included patients with Bell's palsy treated for at least 4 weeks, with the primary outcome being the incomplete recovery rate (defined as House-Brackmann grade ≥2). The main acupuncture points used were Taiyang (EX-HN5), Jiache (ST-6), Dicang (ST-4), and Sibai (ST-2). Four studies used mecobalamin (the active form of vitamin B12) and one used vitamin B12, administered by injection into acupuncture points.

Results showed a statistically significant difference favoring combined treatment. The incomplete recovery rate was 44.5% in the acupuncture-plus-vitamin-B12 group versus 62.6% in the acupuncture-alone group. The relative risk was 0.71 (95% CI: 0.58-0.87; p=0.001), suggesting that patients receiving combined treatment had a 29% greater likelihood of complete recovery than those receiving acupuncture alone.

In subgroup analysis, electroacupuncture demonstrated significantly greater benefit than manual acupuncture (p=0.024). There were no significant differences between vitamin B12 and mecobalamin, or between treatment in the acute versus non-acute stage of disease, although statistical power for these analyses was limited.

Clinical implications suggest a potential synergistic benefit of vitamin B12 when administered by injection into acupuncture points. The proposed mechanism involves maintenance of myelin metabolism by vitamin B12, potentiating the effects of acupuncture on neurotransmitter regulation and local blood flow improvement.

However, the meta-analysis has important limitations that compromise the reliability of the results. First, all included studies had moderate to low methodological quality. Only one study used adequate allocation concealment and masking, and none performed blinded outcome assessment. Second, the total number of participants was small (344) distributed across only 5 studies.

Third, the funnel plot revealed evidence of publication bias, with asymmetric distribution of studies.

In addition, all studies were conducted in China, most used vitamin B12 from the same pharmaceutical company, and some studies did not adequately report funding sources, raising questions about conflicts of interest and selection bias. The heterogeneity of treatment protocols (administration frequency ranging from daily to every other day) also limits the generalizability of the findings.

The authors concluded that, despite the statistically positive result, the evidence remains uncertain due to methodological limitations. They recommend prospective double-blind studies with more rigorous design to definitively establish the efficacy of combined treatment. The quality of evidence was considered low to moderate, requiring caution in the clinical interpretation of these results.