postherpetic neuralgia
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In a recent study, researchers examined whether Vitamin B12 is suitable for treating the pain symptoms in those with postherpetic neuralgia.

Postherpetic neuralgia is a painful complication that occurs after a normally latent virus that resides in neural cells (specifically the sensory ganglia) is reactivated. This virus is the varicella-zoster virus, which is responsible for herpes zoster. Postherpetic neuralgia is also a common complication of shingles.

There are several medications that can be used for pain relief, especially since this complication can be debilitating and often reduce the quality of life of those affected. Pain therapies can be ineffective and some can even have adverse reactions to the drugs, especially when the drugs are utilized in senior patients.

Vitamin B12 has some proven properties, including its ability to contribute to neural development and growth, as well as its ability to contribute to pain relief in neural conditions. Similar results have been shown to be true in animal studies. However, the full mechanism of vitamin B12, its effects, and its interactions are unknown. Wang and colleagues were interested in seeing the effect of Vitamin B12 on managing symptoms in postherpetic neuralgia. Their study was published in Complementary Therapies in Medicine.

The authors performed a systematic review, which involves searching several databases for evidence for or against vitamin B12 efficacy in the context of postherpetic neuralgia therapy. The authors even searched for evidence in unpublished studies. They limited their search to randomized control trials. The authors originally retrieved 9000 articles from their search and were able to narrow it down to four studies for their analysis.

Vitamin B12 may reduce pain and increase the quality of life

Overall, the evidence presented in the studies were of moderate quality. Overall, the overarching results suggest that vitamin B12 increases the quality of life in those with postherpetic neuralgia and reduces pain, based on the 11-point pain intensity numerical rating scale.

With vitamin B12 administration, the evidence also showed that individuals with postherpetic neuralgia had a reduced use of analgesics. The patients examined in the studies were mostly senior patients, so the applicability of these results may be better applied to the elderly.

Results may not be applied to all individuals with postherpetic neuralgia

Despite evidence of some instances of vitamin B12 promoting pain relief in various neural conditions (e.g. reducing lower back pain) and their varying rates of success with either oral or injectable Vitamin B12, there is also contradictory evidence in select disorders suggesting no effect at all. One example of this is the contradictory evidence of vitamin B12 effect in diabetic neuropathy. Even some evidence of Vitamin B12 on postherpetic neuralgia is contradictory.

The authors emphasize that the studies examined were essentially non-comparable at times because of differences in factors like how the vitamin B12 was diluted. There were also several limitations. The studies tended to have small patient numbers, and the phases of postherpetic neuralgia studied also varied. The studies analyzed may have also been of moderate quality because of suspected biases in some of the studies.

In conclusion, despite the suggested benefits of vitamin B12 in quality of life, pain relief, and analgesics use reduction in postherpetic neuralgia, there is a strong recommendation for future studies with clear consistent methods and a larger number of study participants.

Written by Olajumoke Marissa Ologundudu B.Sc. (Hons)

Reference: Wang JY, et al. Vitamin B12 for herpetic neuralgia: A meta-analysis of randomised controlled trials. Complementary Therapies in Medicine.2018; 41:277–282.doi: https://doi.org/10.1016/j.ctim.2018.10.014.

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