Objective: This study explored the efficacy of local methylcobalamin injection in relieving pain and improving the quality of life among subjects with subacute herpetic neuralgia.
Design: A single-center, randomized controlled trial of local methylcobalamin injection was performed.
Subjects: Ninety-eight subjects (age, ≥ 50 years) with unilateral, dermatomal pain ≥ 4 related to herpes zoster on the torso lasting for 30 days after onset of rash were enrolled.
Methods: Subjects were randomized to receive local methylcobalamin injection (N = 33), oral methylcobalamin (N = 33), or subcutaneous 1.0% lidocaine injection (N = 32) for 4 weeks. Worst pain severity, global impression of change, continuous spontaneous pain, paroxysmal pain, allodynia, paresthesia, interference with activities of daily living, and quality of life were assessed after 28-day treatment period.
Results: Time per group interaction and group difference on overall pain at each follow-up point were statistically significant (P < 0.001) among groups. In the injected methylcobalamin group, the overall pain (P < 0.001), continuous spontaneous pain (P < 0.05), paroxysmal pain (P < 0.05), and allodynia (P < 0.05) revealed a significant effect at each follow-up point as compared with the other groups. Twenty subjects achieved pain reduction ≥ 50%, 24 perceived worst pain ≤ 3, 24 stopped using analgesics at end point; activities of daily living and quality of life improved significantly as compared with the other groups (P < 0.001). Although both of the other groups showed a significant response after the 14-day treatment (P < 0.001) compared with the baseline, oral methylcobalamin did not provide any significantly pain relief (P > 0.05).
Conclusions: Local methylcobalamin injection was not only efficacious in relieving pain, but also appears to be tolerable and a potential choice of treatment for subacute herpetic neuralgia.
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