Pain Fluctuations of Women with Subacute Herpetic Neuralgia During Local Methylcobalamin in Combination with Lidocaine Treatment: A Single-Blinded Randomized Controlled Trial

Gang Xu,1 Weizhen Tang,1 Chaosheng Zhou,1 Jie Xu,1 Chao Cheng,1 Weiwei Gong,2,3 Shihong Dong,2 Yu Zhang1 1Department of Rehabilitation Medicine, Affiliated Tenth People’s Hospital of Tongji University, Shanghai Tenth People’s Hospital, Shanghai, 200072, People’s Republic of China; 2Department of Rehabilitation Medicine, Tongji University School of Medicine, Shanghai, 200092, People’s Republic of China; 3Department of Rehabilitation Medicine, Shanghai First Rehabilitation Hospital, Shanghai, 200090, People’s Republic of ChinaCorrespondence: Gang Xu, Department of Rehabilitation Medicine, Affiliated Tenth People’s Hospital of Tongji University, Shanghai Tenth People’s Hospital, 301 Middle Yanchang Road, Shanghai, 200072, People’s Republic of China, Tel +8621-66306496, Fax +8621-66301051, Email sykfsci@126.comPurpose: To evaluate the efficacy and pain fluctuations of methylcobalamin in combination with lidocaine local injection treatment for subacute herpetic neuralgia (SHN).Methods: Seventy-nine women (60.4 ± 2.7 years) with thoracic SHN were enrolled and randomized to receive a combination of methylcobalamin and lidocaine local injection (MI, N=40), or a combination of lidocaine patch 5% and oral methylcobalamin (PO, N=39) for four weeks. Repeated-measures analyses of variance were used to evaluate the effect on pain levels. Generalized estimation equations were used to analyze the cause-effect relationship between pain fluctuations and influencing factors.Results: At the treatment endpoint, the group, treatment time, and group interacted with treatment time effects of the pain scores and area were statistically significant (P< 0.001), The pain scores were 2.9 ± 0.9 (MI) and 4.3 ± 1.5 (PO). 80.00% (MI) or 28.21% (PO) of patients had pain scores ≤ 3, the odds ratio was 2.84 (95% CI: 1.68 to 4.79). The incidence of postherpetic neuralgia was 5.0% (2/40) at 3 months. Pain fluctuated repeatedly during treatment. The pain fluctuation increased from 8.75 log folds in the afternoon, to 79.85 log folds at night. With the ADLs level increasing from 1 to 3, the pain fluctuated from 4.28 to 17.70 log folds. Allodynia, itching, sleep quality, and ADLs were the significant influencing factors (P< 0.05).Conclusion: This study validated the efficacy of methylcobalamin combined with lidocaine for SHN, and confirmed that pain levels in patients with SHN had an obvious circadian rhythm. ADLs were an important cause of pain fluctuations.Keywords: subacute herpetic neuralgia, methylcobalamin, lidocaine, pain fluctuation, activities of daily living