Transcutaneous electrical nerve stimulation in combination with cobalamin injection for postherpetic neuralgia: a single-center randomized controlled trial.

The aim of this study was to explore the efficacy of transcutaneous electrical nerve stimulation (TENS) with locally injected cobalamin in relieving pain and improving activities of daily living in patients with postherpetic neuralgia. Ninety patients (≥50 yrs old) with postherpetic neuralgia with a pain score of 4 or greater were randomized to receive TENS and local injections of cobalamin or lidocaine or a combination of cobalamin and lidocaine for 8 wks. Treatment efficacy was assessed on the basis of worst pain severity, global impression of change, activities of daily living, and quality-of-life. Time × group interaction, group differences, and time effect on worst pain at each follow-up point were statistically significant (P < 0.05) among the groups. In the group receiving TENS and local injection of cobalamin and in the group receiving TENS with a combination of cobalamin and lidocaine, the mean ± SD pain scores were 4.0 ± 1.4 and 4.1 ± 1.2 at endpoint, 28 and 26 patients achieved pain reduction of 30% or greater, and 14 and 10 perceived worst pain of 3 or less, respectively. The activities of daily living and quality-of-life data at the study endpoint showed significant benefits in the group receiving TENS and local injection of cobalamin and in the group receiving TENS and a combination of cobalamin and lidocaine (P < 0.05). In the group receiving TENS and local injection of lidocaine, the mean ± SD pain score was 6.1 ± 1.2 at the endpoint relative to baseline (P < 0.05), and only six patients achieved pain reduction of 30% or greater. TENS in combination with local cobalamin injection has a significant analgesic effect.