The effect of an Intravenous Ketamine Infusion on Postherpetic Neuralgia

Background: About 10~25% patients with herpes zoster suffers from postherpetic neuralgia (PHN). Yet, there is no certain treatment for PHN. Ketamine, an N-methyl-D-aspartate receptor (NMDA) antagonist, plays an important role in the central sensitization. In this aspect, we tried to find out the effect of IV ketamine in herpes zoster patients who suffered from PHN. Methods: 40 herpes zoster patients with Visual Analogue Scale (VAS) > 5 after the antiviral, antidepressant and nerve block therapy over 4 weeks were enrolled in this study. 50mg of ketamine and 2.5mg of midazolam was mixed in 100mL of normal saline and administered intravenously to the patients for 1 hour. And we compare with the group who did not use IV ketamine by the chart review. Results: VAS was significantly decreased by approximately 75% after the use of IV Ketamine whereas there was no significant change of VAS after not the use of IV Ketamine. Conclusions: Use of IV ketamine is beneficial for pain control in treatment of patients with high risk of PHN.