Interventional Treatments for Postherpetic Neuralgia: A Systematic Review

Background: Postherpetic neuralgia, a persistent pain condition often characterized by allodyniaand hyperalgesia, is a deleterious consequence experienced by patients after an acute herpeszoster vesicular eruption has healed. The pain associated with postherpetic neuralgia can severelyaffect a patient’s quality of life, quality of sleep, and ability to participate in activities of daily living.Currently, first-line treatments for this condition include the administration of medication therapiessuch as tricyclic antidepressants, pregabalin, gabapentin, and lidocaine patches, followed by theapplication of tramadol and capsaicin creams and patches as second- or third-line therapies. As notall patients respond to such conservative options, however, interventional therapies are valuablefor those who continue to experience pain.Objective: This review focuses on interventional therapies that have been subjected torandomized controlled trials for the treatment of postherpetic neuralgia, including transcutaneouselectrical nerve stimulation; local botulinum toxin A, cobalamin, and triamcinolone injection;intrathecal methylprednisolone and midazolam injection; stellate ganglion block; dorsal rootganglion destruction; and pulsed radiofrequency therapy. Study Design: Systematic reviewSetting: Hospital department in TaiwanMethods: Search of PubMed database for all randomized controlled trials regarding postherpeticneuralgia that were published before the end of May 2017.Results: The current evidence is insufficient for determining the single best interventionaltreatment. Considering invasiveness, price, and safety, the subcutaneous injection of botulinumtoxin A or triamcinolone, transcutaneous electrical nerve stimulation, peripheral nerve stimulation,and stellate ganglion block are recommended first, followed by paravertebral block and pulsedradiofrequency. If severe pain persists, spinal cord stimulation could be considered. Given thedestructiveness of dorsal root ganglion and adverse events of intrathecal methylprednisoloneinjection, these interventions should be carried out with great care and only followingcomprehensive discussion.Limitations: Although few adverse effects were reported, these procedures are invasive, and acareful assessment of the risk-benefit ratio should be conducted prior to administration.Conclusion: With the exception of intrathecal methylprednisolone injection for postherpeticneuralgia, the evidence for most interventional procedures used to treat postherpetic neuralgia isLevel 2, according to “The Oxford Levels of Evidence 2”. Therefore, these modalities have receivedonly grade B recommendations. Despite the lack of a high level of evidence, spinal cord stimulationand peripheral nerve stimulation are possibly useful for the treatment of postherpetic neuralgia.Key words: Interventional treatment, postherpetic neuralgia, botulinum toxin, steroid, stellateganglion block, peripheral nerve stimulation, paravertebral block, radiofrequency, spinal cordstimulation