Objectives: We wanted to determine whether any treatment had been shown to reduce pain or disability from postherpetic neuralgia (PHN), a common sequela of herpes zoster in elderly patients.
Study design: We undertook a systematic review of English-language randomized controlled trials (RCTs) of treatments of PHN with evaluation periods longer than 24 hours.
Data sources: We systematically searched MEDLINE, Current Contents, and the Cochrane Library. We also searched reference lists of identified trials and reviews and contacted content experts.
Outcomes measured: Two reviewers independently evaluated RCTs for methodologic quality and data extraction. Outcomes of primary focus were pain and quality of life.
Results: Twenty-seven RCTs met inclusion criteria and were reviewed. Six trials of tricyclic antidepressants found evidence for clinically meaningful effects over 6 weeks. All other treatments were evaluated in no more than 2 trials meeting our inclusion criteria. Topical capsaicin 0.075%, gabapentin, and controlled-release oxycodone were shown to be effective, but the clinically meaningful benefit is difficult to quantify. Intrathecal methylprednisolone and possibly bupivacaine sympathetic blocks are helpful in refractory cases. Other treatments evaluated, including topical lidocaine, had no evidence or inconsistent evidence of benefit.
Conclusions: No single best treatment for PHN is known. Tricyclic antidepressants, topical capsaicin, gabapentin, and oxycodone are effective for alleviating PHN; however, long-term, clinically meaningful benefits are uncertain and side effects are common. Patients with PHN refractory to these therapies may benefit from intrathecal methylprednisolone. Little evidence is available regarding treatment of PHN of less than 6 months' duration.