Objective: To describe the case of a patient with postherpetic neuralgia (PHN) who had a marked response to topiramate despite failure of several previous therapies.
Case summary: A 79-year-old white male with multiple medical comorbidities developed severe trigeminal territory PHN requiring treatment with opiates to maintain adequate pain relief. Topiramate was initiated after the patient failed treatment with 4 other antiepileptic medications due to various adverse events. After 3 months of topiramate therapy, with dosages up to 50 mg twice daily, PHN pain had decreased to the point that the patient was able to discontinue the use of opiates entirely. At time of writing, he continued to be maintained on topiramate 50 mg twice daily with good pain relief and no reported adverse effects.
Discussion: Topiramate exhibits a number of actions that may contribute to the relief of neuropathic pain, including modulation of voltage-gated sodium and calcium channels, potentiation of gamma-aminobutyric acid inhibition, and blockade of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainite glutamate receptors. Current evidence-based recommendations consider topiramate to be a third-line agent for the treatment of neuropathic pain based on studies of its use in painful diabetic neuropathy and chronic lumbar radicular pain. A comprehensive search of MEDLINE (1950-August 2008) using the terms postherpetic neuralgia, neuralgia, and topiramate revealed only one previously published case report evaluating the use of topiramate specifically for treatment of PHN.
Conclusions: While it is impossible to determine whether pain relief in this case was due to treatment with topiramate as opposed to spontaneous resolution of pain over time, this additional case report suggests that topiramate may be a useful treatment option for patients with PHN who have not responded to or are intolerant of other interventions. Further studies are needed to determine whether topiramate should receive a stronger recommendation for the treatment of PHN.