Effectiveness of perampanel in managing chronic pain caused by the complex regional pain syndrome A case report

Rationale: The alpha-amino-3-hydroxy-5-methy-4-isoxazole propionate (AMPA) receptor plays a critical role in the development and persistence of pain, and AMPA receptor antagonists are considered possible therapeutic targets for controlling pain. This report describes a patient with complex regional pain syndrome (CRPS) type I in the right lower leg and foot who responded well to perampanel, an AMPA receptor antagonist, for managing the chronic pain. Patient concern: A 61-year-old woman complained of pain in her right lower leg and foot over a period of 7 year (numeric rating scale: 8) due to CRPS type I. Diagnosis: CRPS type 1. Interventions: Despite the combination of 300 mg pregabalin, 225 mg/1950 mg tramadol/acetaminophen, and 10 mg nortriptyline per day, her right lower leg and foot were nearly disabled due to the severity of the pain. High-dose prednisolone was found to be ineffective. Then, perampanel (4 mg; 2 mg twice) was administered to this patient daily. Outcomes: The day after treatment with perampanel, her pain completely disappeared. Additionally, at day 7 and 1 month follow-up, she reported no pain in the right lower leg and foot. Moreover, no adverse effects were reported after the application of perampanel. Lessons: These results suggest that perampanel may potentially be used to treat centralized pain.