Case Report: Intravenous fosphenytoin successfully treated acute exacerbation of secondary trigeminal neuralgia due to petroclival meningioma.

Introduction: Trigeminal neuralgia (TN) is a severe paroxysmal neuropathic pain disorder. While various strategies have been proposed for managing acute exacerbations of classical TN, treatment approaches for secondary TN remain largely undocumented. Here, to the best of our knowledge, we present the first reported case of secondary TN crisis due to a petroclival meningioma, successfully managed with intravenous fosphenytoin. Case description: A 62-year-old woman developed right-sided TN secondary to a petroclival meningioma. Her facial pain resolved after tumor resection but recurred six years later with slight tumor regrowth. Despite escalation of carbamazepine (CBZ) and CyberKnife radiosurgery, she experienced a TN crisis, presenting with persistent severe pain and impaired oral intake. Intravenous fosphenytoin was administered at loading dose over 20 min, resulting in nearly complete pain relief. Because of symptom recurrence, fosphenytoin was continued at maintenance dose for seven days, in parallel with CBZ titration to 800 mg/day and addition of baclofen. Oral intake improved rapidly thereafter, and no further acute exacerbations were observed over three months of follow-up. Conclusion: This case highlights the potential of intravenous fosphenytoin as an effective and rapid treatment for acute crisis of secondary TN, especially when oral therapy is not feasible.