A Case of Recurrent Painful Ophthalmoplegic Neuropathy with Frequent Relapses and Prophylaxis with High-Dose Vitamin B2 Supplementation.

Recurrent painful ophthalmoplegic neuropathy (RPON) is characterized by recurrent unilateral headache associated with ipsilateral ophthalmoplegia due to palsy of one or more ocular cranial nerves, including the oculomotor, trochlear, and abducens nerves. Herein, we report a case of RPON with frequent recurrence over a short period, wherein further recurrence was prevented using high-dose riboflavin. The patient was a 6-year-old boy who presented with a 3-day history of headache, right eye pain, vomiting, and right oculomotor nerve palsy. He had a similar episode 3 years earlier, which resolved spontaneously after 1 month. Initial treatment with intravenous methylprednisolone alleviated eye pain, ocular motility disorder, and ptosis, but not the dilated pupil. Despite steroid treatment, the patient experienced frequent relapses triggered by infectious diseases, resulting in side effects such as moon face and weight gain. High-dose riboflavin (200 mg/day) was initiated as prophylaxis after other treatments, including lower doses of riboflavin and sodium valproate, failed to prevent relapses. The patient remained relapse-free for 9 months after increasing the riboflavin dose. Although it remains unclear whether high-dose riboflavin alone or in combination with valproic acid was effective, this case suggests that high-dose riboflavin might be an effective prophylactic treatment for RPON.