Medulloblastoma causing a corticosteroid-responsive optic neuropathy.

A 25-year-old man had signs of optic nerve dysfunction. A diagnosis of optic neuritis was made and was supported by rapid resolution of signs and symptoms with use of corticosteroids. After initial negative radiologic investigations, his corticosteroid dosage was tapered, and the recurrence of his symptoms and signs prompted repeat computed tomographic scans. A suprasellar mass and a posterior-fossa mass were observed, and frontal craniotomy disclosed typical medulloblastoma, confirmed histologically. Although visual signs and symptoms in medulloblastoma have been reported secondary to optochiasmatic arachnoiditis and to papilledema, to the best of our knowledge this is the first reported case in which direct compression of the optic nerve has occurred as a result of extension of a posterior-fossa medulloblastoma. The favorable response of this compressive tumor to corticosteroids, stimulating an inflammatory optic neuritis, emphasizes the importance of reassessing any optic neuritis that follows an atypical course.