Teaching Video NeuroImages: Convergence retraction nystagmus due to compressive lesion of the dorsal midbrain

Abstract

A 28-year-old man had experienced binocular diplopia for the last 2 months. Around the same time, he noticed mostly nocturnal polyuria and polydipsia and eventually was diagnosed with diabetes insipidus. Extraocular motility testing demonstrated jerky convergence movements on an attempted upgaze and mild lid retraction (video 1). Urgent MRI of the brain revealed a large mass in the dorsal midbrain region, which was also compressing the hypothalamus (figure). The lesion was biopsied and a diagnosis of primary intracranial germinoma arising from pineal tissue was made. Treatment with low-dose radiotherapy commenced. Characteristic clinical features of convergence retraction nystagmus in this case allowed rapid localization of the lesion, its diagnosis, and eventually treatment.1