Midbrain angioma with disconjugate vertical gaze palsy

Loss of depression in one eye with contralateral loss of elevation is rare. It has been attributed to a subnuclear lesion of the oculomotor nerve nuclear complex. We present a patient with these signs who has an arteriovenous malformation occupying his rostral midbrain. We argue that attributing these findings to a subnuclear lesion of the oculomotor nerve complex does not take into consideration the secondary, vertical action of the obliques.