Oculomotor nuclear complex syndrome as a single sign of midbrain haemorrhage

A 73-year-old male patient presented with a mesencephalic dorsal tegmental haemorrhage involving the oculomotor nuclear complex. Clinically the patient exhibited ipsilateral palsy of the third nerve associated with internuclear ophthalmoplegia, transient upbeat nystagmus, bilateral ptosis and paresis of the superior rectus muscle of the contralateral eye, due to involvement of the subnucleus that mainly innervates the contralateral superior rectus muscle. No other neurological deficits were seen. Isolated midbrain haemorrhages are very uncommon and they usually produce combined supranuclear and nuclear disturbances of eye movement. As documented by high resolution CT-scan, these exceptional findings were caused by haemorrhage in the territory of a penetrating branch from a long circumferential midbrain artery. The results of this case are in accordance with Warwicks investigations on the organisation of the oculomotor system in primates.