[Nuclear oculomotor nerve syndrome due to mesencephalic infarction or hemorrhage. Five cases and a review of literature].

A nuclear oculomotor nerve syndrome is rarely caused by mesencephalic lesions. We describe 5 patients, 4 with unilateral syndrome (3 due to ischemia and 1 to mesencephalic hemorrhage) and 1 with bilateral nuclear ischemia of the third cranial nerve. These patients represent 0.2% of those admitted with cerebral vascular pathology over the last 12 years. Symptoms are consistent with descriptions of the anatomic organization of this nucleus, with peripheral paralysis of the contralateral superior rectus and possible bilateral involvement of the eyelid elevator and the pupillary constrictor muscles. A noteworthy symptom seen in these cases is supranuclear paralysis of the upward gaze on the side of the lesion, with ocular elevation achieved in response to oculocephalic stimuli in 2 cases and with Bell's synkinesis in 4. We analyze the nature of 22 published cases of unilateral nuclear damage and of 14 published cases of bilateral nuclear damage. Unilateral damage may or may not lead to ipsilateral pupillary involvement, uni- or bilateral eyelid ptosis, contralateral ocular hypotropia, and possible horizontal paresis of the contralateral gaze. Associated deficits are hemiparesis or crossed hemiataxia. Unresponsive pupils and bilateral ptosis associated with tetraparesis, bilateral ataxia and altered states of consciousness were seen with bilateral nuclear lesions. Infarction is the main cause (in 32 out of 41) and recovery of full ocular movement is uncommon.