Oculomotor Palsy after Flow Diverter Treatment for Paraclinoid Aneurysm: Case Report and Literature Review

Flow diverter placement across the ophthalmic artery carries a reported visual-impairment risk of about 1%, yet oculomotor nerve palsy following treatment of small paraclinoid aneurysms without mass effect has not been described. Our objective was to present a case of a transient oculomotor palsy following a flow diverter treatment for 6 and 2.5 mm paraclinoid aneurysms.

A 57-year-old woman underwent flow diverter treatment for two left paraclinoid aneurysms measuring 6 and 2.5 mm. On the fifth post-operative day, she experienced blurred vision, mild left ptosis, and restricted adduction and elevation of the left eye, while pupillary function remained intact. The diagnosis of left pupil-sparing oculomotor palsy was made. Conservative management led to full resolution of symptoms within three months. Follow-up 3D rotational angiography demonstrated occlusion at the origin of the inferolateral trunk of the left internal carotid artery.

Oculomotor nerve palsy caused by flow diverter coverage of small internal carotid artery branches supplying the cranial nerves may be an under-recognized complication and warrants clinical attention. A review of the literature suggested an approximately 3% incidence of this complication, and we discussed the pathomechanism of the cranial nerve palsy caused by flow diverter treatment.