Usefulness of MRI Slices Parallel to the Optic Chiasma in a Case with Traumatic Optic Nerve Avulsion after a Bear Attack.

ABSTRACT

Optic nerve avulsion is an exceedingly rare condition. Here, we describe a case of optic nerve avulsion in a 74-year-old man with temporal hemianopia in the contralateral eye after a bear attack. Magnetic resonance imaging (MRI) revealed separation of the optic nerve distal to the optic chiasma, whereas the high signal in diffusion-weighted imaging suggested nerve injury from the left side of the optic chiasma to the left optic tract. MRI slices parallel to the optic chiasma were obtained and used for evaluating the site of optic nerve avulsion and nerve injury, which were responsible for temporal hemianopia in the contralateral eye.