Giant Cell Arteritis Presenting as Unilateral Anterior Ischemic Optic Neuropathy Associated With Bilateral Optic Nerve Sheath Enhancement on Magnetic Resonance Imaging.

A 67-year-old man developed jaw claudication followed by loss of vision in the left eye caused by anterior ischemic optic neuropathy (AION). An erythrocyte sedimentation rate was normal, but C-reactive protein was slightly elevated. Although the patient had no evidence of a right optic neuropathy, magnetic resonance imaging (MRI) revealed bilateral optic nerve sheath enhancement. A temporal artery biopsy was consistent with active giant cell arteritis (GCA). Our case demonstrates that bilateral optic nerve sheath enhancement on MRI can be seen in the setting of unilateral AION. This unique combination of clinical and imaging findings has not been reported previously and extends the clinical spectrum of presentation of GCA.