Pearls & Oy-sters: A Challenging Optic Neuropathy-What Not to Miss in Optic Nerve Sheath Enhancement.

Optic neuropathies include a wide range of disorders from ischemic, toxic, demyelinating, or inflammatory processes with acute/subacute onset to more gradual compressive or genetic etiologies. Accurate clinical history and multimodality optic nerve imaging including MRI and optical coherence tomography have greatly improved the diagnosis of patients with optic neuropathies. We report a case of a woman with severe monocular visual acuity deficit. Optic nerve sheath enhancement seen on MRI led to a broad differential diagnosis including demyelinating causes, optic nerve sheath meningioma (ONSM), tuberculosis, and sarcoid optic neuropathy. Lack of response to treatment with steroids or plasmapheresis led to biopsy, which confirmed the diagnosis of ONSM.