The Use of Diffusion MRI in Ischemic Optic Neuropathy and Optic Neuritis

Abstract

Ischemic optic neuropathy and optic neuritis are the most common causes of unilateral non-glaucomatous visual loss. While they have distinctive clinical features, they also share some overlapping profiles that make it difficult to clinically distinguish these two entities. MRI with gadolinium has been proven to be helpful to confirm the diagnosis of optic neuritis, but ischemic optic neuropathy remains a clinical diagnosis. Diffusion MRI, a newly advanced technique, has been used in studying the pathophysiology of optic neuritis, but its use in ischemic optic neuropathy is limited. Diffuse MRI may potentially be of help to diagnose ischemic optic neuropathy.

Ischemic Optic Neuropathies

“…5,11 Imaging of the optic nerve is typically normal in patients with nonarteritic anterior ION. 12,13 Contrast-enhanced magnetic resonance imaging (MRI) of the orbits, performed with fat suppression, is mostly useful to rule out a compressive optic neuropathy or an inflammatory optic neuritis when there is clinical uncertainty.…”

Reduced Apparent Diffusion Coefficient in Neuromyelitis Optica–Associated Optic Neuropathy

“…It has been proposed that diffusion-weighted MR imaging may differentiate ischemic optic neuropathy from optic neuritis (6). In a recent study, diffusion-weighted imaging was abnormal in 5/5 patients with acute ischemic optic neuropathy, but only 2/25 patients with acute optic neuritis (7).…”

Diffusion restriction of the optic nerve in patients with acute visual deficit

“…Both ION and ON present with acute visual loss. Clinically, ON and ION can be distinguished by fundoscopy (identification of AION) and clinical signs, for example, painful eye movement in ON, but as He et al state, “diagnostic certainty may evade the clinician when ‘classic’ features (…), are not found.”…”