MRI findings in patients with acute optic neuritis.
A prospective study

Abstract

Purpose : Idiopathic optic neuritis (ON) is an inflammatory optic neuropathy, that causes acute vision loss often accompanied with pain. Magnetic resonance imaging (MRI) in the acute phase may help to confirm the diagnosis as well as exclude alternative diagnoses. The aim of this study was to evaluate MRI in the acute phase of a first ON episode.

Methods : A prospective cohort study of patients with idiopathic ON including acute ON evaluation with a one year follow-up was performed in the Region of Southern Denmark from 2014-2016. Patients were seen in a coordinated diagnostic investigation including clinical examination, analysis of blood and cerebrospinal fluid, measurement of evoked potentials, optical coherence tomography and MRI (1.5 Tesla scanner). On the MRI, the optic nerves were divided into the following three segments: intra-orbital, canalicular (optic foramen back to chiasm) and chiasmal (chiasm + optic tracts) for lesion characterization. The MRIs were evaluated by a neuroradiologist, who was masked to clinical and serological information.

Results : Sixty-three patients were evaluated for ON and 52 were included in the study. Thirty-one had an MRI evaluation of brain including orbit at a single episode of acute ON. Median time between onset of symptoms and the MRI was 22 days (range 3-55 days). The median age at onset was 40 years (range 17-66 years). Twenty-nine patients had unilateral and two had bilateral ON. Signal abnormalities of the optic nerve were demonstrated in 81 % (25/31) of the patients on MRI. The optic nerve lesions had intraorbital location for 48 % (12/25), canalicular for 8 % (2/25) and combined intraorbital and canalicular for 44% (11/25). Of these 84 % (21/25) had brain MRI abnormalities, 40 % (10/25) of whom met the diagnostic criteria for multiple sclerosis (MS) at the acute ON episode. A total of 80 % (8/10) of the MS-patients had optic nerve lesions located intraorbitally.

Conclusions : In the acute phase of a single ON episode MRI abnormalities of the optic nerve occur frequently. Intraorbital location was the most common. Concurrently, a high occurrence of brain abnormalities was observed.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.