Optic nerve magnetic resonance imaging characteristics in inherited optic neuropathies

Abstract

Purpose : Inherited optic neuropathies include dominant optic atrophy (DOA), Leber’s hereditary optic neuropathy (LHON), and Wolfram syndrome (DIDMOAD). DOA is the most common of these, and mutations in OPA1 account for 40-60% of DOA cases. Few studies have examined or compared findings on neuroimaging of the optic nerves in inherited optic neuropathies. The purpose of this study was to characterize magnetic resonance imaging features of the optic nerves in patients with inherited optic neuropathies.

Methods : Using an updated retrospective database of 111 patients with bilateral optic atrophy referred for genetic testing, magnetic resonance (MR) images were analyzed and compared across genotype groups. Patients were screened using next generation sequencing of 243 genes (including OPA1, WFS1) and the mitochondrial genome (includes all LHON mutations). T2 signal was quantified in MR images (3T) of the orbits and/or brain and normalized to internal standards within each slice. A sample of patients without ocular, central nervous system or visual diagnoses was used to validate the T2 quantification methods.

Results : Eight patient with and 19 without OPA1 mutations had MR images available for analysis. There were 2 patients with DIDMOAD and 1 patient with LHON in our sample who also had MR images available. The optic nerves of optic atrophy patients appeared smaller with increased normalized T2 signal compared to controls. There was a wide range of variability in the degree of optic nerve T2 signal among optic atrophy patients.

Conclusions : Increased T2 signal intensity is not a typical feature of neurodegenerative disease and may reflect nuances in optic atrophy specific to this group of conditions. Differences in T2 signal could represent differences inherent to distinct hereditary optic neuropathies and/or the degree of atrophy or gliosis. Further characterization of these differences on MR imaging can help guide diagnostic genetic testing and provide insight into differences in the pathophysiology of hereditary optic neuropathies.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.