Magnetic resonance imaging in acute unilateral optic neuropathies in adults

Non-arteritic ischaemic optic neuropathy (NAION) and optic neuritis may have overlapping presentations, making differentiation between the two difficult. All adults presenting with acute unilateral optic neuropathy (symptoms <3 weeks of onset) between January 2011 and January 2012 underwent complete neuro-ophthalmic examinations and were diagnosed with either NAION or ON. Patients underwent pre- and post-contrast magnetic resonance (MR) with gadolinium, diffusion-weighed imaging (DWI), T2, short tau inversion recovery (STIR), and gadolinium-enhanced fast imaging employing steady state acquisition (FIESTA) sequences of the brain and orbit. A blinded neuroradiologist analysed the images as normal, consistent with NAION, consistent with ON, or unrelated incidental findings and the results were correlated to clinical diagnoses on initial presentation. Sixteen patients were included, 4 of whom had optic neuritis and 12 had NAION. Concordance rate for the blinded neuroradiological diagnosis and the final clinical diagnosis was seen in only 3 of the 16 patients. Nonspecific or unrelated findings were seen in 6 cases. Our study demonstrates a low concordance rate between radiographic and final clinical diagnoses, with only 3/16 patients correctly diagnosed by blinded neuroradiological evaluation. Despite the limitations of our study, we believe that neuroradiologists can assist clinicians in the final diagnosis of in patients in whom the clinical presentation is uncertain. Future work is necessary to determine whether more rapid imaging in these cases might expand the utility of DWI in optic neuropathy.