Emergencies in Neuro-Ophthalmology: A Case Based Approach

neuropathy (e.g. RAPD, visual field defect, normal or hyperemic disc). The temptation is to make the clinical diagnosis of optic neuritis and schedule an outpatient MRI study. My recommended optic neuropathy protocol is a head and orbit study with T1 fat suppressed orbital views with gadolinium to look at the optic nerve, T1 axial post contrast brain to look for enhancing white matter lesions of active disease, and sagittal, coronal, and axial T2-weighted fluid attenuation inversion recovery (FLAIR) studies to look for demyelinating periventricular white matter lesions. If an imaging study is going to be deferred, the clinician should still test the fellow eye, even if asymptomatic, to look for evidence of not only optic neuropathy but also contralateral superotemporal visual field loss (i.e. the junctional scotoma) that might suggest an alternate diagnosis to optic neuritis such as a compressive lesion. Acutely pituitary apoplexy and ophthalmic artery aneurysm can both mimic a painful acute optic neuropathy but the junctional scotoma is definitely a red flag for a compressive rather than a demyelinating etiology. Likewise, patients who are elderly are unlikely to experience optic neuritis. The diagnosis of optic neuritis does occur in elderly patients but I always recommend cranial and orbital optic nerve directed neuroimaging. A retrobulbar acute painful optic neuropathy in an elderly patient is more likely to be posterior ischemic optic neuropathy from giant cell arteritis or a compressive lesion, including orbital apex fungal disease rather than demyelinating optic neuritis.

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Acute Unilateral Optic Neuropathy

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