Ultrasound-Assisted Diagnosis of Optic Neuritis in the Emergency Department: A Case Report

Background: Optic neuritis is a common cause of subacute unilateral vision loss, occurring in 1-5 per 100,000 persons per year. It is more common in Caucasians, women, and those from countries with northern latitudes. Those aged 20-49 years are at greatest risk. The condition arises due to inflammation of the optic nerve. Inflammation may occur due to systemic inflammatory disorders, most commonly multiple sclerosis.

Case report: A 21-year-old African-American male presented to our emergency department with a complaint of painful unilateral vision loss. On examination he was found to have a relative afferent pupillary defect and red desaturation. A bedside ultrasound suggested pseudopapilledema suggestive of optic neuritis. He was admitted to Neurology for confirmation of and treatment for optic neuritis. Magnetic resonance imaging confirmed optic neuritis. The patient was treated with i.v. steroids and discharged after improvement in visual function. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Optic neuritis is a clinical diagnosis. The subtle historical components and examination findings make it a diagnostic challenge for the busy emergency physician. Early diagnosis may improve visual outcomes. Discovery of pseudopapilledema on bedside ultrasound may be seen in optic neuritis, and is another finding that emergency physicians may assess for in patient presenting with unilateral vision loss.