Atypical Multiple Sclerosis Presenting as Bilateral Optic Neuritis

Abstract

Purpose: We report a case of multiple sclerosis with bilateral optic neuritis that was atypical in terms of both the clinical signs and symptoms.Case summary: A 34-year-old female visited the department of neurology with a complaint of sudden-onset, left lower extremity weakness and numbness that had developed 3 weeks prior, and bilateral blurred vision that had commenced 2 weeks prior. The patient was diagnosed with multiple sclerosis and prescribed high-dose intravenous methylprednisolone for 3 days, but the blurred vision did not improve. The patient was referred to the ophthalmology department. The initial best-corrected visual acuity was 0.04 in both eyes, and the relative afferent pupillary defect test was positive for the left eye. The Ishihara color test scores were 1/17 for both eyes. No optic disc swelling was evident on fundus examination. Brain and spine magnetic resonance imaging (T2-weighted) performed during the initial visit revealed lesions of high signal intensity in the frontal, subcortical white matter; the optic chiasm; the left retrobulbar optic segment; the medulla; and the spinal C2-5 processes. Aquaproin-4 immunogloblin G antibody (AQP4-IgG Ab) was not detected in serum. One month after prescription of the oral steroid, the vision improved to 1.0 in the right and 0.8 in the left eye. The patient was lost to follow-up after prescription of interferon-beta for 4 years, without recurrence.Conclusions: Binocular optic neuritis accompanied by severe visual loss is a rare form of multiple sclerosis. A thorough diagnosis (with a focus on exclusion) is required, as is appropriate treatment.