LAUSR

There are a variety of clinical phenotypes and radiological features that continue to make a diagnosis of neuromyelitis optica spectrum disorder (NMOSD) challenging. We present an atypical case of an adult woman who presented with flaccid paralysis of all extremities with unusual neuroimaging features, including extensive enhancing lesions in the upper cervical cord and conus medullaris with associated leptomeningeal enhancement. She was ultimately found to have AQP4 antibody-positive NMOSD. We discuss the factors that complicated a timely diagnosis, including her atypical radiographic features and an initially negative cell-based assay for myelin oligodendrocyte glycoprotein (MOG) and aquaporin-4 (AQP4) antibodies. Despite the rarity of conus medullaris involvement or leptomeningeal enhancement in AQP4 antibody-positive NMOSD, it is important to maintain a high level of clinical suspicion to avoid diagnostic and therapeutic delays. Though cell-based assays have high sensitivities, testing should be repeated on negative values in these scenarios.