To highlight the diagnostic value of bright spotty lesions (BSLs) as a neuroimaging marker for neuromyelitis optica spectrum disorder (NMOSD).

NMOSD is an autoimmune central nervous system disease with a complex clinical course. Although longitudinally extensive transverse myelitis (LETM) is a significant magnetic resonance imaging (MRI) finding, it is not unique to NMOSD and is seen in various causes of myelitis. BSLs, defined as hyperintense intramedullary lesions on axial T2-weighted images, are a recent neuroimaging discovery whose specificity and ability to differentiate NMOSD from other demyelinating disorders have not been entirely investigated. 

A single-center retrospective study of patients recruited at the Department of Neurology, West Virginia University, was conducted between August 1st, 2013, and February 28th, 2022. Eleven confirmed cases of seropositive NMOSD were included from a total of 37 patients. Comparison studies were done with a control group (n=18) of alternative causes of myelitis, including multiple sclerosis, idiopathic transverse myelitis, and neurosarcoidosis. All patients underwent MRIs of the brain and cervico-dorsal spine using our Siemens MAGNETOM® Verio 3.0T and MAGNETOM® Aera 1.5T machines, and two neuroradiologists manually reviewed the scans.

We report 11 seropositive NMO cases, all seen in women from 25-75 years at the time of diagnosis (most were older than 65). Presentations were diverse, including paresthesia, extremity weakness, and visual changes. Five of the 11 NMOSD patients (45%) had BSLs on spinal MRI, compared to none in the control group; of these, four (80%) also demonstrated LETM. Treatment with immunotherapy and symptomatic management led to clinical improvement in all cases. 

Axial-BSLs are a newly defined spinal MRI finding with high specificity for NMOSD, which can be used in combination with LETM to enhance their diagnostic potential. The absence of BSLs in our control group establishes its prolific role in distinguishing NMOSD from other etiologies of myelitis.