MOG encephalomyelitis: distinct clinical, MRI and CSF features in patients with longitudinal extensive transverse myelitis as first clinical presentation

Based on clinical, immunological and histopathological evidence, MOG-IgG-associated encephalomyelitis (MOG-EM) has emerged as a distinct disease entity different from multiple sclerosis (MS) and aquaporin-4-antibody-positive neuromyelitis optica spectrum disorder (NMOSD). MOG-EM is associated with a broader clinical phenotype including optic neuritis, myelitis, brainstem lesions and acute disseminated encephalomyelitis with a substantial clinical and radiological overlap to other demyelinating CNS disorders. To evaluate common clinical, MRI and CSF findings, as well as therapy responses in patients with longitudinal extensive transverse myelitis (LETM) as initial clinical presentation of MOG-EM. After excluding patients with a known diagnosis of MS, we identified 153 patients with myelitis of which 7 fulfilled the inclusion criteria and were investigated for MRI, CSF and clinical parameters. Patients with LETM as first clinical presentation of MOG-EM display similar characteristics, namely a lack of gadolinium-enhancement in spinal cord MRI, marked pleocytosis, negative oligoclonal bands, a previous history of infections/vaccinations and response to antibody-depleting treatments for acute attacks and long-term treatment. We identify common pathological findings in patients with LETM as first clinical presentation of MOG-EM which distinguishes it from other forms of LETM and should lead to testing for MOG-IgG in these cases.