Non-infectious myelitis in SLE is caused by heterogeneous disease processes including SLE myelitis, comorbid multiple sclerosis (MS), and anti-aquaporin-4 antibody (AQP4) or anti-myelin oligodendrocyte glycoprotein (MOG)-associated neuromyelitis optica spectrum disease (NMOSD). To date, these conditions, which necessitate different treatments and vary in prognosis, are difficult to differentiate.

Medical records of 174 patients of the Swiss Systemic Erythematosus Lupus Cohort Study (SSCS) and 2,297 patients of the Brigham and Women’s Hospital Lupus Cohort Study were screened for the three conditions and an attending neurologist confirmed individual diagnoses.  To be classified as NMO, subjects had to have a positive NMO antibody and a neurologic syndrome typical of NMO. To be classified as MS, subjects had to have 2 separate neurologic syndromes typical of MS with characteristic brain lesions. Data were extracted regarding demographic, clinical, laboratory, and radiographic features.

Eighteen subjects with SLE were included: myelitis n=7, NMO n=5, and MS n=6. The median SLEDAI-2K score at time of neurologic syndrome presentation was higher in myelitis subjects compared to subjects with NMO or MS. Subjects with myelitis were also more likely to have elevated anti-dsDNA antibodies at presentation (86%) compared to subjects with NMO (50%) or MS (0%). When lumbar puncture was pursued, 100% of subjects with MS had oligoclonal bands, compared to 67% of subjects with myelitis and 0% of subjects with NMO.

We found that subjects with SLE myelitis had higher SLE disease activity at myelitis onset. Moreover, SLE patients with NMO and MS could be differentiated by radiological presentation and presence of oligoclonal bands. Our study provides first insights into differential clinical and paraclinical presentation of myelitis in SLE patients.