Pure Relapsing Short Myelitis: Part of the Multiple Sclerosis Spectrum or New Entity?

BACKGROUND AND OBJECTIVES: Pure relapsing short myelitis with clinical and paraclinical features suggesting multiple sclerosis (MS) has been described recently. Here, we evaluated the existence of this potential new form of MS by retrospectively searching for similar cases in the databases of the French tertiary MS centers. METHODS: Patients were included based on the present criteria: at least 2 short (<3 vertebral segments) myelitis episodes; minimum follow-up of 3 years; no MS-like brain lesion during all the follow-up; tested negative for both anti–myelin oligodendrocyte glycoprotein and anti–aquaporin 4 antibodies in serum; presence of oligoclonal bands in CSF; and comprehensive workup to exclude alternative diagnoses. RESULTS: Eighteen patients fulfilled all criteria. The sex ratio (females/males) was 5/1; the median (range) age at first relapse was 35.5 (25–54) years, the disease duration was 80.5 (50–308) months, and the annualized relapse rate was 0.36 (0.1–0.5). The median (range) number of relapses per patient was 2 (2–5), and the median (range) Expanded Disability Status Scale score at last follow-up was 1 (0–7.5). In CSF, the median (range) protein level was 0.34 g/L (0.18–0.77), and the median (range) number of mononuclear cells was 3 (0–28). Spinal cord MRI demonstrated a median (range) number of 2 (1–5) lesions per examination and 3 [1–7] on the last examination. Fifty-five percent of lesions involved the cervical levels. Secondary progressive evolution occurred in 3 of 18 (17%) patients. DISCUSSION: Pure spinal MS could be a rare entity in the MS disease spectrum. However, the existence of a distinct entity in the inflammatory CNS disorders cannot be excluded.