NMO-IgG-negative relapsing myelitis

Abstract

Idiopathic transverse myelitis (I-TM) is typically monophasic, while relapsing forms are usually referred to spinal cord-restricted neuromyelitis optica (NMO), atypical multiple sclerosis (MS), or myelitis during the course of infections and connectivitis. Our objective was to evaluate the frequency of recurrent I-TM; to clarify the nosology of these forms through comparison with NMO and post-infectious TM (P-TM). Prospective cohort study on patients presenting with I-TM was carried out inpatients of Infectious and Neurologic Disease Clinics, Italy. Over an 8-year period, we recruited 13 patients with I-TM and 16 with P-TM. The patients were followed-up for at least 3 years with repeated brain and spinal cord magnetic resonance imaging (MRI) examinations, multimodal evoked potentials and serum screen for connectivitis. Relapses were defined on clinical and imaging criteria. Four patients with I-TM (31%) had a relapsing course . They were all males with age >50, and severe at-onset disability. The final outcome was poor in three out of four patients. Serum NMO-immunoglobulin G was undetectable in all patients. Longitudinally extensive myelitis was not predictive of relapses. I-TM and P-TM shared clinical, cerebrospinal fluid (CSF) and MRI features, as well as a similar rate (54 vs 38%) of peripheral nervous system involvement (polyradiculoneuritis), and an identical rate of relapses (31% for both forms). Our series support the existence of relapsing I-TM as a disease entity that does not appear related to NMO, nor to MS, cannot be further specified and shares many features with P-TM. The likelihood of relapses was unpredictable based on clinical, CSF and MRI findings.