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Background: Recurrent myelitis (rM) represents a pathogenetically heterogeneous group of inflammatory diseases with a selective involvement of the spinal cord. The recent description of NMO Ig-G antibody, the specific biomarker for Neuromyelites Optica (NMO), also in patients with recurrent myelitis with longitudinally extensive transverse spinal cord lesions (LETM), has brought to consider this disease an incomplete form of NMO (NMO Spectrum of Disorders). Methods: we retrospectively selected patients (pts) with rM attended our neurological department between January 2000 and March 2010. All patients underwent a complete clinical, serological and neuro-radiological evaluation. Other possible diagnosis i.e. Multiple Sclerosis, infective and degenerative diseases as well as systemic inflammatory syndromes were accurately excluded. Results: we recruited 38 pts (27 females). The mean age at onset and disease duration were 41 years and 5,5 years respectively. An EDSS of 6.0 was reached by 26 % of pts after 5 years, mean EDSS at the end of follow-up was 4.0 (range 1-9) with an ARR of 1,3. NMO-IgG were found in 13 out of the 30 pts tested (43%). We divided pts into 2 subgroups according to the presence of LETM. Twenty-four pts developed LETM during follow-up. There was no significant difference between baseline clinical and demographic characteristics. On the contrary, there was a trend towards a higher prevalence of NMO-IgG positive status in LETM group. We observed a higher ARR in the LETM group (1,6 vs 0,6, p< 0,005) and even if there was no difference in the proportion of pts reaching an EDSS of 6.0, the time to this endpoint was significantly shorter in LETM group (4 vs 8 years). When we compared NMO-IgG positive patients vs negative we observed, in the first group a significant prevalence of LETM ( 77% vs 31%) and a higher ARR (1,8 vs 0,8 p< 0,05). Conclusion: We have observed a significant correlation between the presence of NMO-IgG and LETM, confirming that this subgroup of patients has to be considered a limited “spinal restricted” form of NMO with a more severe prognosis. Our results should help the clinicians in the therapeutical decision process: an immunosuppressive treatment has to be started as soon as possible to prevent disease progression, in the presence of NMO-IgG positivity or evidence of LETM at spinal cord MRI.

Read More: Clinical, serological and neuroradiological characterisation of recurrent myelitis: identification of possible prognostic factors