Neuromyelitis optica IgG status in acute partial transverse myelitis

Background: Neuromyelitis optica (NMO) IgG is a specific marker for NMO. Furthermore, a high proportion of patients with longitudinally extensive transverse myelitis (characterized by spinal cord lesions extending 3 vertebral segments or more on magnetic resonance imaging) are seropositive for NMO-IgG and are considered to have a limited form of NMO. The NMO-IgG status in mild cases of acute partial transverse myelitis asociated with minimal magnetic resonance imaging abnormalities (spinal cord lesions <2 vertebral segments on magnetic resonance imaging) is unknown. Objective: To investigate the NMO-IgG status of patients with acute partial transverse myelitis and a normal cerebral magnetic resonance image. Design: Observational, retrospective consecutive case series with longitudinal follow-up. Setting: Allegheny Multiple Sclerosis Treatment Center. Patients: Three groups of patients were tested for NMOIgG. Group 1 consisted of 22 patients with acute partial transverse myelitis, group 2 consisted of 4 patients with definite NMO ( by 1999 criteria of Wingerchuk et al), and group 3 consisted of 6 patients with definite multiple sclerosis. Main Outcome Measure: NMO-IgG status. A commercially available assay for NMO antibodies was performed at the Mayo Clinic. Testing was performed during the convalescent stage of the illness. Results: Of the 22 patients with acute partial transverse myelitis, only 1 was seropositive for NMO-IgG at presentation. This patient subsequently developed recurrent episodes of longitudinally extensive transverse myelitis that are typicaly seen in association with NMOIgG. Three of the 4 patients meeting criteria for NMO were seropositive. None of the patients with multiple sclerosis had NMO-IgG detected. Conclusion: NMO-IgG is rarely encountered in patients with acute partial transverse myelitis, which is in sharp contrast to the high frequency of this antibody in patients with NMO and longitudinally extensive transverse myelitis.