DIFFERENTIAL DIAGNOSIS OF LONGITUDINALLY EXTENSIVE TRANSVERSE MYELITIS.

Background: Longitudinally extensive transverse myelitis (LETM), a propagated spinal cord (SC) inflammation causing hyperintensity on T2-weighted magnetic resonance imaging (MRI) over 3 or more vertebral segments, is widely regarded as a spectrum of neuromyelitis optica (NMOSD). 2he broad differential diagnosis of LETM patients is a subject of recent discussion, but fairly studied. Objectives: To report the differential diagnosis of LETM patients. Methods: A cross-sectional evaluation of 128 consecutive patients admitted to the Neurology Department - Sao Paulo University Hospital, between January 2005 and November 2012, meeting the inclusion criteria of inflammatory transverse myelitis according to the Transverse Myelitis Consortium Working Group (TMCWG) and contiguous spinal cord MRI lesion extending over 3 or more vertebral segments. Complete demographic and clinical histories were taken, together with laboratory exams, spinal fluid analysis, and brain and spinal cord MRI. Indirect immunofluorescence assay was used to evaluate aquaporin-4 antibody (NMO-IgG). Results: 128 female patients (70%), 28 Caucasian (15%), with mean age of 38 years (range 11-72yr). Differential diagnosis of patients included: 84 with NMO (46.8%), 25 recurrent LETM (14%), 30 isolated LETM (16%), 3 MS (1.6%), infectious in 20 (11%), systemic disease in 8 (4.4%), arterial-venous malformation in 8 (4.4%), metabolic in 2 (1%), tumor in 2 (1%) and actinic in 1 (0.5%). NMO-IgG seropositivity was exclusively found in: NMO patients (65%), recurrent LETM (44%) and isolated LETM (20%). LETM associated with rheumatologic, infectious vascular, metabolic, tumoral and actinic etiology were all NMO-IgG negative. Conclusions: NMOSD is the main diagnosis of LETM in our sample, mainly considering those who are NMO-IgG positive (63%). However, it is essential to maintain a high index of suspicion for possible and serious etiologies: infectious and vascular LETM may represent a critical subset with a distinct therapy and prognosis. NMO-IgG was negative for all patients with non-inflammatory myelopathy, mimicking LETM, and infectious myelitis presenting as extensive spinal cord lesion. "Idiopathic" seronegative LETM represent almost 14% of the entire cohort. 2he role of current antiaquaporin-4 antibody assays, as well as new antibodies associated with LETM, such as anti-MOG, must be better studied, especially in sero-negative patients. [ABSTRACT FROM AUTHOR]