Background: Longitudinally extensive transverse myelitis (LETM) is a frequent manifestation of neuromyelitis optica spectrum disorder (NMOSD). However, it can also occur in other immune-mediated diseases of the central nervous system (CNS). Positive aquoporin-4 antibodies (AQP4-ab) predict higher relapse rate after LETM.
Objective: To assess clinical and brain/spinal cord magnetic resonance imaging (MRI) features of LETM immune-mediated at onset and to compare AQP4-ab negative (N-LETM) with AQP4-ab positive (P-LETM) patients.
Methods: Thirty LETM patients remitted for consideration of inflammatory CNS diseases were included. Demographics, clinical, serological, disability and neuroimaging features at onset we reviewed retrospectively and divided into two groups according to serological status. AQP4-ab were tested using indirect immunofluorescence.
Results: Twenty-one patients were N-LETM. We did not find significant differences between both groups as regards gender, age at onset, dysfunction (motor, sensory, bladder/bowel) or disability. However, recurrences (p=0.04) of myelitis and number of relapses (p=0.03) were associated to P-LETM. N-LETM was associated with normal brain MRI (p=0.04) at onset. AQP4-ab positive were only observed in NMOSD patients. N-LETM (24%) and P-LETM (56%) patients had relapses of optic neuritis (ON) during the follow-up.
Conclusion: LETM at onset is a heterogeneous syndrome with similar clinical and neuroimaging features between both groups. N-LETM displayed a lower relapse rate of myelitis and ON.
Keywords: Aquaporin-4 antibodies; Longitudinally extensive transverse myelitis; Multiple sclerosis; Neuromyelitis optica spectrum disorders.
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