Short transverse myelitis in Chinese patients with neuromyelitis optica spectrum disorders

Short transverse myelitis (STM) is considered uncommon in neuromyelitis optica spectrum disorders (NMOSD). Poor recognition of STM occurring in NMOSD may lead to increased delay in diagnosis and appropriate treatment.

The aim of this study was to assess the frequency and characteristics of STM in Chinese patients with NMOSD.

We enrolled 91 patients with NMOSD based on the 2015 International Consensus Diagnostic Criteria for NMOSD. The patients were divided into STM group and longitudinally extensive transverse myelitis (LETM) group according to the length of initial spinal cord lesions at the initial myelitis manifestation of NMOSD.

Initial STM was observed in 18 patients (18/91, 19.8%). The STM episode was the first manifestation of NMOSD in 9 patients (50%) and preceded by optic neuritis in 3 patients (16.7%), area postrema syndrome in 5(27.8%) and brainstem syndrome in 1(5.6%). Compared to the NMOSD patients with an initial LETM, patients with STM suffered less motor and bowel or bladder disability, had minor EDSS at clinical onset, but suffered earlier relapse (P＜.05). Thirteen patients had single short spinal lesion (13/18, 72.2%) and 5 patients had two short lesions. Of the 23 STM lesions, 4 lesions spanned 2.5 vertebral segments, 12 showed a length of continuous 2 vertebral segments, 7 were confined to single vertebral segment. The lesions on axial imaging involved the central grey matter in 61.1% (11/18) patients with STM and in 95.9%（70/73）patients with LETM (P＜.05). Both the patients with STM（50%）and LETM (34.2%) had brain lesions.

Initial STM does not exclude consideration of NMOSD diagnosis.