Risk factors for idiopathic myelitis at admission and predictors for late diagnostic change

Immune-mediated myelopathy (IMM) diagnosis is challenging, and its etiology may remain unclear despite extensive investigation. We evaluated diagnostic changes in IMM patients during follow-up. We included 80 patients, 61.3% female, with median follow-up time 62.5 months. Diagnoses at discharge were: 48.8% Multiple Sclerosis-IMM (MS-IMM), 32.5% I-IMM, 11.3% Neuromyelitis Optica Spectrum Disorders-IMM (NMOSD-IMM), 1.3% MOG encephalomyelitis (MOGAD), and 6.2% Others IMM (O-IMM). Twenty-two  patients (27.5%) changed diagnosis (median 15.5  months): 68.8% MS-IMM, 12.5%  NMOSD-IMM, 3.8% MOGAD, 10.0% I-IMM, and 5.0% O-IMM. Most patients that changed diagnosis were I-IMM. Predictive factors for diagnostic change in I-IMM were: autonomous gait (p = 0.029), lesions suggestive of MS (p = 0.039), higher number of lesions (p = 0.043), lesions length < 3 vertebral bodies (p = 0.033), cervical involvement (p = 0.038), and lower EDSS at admission (p = 0.013). Etiologic reclassifications in IMM are common, therefore patients require an appropriate follow-up time to increase diagnostic accuracy.