Patients with acute disseminated encephalomyelitis (ADEM) are presumed to have radiological monophasic disease, but this is uncertain since follow-up brain MRI is not routinely performed. We aimed to ascertain combined radiological and clinical monophasic disease in ADEM patients and to assess whether performing early (<6 months) follow-up brain MRI has prognostic value for subsequent multiphasic disease. We retrospectively studied the medical records of patients initially diagnosed with ADEM (years 2000-2014) at the Massachusetts General Hospital, USA. A neuroimaging specialist, masked to clinical events, reviewed all available brain MRIs. We included 62 patients (25 male; 30 pediatric; median clinical follow-up 3 years) and classified them into two subgroups: (1) clinically monophasic (no new, recurrent or worsening neurological symptoms >3 months after onset) (n = 45), and (2) clinically multiphasic (clinical relapse >3 months after onset) (n = 17). All clinically monophasic patients with brain MRI follow-up (n = 30) also had radiological monophasic disease a median of 2 years after ADEM onset. New lesions (58 vs. 14%) and persistent lesions (100 vs. 18%) on early brain MRI [available in 40 patients (65%)], as well as clinical flares (53 vs. 20%), were more common in clinically multiphasic versus monophasic patients. These early follow-up data allowed us to predict multiphasic disease with reasonable accuracy in a multivariable model (AUC = 0.73). We conclude that performing early follow-up brain MRI routinely in ADEM patients would aid clinicians in predicting multiphasic disease and may stratify patients who would benefit from initiation of disease-modifying therapy for multiple sclerosis.
Keywords: Acute disseminated encephalomyelitis; MRI; Multiple sclerosis; No evidence of disease activity (NEDA); Prognostic factors.