Which statement correctly distinguishes pediatric MS from ADEM?

• A. ADEM involves dissemination in time and space; MS is a single episode
• B. MS involves dissemination in time and space; ADEM is typically a single episode
• C. They cannot be distinguished clinically
• D. ADEM never involves encephalopathy

Answer: (B)

Pattern of evolution over time and across the brain and spinal cord distinguishes pediatric MS from ADEM. Multiple sclerosis in children typically shows dissemination in time and space: new neurological symptoms or new lesions on MRI appear at different times and in different CNS locations, reflecting ongoing inflammatory activity and relapses. Acute disseminated encephalomyelitis (ADEM), on the other hand, is usually a monophasic event—a single, acute inflammatory attack often following an infection or vaccination—with multifocal symptoms and often encephalopathy, followed by recovery and without subsequent relapses. This is why a statement describing MS as involving dissemination in time and space and ADEM as typically a single episode matches the clinical pattern. Note that ADEM can include encephalopathy, so saying it never involves encephalopathy is inaccurate.