|T1 post-gad||T2||T2 6 weeks later|
When this patient initially presented with multiple enhancing white matter lesions after an acute viral syndrome, the diagnosis of ADEM was considered. ADEM (acute disseminated encephalomyelitis) is an immune mediated process which occurs secondary to prior vaccination or viral syndrome. ADEM tends to occur in children and young adults with an abrupt onset and follows a monophasic course. Patients may present one to three weeks after their vaccination or viral syndrome with headache, fever, or drowsiness. Patients may then rapidly progress with seizures, focal neurologic deficit, and eventually even death. On imaging it may be impossible to differentiate ADEM from multiple sclerosis. The best way to tell them apart is with follow-up MRI. If new lesions occur, multiple sclerosis is more likely due to the biphasic nature of ADEM. The presence of the new enhancing lesion on the follow-up MRI in this patient makes multiple sclerosis more likely. Related Cases
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