When ADEM Looks Like Migraine: A Case Study in Delayed Diagnosis
Acute disseminated encephalomyelitis, or ADEM, is a rare autoimmune condition in which the body's immune system attacks the protective myelin coating surrounding nerve fibers in the brain and spinal cord. It most often affects children, but adults can develop it too — and when they do, the diagnosis is frequently missed, sometimes with serious consequences. A case report published in May 2025 in the journal Medicine illustrates exactly how dangerous this diagnostic gap can be, describing an adult whose ADEM was mistaken for complex migraine until his condition had already become life-threatening.
The patient, a 35-year-old man, initially came to medical attention with severe headaches, visual disturbances, and sensitivity to light and sound. These symptoms fit the profile for complex migraine well enough that his first care team diagnosed him accordingly. A brain MRI at that visit showed only nonspecific findings, which did not raise alarms. He was discharged and experienced brief improvement before things began to change.
Over the following days, new and alarming symptoms emerged: speech difficulties, numbness in his right hand, episodes of disorientation, and a bluish discoloration of his lips. He made multiple visits to healthcare facilities as his condition deteriorated, eventually arriving at the hospital with a significantly decreased level of consciousness. A second MRI finally revealed the answer: multifocal high-signal lesions on T2-weighted FLAIR sequences throughout the white matter, the characteristic pattern of ADEM. Cerebrospinal fluid analysis showed elevated protein and lymphocytic pleocytosis. After infectious and other autoimmune causes were ruled out, a diagnosis of ADEM was confirmed.
Treatment began immediately with high-dose intravenous methylprednisolone, the cornerstone of first-line ADEM therapy, followed by a tapering oral corticosteroid course. Supportive medications including antipsychotics and anticonvulsants were also used. Within two weeks, the patient showed substantial neurological improvement, including restoration of orientation and motor function, and remained stable at follow-up. The outcome was favorable — but only because the correct diagnosis was eventually reached.
The authors point to a sobering statistic: ADEM is misdiagnosed on the first clinical encounter more than 80% of the time in adults. Adults with the condition also tend to face longer hospital stays, higher rates of ICU admission, and worse overall outcomes compared to children. The symptom overlap with migraine is particularly dangerous in early stages, when MRI findings may still be subtle or nonspecific. This case is a reminder that when an adult presents with atypical migraine features, particularly progressive neurological symptoms or those not responding to standard migraine treatment, ADEM deserves serious consideration. Early repeat imaging, lumbar puncture, and prompt corticosteroid therapy can make the difference between full recovery and lasting disability.