Acute disseminated encephalomyelitis with probable measles vaccine failure.

The patient is a 10-year-old male who experienced somnolence and incomplete quadriplegia after headache and vomiting, without exanthema, for 3 days. The clinical course and magnetic resonance imaging findings of the brain and spinal cord were compatible with acute disseminated encephalomyelitis. The serologic examination revealed that the patient had rubeola because titers of IgM and IgG antibody to measles virus measured by enzyme immunoassay were 0.91 and 40 (cutoff = 0.80 and 2), respectively, at 5 weeks after the onset, the IgM titer had become negative (0.56), and the IgG titer had decreased to 17.7 at 13 weeks after the onset. Because the patient had received a measles-mumps-rubella vaccine at 12 months of age, the acute disseminated encephalomyelitis was thought to be attributed to the modified measles resulting from measles vaccine failure.