Acute disseminated encephalomyelitis after influenza vaccination.

A 12-year-old, previously healthy boy was seen with typical signs of acute disseminated encephalomyelitis four days after influenza vaccination. Computerized tomography demonstrated an extensive subcortical low-density area in the left cerebral hemisphere. The CSF contained elevated levels of immunoglobulins, especially IgG, and an abnormal kappa:lambda chain ratio. Skin tests for hypersensitivity to egg protein were negative, but reaugmentation of CSF protein and immunoglobulin levels was observed within ten days after skin tests.