Demyelinating encephalopathy in Lyme disease.

A 38-year-old man from southeastern Connecticut developed a diffuse encephalopathy with partial complex seizures, followed weeks later by arthritis, cryoglobulinemia, and increased serum IgM. CT showed confluent low-density lesions in the deep cerebral white matter consistent with demyelination. Neither the encephalopathy nor the CT abnormalities improved. Lyme disease was diagnosed serologically 4 years later.