Acute transverse myelitis after Japanese B encephalitis vaccination in a 4-year-old girl.

Fourteen days after Japanese B encephalitis (JBE) vaccination, a 4-year-old girl developed the full clinical manifestation of ATM within 24h. She showed acute ascending flaccid paraplegia with sensory disturbance, bladder dysfunction and meningeal sign. Cerebrospinal fluid examination revealed neutrophil pleocytosis and elevated protein level. Magnetic resonance imaging (MRI) showed diffuse swelling of the cervical and lumbar cord with low signal intensity on T1 and high signal intensity on T2-weighted imaging. These findings suggested that she had developed meningo-radiculomyelopathy. Since sequential MRI studies showed prompt reduction of the cord swelling, the high-dose methylprednisolone therapy employed seemed to have been effective for improvement of inflammation. Even with such potent drug treatment, she still has substantial flaccid diplegia and sphincter disorder 1 year later, and so we are convinced that the pathological change of the cord was as severe as in necrotizing myelopathy. Although the pathological process remains unknown, cellular autoimmune mechanism against the JBE vaccination is suspected.