Postvaccination myelitis: MRI appearance and follow-up

We report the assessment by MRI of a case of radiculomyelitis after vaccination against tetanus-poliomyelitis. In the acute stage the appearance was an isolated myelitis of the conus medullaris with contrast enhancement. The upper thoracic cord presented central areas of high signal intensity on T2 weighted images. Rapid clinical recovery was correlated with resolution of abnormal enhancement. Follow-up MR at 5 months showed persistence of slight T2 prolongation in the conus medullaris and syringohydromyela of the thoracic cord. A single lesion of the spinal cord is a rare presentation of acute disseminated encephalomyelitis, the course of such lesions, to date not previously displayed by MR, is unknown. Proper diagnosis should help prevent administration of further vaccine doses.