Encephalomyelopathy following intrathecal methotrexate treatment in a child with acute leukemia.

A previously undescribed type of encephalomyelopathy after prophylactic intrathecal methotrexate (MTX) treatment for acute leukemia is reported. The patient was treated systemically with vincristine, MTX, stereoids and mercaptopurine. Radiation therapy was not given. The neurologic symptoms started 24 hours after the completion of the fifth intrathecal MTX instillation and death ensued 18 days later. The lesions consisted of superficial and sharply circumscribed areas of incomplete necrosis with astrocytosis on the base of the brain and along the insula regions, around the foramina of Luschka, and over the superior and inferior colliculi. Similar superficial lesions were found over the surface of the cerebellum and along most of the surface of the spinal cord. Most of the affected areas in the brain were located under the large subarachnoid cisterns. In the cord the lesions were most pronounced along the entrance zones of the roots. There was also a severe loss of anterior horn cells. There were no signs of meningeal leukemia, no pathological changes were caused by the intrathecal MTX treatment.