Neurological complications of childhood leukaemia.

We have reviewed the neurological complications not directly attributable to leukaemic infiltration in a group of 438 children with leukaemia or lymphoma. 61 children had one or more complications due chiefly to bleeding, infection, or drug toxicity. Early death from intracranial haemorrhage occurred in 1% of children with lymphoblastic leukaemia and 7% of children with myeloblastic leukaemia. Measles and chicken pox were the most serious infective complications; one child remains severely retarded after presumed measles encephalitis, one child with chicken pox died, and a second remains disabled. 2 additional cases of measles encephalitis and one of progressive multifocal leucoencephalopathy are described. Drugs which caused neurotoxicity included vincristine, cytosine arabinoside, L-asparaginase, and phenothiazines, but most problems were caused by methotrexate. Methotrexate toxicity was more prevalent and more serious in children who had had previous central nervous system leukaemia. We conclude that viral infections and methotrexate pose the greatest neurological hazards to children with leukaemia.