Encephalopathy following CNS prophylaxis in childhood lymphoblastic leukemia

In our clinic population of children with acute lymphoblastic leukemia an increased frequency of encephalopathy occurred during a 12-month period. During the same period no encephalopathy was observed in 23 leukemic children who had not received prophylactic central nervous system treatment but were receiving systemic chemotherapy. The reason for this high incidence of encephalopathy is far in excess of what has been reported from other centers employing similar CNS prophylaxis. Whether this reflects geographical differences in virus infection or other factors is not clear. Encephalopathy in a leukemic child must be differentiated among infection, meningeal leukemia, toxic effects of intrathecal methotrexate, or unknown causes. Concurrent respiratory or gastrointestinal symptoms, normal intraspinal pressure, pleocytosis with no evidence of "blast" cells on careful examination of the cerebrospinal fluid, and exclusion of bacteria and fungal infection by appropriate stains and culture suggest a viral, protozoan, mycoplasma, or unknown etiology. Erroneous treatment with intrathecal methotrexate or irradiation may inhibit spontaneous recovery. In most cases the meningoencephalopathy is self-limited and requires only supportive care. With the advent of new approaches to the therapy of childhood leukemia which have prolonged survival, complications and toxicities of therapy not previously appreciated will probably become apparent. Observation and reporting of such complications will be of benefit and interest to pediatricians who care for leukemic children and to their patients.