[Non-leukemic disease of the central nervous system in children with acute lymphoblastic leukemia. III. Subacute sclerosing panencephalitis (author's transl)].

Diseases of the central nervous system (CNS) occurring during treatment of acute lymphoblastic leukemia (ALL) may be of leukemic or nonleukemic origin. Well known examples for CNS disease of nonleukemic origin are somnolence following prophylactic CNS irradiation, methotrexate-induced encephalopathy and acute infections caused by bacteria, viruses and toxoplasma gondii. Less known is the fact that also subacute CNS infections may occur in patients undergoing cytostatic therapy. Progressive multifocal leukoencephalopathy and subacute sclerosing panencephalitis (SSPE) are examples of this category of disease. Up to now 11 well documented cases of SSPE were reported occurring during treatment of ALL. Main clinical features were disorders of behaviour, consciousness and speach, seizures, paresis and inappropriate secretion of ADH. Several authors were able to demonstrate a deficiency of cellular immunity in patients with SSPE. In some cases this deficiency was consistent with reduced reactivity of T-lymphocytes against measles antigen only. The presence of inhibiting factors may be responsible for this phenomenon. Other authors found a normal or increased function of cellular immunity in SSPE; In hamsters occurrence of SSPE is induced by the simultaneous injection of hamster-adapted SSPE virus and antihamster lymphocyte serum. We, therefore, conclude that also in humans SSPE appearing during treatment of ALL is due to immunosuppression.