Visual-evoked potentials in long-term survivors of acute lymphoblastic leukemia in childhood. The German Late Effects Working Group.

Visual-evoked potentials (VEPs) were studied in 92 asymptomatic long-term survivors of acute lymphoblastic leukemia (ALL) in first complete remission 6-7 years after cessation of therapy in order to detect therapy-related disturbances in conduction velocity capacities within central nerve fibers. Subjects were grouped with respect to CNS prophylaxis: a) ith. MTX and 18 GY cranial irradiation (group A, n = 58), b) ith. MTX and iv. MHD-MTX, no cranial irradiation (group B, n = 34). At follow-up VEPs were abnormal in 10 subjects (10.9%) with comparable rates in both CNS prophylaxis groups (A: 7/58 [12.1%], B: 3/34 [8.8%]; p = 0.56). Participants with radiological signs of leukodystrophy (n = 14), all within the irradiated CNS prophylaxis group showed significantly prolonged P100 latencies and had a 6.1-fold increased relative risk to develop VEP disturbances. No correlation could be established between VEP outcome and illness- or treatment-related parameters. VEP outcome was not correlated with age at diagnosis or gender. Thus, VEP recordings showed a close relationship with radiation-induced CNS white-matter disturbances. However, their value for clinical practice, routinely performed follow-up evaluations or standardized posttreatment surveillance studies is negligible.