Effects of cranial radiation on hearing in children with acute lymphocytic leukemia.

We serially assessed the hearing sensitivity of 61 children with acute lymphocytic leukemia who were admitted to our Total Therapy IX study between December, 1975, and July, 1977. Their treatment included combined chemotherapy, 2,400 rads of cranial radiation, and intrathecal methotrexate. Subjects initially received an otologic examination and middle ear function testing. Audiometric testing was not done until ears were free of outer or middle ear pathology. If the child had no outer or middle ear disease, audiometric thresholds were obtained for the test frequencies: 500, 1,000, 2,000, 4,000, 6,000, and 8,000 Hz. Pure-tone thresholds were obtained before irradiation (61 patients) and at 6, 12, and 36 months thereafter (49, 46, and 22 patients, respectively). The median age at time of baseline testing was 10 years, 2 months. A paired sample test based on group data was used to test whether there were any significant changes from the threshold values at 6, 12, and 36 months after irradiation. Thresholds were not significantly affected for any test frequency at any test time. Assessments of individual audiograms indicated that none of the children had any significant reductions in hearing levels at the end of the third year after cranial irradiation.