THE IMPACT OF PERIOPERATIVE FACTORS ON SUBSEQUENT INTELLIGENCE QUOTIENT DEFICITS IN CHILDREN TREATED FOR MEDULLOBLASTOMA POSTERIOR-FOSSA PRIMITIVE NEUROECTODERMAL TUMORS

Background. Despite success in treating children with medulloblastoma/ posterior fossa primitive neuroectodermal tumor (PF PNET), some childr en survive with significant neurocognitive sequelae. This study was pe rformed to understand better the significance of perioperative factors on subsequent full scale intelligence quotient (FSIQ) deterioration i n these children. Methods. Twenty-eight children who underwent prospec tive and serial neurocognitive testing were studied. All children unde rwent surgery followed by radiotherapy with or without chemotherapy be tween 1983 and 1987 for medulloblastoma/PF PNET and were disease free when this study was conducted. IQ testing was performed before surgery and after the completion of radiation therapy. The clinical courses o f the patients were correlated with changes in the corresponding intel ligence quotients of each child. Factors correlating with neurocogniti ve declines were examined by chi-square or Fisher exact test analysis. Differences in mean IQs were examined by the t test. Factors found to be significant were analyzed by exact logistic regression analysis. R esults. The presence of adverse factors such as neurologic deficits, m eningitis, or shunt infections, or the need for repeat surgery was cor related significantly with IQ deficits after treatment. Of the subset of children with one or more of these factors, 13 of 16 (81%) sustaine d decreases in FSIQ; 7 of 16 (43.8%) had decreases of 20 points of mor e. In contrast, only 3 of 12 (25%) of the children without the factors sustained FSIQ decreases, and no child sustained a decrease of more t han 13 points. The mean FSIQ change after treatment in the group with factors was -15.7 (95% confidence interval [CI]: -24.0, -8.4), and the median was -18. The mean FSIQ change in the group without factors was 4.8 (95% CI: -0.5, 10.1), and the median was 5. The difference in mea n FSIQ change between the two groups was significant (P < 0.0001). On univariate analysis, both the presence of adverse factors and an age l ess than six years correlated with neurocognitive deficit. On regressi on analysis, only the presence of adverse factors was significant (odd s ratio 11.53; 95% CI, 1.65-116.58; P = 0.009), whereas age was not (P = 0.27). Conclusions. Perioperative events or complications may accou nt for some of the neurocognitive deterioration seen in these children after treatment, especially in the very young. The occurrence of thes e factors is associated with a significantly greater risk of IQ deteri oration. Studies of the neurocognitive effects of treatment for childr en with medulloblastoma/PF PNET should include an analysis of these po stoperative factors.