The effect of cerebellar damage on intellectual function in 76 children treated surgically for malignant posterior fossa tumor was investigated at the Gustave Roussy Institute, Villejuif, and the Department of Pediatric Neurosurgery, Necker Hospital, Paris, France. Inclusion criteria included a tumor treated initially with surgery followed by irradiation and/or chemotherapy, age older than 4 years at time of psychological evaluation, and evaluation at >1 year after diagnosis and >6 months after treatment. Mean age at diagnosis was 5.7 +/- 3.8 years. Shunt surgery was performed in 31 children, 12 preoperatively, 17 postoperatively, and 2 at time of tumor resection. The vermis was split in 61.5% of medulloblastoma cases and in 29.4% of ependymoma resections (p=0.03). Postoperative complications occurred in 47% of children whose hydrocephalus was treated prior to tumor resection and in 67% treated later (p=0.07).
Postoperative cerebellar syndrome (transient short-term cognitive deficits) was higher in patients with preoperative hydrocephalus than in those without (58% and 33%, respectively; p=0.03). Cerebellar mutism occurred in 9 patients (12%), and incision of the vermis (in 7) was more frequent than in patients without this complication. Risk factors for persistent cerebellar syndrome were preoperative hydrocephalus, cardiovascular instability, and postoperative complications. At time of testing, 13 children (17%) had special education needs and one child was not attending school. On Wechsler Scales of IQ, the mean verbal intelligence quotient (VIQ) was 87 +/- 19 SD) and the mean performance quotient (PIQ) was 76 +/- 17.5. The Purdue Pegboard test results measuring hand skills correlated with IQ scores. A low VIQ was associated with impaired hand skills (p<0.0001) and preoperative hydrocephalus (p=0.02), whereas a low PIQ was associated with impaired hand skills (p<0.0001) and incision of the vermis (p=0.02). Impaired hand skills were associated with postoperative cerebellar mutism, oculomotor deficits, cerebellar syndrome, and the need for rehabilitation therapy. 
COMMENT. In this study involving multifaceted therapies for malignant posterior fossa tumors, IQ scores were correlated with preoperative hydrocephalus, incision of the vermis, and degree of postoperative cerebellar damage. A recent study in the Netherlands involving 23 children treated surgically for cerebellar astrocytoma and without additional radio- and chemotherapy, also revealed long-term neurologic, psychological, and behavioral sequelae, a high percentage requiring special education. (Ped Neur Briefs May 2004;18:39-40) . In children following cerebellar tumor resection, with or without radio- or chemotherapy, a cerebellar cognitive affective syndrome with persistent deficits is a significant complication.