The prognostic role of clinical, pathological, and therapeutic factors in cases of medulloblastoma reported in the literature are reviewed at the University of Turin, Italy. Improvements in neurosurgical techniques and the addition of cranio-spinal axis radiotherapy and chemotherapy can account for a drop in operative mortality from 32% before the 1960s to 10% after 1970, and an increase in 5-year survival rate from 2-11% to 50-70% in the same time periods. Local recurrence in the posterior fossa is the most frequent cause of failed treatment, and higher doses of irradiation (>50 Gy) may prolong survival but have long-term side effects. Low-dose craniospinal radiotherapy plus adjuvant chemotherapy provides survival rates similar to those of high-dose irradiation, with less sequelae. Treatment is planned according to Chang’s staging scheme, cases showing distant seeding receiving chemotherapy. The extent of surgical resection plays a controversial role in prognosis, but many surgeons favor a wide excision. The role of age at diagnosis is also uncertain, some authors concluding that 5-year survival is lower in children under 5 years, while others have found a better prognosis for infants, younger than 2 years. The prognostic significance of the pathology and cell differentiation of the tumor has been studied extensively with conflicting results. Tumors with a high proliferative rate are more susceptible to apoptosis and respond best to radiation. Almost 50% of medulloblastomas analyzed genetically exhibit deletion of the short arm of chromosome 17, a finding linked to shortened survival in some studies. 
COMMENT. The prognosis of medulloblastoma is generally poor, 50% having recurrence, with death resulting within 5 to 7 years after diagnosis. Relapses after 8 years freedom from recurrence are rare. Factors having a significant influence on survival include radiotherapy and metastases at the time of diagnosis. The extent of surgical excision may also be important. Ongoing research in cytogenetics of medulloblastoma may provide a better understanding of prognosis. See Progress in Pediatric Neurology II, PNB Publ,1994;p346, for reviews of long-term neurologic problems with medulloblastoma. Surveillance brain scans failed to detect recurrent disease and had no impact on outcome.
Indications for ventricular drainage and V-P shunting in posterior fossa tumors are reviewed from the Dept of Neurosurgery, Gdansk Medical University, Poland . Of 21 children with medulloblastoma, 20 had V-P shunts, 18 before and 2 after tumor resection. Symptomatic hydrocephalus occurred in 16 cases. Indications for V-P shunt included nonoperable tumor, acute hydrocephalus, and persistently elevated intracranial pressure after tumor removal.
Multiple shunt failures in hydrocephalic children are analysed for relevant factors at the Division of Neurosurgery, UCLA School of Medicine, Los Angeles, CA . Of 244 with shunts, 136 had no failure (predominantly congenital hydrocephalus), 52 had one revision, 34 had 2 or 3 revisions, and 22 had 4 or more revisions. As the number of failures increased, the interval between revisions shortened. Repeated revisions were associated with an increase in CSF monocytes.