Medulloblastoma in childhood: results of radical resection and low-dose neuraxis radiation therapy.

This review concerns 22 children who were treated from 1980 through 1983 for medulloblastoma in the posterior fossa. Treatment included attempts at radical resection of the tumor and postoperative craniospinal radiation therapy, with 5000 to 5500 rads directed to the posterior fossa and 2500 rads to the remaining craniospinal axis. This lower radiation dose to the neuraxis was used to avoid late adverse effects upon the growing central nervous system of the children. Gross confirmation of total resection was obtained in 13 patients (the "total resection group"); however, nine patients had a subtotal resection leaving a small portion of the tumor extending into the cerebellar peduncles or the cerebellopontine angle, or else encasing the posterior inferior cerebellar artery (the "subtotal resection group"). Six patients in the total resection group demonstrated tumor extension into the cerebellar peduncles, which was removed by means of a surgical carbon dioxide laser without neurological sequelae. Biopsy of the arachnoid membrane from the cisterna magna and cytological examination of the cerebrospinal fluid (CSF) prior to manipulation of the tumor were carried out in 12 patients. All but one showed dissemination of medulloblastoma cells. Myelography and CSF cytological study were undertaken 2 months after radiation therapy in 12 patients and were positive in two. There were no case mortalities in the total resection group during the 24- to 67-month follow-up period, whereas the 1-year survival rate in the "subtotal resection group" was only 44.4%. This study suggests that medulloblastoma can be controlled with a low radiation dose to the neuraxis, should a grossly confirmed total resection be achieved at craniotomy.