Patients receive rituximab IV on day 1. On days 2 and 3, patients receive carboplatin intra-arterially over 10 minutes, cyclophosphamide IV over 10 minutes, and etoposide or etoposide phosphate IV over 10 minutes in conjunction with blood-brain barrier disruption. Patients also receive high-dose sodium thiosulfate IV over 15 minutes administered 4 and 8 hours after carboplatin on days 2 and 3 and intraventricular or intrathecal cytarabine on day 14. Beginning 48 hours after the last dose of chemotherapy, patients receive filgrastim (G-CSF)* subcutaneously (SC) daily for 7-10 days or until blood counts recover. Treatment repeats every 4 weeks for up to 12 courses.