Treatment will continue unless the disease gets worse or unacceptable side effects occur. Treatment will be given on an outpatient basis. At the end of the study, vital signs, a complete physical and neurological exam, and routine blood tests (about 1 tablespoon) will be performed. CSF samples for cytology, protein, glucose, and cell count will be taken. The Gd-MRI scan will be repeated. You will be asked to complete a questionnaire about how you are feeling.