Clinical History.—Acute lymphoblastic leukemia was diagnosed in this girl at 6 years of age. She was treated with asparaginase, 23,000 IU intravenously, for four days. High daily doses of prednisone (25 mg three times a day) and vincristine sulfate (1.2 mg intravenously, weekly for one month) were given. The corticosteroid therapy was discontinued after two months because severe osteoporosis and sustained compression fractures of L-1 and L-2 vertebrae developed. She was given long-term maintenance therapy of methotrexate, 10 mg twice a week, for five years. She was also given intrathecal methotrexate prophylactically three times at weekly intervals early in the course of treatment.
At the age of 8 years, seizures developed, and an EEG at that time showed slow wave activity in the right temporal occipital region. Although skull roentgenograms were normal (Fig 1), a radionuclide brain scan at 10 years of age showed abnormal uptake in the right