Computed tomography in the follow-up of medulloblastomas and ependymomas.

The course of 36 patients with medulloblastoma and ependymoma was evaluated prospectively by clinical examination, radionuclide (RN) studies and computed tomography (CT). Seventeen of the 36 patients (47%) had tumor recurrence. Twelve (41%) of the 29 patients with medulloblastoma had recurrent tumors of which 7 of 12 (58%) were at the primary site and 2 of 12 (17%) were within the ventricles while 10 of 12 (83%) were in the subarachnoid space. Five of the 7 patients with ependymoma had recurrent tumors. In 4 of the 5 patients tumor recurred at the primary site while subarachnoid seeding occurred in 2 of 5 patients (40%) and intraventricular metastases were found in 4 of 5 patients (80%). Progressive ventricular enlargement often accompanied subarachnoid seeding, presumably secondary to obstruction of cerebrospinal fluid (CSF) flow in the subarachnoid pathways. CT and RN scans were frequently complementary in detecting tumor recurrence.