Brain stem gliomas in childhood. Rational approach and treatment.

Thirty-six infants and children with brain stem glioma diagnosed between 1967 and 1980 were reviewed. Posterior fossa craniotomy was performed in 25, with biopsy or partial resection in 18, cyst aspiration in 2, and exploration alone in 5. The 19 surgical specimens obtained revealed neoplastic cells in 15 but only gliosis or blood clot in 4. There was a significant discrepancy in pathological spectrum between autopsy and surgical specimens. The review of the literature shows that 51.6% of autopsy confirmed tumors were malignant while 26.8% of surgically biopsied tumors were benign. Since biopsy specimens often misrepresent the true pathology, we felt that surgery undertaken to obtain precise histological verification of brain stem gliomas is futile. Rather, we employ computed tomography (CT) with high-resolution metrizamide CT cisternography to distinguish surgically resectable extra-axial tumors adjacent to the brain stem from the unresectable intrinsic brain stem gliomas. Radiation therapy is the choice of treatment should CT indicate clear evidence of intrinsic brain stem tumor. However, posterior fossa craniotomy should be undertaken only for aspiration of cystic intrinsic stem tumors, resection of extra-axial juxtastem tumors and, although rare, in instances when CT is unable to definitively distinguish extra-axial from intra-axial mass for verification of lesion location.