[Brain stem glioma]

Brain-stem gliomas occur mainly in childhood and are localized in the mesencephalon, pons and medulla oblongata. Diagnosis is a domain of MRI, requiring T2, T1 and KM. CT shows hemorrhage and calcification well. The criteria are the primary site, size, tumor growth, brain-stem enlargement, delineation, intralesional structure, exophytic components and enhancement. Secondary criteria are herniation, hydrocephalus and liquorgenic seeding. In CT glioma are hypodense, in MRI hyperintense in T2 and hypointense in T1. Enhancement is seen in 25-60% and does not allow differentiation of tumor vs nontumor or gradings. Factors influencing poor outcome are high grade, a short history, cranial nerve involvement, severe brain-stem enlargement, pontine site, diffuse growth and recurrency. The 5-year-survival rate is 30% (after radiation: focal tumors 85%, diffuse 20%). Most frequent are symptoms of brain pressure, cerebellum, cranial nerves and pyramidal tract. There is no agreement on whether biopsy is necessary or not. A diagnosis of tumor is highly suggestive if classical MRI findings fit the clinical history.