Removal of intraponto-mesencephalic spongioblastoma.

Excision of a circumscribed spongioblastoma with intrapontine-intramesencephalic extension was performed via the floor of the fourth ventricle in two girls 14 and 5 years of age. The preoperative neurological deficits (severe hemiparesis, cerebellar, and sixth and seventh cranial nerve disturbances) showed slow but continuous improvement to a satisfying neurological condition, if compared with the preoperative state. The indication for this microsurgical procedure is supported by findings, that indicate the tumour to be benign: (1) a long history, (2) a well circumscribed tumour including a cyst, as seen on CT, and (3) a localized protrusion of the floor of the fourth ventricle on ventriculography.