Cavernous angiomas of the brain stem - Intra-axial anatomical pitfalls and surgical strategies

BACKGROUND We review the surgical anatomy of the brain stem in relation to the surgical approaches adopted for treatment of cavernomas and identify possible "safe entry zones" on the anterior face of the brainstem. METHODS Twelve symptomatic patients with cavernoma or telangectasia of the brain stem were surgically treated. The brain stem was divided into the following anatomical areas: ventral medulla, dorsal medulla, dorsal pens, ventral pens, ventral mesencephalon, and dorsal mesencephalon, so that the surgical approach could be "individualized" according to the position of the cavernoma, the nerve fasciculi and nuclei. RESULTS On the anterior surface of the brain stem a medullar paramedian oblique access to the anterolateral sulcus and a paramedian sagittal pens access seem to avoid the main nerve fasciculi and nuclei. CONCLUSIONS Although the parenchymal window produced by the cavernoma is the most important parameter for the choice of approach, fairly safe entry zones may be identified even on the anterior surface of the medulla and pens. (C) 1999 by Elsevier Science Inc.