The superior fovea triangle approach: a novel safe entry zone to the brainstem.

The authors describe a safe entry zone, the superior fovea triangle, on the floor of the fourth ventricle for resection of deep dorsal pontine lesions at the level of the facial colliculus. Clinical data from a patient undergoing a suboccipital telovelar transsuperior fovea triangle approach to a deep pontine cavernous malformation were reviewed and supplemented with 6 formalin-fixed adult human brainstem and 2 silicone-injected adult human cadaveric heads using the fiber dissection technique to illustrate the utility of this novel safe entry zone. The superior fovea has a triangular shape that is an important landmark for the motor nucleus of the trigeminal, abducens, and facial nerves. The inferior half of the superior fovea triangle may be incised to remove deep dorsal pontine lesions through the floor of the fourth ventricle. The superior fovea triangle may be used as a safe entry zone for dorsally located lesions at the level of the facial colliculus.