Anatomical and Objective Evaluation of the Main Surgical Approaches to Pontine Intra-Axial Lesions

Apparently similar intra-axial pontine lesions may demand distinct surgical approaches. Selecting the optimal approach reduces unnecessary manipulation of tracts and nuclei. This study aims to reveal a quantitative analysis of main surgical corridors dealing with intrinsic pontine pathology. Six approaches were performed repeatedly in 10 cadaveric heads: 1) retrosigmoid, 2) retrolabyrinthine, 3) subtemporal transtentorial, 4) anterior petrosectomy, 5) combined petrosal approach, and 6) suboccipital telovelar. Six safe entry zones were studied: peritrigeminal, supratrigeminal, lateral pontine, supracollicular, infracollicular, and median sulcus of fourth ventricle. A neuronavigation device was used to collect 3-dimensional coordinates from fixed points over the edge of craniotomies and brainstem surface; 4 variables were studied: 1) angles of attack; 2) areas of exposure; 3) lengths of exposure; and 4) trajectories. The mean area of exposure generated by the retrosigmoid approach over the brainstem was 538.6 ± 161.0 mm2, whereas that yielded by the retrolabyrinthine was 475.0 ± 173.4 mm2. There were no significant differences between both when considering areas of exposure and angles. Adding a tentorial cut to the subtemporal approach exposed the superior part of the lateral surface of pons; the area of exposure increased a mean of 33% (P