Supracerebellar infratentorial variant approaches to the intercollicular safe entry zone.

OBJECTIVE: To describe and compare surgical exposure through microsurgical cadaveric dissection of the intercollicular region afforded by the median, paramedian and extreme-lateral supracerebellar infratentorial (SCIT) approaches.

METHODS: Ten cadaveric heads were dissected using the SCIT variants approaches. Neuronavigation system was used to determine tridimensional coordinates for the intercollicular zone in each route. The area of surgical and angular exposures were evaluated and determined by software analysis for each specimen.

RESULTS: The median surgical exposure was similar for the different craniotomies, 282.9 ± 72.4 mm2 for the median, 341.2 ± 71.2 mm2 for the paramedian and 312.0 ± 79.3 mm2 for the extreme-lateral (p = 0.33). The vertical angular exposure to the center of the intercollicular safe entry zone was also similar between the approaches (p=0.92). On the other hand, the horizontal angular exposure was significantly wider for the median approach (p<0.001).

CONCLUSION: All the SCIT approaches warrant a safe route to the quadrigeminal plate. Among the different variants the median approach had the smaller median surgical area exposure but presented superior results to access the intercollicular safe entry zone.