A Comparison between the Kawase's and Extended Retrosigmoid Approaches (Retrosigmoid Transtentorial and Retrosigmoid Intradural Suprameatal Approaches) for Accessing the Petroclival Tumors. A Cadaveric Study

Background: The aim of our study was to compare the area of exposure at the ventral brainstem and petroclival region offered by the Kawase's, retrosigmoid transtentorial (RTT) and the retrosigmoid intradural suprameatal (RISA) approaches in cadaveric models.

Methods: We performed 15 approaches (5 Kawase's, 5 RISA and 5 RTT) on silicone injected adult cadaver heads. Ventral brainstem and petroclival areas of exposure were measured and compared.

Results: The mean ventral brainstem area exposed by the Kawase's approach was 55.00 + 24.1 mm2, which was significantly less than that exposed by RTT 441 + 63.3 mm2 and RISA 311 + 61 mm2 (p < 0.05). The area of ventral brainstem exposure was significantly more through RTT than through RISA (p = 0.01). The mean petroclival area of exposure through the Kawase's approach was significantly smaller than that obtained through the RTT and RISA approaches (101.75 + 45.01 mm2, 696 + 57.7 mm2 and 716.7+ 51.4 mm2 respectively).

Conclusion: Retrosigmoid approaches provide a greater exposure of the brainstem and petroclival areas. Kawase's approach is ideally suited for lesions around the Meckel's cave with an extension into the middle fossa. These approaches can be used in conjunction with each other to access the petroclival tumors.