J Neurol Surg B Skull Base 2013; 74 - A020
DOI: 10.1055/s-0033-1336153

Quantitative Comparison of Retrosigmoid Intradural Suprameatal Approach and Retrosigmoid Transtentorial Approach: Implications for Tumors in the Petroclival Region

Sudheer Ambekar 1(presenter), Chiazo Amene 1, Osama Ahmed 1, Bharat Guthikonda 1, Anil Nanda 1
  • 1Shreveport, LA, USA

Background: Retrosigmoid transtentorial (RTT) and retrosigmoid intradural suprameatal (RISA) approaches have been used in the treatment of petroclival tumors. To our knowledge, the amount of surgical exposure obtained by these approaches has not been compared so far.

Objective: To compare the area of exposure of brainstem and petroclival region obtained through RTT and RISA in cadaveric specimens.

Methods: Five cadaveric specimens with a total of 10 sides were analyzed. RTT and RISA were performed on five sides each. Maximum superoventral exposure of brainstem above the the V cranial nerve and maximum inferoventral exposure of brainstem between the V and VII-VIII complex were obtained to calculate the area of brainstem exposed in each approach. The maximum superomedial and inferomedial exposure of the petroclival area was measured medial to Meckel’s cave, and the area of exposure was calculated. These values were compared between the two approaches.

Results: Brainstem area exposure with RTT was 441 ± 63 mm2, and with RISA it was 311 ± 61 mm2. Mann-Whitney test revealed that the difference was significant (P = 0.031). It was noted that the maximal superior and ventral exposure of brainstem obtained through RTT was greater than that obtained through RISA, and the difference was significant (P = 0.008). The area of petroclival exposure medial to Meckel’s cave through RTT was 696 ± 57 mm2, and through RISA it was 716 ± 51 mm2 (P = 0.69). The area of brainstem exposure between the V and VII-VIII complex through RTT and RISA was 387 ± 86 mm2 and 378 ± 76 mm2, respectively, without any significant difference (P = 0.84). The area of surgical freedom at Meckel’s cave was observed to be greater with the RISA than with RTT.

Conclusion: The retrosigmoid transtentorial approach is an excellent approach to ventrolateral brainstem and petroclival region. It provides greater superoventral exposure of the ventrolateral brainstem than the retrosigmoid intradural suprameatal approach while providing similar petroclival exposure. Hence, RTT may be used for accessing tumors in the petroclival region. However, RISA provides more area of surgical freedom than the RTT at the Meckel’s cave.