Quantification of Increased Basilar Artery Proximal Control Obtained by Transecting the Tentorium in a Subtemporal Approach

Introduction: Basilar apex aneurysms remain one of the most difficult aneurysms to control proximally. The subtemporal approach to basilar apex aneurysms is often advocated when the aneurysm is below the posterior clinoids. We used a stereotactic method to quantify increased proximal control of the basilar artery obtained by transecting the tentorium during a subtemporal approach. Methods: A subtemporal approach to the basilar apex was performed on three latex-injected cadaveric heads (three sides). Using a stereotactic method, the point of maximum proximal control of the basilar artery was measured from the basilar apex. Proximal control was compared before and after transecting the tentorium both anterior and posterior to the trochlear nerve. Results: Our preliminary results show that working inferior to the oculomotor nerve the proximal control measured before transecting the tentorium was 7.7 ± 2.8 mm. After transecting the tentorium just behind the trochlear nerve this was essentially unchanged at 8.6 ± 2.4 mm, but increased significantly to 12.7 ± 2.0 mm after cutting in front of the trochlear nerve (P = 0.022, repeated measures ANOVA, BonFeronni adjusted). Conclusion: We conclude that transecting the tentorium in a subtemporal approach to the basilar apex improves proximal control. In the future we intend to investigate the effect of cutting the tentorium on other measurements such as working area and surgical freedom.