Utility of three-dimensional computed tomographic angiography for assessment of relationships between the vertebrobasilar system and the cranial base

Quantitative Anterior and Posterior Clinoidectomy Analysis and Mobilization of the Oculomotor Nerve during Surgical Exposure of the Basilar Apex Using Frameless Stereotaxis

Background  Anterior and posterior clinoidectomies have been proposed to augment exposure of the basilar apex. A sequential quantitative benefit analysis offered by these maneuvers has not been reported. Methods  Fourteen datasets from eight cadaveric specimens were analyzed. A modified orbitozygomatic frontotemporal craniotomy was performed. The extent of proximal control of the basilar artery was determined through the exposed opticocarotid and carotidoculomotor triangles before and after clinoidectomies and mobilization of the third nerve at the porous oculomotarius. Results  Removal of the anterior and posterior clinoids significantly improved proximal basilar artery access ( p  < 0.012) and increased the opticocarotid triangle and carotidoculomotor triangle areas ( p  < 0.017). Surgical freedom increased inferosuperiorally in the opticocarotid triangle following anterior clinoidectomy ( p  < 0.047) and in carotidoculomotor triangle following posterior clinoidectomy ( p  < 0.047). Mobilization of the third nerve increased surgical freedom in the mediolateral projection of the carotidoculomotor triangle ( p  < 0.047). Conclusion  Anterior and posterior clinoidectomies significantly improved the area of exposure of the opticocarotid triangle, carotidoculomotor triangle, and the exposed length of the basilar artery available for proximal control. This improvement is extremely important for large or giant aneurysms of the upper basilar artery or aneurysms hidden by the posterior clinoid.

How useful is the 3-dimensional, surgeon’s perspective-adjusted visualisation of the vessel anatomy during aneurysm surgery? A prospective clinical trial

We hypothesized that neuronavigational 3-dimensional display of vessel and aneurysm anatomy, which is adjusted to the actual surgeon's view, could be helpful during the critical steps of aneurysm treatment. A total number of 32 patients with 42 aneurysms entered this prospective clinical trial. With a neuronavigational system, a 3-dimensional image of the arterial vascular anatomy was generated by autosegmentation of a computerized tomography (CT) angiographic data set. The 3-dimensional image was then adjusted to the surgeon's perspective by rotation. The neurosurgeon linked the 3-dimensional image information with the vascular structures in his surgical field by a neuronavigational pointer. He had the opportunity to further rotate the image with the displayed pointer for visualization of hidden structures. After operation, the neurosurgeon had to define with which expectations neuronavigation was applied and to evaluate if these expectations were fulfilled. The expectations with which the neurosurgeon used neuronavigation were to localize the aneurysm (n = 24), to understand the branching anatomy (n = 18), to visualize hidden structures (n = 8), to evaluate the projection of the aneurysm dome (n = 5) and to tailor the approach (n = 2). In 5 of the 42 aneurysms that were either very small or located in close vicinity to the skull base, the neurosurgeon's expectations were not fulfilled. A favorable outcome was achieved in 29 of the 32 patients (91%). Neuronavigational 3-dimensional display of the vessel anatomy was considered useful by the vascular neurosurgeon. Possibly, this technique has the potential to improve operative results by reduction of the surgical trauma and avoidance of intraoperative complications.