Skull Base Approaches for Complex Vertebrobasilar Aneurysms

Abstract

Purpose: The authors' experience in the treatment of vertebrobasila (VB) aneurysms has been revised. Different skull base approaches were used based on the location, size, and morphological features of the lesions. The rationale of the choice of each approach is discussed. Method: One hundred twenty-eight patients harboring 135 VB aneurysms were operated on in 15 years. Of these lesions, 18% were giant. Different approaches have been used. The majority of patients harboring distal basilar artery aneurysms underwent an extended pterional approach; the exposition of lesions located below the posterior biclinoidal line required a transcavernous route. Most complex lesions were treated through a cranio-orbitary approach. Most middle basilar artery aneurysms were treated through a retrolabyrinthine petrosal presigmoid approach; for more complex lesions a combined transpetrosal approach was used. Aneurysms of the inferior third of the basilar trunk and of the VB junction were operated on by a high posterolateral approach. Distal vertebral lesions were treated through an inferior posterolateral approach. The subtemporal approach was performed for lesions located distally in the PCA or in the SCA. The retrosigmoid approach was used for lesions of distal AICA or PICA. Result: Skull base approaches allow the best lesional control and handling in the surgical treatment of complex VB aneurysms, providing straight access, wide working room, short working distance, and lesional control from different angles with minimal retraction or manipulation of critical neurovascular structures. These approaches give complete vascular control allowing the exposure of the parent and efferent vessels (to achieve temporary occlusion), the exposure of the complete implant base (to obtain the best dip positioning), and a wide exposure of the sac (to manipulate it from different angles). Conclusion: The treatment of VB aneurysms is challenging because these lesions are deeply located in very limited subarachnoid spaces, in intimate relationship with the brainstem and its vasculature. VB aneurysms present special intrinsic features (prevalence of large and giant lesions with frequent presence of intraluminal thrombosis and of atherosclerotic changes of sac and parental artery), that make the endovascular treatment ineffective, especially in complex cases, so that surgery remains the best therapeutic option. The application of any helpful technical and methodological resource, surgical or alternative, is required to achieve optimal results.