Vascular anatomy of the sellar region and complications during endoscopic endonasal transsphenoidal surgery for pituitary adenomas

In general, transsphenoidal surgery has been considered to have a low rate of complication and mortality. Among the postoperative complications associated with transsphenoidal surgery (TSS), such as cerebrospinal fluid leakage, hypopituitarism, diabetes insipidus, vascular injury, meningitis, cranial nerve neuropathy, and nasal bleeding, vascular injury is unusual, but most possibly fatal complication. Therefore, the pituitary neurosurgeons need to have the knowledge about the possible incidence during the intra-and post-operative phase. Vascular injuries during the TSS described in the literature include fatal hemorrhage from internal carotid artery (ICA), ICA occlusion, pseudoaneurysm formation, carotid cavernous fistula, subarachnoid hemorrhage, vasospasm, and distal embolism with cerebral infarction. It is important to understand the patient’s vascular anatomy at the sella and its surrounding structures, during the preoperative examination of the TSS, to avoid the vascular complications. Although recent advancement of the operative techniques and instruments of transsphenoidal approach enable the neurosurgeons to dissect arteries derived from the ICA and external carotid artery (ECA) during the surgery, it remains a difficult problem to preserve intact vessels even for the expert pituitary neurosurgeons. In particular, the introduction of endoscope into the TSS dramatically improved intraoperative visualization and diminished traumatization. Subsequently, the operative indication for performing TSS gradually developed to include the suprasellar, parasellar, clival, and cervicomedullary junction (extended transsphenoidal surgery). However, since the indications for the use of TSS have grown, this fact can lead to increasing chances of intraoperative vascular injuries, and till now has not been reached a definite conclusion, whether TSS has a significant difference in the complication rate between endoscope and microscope techniques. Another advancement of preoperative neuroradiological investigation to detect such arteries derived from the ICA and the ECA is also useful for their precise localization and avoidance of fatal complications. Especially, the role of digital subtraction angiography in the operating room is significant, because, once the arterial injury during TSS happens, the emergent detection of affected vessel(s) and the management of the trauma is required. In addition, the development of endovascular surgery both in the techniques and the instruments remarkably changed the principles of treatment for intraoperative vascular injury during the TSS. Especially, in cases of ICA injury, the endovascular treatment with parent artery occlusion can be performed with acceptable morbidity and mortality rates. This technique can be also applied to the pseudoaneurysm, which arises from the injury site of the ICA at the postoperative delayed period, and causes fatal and massive epistaxis. However, vascular injury during endoscopic endonasal TSS is not well studied or reported, despite it is still a feared complication. The anatomic substrate for such complication in each stage of the TSS (naso-sphenoidal, spheno-planum, dural, intrasellar, and suprasellar phase) is discussed with respect to operative and neuroradiological aspects, identification of risk factors, management strategies for avoidance of such serious vascular complications, and their outcomes. © 2016 by Nova Science Publishers, Inc. All rights reserved.[Book Chapter]Embargo Period 12 month