A case of carotid blowout syndrome following endoscopic endonasal surgery and proton beam therapy for chondrosarcoma: Considering the role of nasoseptal mucosal flap for minimizing bleeding

Background: Following advancements in endoscopic endonasal surgery (EES), neurosurgeons have become increasingly proficient in exposing the internal carotid artery (ICA) through EES. Consequently, they are also more frequently encountering carotid blowout syndrome (CBS), a potentially fatal complication. Therefore, it is essential for neurosurgeons to be well-prepared to manage the emergency effectively. Case Description: A 64-year-old man underwent EES for a left clival chondrosarcoma. Following tumor resection, the left ICA was covered with a nasoseptal mucosal flap to mitigate the risk of CBS associated with postoperative radiation therapy. Approximately 8 years after undergoing proton beam therapy, the patient presented with sudden epistaxis and was admitted to the hospital. After achieving temporary hemostasis in the outpatient department, a cerebral angiogram revealed a pseudoaneurysm at the end of the petrous portion of the ICA, which was suspected to be the bleeding point. Revascularization of the left ICA with high-flow bypass (HFB) and parent artery occlusion was planned. Due to recurrent preoperative epistaxis, emergent hemostasis through EES was performed. The bleeding was effectively controlled because the pseudoaneurysm was covered by the nasoseptal mucosal flap. The patient subsequently underwent the planned HFB procedure without complication. Conclusion: In the present case, the nasoseptal mucosal flap likely facilitated rapid, temporary hemostasis at the onset of CBS, playing a critical role in the patient’s survival. Neurosurgeons should consider the use of nasoseptal mucosal flaps not only for the prevention of cerebrospinal fluid leakage but also as a protective barrier and a means of facilitating hemostatic control in the event of CBS.