Therapeutic management of intracranial internal carotid artery blowout syndrome: an institutional case series and individual participant data meta-analysis

OBJECTIVE: Carotid blowout syndrome is a constellation of clinical presentations involving injury to the extracranial carotid system. It is frequently secondary to postradiation effects or direct invasion from head and neck cancers and is often managed via endovascular therapy (EVT). However, intracranial internal carotid artery blowout syndrome (ICABS) is a less described entity, has no predefined management algorithms, and can be difficult to manage due to the inherent anatomical limitations of the intracranial carotid. The aim of this study was to perform an individual participant data meta-analysis and present an institutional case series to describe the clinical course of ICABS, as well as to provide a treatment algorithm for this rare syndrome. METHODS: A search for all reported ICABS cases was performed using PubMed, Embase, Scopus, Web of Science, and Google Scholar until June 30, 2024. Additional cases from our institution were added. The primary outcomes were hemorrhagic control, postoperative complications, and all-cause mortality. RESULTS: The database search yielded 31 studies, and with the addition of 8 patients from the study institution, 80 patients (median age was 55 years) with ICABS were analyzed. The most common injury type was acute blowout (53.8%) and the most commonly affected segment was the petrous internal carotid artery (43.8%). The most frequent underlying diagnosis was head and neck cancer (52.5%). Radiation therapy (37.5%) and surgery (37.4%) were the most common preceding interventions. Overall bleeding control after individualized therapy was attained in 81.2% of patients, with most requiring parent vessel sacrifice (41.2%). The overall postoperative complication rate was 35%. The overall mortality rate was 27.5%, with mortality occurring predominantly in the conservative treatment group (60%) compared with the EVT (27.6%) and surgery (17.6%) groups. CONCLUSIONS: ICABS is rare and often fatal. It frequently occurs after radiation therapy for head and neck cancer or iatrogenically during transsphenoidal surgery. First-line treatment for acute ICABS is often EVT, as it offers a rapid means of halting further hemorrhage. Emerging technologies have allowed for more vessel-preserving strategies and warrant further investigation. Herein, an evidence-based algorithm is provided to help guide management. Systematic review registration no.: CRD42022385494 (www.crd.york.ac.uk/prospero/).