INTRASPHENOID PROLAPSE OF THE INTERNAL CAROTID-ARTERY - COMPUTED-TOMOGRAPHY OF 300 SINUSES

Objectives: Endonasal sphenoidotomy is a high risk operation: fatal complications due to direct lesion to the internal carotid artery have been reported. We conducted a prospective analysis of carotid prolapse within the sphenoid cavity in order to draw attention to this dangerous anatomic variant. Methods: Tomodensitometry of the sinuses was performed in 150 patients (mean age 35 years; range 20-70) with inflammatory nasal symptoms of less than one year duration (mean 5.2 months). Cases with benign or malignant tumours, polyposis or a past his tory of sinus trauma were excluded. Transversal sections were analyzed by one radiologist and one ear-nose throat specialist. The diagnosis of carotid prolapse was defined as an intrasphenoid protrusion of the artery at least as long as one-third of its circumference. Results of the analysis were expressed as percent for 300 sinuses. Results: Prolapse of the internal carotid was found in 20.3% of the sinuses (n=61). In all cases a thin (> 1 mm) bony structure surrounded the artery. No prolapse was observed into the posterior ethmoid cells. Conclusions: Intrasphenoid prolapse of the internal carotid artery is a major risk factor in nasal and sinus surgery. The high incidence (1 out of 5 sinuses) indicates the need for routine preoperative imagery to reduce surgical risk.