Endoscopic Transnasal Approach to the Petrous Apex

Objective: Different microsurgical approaches offer safe resection of petrous apex lesions. In the past few years, endoscopic skull base surgery has come more and more into focus. The endoscopic transsphenoidal approach was extended by bony resection of the clivus or the pyramid to reach the petrous apex.

Design: The aim of this report is to show the feasibility of this approach and define its advantages and disadvantages.

Material and Methods: A pure endoscopic transnasally navigated approach was used in eight cases. Entities included fungal abscess, chondrosarcoma, adenoid cystic carcinoma, Rathke's cyst, epidermoid, and cholesterol granuloma. The four-hand, two-nostril technique with a 4-mm 0° to 45° endoscope was used. A thin-sliced CT served for neuronavigation, combined with CT angiography or fusion with MR carotid artery sensitive series, and registration was achieved by surface matching.

Results: Processes of the petrous apex can be reached by transnasal endoscopy. Bony resection can be achieved only in a straight trajectory from the contralateral nostril to the medial wall of the carotid artery. Soft tissue can be resected up to the inner auditory canal and jugular foramen with angled curettes. No bleeding, cerebrospinal fluid (CSF) fistula, or new neurological deficits were encountered.

Conclusions: The pure endoscopic transnasal approach is suitable for different pathologies of the petrous apex. In this series, the complication rate was low, and only minor side effects of the approach were observed. Bony resection is limited by the course of the carotid artery. Thus, soft tissue tumors are the candidates of choice.