Endoscopic Endonasal Approach for Petrous Bone Lesions

Objective: To elucidate the indication and limitation of endoscopic endonasal approach to petrous bone lesions, based on comparison of the surgical views between via an endonasal route and via a transcranial route in clinical cases.

Methods: We evaluated surgical views and accessible areas during combined endoscopic-endonasal and microscopic-transcranial (anterior petrosal) surgeries in 2 patients with chordoma and cavernous angioma invading into petrous bone.

Results: In transcranial anterior petrosal approach with preserving greater superficial petrosal nerve, trigeminal nerve and middle and inner ear, limitation is the jugular tubercle. Caudal regions of the jugular tubercle are deep with blind corners and difficult to get orientation. Endoscopic endonasal approach is suitable to approach inferior side of the petrous bone and antero-lateral area of the foramen magnum. Detection of internal auditory canal, jugular foramen and hypoglossal canal via the endonasal route is easier than via the transcranial route. On the other hand, sophisticated procedures are difficult in dorsolateral side of internal carotid artery. Adhesive or invasive tumors in this area required removal via the transcranial route.

Conclusion: Accessible areas of endoscopic endonasal approach and anterior petrosal approach to the petrous bone are mutually complementary. Based on tumor location in the petrous bone, appropriate surgical corridor should be selected. Combined endonasal and transcranial surgery is recommended for extensive tumors in the petrous bone.