A Combined Extradural-Intradural Technique for an En Bloc Anterior Petrosectomy: A Cadaveric Feasibility Study

Flavia Dones; Ioannis Kournoutas; Vera Vigo; Rina Di Bonaventura; Kunal Raygor; Ivan H El-Sayed; Adib A Abla; Roberto Rodriguez Rubio

doi:10.1016/j.wneu.2018.12.089

A Combined Extradural-Intradural Technique for an En Bloc Anterior Petrosectomy: A Cadaveric Feasibility Study

World Neurosurg. 2019 Apr:124:e315-e323. doi: 10.1016/j.wneu.2018.12.089. Epub 2019 Jan 9.

Authors

Flavia Dones¹, Ioannis Kournoutas¹, Vera Vigo¹, Rina Di Bonaventura¹, Kunal Raygor², Ivan H El-Sayed³, Adib A Abla⁴, Roberto Rodriguez Rubio⁵

Affiliations

¹ Skull Base and Cerebrovascular Laboratory, University of California, San Francisco, California, USA.
² Department of Neurological Surgery, University of California, San Francisco, California, USA.
³ Skull Base and Cerebrovascular Laboratory, University of California, San Francisco, California, USA; Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, California, USA.
⁴ Skull Base and Cerebrovascular Laboratory, University of California, San Francisco, California, USA; Department of Neurological Surgery, University of California, San Francisco, California, USA.
⁵ Skull Base and Cerebrovascular Laboratory, University of California, San Francisco, California, USA; Department of Neurological Surgery, University of California, San Francisco, California, USA; Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, California, USA. Electronic address: neurodriguez@gmail.com.

PMID: 30639606
DOI: 10.1016/j.wneu.2018.12.089

Abstract

Introduction: The anterior petrosectomy approach is among the most popular for exposure of the petroclival region. However, the complexity of the anatomy, drilling time required, and risk of injury to neurovascular structures have made this procedure especially challenging. We have proposed a novel combined extradural-intradural technique for en bloc anterior petrosectomy-or one-piece Kawase-and have charted the landmarks that define its surgical boundaries.

Methods: The approach was performed on 14 embalmed specimens. The one-piece Kawase approach consists of 3 extradural drilling steps, followed by incision of the dura and skeletonization of the superior petrosal sinus. The procedure culminates with 2 intradural drilling steps. The bone piece was then removed en bloc, and the maximum anteroposterior, superoinferior, and mediolateral lengths were recorded. The linear distances between the main neurovascular landmarks were also measured using a stereotactic navigation system.

Results: The mean measurements were 17.6 ± 2.6 mm for the anteroposterior distance, 10.5 ± 2.3 mm for the superoinferior distance, and 9.5 ± 2.6 mm for the mediolateral distance. The medial linear distance from the mandibular nerve/greater superficial petrosal nerve to the internal carotid artery was 6.8 ± 1.3 mm, to the facial hiatus was 11.6 ± 2.2 mm, and to the lateral internal acoustic canal was 17.9 ± 1.8 mm. The average distance from the porus trigeminus to the medial internal acoustic canal was 19.4 mm.

Conclusions: The advantages of this technique include the wide exposure of the petroclival region, extensive visualization of critical structures via extradural and intradural corridors, and minimization of bone drilling, which could reduce heat damage. Clinical application of the illustrated technique is required to test its reliability in different pathological subsets.

Keywords: Extradural–intradural drilling; Internal acoustic canal; Kawase approach; Middle fossa; One-piece; Petroclival region; Trigeminal landmarks.

Published by Elsevier Inc.