Comparison of Anatomical Exposure during Petrosectomy among Anterior Transpetrosal versus Various Methods of Endoscopic Endonasal Approaches: An Experimental Study in Cadavers”

Background: The approach to the petroclival area is challenging. The transcranial anterior petrosectomy (AP) is a classic approach; however, it may encounter adverse consequences. In the past decade, endoscopic endonasal approaches (EEA) were designed to decrease complications and enhance surgical exposure. We aim to describe surgical techniques and compare the anatomical exposure among the AP and three types of EEAs.

Methods: Ten cadaveric heads, 20 sides, were used for anatomical dissection. The specimens were divided into the four groups; undergoing AP, EEA for medial petrosectomy (MP), inferior petrosectomy (IP), and inferomedial petrosectomy (IMP). Outcomes were areas of exposure, angles of attack to neurovascular structures, and bone resection volumes.

Results: The AP had comparable areas of exposure to that in the MP (308 ± 50.6 vs. 258 ± 20.9 mm², p = NS), but was higher than the IP (118 ± 14.5 mm², p < 0.01), and lower than the IMP technique (438 ± 46.7 mm², p < 0.01). The AP had higher angle of attack to the distal part of CN VII/VIII complex than the IP and IMP technique (78 ± 9.6 vs. 30 ± 5.8 vs. 41 ± 6 degrees, p < 0.01). The IMP technique had higher angle of attack to the midpons (45 ± 7.9 vs. 36 ± 3.3 degrees, p = 0.04) and the AICA (45 ± 3.6 vs. 36 ± 3.5 degrees, p < 0.01) than the MP technique. The IMP technique had higher the angle of attack to the proximal part of CN VII/VIII complex (44 ± 4 vs. 32 ± 5.8 degrees, p < 0.01), the flocculus (39 ± 5.4 vs. 28 ± 4.3 degrees, p < 0.01) than the IP technique. The bone resection volume in the AP (mm³) was significantly lower than that in the MP, the IP, and the IMP technique (940 ± 207 vs. 1,660 ± 230 vs 2,340 ± 357 vs. 3,360 ± 151 mm³, p < 0.01).

Conclusion: The AP and each EEA techniques had specific advantages for each specific areas. We suggested the AP for ventrolateral pons and anterosuperior internal acoustic canal; the MP for midline clivus, not beyond paraclival internal carotid artery and CN VI; the IP for ventrolateral brainstem; and the IMP to enhance lateral corridor of abducens nerve.

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
12 February 2021