Infralabyrinthine approach to the petrous apex

Abstract

This study measures the anatomical dimensions of the path to the petrous apex (PA) via the infralabyrinthine approach in temporal bones of adult Indian subjects, and studies the anatomical variation encountered in this approach. Forty-two temporal bones were dissected to gain access to the PA via the infralabyrinthine approach. The horizontal and vertical dimensions of the access window created as well as the length of the track to the PA from the vertical portion of facial nerve were measured with two-point calipers. Complete dissection was possible in only 21 bones (50%). In the remainder, after preliminary cortical mastoidectomy, an access window to the PA could not be created due to a high jugular bulb. The mean dimensions of the window in dissected bones were 4.60 mm vertically (SD = 0.94 mm) and 6.45 mm (SD = 1.44 mm) horizontally, and the depth of the track to the PA was 30.26 mm (SD = 3.62 mm). The infralabyrinthine approach to the PA provides wide access to lesions of the posterior and inferior PA. In up to 50% of temporal bones, as evidenced by this series, access may be limited by a high jugular bulb. The possibility of this anatomical variation should be considered when the surgical approach to a PA lesion via the infralabyrinthine approach is being planned.

Decompression of the Jugular Bulb for Enhanced Infralabyrinthine Access to the Petroclival Region: A Quantitative Analysis

“…The transmastoid infralabyrinthine approach was described by Dearmin in 1937 13 and has advantages of hearing preservation, preservation of facial nerve function, and maintenance of the posterior wall of the external auditory canal. Wider access at the mastoid becomes severely restricted more deeply, however, by the jugular bulb in half of the temporal bones dissected by Jacob and Rupa, 15 and in 40% by Haberkamp. 14 This report demonstrates the feasibility of widening this surgical corridor with decompression and retraction of the jugular bulb, supporting similar findings in other studies.…”

“…The transmastoid infralabyrinthine approach was described by Dearmin in 1937 13 and has advantages of hearing preservation, preservation of facial nerve function, and maintenance of the posterior wall of the external auditory canal. Wider access at the mastoid becomes severely restricted more deeply, however, by the jugular bulb that may severely limit or prevent access to the petrous apex in as many as 50% of cases based on cadaveric temporal bone dissection 14,15 or in 74% of cases based on computed tomography (CT) imaging. 16 Some reports have highlighted the feasibility and safety of decompressing and retracting the jugular bulb to improve infralabyrinthine drainage of cholesterol granulomas.…”

Initial Experience With the Retrosigmoid Inframeatal Approach in Skull Base Surgery

“…Preoperative analysis of surgical anatomy of lesion and nearby structures in preoperative imaging is mandatory to detect possible deviation from the normal anatomy, particularly a high located jugular bulb, which can impede the surgical approach (20).…”

Progress toward robotic surgery of the lateral skull base: Integration of a dexterous continuum manipulator and flexible ring curette

“…Tumors, cysts and infections of the lateral sku ll base present unique surgical challenges. Vital structures such as the cochlea, labyrinth, and facial nerve often lie along the straight path from surface to lesion, and the intervening dense bone sometimes leaves little option for co mplete removal without sacrificing these structures or waiting for the d isease to become so extensive as to impair their function and justify their sacrifice [1] [2]. Moreover, surgical mishaps involving the carotid artery or jugular vein/sigmoid sinus in the deep temporal bone can have disastrous consequences: these vessels are embedded in the bone and cannot be easily mobilized to control hemorrhage.…”