Applied Anatomy Study Of The Modify Infralabyrinthine Approach To The Internal Auditory Canal Surgery

Objective To study surgical methods in order to expose the internal auditory canal (IAC) via the modify infralabyrinthine approach resected the posterior semicircular canal (PSC), and to provide anatomic markers, anatomic parameters and evidence for operation on IAC through this approach. And to study the superiority and safety of this approach.Methods Under the microscope (× 6-16), exposure of IAC via the modify infralabyrinthine approach was simulated on 20 adult cadaveric heads (40 sides) fixed with 10% formaldehyde, in each surgery the PSC was removed, Simultaneously, exposed the IAC. Observe mastoid emissary. Measure the following parameters: the width of middle sigmoid sinus, the shortest distance from the anterior border of middle sigmoid sinus to the mastoid segment of facial nerve, the height of jugular bulb, the shortest distance from the top of jugular bulb to the inferior border of IAC, the shortest distance from the top of jugular bulb to the superior border of IAC, the shortest distance from the posterior extremity of horizontal semicircular canal (HSC) to the cerebral dura mater of posterior cranial fossa, the height of internal acoustic porus, the length of the posterior wall of IAC. Measurements were repeated three times and averaged. Acquired data were analysesed by SPSS 11.5 or PEMS software. Results Appearance frequency of mastoid emissary was 80% (32/40), furthermore, 68.75% (22/32) porus of the mastoid emissary were in front of the occipitomastoid suture. The shortest distance from the anterior border of middle sigmoid sinus to the mastoid segment of facial nerve was (9.84±2.48)mm; The height of jugular bulb was (5.40±1.48)mm; The shortest distance from the top of jugular bulb to the inferior border of IAC was (3.03±1.93)mm; The shortest distance from the top of jugular bulb to the superior border of IAC was (8.24±2.36)mm; The shortest distance from the posterior extremity of HSC to the cerebral dura mater of posterior cranial fossa was (5.60± 1.28)mm; The height of internal acoustic porus was (4.13±0.85)mm; The length of the posterior wall of IAC was (8.74±1.31 )mm; The length of the exposed IAC (IAC was exposed successfully in 33/40 sides of specimens via the modify infralabyrinthine approach) was (5.45 ± 1.04)mm, which was (61.52 ± 10.00)% of the...