The Safe Zone of Posterior Semicircular Canal Resection in Suboccipital Retrosigmoid Sinus Approach for Acoustic Neuroma Surgery

Abstract

The aim of the study was to find the safe zone of posterior semicircular canal resection that can avoid structure damage in suboccipital retrosigmoid sinus approach for acoustic neuroma. One hundred twenty subjects (72 male and 48 female subjects) were involved in this study anonymously. Five parameters are measured in computed tomography: L1 is the line that goes through the common bony crus and parallel to the plane that contains posterior semicircular canal at axial plane. L2 is the middle sagittal line at axial plane. A is the point of posterior wall of the internal auditory canal at the level of the common bony crus. B is the intersection point of L1 and posterior wall of auditory canal. L3 is the line that goes through the plane that contains posterior semicircular canal at coronary plane. L4 is the middle sagittal line at coronary plane. C is the common bony crus. D is the ampulla. E is the most posterior point of posterior wall of auditory canal at the plane that goes through the posterior semicircular canal. The angle between L1 and L2 was 41.76 (SD, 5.64) degrees on the right and 43.40 (SD, 5.25) degrees on the left (P = 0.003). The distance between A and B was 0.59 (SD, 0.13) cm. The angle between L3 and L4 was 16.57 (SD, 6.51) degrees on the right and 17.57 (SD, 6.98) degrees on the left (P = 0.017). The distance between C and D was 0.60 (SD, 0.05) cm. The distance between E and line CD was 0.48 (SD, 0.09).

Analysis of the effect of neuroendoscopy-assisted microscopy in the treatment of Large (Koos grade IV) vestibular schwannoma

“…Ammirati et al (25) reported that the most commonly damaged structures were: the common peduncle (52%), the posterior semicircular canal (23%), the vestibule (21%), and the superior semicircular canal (4%). Lui et al (26) studied the safe resection area between the external lip of the internal auditory canal and the posterior semicircle in 120 patients. The maximum safe resection range of the posterior lip of the internal auditory canal was 7-9 mm, and the distance between the posterior superior wall of the internal auditory canal to the anterior edge of the jugular foramen was (3.94 ± 1.75) mm, moreover, the study showed that the length of the posterolateral wall of the internal auditory canal was 9.7 +/-1.6 mm.…”

Risk of Posterior Semicircular Canal Trauma When Using a Retrosigmoid Approach for Acoustic Neuroma Surgery and Role of Endoscopy: An Imaging Study

“…Lui et al studied the safe zone of drilling with respect to the posterior semicircular canal. 18 Their results show that the range of the safe drilling zone is significantly wide, which presents some difficulty in setting a safe zone. Important in the interpretation of their data is that IAC anatomy is not the only parameter that matters; the angle of vision and size of craniotomy can also have great effects on exposure limits.…”