Simple and safe exposure of the sigmoid sinus with presigmoid approaches

Abstract

Although entire exposure of the sigmoid sinus has been recognized as a complicated procedure in presigmoid approaches, we developed a new technique to expose the sigmoid sinus quite safely and simply without tough bone work. This study aims to demonstrate our technique in detail and present the effect of the procedure. Between January 2004 and December 2010, 77 patients underwent operations via presigmoid approaches in our institute. In all cases, the sigmoid sinus was completely exposed with our new surgical technique. The key step to expose the sigmoid sinus in our technique is dissection of the sinus from the overlying inner cortical bone in an antegrade direction from the junction of the transverse-sigmoid sinus to the jugular bulb using a bone dissector, avoiding meticulous bone drilling. We retrospectively examined a surgical video of all cases and determined the operative time required to entirely expose the sigmoid sinus from the transverse-sigmoid junction to the jugular bulb. In all 77 cases, the sigmoid sinuses were safely exposed with our new technique, and there was no episode of sinus injury. The operative time required to expose the sigmoid sinus ranged from 9.4 to 28.2 min (mean, 14.5 min). Standard drilling techniques took 32.3 min (range, 18.4-46.6 min) in last 20 cases before adoption of new technique. The new technique significantly shortened the surgical time to expose the sigmoid sinus (p < 0.01, Welch's t test). Our new technique is very useful for safely and simply exposing the sigmoid sinus, especially for standard neurosurgeons.

Mastoid notch as a landmark for localization of the transverse-sigmoid sinus junction

“…The accurate placement of the keyhole at the transverse-sigmoid sinus junction is one of the most important steps in this procedure [11][12][13][14]. Goto T used the lateral end of the transverse sinus, the ASTS, the mastoid emissary foramen and the midpoint of the transverse sinus as the site of 4 key holes to complete the exposure of the sigmoid sinus [2]. To avoid extensive bony defects in the periauricular area, Jia recommended a two-bone flap craniotomy technique for the transpetrosal presigmoid approach; this technique required that the first bone flap distinctly expose the ASTS to facilitate the dissection of the sigmoid sinus away from the inner table of the mastoid bone [15].…”

“…The anterosuperior and inferomedial points of the transverse-sigmoid sinus junction (ASTS and IMTS) represent the most posterior edge of the middle fossa and the most superolateral limit of the retrosigmoid approach, respectively. Accurately locating these key points on the external surface of the cranium is important in lateral skull base craniectomy [1][2][3][4]. Traditionally the squamosal-parietomastoid suture junction (SP) and asterion have been regarded as the classic landmarks for assisting with identifying the ASTS and IMTS, respectively [5][6][7].…”

Localization of Anterosuperior Point of Transverse-sigmoid Sinus Junction Using a Reference Coordinate System on Lateral Skull Surface

“…In such surgical procedure, exposure of the sigmoid sinus from the transverse-sigmoid sinus junction to the jugular bulb remains an essential and hazardous step. [ 1 2 3 10 11 ] Many experts have described their techniques to expose the sigmoid sinus safely without extensive bony defect. In such procedures, accurate localization of the ASTS is very important for the intervention.…”

“…Goto et al . [ 1 ] introduced a surgical skill for safely and simply exposing the sigmoid sinus. The authors used four key holes, including the lateral end of the transverse sinus, ASTS, mastoid emissary foramen, and midpoint of the transverse sinus, for guidance to complete the exposure of the sigmoid sinus.…”

“…During the transpetrosal-presigmoid approach, accurate determination of the surface projection of the anterosuperior point of the transverse-sigmoid sinus junction (ASTS) is particularly important when trying to expose sigmoid sinus safely. [ 1 2 3 ] Traditionally, neurosurgeons have regarded the squamosal-parietomastoid suture junction (SP) as the classic landmark to determine the ASTS. [ 4 5 6 ] However, the cranial sutures of some patients, especially the elderly, have been reported to be not obviously recognizable and palpable in craniotomy.…”