Entry Point to the Sylvian Fissure for the Pterional Transsylvian Approach

Abstract

Background Although the anatomy of the Sylvian fissure is understood, there is little information on where to start its dissection in the pterional transsylvian (PT-TS) approach. At small craniotomy using the PT-TS approach, we set the entry point to the Sylvian fissure at 15 mm behind the anterior edge of the craniotomy along the Sylvian fissure and designated this site “point 15.” Here we compared the utility of “point 15” with the Sylvian point (point on the Sylvian fissure giving rise to the horizontal and anterior ascending rami) that had been recommended earlier as the entry site for opening the Sylvian fissure.

Materials and Methods This study includes 16 patients with 7 ruptured and 9 unruptured anterior circulation aneurysms. We evaluated the usefulness of “point 15” in the PT-TS approach for aneurysmal neck clipping with respect to the adequacy of anatomical exposure and low invasiveness.

Results In 12 patients “point 15” provided for excellent anatomical exposure of the Sylvian fissure; complete neck clipping was possible with minimal brain retraction and damage. In two patients with ruptured aneurysms and thick subarachnoid hemorrhage and in two patients with unruptured aneurysms, the dissection had to be enlarged 3 to 4 mm distally without reaching the Sylvian point. In the latter two patients the Sylvian veins were tethered to frontal and temporal lobes.

Conclusions The “point 15” was an easily set entry point to the Sylvian fissure. It provided for sufficient anatomical exposure at surgery for anterior circulation aneurysms; additional posterior dissection was required in rare cases. We found that “point 15” was useful in small craniotomies using the PT-TS approach.

Keywords

sylvian fissure - transsylvian approach - sylvian vein - entry point - sylvian point

• References

• 1 Figueiredo EG, Deshmukh P, Zabramski JM, Preul MC, Crawford NR, Spetzler RF. The pterional-transsylvian approach: an analytical study. Neurosurgery 2006; 59 (4) (Suppl. 02) ONS263-ONS269 , discussion ONS269
• 2 Aydin IH, Tüzün Y, Takçi E, Kadioğlu HH, Kayaoğlu CR, Barlas E. The anatomical variations of sylvian veins and cisterns. Minim Invasive Neurosurg 1997; 40: 68-73
• 3 Yasargil MG. Microneurosurgery. Vol. 1. Stuttgart, New York: Georg Thieme Verlag; 1984
• 4 Kazumata K, Kamiyama H, Ishikawa T , et al. Operative anatomy and classification of the sylvian veins for the distal transsylvian approach. Neurol Med Chir (Tokyo) 2003; 43: 427-433 , discussion 434
• 5 Rhoton Jr AL. Aneurysms. Neurosurgery 2002; 51 (Suppl. 01) 121-158
• 6 Wen HT, Rhoton Jr AL, de Oliveira E, Castro LH, Figueiredo EG, Teixeira MJ. Microsurgical anatomy of the temporal lobe: part 2—sylvian fissure region and its clinical application. Neurosurgery 2009; 65 (6, Suppl): 1-35 , discussion 36
• 7 Heros RC, Fritsch MJ. Surgical management of middle cerebral artery aneurysms. Neurosurgery 2001; 48: 780-785 , discussion 785–786
• 8 Ito Z. Microsurgery of Cerebral Aneurysms. Tokyo: Nishimura/Elsevier; 1985
• 9 Türe U, Yaşargil DCH, Al-Mefty O, Yaşargil MG. Topographic anatomy of the insular region. J Neurosurg 1999; 90: 720-733
• 10 Gibo H, Carver CC, Rhoton Jr AL, Lenkey C, Mitchell RJ. Microsurgical anatomy of the middle cerebral artery. J Neurosurg 1981; 54: 151-169
• 11 Sugita K. Microneurosurgical Atlas. Berlin: Springer Verlag; 1985
• 12 Shimizu S, Tanriover N, Rhoton Jr AL, Yoshioka N, Fujii K. MacCarty keyhole and inferior orbital fissure in orbitozygomatic craniotomy. Neurosurgery 2005; 57 (1, Suppl): 152-159 , discussion 152–159
• 13 Vishteh AG, Marciano FF, David CA , et al. The pterional approach. Oper Tech Neurosurg 1998; 1: 39-49
• 14 Yasargil MG, Krisht AF, Ture U, Al-Mefty O, Yasargil DC. Microsurgery of insular gliomas: Part II: Opening of the sylvian fissure. Contemp Neurosurg 2002; 24: 1-5
• 15 Naidich TP, Valavanis AG, Kubik S. Anatomic relationships along the low-middle convexity: Part I—Normal specimens and magnetic resonance imaging. Neurosurgery 1995; 36: 517-532
• 16 Nathal E, Gomez-Amador JL. Anatomic and surgical basis of the sphenoid ridge keyhole approach for cerebral aneurysms. Neurosurgery 2005; 56 (1, Suppl): 178-185 , discussion 178–185
• 17 Paladino J, Mrak G, Miklić P, Jednacak H, Mihaljević D. The keyhole concept in aneurysm surgery—a comparative study: keyhole versus standard craniotomy. Minim Invasive Neurosurg 2005; 48: 251-258