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
