Validação anatômica da trepanação sobre o ponto esfeno-pterional nas craniotomias frontolaterais

Abstract

Introduction: Frontotemporal craniotomies, including pterional craniotomies, are the most commonly performed neurosurgical approaches. We studied the external bony landmarks on the lateral surface of the skull to identify a “strategic” point where both the anterior and middle cranial fossae are exposed simultaneously during frontotemporal craniotomies through a single burr hole placed over the sphenoidal portion of the pterion (spheno-pterional point). Objetive: The aim of this work was to anatomically define the spheno-pterional point via craniometric measurements taken on the lateral surface of the human skull. Method: This work used one hundred adult (age > 18 yo) human dry crania (200 sides) with the calvaria removed, which were cataloged by gender and age. Under direct visual control of the inner and outer surfaces of the skull and by using laser transillumination, the spheno-pterional point was accurately identified in the temporal fossa. Measurements were taken based on easily identifiable bony landmarks, such as the frontozygomatic suture and the zygomatic arch. A horizontal line was established parallel to the superior border of the zygomatic arch extending from the spheno-pterional point up to the zygomatic process of the frontal bone, and a vertical line was drawn by connecting perpendicularly the frontozygomatic suture to the horizontal line. Based on these lines, the horizontal and vertical distances were established between the spheno-pterional point and the frontozygomatic suture. Result: The frontozygomatic suture was identified in all specimens (100%) on both the left and right sides. Regardless of gender or the side of the skull, the mean horizontal distance was 21.72 mm (SD, 3.17 mm; range, 14.25 mm-32.58 mm), and the mean vertical distance was 4.76 mm (SD, 1.74 mm; range, 0.00-9.73 mm). Neither the horizontal (right side, p=0.621; left side, p=0.341) nor the vertical measurements (right side, p=0.460; left side, p=0.609) differed significantly between genders. Therefore, males and females present, on average, the same vertical and horizontal measurements on both sides. The burr hole placed over the sphenopterional point simultaneously exposed both the frontal and middle fossae in the frontolateral craniotomies. Conclusions: According to our measurements, this point is located, on average, 21.72 mm posterior and 4.76 mm superior from the frontozygomatic suture, over the sphenoidal bone component of the pterion region. This modified keyhole eliminates the need for burr holes over the traditional keyhole as well as over the squamous temporal bone.