Parietal Foramen as A Landmark to Locate Intracranial Vascular and Parenchymal Structures

Abstract The aim of this study was to define the location of the parietal foramina (PF) with reference to skull landmarks and correlate the PF with cerebral and vascular structures to optimize neurosurgical procedures in the intracranial compartment. Two hundred and thirty-eight parietal bones studied by magnetic resonance imaging (MRI) of 119 patients were reviewed. The cephalometric points, inion, bregma, sagittal suture and lambda were used as anatomical references to locate the PF and define its anatomical relationships to parenchymal cerebral structures, especially some eloquent areas. The PF was identified in the MRI in 83 of the 119 individuals (69.7%) and was located at an average distance of 9.5 ± 0.8 cm (mean ± SD) posteriorly and 0.9 ± 0.3cm laterally to the Bregma. In over 90% of cases, the PF was located within a 2 cm radius of the bregma-PF distance’s mean value. Surgeons operating in the parietal region should be aware of the frequency of PF (69.7%), its location (superolateral to lambda) and its stable relationship with underlying anatomical structures. 88% of the 62 left PF’s were situated within 1cm, laterally to the left margin of the superior sagittal sinus (SSS). 60% of the right PF were situated within 1.3 cm laterally from the right margin of the SSS, while 40% were directly above the SSS. We propose that the PF should be used as the reference for the superior sagittal sinus during its course through the parietal lobe, as its constancy overtakes other commonly used landmarks (sagittal suture and midline). In conclusion, clinicians should be aware of the PF to both avoid iatrogenic injury to an emissary vein that courses through it that can lead to air embolism and as a guide to maneuvering through the parietal region.