Anatomic survey of arachnoid foveolae and the clinical correlation to cranial bone grafting.

INTRODUCTION

When performing in situ harvesting of cranial bone grafts, there is a risk of entering the pericranial-intracranial venous system, either directly or indirectly through the arachnoid foveolae. The aims of this study were to investigate the size and location of arachnoid foveolae and to provide an anatomic road map to prevent penetrating these structures.

METHODS

Three hundred dry skulls were selected from the Hamann-Todd osteological collection (Cleveland, OH); skulls were collected between 1912 and 1938. Our study skulls were limited to whites or African American adults. Exclusion criteria included children (<18 y), ethnic groups other than African Americans and whites, skulls demonstrating fracture or craniofacial abnormalities, or any skull whose age, ethnicity, and sex could not be confirmed. From the 300 skulls in the collection, 200 met the criteria and were included in our review. The mean age of these 200 individuals was 43.86 years, with a male-to-female proportion of 100:100, and a white-to-African American proportion of 144:56. A 500-W candescent light was used to transilluminate the arachnoid foveola, and digital photographs with scale were obtained. The location and diameters of foveolae for arachnoid granulations relative to the coronal and sagittal suture were measured.

CONCLUSIONS

Approximately 90% of major arachnoid foveolae are located within 2.5 cm of the coronal and 1.5 cm of the sagittal suture for the left and right parietal bones. Major arachnoid foveolae are located at closer distances to the superior sagittal suture and the coronal suture in the right and left parietal bone than minor foveolae. The results of this study imply that potential complications can be minimized by avoiding these areas and by harvesting in situ bone grafts from the absolute and relative safe zones described in this study.