Localization of the bregma and its clinical relevance

Abstract

Objectives: External landmarks on the skull are important guides in various neurosurgical procedures. The localization of the bregma is vitally important in bedside ventriculostomy and craniotomies. The aim of the current study was to verify the localization of the bregma. Methods: This was performed on dry skulls (n=72) and sagittal computerized tomography (CT) images of patients (n=100). The age and the sex of dry skulls were unknown. Of the 100 patients, 48 were males and 52 were females and the mean age for males was 51.14 and for females was 55.34. The distance between nasion to inion and nasion to bregma were measured from both dry skulls and on multiplanar reformation (MPR) sagittal images. The ratio of the two measurements was calculated. Results: The nasion to bregma distances on 72 dry skulls ranged between 120-140 mm: the average distance was 124.3±6.9 mm. The nasion to inion distance ranged between 295-345 mm; the average was 320.8±14.4 mm. The ratio of nasion to bregma distance to nasion to inion distance was calculated as 0.384. The nasion to bregma distance obtained from 100 CT images scans ranged from 107 to 139 mm (average 126.6±7.3) mm. The nasion to inion distances ranged between 301 and 356 (average 330.2±15.2) mm. The ratio of nasion to bregma distance to nasion to inion distance was calculated as 0.383. Measurements for females were lower than males, but there was no statistical significance between genders. The multiplication of the nasion to inion distance by 0.38 gave the location of bregma for both genders. Conclusion: An accurate and reliable ratio (0.38 times the distance from nasion to inion) was obtained to define the bregma. The coronal suture lay on each side of bregma, so knowing the exact localization of bregma and of the coronal suture can be vitally important in various surgical procedures to the cranium.