A craniometric study of bicoronal craniosynostosis (BCC).

We compared 20 cases of bicoronal craniosyntosis (BCC) using the linear and angular values of the normal statistical material for the same age and sex. The skull in BCC is significantly shortened and flattened but with normal width. The height of the frontal arch (FNBR) is significantly decreased. The base of the skull is depressed with angle AB2 significantly increased, and angle NTNO significantly decreased and, even in some cases, with negative angular values. This is inducing a sinking of LEA (length from N to T), and in some cases LEA is lower than the line LNO (distance from N to O). The cephalic index (CI) was significantly increased, and the calculated cranial capacity (CC) was significantly decreased. Bregma (BR) is moving anteriorly in BCC, inducing an anterior movement of the calvaria with a bulge around BR. In this anterior movement we designate lack of positive occipital rotation. In BCC there is an evident lack of positive occipital rotation. Superimposing our drawings on the reference line NBA, we found for the first time a movement of anatomical landmarks similar to that observed in the negative occipital rotation in vestibular orientation.