The assessment of relationship between the skull base development and the severity of frontal plagiocephaly after bilateral fronto-orbital advancement in the early life

The deformation of the skull base in patients with unilateral frontal plagiocephaly (UFP) is well known, but the mechanism is not still clear. We analyzed the skull base in the patients with UFP who underwent fronto-orbital advancement (FOA) in the early life during the last decade. We assessed the treatment results and outcome of FOA performed in six patients, four girls and two boys younger than 2 years, in the last decade. Also, the basal cranium’s angles were measured by 3D reconstruction images on computed tomography (CT) scan. The mean patients’ age at FOAs was 11 months. Two cases were classified as grade 2A, two cases as grade 2B, and two cases as grade 3 (the classification of Di Rocco and Velardi). The ethmoidal axis was deviated a mean of 8.2° to the affected side. The mean angle between the petrosal pyramids and the midline (anterior-petrosal-sagittal angle, APSA) was 75.3° on the affected side and 66.2° on the normal side. The mean difference of APSA was 9.2°. On the follow-up CT images 5 years after surgery, the deviations of the ethmoidal axis clearly decreased, 5.7°, but the differences of APSA did not change, 8.8°. The midline distortion of anterior skull base should be considered to be spontaneously corrected during the follow-up periods in patients with all types of UFP who underwent FOA, unlike posterior skull base in the patients with grades 2B and 3 classification.