Timing of Ossification of the Anterior Skull Base in Syndromic Synostosis.

The anterior skull base undergoes a progressive ossification after birth. This has implications on the epidural dissection of early trans-craniofacial osteotomy procedures such as monobloc advancements. Our purpose was to determine the rate of ossification in syndromic synostosis patients relative to a normal cohort to establish when maturation of the anterior skull base is complete. The authors analyzed CT scans from 35 patients with Crouzon, Apert or Pfeiffer syndrome, and 84 patients without any craniofacial anomaly between the ages of 0 and 6 years. The non-ossified anterior skull base area was measured using 3D Slicer. The authors compared the sizes of the defects at different ages between the three syndromes and with the control group using Mann-Whitney test. Significance was set at P < 0.05. All patients less than 12 months of age had a measurable defect anterior to the cribriform whereas patients greater than five years of age had full ossification of the anterior skull base with no evidence of defect. The relationship of defect size and age at scan was non-linear, with most defects closing rapidly in the first six months. The temporal closure pattern of the defect was similar between the three syndromes and the control group with no significant difference. Our findings indicate that syndromic children undergo skull base maturation at the same rate as non-syndromic cases, with the majority ossified by three years of age. Anterior skull base surgeries performed before three years should optimize visualization of this area during dissection.