Minor Suture Fusion in Syndromic Craniosynostosis

Background: Infants with craniofacial dysostosis syndromes may present with mid-face abnormalities but without major (calvarial) suture synostosis and head shape anomalies. Delayed presentation of their calvarial phenotype is known as progressive postnatal craniosynostosis. Minor sutures/synchondroses are continuations of major sutures toward and within the skull base. The authors hypothesized that minor suture synostosis is present in infants with syndromic, progressive postnatal craniosynostosis, and is associated with major suture synostosis. Methods: The authors performed a two-institution review of infants (<1 year) with syndromic craniosynostosis and available computed tomographic scans. Major (i.e., metopic, sagittal, coronal, and lambdoid) and minor suture/synchondrosis fusion was determined by two craniofacial surgeons and one radiologist using Mimics or Radiant software. Results: Seventy-three patients with 84 scans were included. Those with FGFR2 mutations were more likely to lack any major suture fusion (OR, 19.0; p = 0.044). Minor suture fusion occurred more often in the posterior branch of the coronal arch (OR, 3.33; p < 0.001), squamosal arch (OR, 7.32; p < 0.001), and posterior intraoccipital synchondroses (OR, 15.84; p < 0.001), among FGFR2 versus other patients. Patients (n = 9) with multiple scans showed a pattern of minor suture fusion followed by increased minor and major suture synostosis. Over 84 percent of FGFR2 patients had minor suture fusion; however, six (13 percent) were identified with isolated major suture synostosis. Conclusions: Minor suture fusion occurs in most patients with FGFR2-related craniofacial dysostosis. Syndromic patients with patent calvarial sutures should be investigated for minor suture involvement. These data have important implications for the pathophysiology of skull growth and development in this select group of patients.