Physiological Changes and Clinical Implications of Syndromic Craniosynostosis.

Syndromic craniosynostosis has severe cranial stenosis and deformity, combined with hypoplastic maxillary bone and other developmental skeletal lesions. Among these various lesions, upper air way obstruction by hypoplastic maxillary bone could be the first life-threatening condition after birth. Aggressive cranial vault expansion for severely deformed cranial vaults due to multiple synostoses is necessary even in infancy, to normalize the intracranial pressure. Fronto-orbital advancement (FOA) is recommended for patients with hypoplastic anterior part of cranium induced by bicoronal and/or metopic synostoses, and posterior cranial vault expansion is recommended for those with flattening of the posterior part of the cranium by lambdoid synostosis. Although sufficient spontaneous reshaping of the cranium can be expected by expansive cranioplasty, keeping the cranial bone flap expanded sufficiently is often difficult when the initial expansion is performed during infancy. So far distraction osteogenesis (DO) is the only method to make it possible and to provide low rates of re-expansion of the cranial vault. DO is quite beneficial for both FOA and posterior cranial vault expansion, compared with the conventional methods. Associated hydrocephalus and chronic tonsillar herniation due to lambdoid synostosis can be surgically treatable. Abnormal venous drainages from the intracranial space and air way obstruction should be always considered at any surgical procedures. Neurosurgeons have to know well about the managements not only of the deformed cranial vault and the associated brain lesions but also of other multiple skeletal lesions associated with syndromic craniosynostosis, to improve treatment outcome.