WP Chung O T in Craniofacial Surgery 9781496348265

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Chapter 1 Fronto-Orbital Advancement

■■ Key relevant anatomic features include the following: ■■ Central ridging/bulged metopic suture ■■ Characteristic triangular-shaped forehead (bilateral fronto-orbital hypoplasia) occurs to varying degrees, with classification schemes related to the severity of angulation ■■ Hypotelorism ■■ Lateral orbital rim posteriorly displaced and hypoplastic ■■ Flattened profile of the squamosal bone ■■ Biparietal widening of the skull Unilateral coronal craniosynostosis 6,9,10 ■■ Premature bony bridging of the coronal suture, typically in the approximate midpoint of the course of the coronal suture ■■ Patent sagittal suture is displaced away from the fused suture posteriorly and toward it anteriorly. ■■ Key features: ■■ Flattened ipsilateral forehead ■■ Contralateral forehead bossing ■■ Intrinsic orbital changes (pathognomonic harlequin deformity) ●● Ipsilateral flattened supraorbital rim and vertically taller/narrower orbit with steep superior orbital fissure and greater/lesser sphenoid wings ●● Depression (inferior displacement) of contralateral supraorbital rim ■■ Squamosal-temporal bone convexity ■■ Depression of the free border of the superolateral orbital rim ■■ Protrusive zygoma, ipsilateral to the coronal fusion ■■ Raised eyebrow and widened palpebral opening ipsilat- eral to the fused suture ■■ Root of nose deviation toward the affected (fused) side and nasal tip towards the contralateral (open) side ■■ Ear displacement anteriorly/superiorly, ipsilateral to fused suture ■■ Contralateral chin point deviation ■■ Base of skull deformity ●● Severity can be determined by evaluating the sphenope- trosal angle and the degree of angulation from midline structures (cribriform plate) ipsilateral to fusion 2,6,9 Bilateral coronal craniosynostosis 2 ■■ Bilateral premature fusion of the coronal suture with sym- metric foreshortened anterior cranial base ■■ Key features: ■■ Bilateral retrusion of frontal bone and supraorbital rims ■■ Bilateral lateral bulge of squamous temporal bones ■■ Increased biparietal diameter ■■ Syndromic vs nonsyndromic features include midface hypoplasia and mandibular deformity in syndromic cases ■■ Frontosphenoidal synostosis 11–13 ■■ Rare case of anterior plagiocephaly ■■ Often misdiagnosed ■■ Requires 3D CT reconstruction to identify in isolated cases ■■ Angulation of the anterior cranial base ■■ Deflection of the anterior cranial fossa opposite to fused suture ■■ Altered relationship between cranial vault and facial skel- eton, resulting in a phenotype similar to UCS ■■ Contralateral bossing and ipsilateral brow depression ■■ Nasal tip deviation reported in 50% of cases

■■ Harlequin deformity may not be present or be minimally evident. ■■ Key orbital/ophthalmologic evaluation ■■ Orbital size/shape ■■ Globe position/prominence ■■ Corneal inflammation (exposure) ■■ Distinct structural differences between ipsilateral and con- tralateral orbits ■■ Extraocular movement (strabismus), particularly superior oblique dysfunction ■■ Visual acuity ■■ Lid margin and levator function (anterior plagiocephaly) ■■ Supratarsal crease reduction (anterior plagiocephaly) ■■ Hypertelorism (brachycephaly) in some syndromic cases ■■ Malar recession in syndromic cases ■■ The definitive diagnostic study for craniosynostosis is a CT scan demonstrating fusion of a cranial vault suture. ■■ However, imaging of cranial anatomy has been used less frequently, as the typical clinical structure in the individual forms of craniosynostosis is more recognized. ■■ This has been highlighted by concerns related to exposure of infants to ionizing radiation by CT scan and for seda- tion and anesthetics often required to obtain MR scans. ■■ Ultrasound examinations, except in the very young, are not accurate enough to serve as a definitive diagnostic source and therefore used infrequently. ■■ Occasional cases of craniosynostosis are best examined using CT scan, with 3D reconstruction, which may help in certain forms of craniosynostosis for planning of surgery ( FIG 1 ). ■■ With a typical clinical exam, or confirmatory CT scan, cra- nioplasty is typically performed early in life to take advan- tage of the potential for better intellectual development (up to 6 months of age). 4,7 ■■ The counterargument to earlier surgery is the potential increase in the number of cases requiring revision surgery, as structurally it is more difficult to account for continuing growth when surgery is performed at earlier stages of life. ■■ Bone manipulation and stabilities are enhanced in older-age children beyond 6 months of age, but the issue of deleteri- ous impact on brain development is now creating more con- cern , leading to promoting delayed surgery. 14,15 ■■ An advantage of earlier surgery is better malleability of bone. ■■ Larger bone defects may fill in secondarily by subsequent growth of the brain and dura. ■■ Potentially improved neurologic outcome ■■ Disadvantages of early surgery include the following: ■■ Increased risk for proportionate blood loss with smaller amounts of volume lost ■■ A potential increased requirement for repeat surgeries in the future ■■ Advantages of later surgery (delayed to 1 year of age): ■■ More mature brain and bone systems to be operated on ■■ Blood loss is not as strong a concern due to increased body weight and proportionate circulating blood volume. ■■ Structures may be fixed in place more securely with lesser concern about growth restriction.

IMAGING

SURGICAL MANAGEMENT

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