Radiographic Findings

Radiographic findings reflect the deformities of the cranium observed clinically. The initial examination is a skull series consisting of anteroposterior or Caldwell, Towne, and both lateral projections. The shape of the head is ascertained. The anterior fontanel should be visible at least until 7 months of age. The sagittal, coronal, and lambdoid sutures are all identified. The metopic suture closes any time from before birth to after 3 months of age.¹¹ As many as 10% may remain open into adulthood. Closure of only a short segment of a suture is as effective in preventing separation of the opposing bones as total obliteration (see e-Fig. 20-5). The key findings to the diagnosis of craniosynostosis on skull series are (1) abnormal head shape and (2) obliteration of a portion of a suture.

According to Jane and Persing, cranial restructuring techniques have focused on (1) release of sutural synostosis, (2) remodeling of cranial bone, (3) active reduction of an abnormally long dimension of the skull, and (4) active expansion of abnormally narrow areas.¹²

In most instances, three-dimensional computed tomography (CT) is required in planning for cranial restructuring. It is important to keep the radiation dose as low as reasonably achievable. This is quite easy in examination for bone changes and is accomplished by lowering both the kilovolt (kV) and milliampere (mA). Exams performed at 40 mA and 100 to 120 kV at 1 second with a slice thickness of 1.25 millimeters (mm) give a CT dose index “dose” of approximately 5 mGy (500 millirads). Images are reconfigured to 0.625 mm for reformatted images and three-dimensional reconstruction (Figs. 20-16 through 20-20 and e-Fig. 20-21). In syndromic children, magnetic resonance imaging (MRI) of the brain may be performed for developmental anomalies.

Associated Abnormalities

Limb defects are the most common feature of syndromes associated with craniosynostosis, occurring in 84%.¹ Syndactyly and polysyndactyly constitute 30% of the limb defects, and deficiencies account for 22%.

Several types of acrocephalosyndactyly and acrocephalopolysyndactyly have been described. Some are clearly defined; others are less clear and are likely to undergo reclassification as further information becomes available.

The best known acrocephalosyndactyly is Apert syndrome (acrocephalosyndactyly type I), in which usually bicoronal synostosis is associated with symmetric complex syndactyly of at least the second, third, and fourth digits, resulting in the “mitten-hand” and “sock-foot” appearance (e-Fig. 20-22). Mental retardation is present in varying degrees. Evaluation of craniofacial deformities may be assisted by CT (e-Fig. 20-23, Fig. 20-24, and e-Fig. 20-25).

Acrocephalosyndactyly types II, III, and IV are known as Apert-Crouzon disease, Saethre-Chotzen syndrome, and Waardenburg syndrome; they involve varying degrees of facial abnormality and syndactylies in patterns generally repetitive for each type. Acrocephalosyndactyly type V, Pfeiffer syndrome, has only soft tissue syndactyly, which is not marked, but the thumbs and great toes are deformed and broad. All forms are transmitted by dominant inheritance (Fig. 20-26).

Carpenter syndrome (acrocephalopolysyndactyly type II) is characterized by a high incidence of mental retardation and the presence of preaxial polydactyly of the feet. Types I and III are known as Noack syndrome and Sakati-Nyhan syndrome.

In Crouzon syndrome, the cardinal elements originally included (1) brachycephaly, (2) facial dysostosis with a hooked parrot nose and small maxilla with class III malocclusion, (3) bilateral exophthalmos, and (4) genetic transmission and familial incidence. It usually does not result in mental retardation (e-Fig. 20-27 and Fig. 20-28).

The serious complications of these syndromes include progressive exophthalmos, progressive loss of vision, progressive increase in intracranial pressure, and mental retardation. Some of these are indications for surgical therapy. In addition, the maxillary hypoplasia may cause upper airway obstruction, and affected children may have sleep apnea. Surgical procedures to move the face forward are performed to improve the airway, dental occlusion, and appearance.

Kleeblattschädel (cloverleaf skull) results from closure of all sutures except the squamosal sutures, leading to severe temporal and vertex bulging with exophthalmos (see Fig. 20-12). Hydrocephalus develops in utero, deforming the very plastic skull into a superior portion related to the position of the dilated frontal lobes and bilateral inferolateral portions corresponding to the dilated temporal lobes. Most patients do not survive infancy (see Fig. 20-12). Kleeblattschädel may be found in thanatophoric dysplasia type II.

Goldenhar Syndrome and Hemifacial Microsomia

Goldenhar syndrome is part of the oculoauricular vertebral spectrum, which includes hemifacial microsomia.13,14 Most reported cases are sporadic. An increased incidence of Goldenhar syndrome is present in infants of mothers with diabetes. The phenotype has been reported in association with other conditions, including trisomy 18, and with maternal thalidomide, primidone, and retinoic acid use.

The hallmarks of Goldenhar syndrome are epibulbar dermoids, preauricular appendages, mandibular hypoplasia, microtia, and vertebral anomalies. Extreme variability of expression is characteristic of this anomaly. Most frequently, the orbital lesions, mandibular hypoplasia (Fig. 20-29), and microtia are unilateral and on the same side.¹⁵ Colobomas of the upper eyelid occur in 60% of patients and may be large, requiring immediate repair to prevent corneal ulceration. Deafness is common because of associated anomalies of the middle and inner ear.¹⁶ Vertebral anomalies occur in 60% of patients and are most often cervical; these anomalies include basilar invagination, occipitalization of the atlas, C1-2 instability, cervical synostosis, hemivertebra, butterfly vertebrae, scoliosis, kyphosis, and Sprengel deformities (e-Fig. 20-30).¹⁷ Verterbral anomalies below the cervical spine are found in only 10% of patients. The anomalies may be severe, however, and associated with costal malformations similar to Jarcho-Levin syndrome.

Hemifacial microsomia is a variable complex malformation of asymmetric hypoplasia of the face and ear with microsomia, unilateral microtia, and ipsilateral hypoplasis of the mandibular ramus and condyle. Hemifacial microsomia implies unilateral involvement, but the structures affected are bilateral and are only affected to different degrees. Primate and rodent studies have suggested that hemifacial microsomia may be caused by a hemorrhagic event involving the stapedial artery during early stages of craniofacial development.¹⁸ Patients with hemifacial microsomia resemble those with Goldenhar syndrome, but the presence of epibulbar dermoids, lipodermoids, auricular appendices, pretragal blind-ending fissures, and vertebral anomalies favors a diagnosis of Goldenhar syndrome.

A wide variety of additional anomalies have been described in patients with Goldenhar syndrome and hemifacial microsomia, including renal anomalies, radial anomalies, clubfoot, and congenital hip dislocation. It may be linked with VATER sequence (vertebral defects, imperforate anus, tracheoesophageal fistula, and radial and renal dysplasia). Cerebral anomalies include Chiari I malformation, lipoma, agenesis of the corpus callosum, and abnormalities in the pons. Cardiovascular anomalies, including ventricular septal defects, atrial septal defects, and pulmonic stenosis, are found. Vascular anomalies, especially portal venous anomalies (i.e., cavernous transformation) may be present. The mode of inheritance is thought to be autosomal or X-linked dominant in most cases.

Treacher Collins Syndrome

The condition has been diagnosed in utero by ultrasonography and is autosomal dominant, with variable penetrance and expression. The facial features of Treacher Collins syndrome are characteristic.19,20 Abnormalities are typically bilateral and symmetric: micrognathia, narrow face, depressed cheekbones, antimongoloid slant of eyes, malformed small ears, large downturned mouth, high-arched or cleft palate, and conductive hearing loss. The features are characterized by abnormalities in the derivatives of the first and second branchial arches.²⁰ Mutations in the TCOF1 gene are associated with Treacher Collins syndrome, and numerous other associated mutations may be present.²¹ The features demonstrated on imaging are primarily facial, consisting of mandibular, zygomatic, maxillary, and supraorbital hypoplasia. The orbits are described as being egg shaped. The mandibular shape of a short body and ramus is characteristic and varies with the patient’s age. The mandibular condyle and coronoid process may be severely hypoplastic, flat, or even absent. Mandibular growth is severely affected (Fig. 20-31). Ear abnormalities include hypoplasia or absence of the middle ear. The ossicles and cochlea and vestibular apparatus may be severely malformed. Radiographic detection of zygomatic hypoplasia or aplasia is an important supporting finding for the diagnosis. Craniofacial three-dimensional CT for morphologic mapping has become invaluable for planning surgical treatment.²²

Pierre Robin Sequence

Pierre Robin sequence, or Robin sequence, represents a nonrandom association of micrognathia, cleft palate, and glossoptosis.²³ Pierre Robin sequence is causally heterogeneous and pathogenetically and phenotypically variable.²⁴ Patients with Pierre Robin sequence are classified as isolated (most common), syndromic, or with associated anomalies. Numerous syndromes, including Stickler and velocardiofacial syndromes, are associated with Pierre Robin sequence.²⁵ Respiratory compromise from mechanical and central nervous system causes is common. The mandible may be small or may be normal sized and retrognathic in position as a result of a large cranial base (Fig. 20-32). Typically, a reduction in cranial base and maxillary and mandibular lengths is seen.²⁶ Mandibular deficiency is most pronounced in the body.

Cardiovascular anomalies include septal defects and patent ductus arteriosus. Numerous skeletal anomalies include anomalies of the ribs, sternum, and spine, and limb reductions. Airway management is similar in both nonsyndromic and syndromic Pierre Robin sequence. The infant may be managed with positioning, nasal pharyngeal airway, tie-tongue adhesions, or mandibular distraction.27–30 Cine MRI or CT gives dynamic and three-dimensional information that may be useful in the evaluation of the airways of these patients.

Cranioschisis (Cranium Bifidum)

Cranioschisis, or cranium bifidum, usually occurs in the median sagittal plane, anteriorly or posteriorly (Figs. 20-32 and 20-33). Both sites are characterized by bony defects and may accompany meningocele or meningoencephalocele.³¹ Meningoceles are characterized by a hernia sac, which is covered with skin and contains only meninges and cerebrospinal fluid (e-Fig. 20-34). Meningoencephaloceles also contain brain (e-Fig. 20-35). Rarely, cranioschisis may be associated with only a scalp nodule, with or without intracranial communication. Occasionally, small cranial defects—for example, cranium bifidum occultum—through which no herniation occurs are encountered (e-Fig. 20-36). MRI is most effective for evaluation of the sac contents.

Cranium bifidum with encephalocele often occurs in the sphenoid bone or in the cribriform plate of the ethmoid. In such cases, the protruding mass of brain and covering meninges may extend into the nasal cavity, nasopharynx, sphenoid sinus, posterior portion of one orbit, or one of the pterygoid fossae. Important clinical signs include facial deformity with increased distance between the orbits (hypertelorism) and broadened base of the nose.

Lacunar Skull of the Newborn (Lückenschädel, Craniolacunia)

Lacunar skull develops during fetal life and is present at birth.³² It is nearly always associated with meningomyelocele, myelocele, or encephalocele and Chiari II malformation. The cause is unknown, but it is probably a dysplasia of the calvarium and the internal periosteum (i.e., the dura). It is not caused by fetal increased intracranial pressure because it is found in infants whose skulls are normal or are small in size without evidence of hydrocephalus. The characteristic “soap bubble” rarefactions in the upper part of the calvarium are easily recognized (Fig. 20-37). These begin to fade after birth and usually disappear by 4 to 5 months of age, even in the presence of progressive hydrocephalus in some instances. Normal convolutional rarefactions differ from lacunar rarefactions in that they are not obvious until the end of the first year and tend to appear first in the posterior and lower lateral portions of the calvarium.

Sinus Pericranii

The term sinus pericranii is used for a soft, fluctuant mass, often of a red-to-blue color, observed in the scalp over the region of the sagittal or transverse sinuses. It responds in size to maneuvers that tend to increase intracranial pressure and may be associated with an underlying bony defect of the calvarium. It results from an abnormal communication between the intracranial and extracranial venous systems, and its significance is cosmetic.33–35 It must be differentiated from more serious lesions such as arteriovenous malformations, angiomas and hemangiomas, sebaceous or dermoid cysts, meningocele, encephalocele, and abscess. MRI is the best imaging modality for demonstrating the presence of an abnormal vascular communication (Fig. 20-38).

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