Positional deformation and craniosynostoses
Positional plagiocephaly frequently results from an infant's habitual head position (supine sleeping). Unlike true synostoses, lambdoid sutures remain open on imaging in positional plagiocephaly.
Syndromic craniosynostoses are characterized by premature suture fusion and are often accompanied by anomalies of the face and other systems:
- Apert syndrome (Apert syndrome): manifests as brachycephaly due to early closure of the coronal sutures. A characteristic feature is a wide median calvarial defect. Features include hypertelorism, flattening of the anterior cranial fossae, and syndactyly ("mitten" hand).
- Crouzon syndrome (Crouzon syndrome): is distinguished by more complex suture involvement (coronal, sagittal, etc.) without a median calvarial defect. Exorbitism and maxillary hypoplasia are frequently observed, while the limbs remain intact. The risk of cerebellar tonsillar herniation is higher here.
Neonatal airway obstructions
Mucosal edema is the most frequent cause of nasal obstruction, followed by choanal atresia.
Choanal atresia results from failed canalization and can be bony, fibrous, or membranous. Bilateral atresia causes acute respiratory distress in newborns, particularly during feeding. Unilateral atresia is frequently diagnosed later due to chronic discharge.
Congenital pyriform aperture stenosis is a focal narrowing of the anterior nasal cavity, often associated with a single central maxillary incisor. Bone-window computed tomography after decongestant administration is optimal for diagnosis.
Associated brain pathologies and ICP
In craniosynostoses, brain structure may be normal, but anomalies can occur: ventriculomegaly, agenesis of the corpus callosum, or Chiari I malformation (cerebellar tonsillar herniation).
Elevated intracranial pressure (ICP) is difficult to assess reliably based on imaging alone; the clinical picture is primary. Hydrocephalus is identified in 4–25% of patients with craniosynostoses, but it serves as a marker of elevated ICP in only 40% of cases.
Skeletal dysplasias
Fibrous dysplasia is the gradual replacement of bone tissue with fibrous tissue. On CT, lesions appear as bone expansion with a typical ground-glass pattern (ground-glass appearance).
- McCune-Albright syndrome combines dysplasia with endocrine hypersecretion and café-au-lait spots.
- Cherubism is a hereditary form affecting the jaws (mandibular condyles are spared). Teeth within affected areas may undergo resorption, displacement, or appear "floating".
Briefly: answers to topical questions
Which cranial and facial bones are most commonly affected in fibrous dysplasia?
In the monostotic form of fibrous dysplasia, the bones of the skull and facial skeleton are affected in approximately 20% of cases. Cherubism is a hereditary form affecting the maxilla and mandible; the mandibular condyles are typically spared.
What types of craniosynostoses exist based on the number of involved sutures?
Based on the number of involved sutures, primary craniosynostoses are divided into two main categories.
- Simple non-syndromic forms — typically involve a single suture. The most common type is simple sagittal synostosis. Unicoronal synostosis is another example.
- Complex syndromic forms — involve multiple sutures. These include bicoronal synostosis (e.g., in Apert syndrome) and complex synostosis involving the coronal, sagittal, metopic, and squamosal sutures (in Crouzon syndrome).
Syndrome distinctions: Apert — "Hand anomalies" (syndactyly, mitten hand) and open calvarial defect; Crouzon — "Complex synostosis" without hand involvement.
Class and exam questions
How to differentiate positional plagiocephaly from craniosynostosis on X-ray?
In positional deformation, sutures (such as the lambdoid) remain open, whereas in synostosis, they prematurely close.
What is the danger of bilateral choanal atresia?
It causes acute respiratory distress syndrome in newborns, which worsens during feeding, and requires emergency intervention.
What are the characteristic CT findings of fibrous dysplasia?
Bone expansion (ballooning) with a characteristic ground-glass appearance.
What else to study on this topic
- Imaging techniques: the role of CT venography and 3D reconstructions.
- Features of prenatal diagnosis of syndromic synostoses.
- CHARGE association and its imaging manifestations.
- Impact of facial anomalies on the airways (basilar kyphosis, dental crowding).
- Standardization of CT/MRI protocols for pediatric brain tumor patients.
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