Craniosynostosis and Craniofacial Dysostosis

Introduction

• Craniosynostosis occurs due to the premature fusion of one or more sutures in the skull, which leads to irregular skeletal expansion and a characteristic abnormal head shape.1,2 In 80% of cases, craniosynostosis occurs in isolation with only cranial suture involvement.¹
• Craniofacial dysostosis describes syndromic forms of craniosynostosis where cranial suture anomalies are associated with midface skeletal anomalies and various other organ system defects.² Syndromic craniosynostosis accounts for 20% of cases.¹
• Syndromic craniosynostosis affects between 1 in 25,000 and 1 in 100,000 infants.³
• Craniofacial dysostosis syndromes typically have an identifiable genetic cause.¹ Mutations in genes encoding the fibroblast growth factor receptors (FGFRs) are responsible for the most common syndromes, listed in Table 1.

Common Features and Comorbidities

• Craniofacial dysostosis syndromes often involve midface, tracheal and spinal anomalies as well as obstructive sleep apnea, all of which can contribute to a challenging airway.
  • Maxillary hypoplasia, proptosis, mandibular prognathia, a high-arched palate, a large tongue in relation to a small oral cavity, small nares, and some degree of choanal stenosis are shared features of some of the most common craniofacial dysostosis syndromes,^1-5 as seen in Figure 1.

• Craniosynostosis can lead to increased intracranial pressure (ICP), which is most commonly seen in syndromic forms.¹ Elevated ICP can occur due to hydrocephalus, chronic airway obstruction, craniocerebral disproportion, or abnormalities in venous drainage of the brain.
• Patients with craniosynostosis typically undergo surgery for cranial vault reconstruction before one year of age.¹ Patients with syndromic craniosynostosis frequently require additional general anesthetics for various diagnostic, craniofacial, airway optimization, and neurosurgical procedures.⁴

Airway Management Considerations

• Many craniosynostosis syndromes present airway problems such as difficult mask ventilation or intubation. Careful preoperative airway assessment and planning is required.¹
• Maxillary hypoplasia, mandibular prognathia, a high-arched palate, large tongue, small nares, and choanal stenosis can result in multilevel upper airway obstruction and obstructive sleep apnea.^1-5
  • In some cases, severe upper airway obstruction necessitates tracheostomy placement early in infancy.
• Vertebral fusions can lead to limited movement of the cervical spine.⁴
• Tracheal ring abnormalities or cartilaginous sleeves may be present. Patients may also have laryngomalacia and/or tracheobronchomalacia.⁴
• Perioperative upper airway obstruction is common during induction of anesthesia, with resultant difficult bag-mask ventilation.⁴ Upper airway obstruction can occasionally occur after emergence from anesthesia as well.
  • Mask fit may be problematic due to midface hypoplasia and proptosis.⁵
  • Gently holding the mouth open (rather than closing it) during mask ventilation allows for air movement through the oral cavity while minimizing obstruction due to the tongue.⁵
  • An appropriately sized oral and/or nasopharyngeal airway is often useful. Spraying the mouth with a topical anesthetic prior to induction will facilitate the placement of an oral airway at lighter depths of anesthesia during mask induction.⁵
  • A supraglottic airway is effective in relieving upper airway obstruction.⁴
• Intubation is usually not as difficult, with some notable exceptions.⁴
  • Intubation may be difficult if there is a problem with neck mobility.⁵
  • Video laryngoscopy or fiberoptic techniques should be considered in patients with cervical spine concerns.
  • Tracheal anomalies may necessitate the use of a smaller endotracheal tube.⁵
  • In patients who have had prior frontofacial distraction surgery, difficult laryngoscopy may occur due to an altered maxilla-mandibular relationship and a reduction in temporomandibular joint movement.⁴