Craniosynostosis

Aka: Craniosynostosis, Trigonocephaly, Metopic Synostosis, Brachycephaly, Bicoronal Synostosis, Frontal Plagiocephaly, Unilateral Coronal Synostosis, Occipital Plagiocephaly, Synostotic Plagiocephaly, Scaphocephaly, Sagittal Synostosis, Cranial Suture Premature Closure

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II. Definition

  1. Premature fusion of cranial Sutures
  2. Growth restriction perpendicular to fused Suture
  3. Compensatory skull overgrowth in unrestricted areas
  4. Images
    1. NicuNormalSutures.jpg

III. Epidemiology

  1. Incidence: 0.4 per 1000 live births
  2. Sagittal Suture is most commonly affected

IV. Causes

  1. Idiopathic
  2. Hyperthyroidism
  3. Rickets
  4. Hyperparathyroidism
  5. Underlying genetic disorder
    1. Apert's Syndrome
    2. Crouzon's Syndrome
    3. Pfeiffer's Syndrome

V. Risk Factors

  1. Caucasian mother
  2. Advanced maternal age
  3. Male infant
  4. Maternal Tobacco Abuse
  5. Mother living at high altitude
  6. Fertility treatments
  7. Paternal occupation in agriculture, forestry, mechanics
  8. Maternal exposure to nitrosatables
    1. Nitrofurantoin
    2. Chlorpheniramine

VI. Evaluation

  1. Observe head shape for abnormality
    1. Asymmetry
    2. Elongated, broad, or triangular shape
    3. Ridging at Suture lines beyond first week of life
  2. Check Head Circumference
    1. Evaluate for Hydrocephalus and Microcephaly
  3. Evaluate for other musculoskeletal abnormalities
    1. Spine, fingers, and toe abnormalities

VII. Metopic Synostosis (Trigonocephaly)

  1. Images
    1. NicuTrigonocephaly.jpg
  2. Pathophysiology
    1. Metopic Suture (sagittal plane of forehead) closure
  3. Characteristics
    1. Forehead elongates
      1. Anteroposterior distance increases
    2. Forehead less rounded and more pointed
    3. Ridge forms down center of frontal forehead
    4. Eyes appear closer together
    5. Eyebrows appear pinched
  4. Management
    1. Surgery to increase anterior cranial volume

VIII. Bicoronal Synostosis (Brachycephaly)

  1. Images
    1. NicuBrachycephaly.jpg
  2. Pathophysiology
    1. Coronal Suture closure
      1. Anterior to Parietal Bones (Passes between ears)
    2. Metopic Suture may also be affected
  3. Characteristics
    1. Skull widens and becomes nearly circular in shape
    2. Forehead flattens
  4. Associated Conditions
    1. Crouzon's Syndrome
    2. Apert's Syndrome
  5. Management
    1. Surgery to increase anteroposterior length

IX. Unilateral Coronal Synostosis (Frontal Plagiocephaly)

  1. Images
    1. NicuPlagiocephaly.jpg
  2. Pathophysiology
    1. Unilateral coronal Suture closure
  3. Characteristics
    1. Asymmetric flattening of affected side of forehead
      1. Eyebrow appears to wink (flat on affected side)
      2. More evident by looking at child in mirror
    2. Forehead elongates
      1. Anteroposterior distance increases
    3. Forehead less rounded and more pointed
  4. Differential Diagnosis
    1. Similar to Trigonocephaly but asymmetric

X. Occipital Plagiocephaly (Unilambdoid Synostosis)

  1. Images
    1. NicuPositionalHeadDeformity.jpg
  2. Pathophysiology
    1. Unilateral lambdoid Suture closure
    2. Lamboid Suture sits behind Posterior Fontanelle
  3. Characteristics
    1. Asymmetric flattening of affected side of occiput
    2. Similar to Frontal Plagiocephaly but affects occiput
    3. Occiput may appear more pointed
  4. Differential Diagnosis
    1. Positional Head Deformity may give similar appearance

XI. Sagittal Synostosis (Scaphocephaly)

  1. Images
    1. NicuScaphocephaly.jpg
  2. Epidemiology
    1. Most common Craniosynostosis form (1 in 4200 births)
    2. More common in boys (3x)
  3. Pathophysiology
    1. Sagittal Suture (between Parietal Bones) closure
  4. Characteristics
    1. Skull elongates to become long and narrow
  5. Management
    1. Strip craniectomy (now performed via endoscopy) or
    2. Cranial vault remodeling

XII. Imaging

  1. Skull films (Anteroposterior and lateral views)
    1. Signs of Suture fusion
      1. Bone bridging over Suture
      2. Indistinct Suture
      3. Suture margin sclerosis
    2. Signs of Increased Intracranial Pressure
      1. Cortical thinning
      2. Suture widening
      3. Thumbprinting
  2. Cranial Ultrasound (if Anterior Fontanelle open)
    1. Signs of Increased Intracranial Pressure
      1. Ventricular dilatation
    2. May also be effective in Lambdoid Suture evaluation
      1. Sze (2003) Pediatr Radiol 33(9):630-6 [PubMed]
  3. CT with 3D Reconstruction or MRI Brain
    1. Sutures more accurately defined that plain XRay
    2. Evaluate for coexisting intracranial abnormalities
      1. Hydrocephalus
      2. Corpus callosum agenesis

XIII. Complications: Untreated Craniosynostosis

  1. Increased Intracranial Pressure
  2. Facial asymmetry
  3. Malocclusion
  4. Orbit asymmetry (associated with Strabismus)

XIV. Management

  1. Identify and refer for surgery at earliest possible age

XV. References

  1. Aviv (2002) Clin Radiol 57:93-102 [PubMed]
  2. Kabbani (2004) Am Fam Physician 69:2863-70 [PubMed]
  3. McIntyre (1997) Am Fam Physician 55(4):1173-8 [PubMed]
  4. Ridgway (2004) Pediatr Clin North Am 51(2) [PubMed]

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