What is the difference between plagiocephaly and brachycephaly?

Differences Between Plagiocephaly and Brachycephaly

Plagiocephaly is characterized by asymmetric flattening of one side of the occipital region resulting in a parallelogram-shaped skull, while brachycephaly involves symmetric flattening of the entire occipital region causing a foreshortened head in the anterior-posterior dimension. 1, 2

Diagnostic Characteristics

Plagiocephaly

• Definition: Asymmetric deformation with unilateral posterior flattening and contralateral frontal flattening, creating a parallelogram shape 3
• Measurement: Assessed using Cranial Vault Asymmetry (CVA) or Cranial Vault Asymmetry Index (CVAI) 4
• Clinical presentation: Often associated with:
  • Facial asymmetry
  • Ear position displacement
  • Unilateral flattening

Brachycephaly

• Definition: Symmetric flattening of the entire occipital (back) region of the head 2
• Measurement: Assessed using Cephalic Index (CI) - ratio of head width to length 4
• Clinical presentation:
  • Widened head appearance
  • Shortened anterior-posterior dimension
  • Bilateral occipital flattening

Combined Presentation

• Many infants present with a combination of both conditions 4
• Classification systems use both CVA and CI measurements to differentiate between pure plagiocephaly, pure brachycephaly, or combined deformities 4

Etiology

Both conditions are typically positional deformities resulting from:

• Supine sleeping position (recommended to prevent SIDS)
• Prolonged time in one position
• Congenital muscular torticollis (more common with plagiocephaly)
• Prematurity
• Multiple births
• Assisted labor 3

Diagnostic Approach

• Clinical examination is typically sufficient for diagnosis 2
• Imaging is rarely necessary except when clinical diagnosis is equivocal
• When needed, preferred imaging includes:
  • 3D cranial topographical imaging
  • Skull x-rays
  • Ultrasound (CT scanning is generally avoided) 2
• Diagonal caliper measurements can assess plagiocephaly severity by measuring diagonal length differences 3

Treatment Approaches

Both conditions can be treated with:

1. Conservative approaches (first-line for mild to moderate cases):

   • Repositioning education
   • Physical therapy (superior to repositioning alone)
   • Neck stretching exercises for associated torticollis 2

2. Cranial molding helmets (for moderate to severe cases or when repositioning fails):

   • More rapid and greater degree of correction
   • Earlier treatment (before 6 months) yields better outcomes
   • Treatment typically continues until 12 months or correction plateaus 2, 1

Important Clinical Considerations

• Early intervention is critical for both conditions, with better outcomes when treatment is initiated before 6 months of age 5
• The American Academy of Pediatrics warns against using soft positioning pillows due to SIDS risk 2
• Long-term studies show greater improvement in head shape with helmet therapy compared to repositioning alone 5
• Regular follow-up is necessary to monitor progress and adjust treatment 2