Hemifacial Microsomia - Classification

Classification systems

Several classification systems have been proposed especially by Pruzansky (1982), Lauritzen et al (1985), David (1987), Vento et al (1991), and Horgan et al (1995). The most comprehensive classification system is OMENS+ as described by Horgan et al. However, surgeons find the classification of the skeletal deformity by Pruzansky, as modified by Kaban (which is incorporated in OMENS+) to be most useful in practice.

OMENS+

OMENS+ subdivides and grades each of the principal deformities. These are:
 O = Orbit
 M = Mandible
 E = Ear
 N = Nerves
 S = Soft Tissues
 + = Extra-craniofacial features

Pruzansky

Pruzansky subdivides the ear and the mandible deformities.

Mandible

  • I a small ramus with identifiable anatomy
  • II a functioning TMJ but with an abnormal shape and glenoid fossa (IIa and IIb as modified by Kaban)
    • IIa  the glenoid fossa is in an acceptable functional position 
    • IIb  the TMJ is abnormally placed and cannot be incorporated in the surgical construction
  • III an absent ramus and nonexistent glenoid fossa

This system has two weaknesses.

• It is possible to have a Pruzansky II with a functioning TMJ but with or without a zygomatic arch and glenoid fossa.
• It is possible to have a Pruzansky III with no condyle and no functioning TMJ with or without a zygomatic arch and a glenoid fossa.

3D-CT enables classification of this condition.

Pruzansky I

Pruzansky I

Pruzansky IIa

Pruzansky IIa

Pruzansky IIb

Pruzansky IIb

Pruzansky III

Pruzansky III