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Internal Medicine

Hemifacial microsomia (HFM)

Introduction

Hemifacial microsomia (HFM) or first & second brachial arch syndrome is an asymmetric craniofacial malformation which results in hypoplasia of the components of the first and second branchial arches: maxilla, mandible, external and middle ear, facial and trigeminal nerves, muscles of mastication, and overlying soft tissue.

  • 2nd M/C birth defect of the face (after cleft lip and cleft palate)
  • Usually unilateral, but sometimes bilateral (20% cases) but always asymmetrical

Classification

Figueroa and Pruzanksky classification:

  • Type I: Mild hypoplasia of the ramus, and the body of the mandible is slightly affected.
  • Type II: The condyle and ramus are small, the head of the condyle is flattened, the glenoid fossa is absent, the condyle is hinged on a flat, often convex, infratemporal surface, the coronoid may be absent.
  • Type III: The ramus is reduced to a thin lamina of bone or is completely absent. There is no evidence of a TMJ.

Clinical features

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This 6-year-old girl demonstrates the typical characteristics of hemifacial microsomia. Frontal (A) and lateral (B) views demonstrate facial asymmetry and severe microtia with aural atresia. The chin point is deviated toward the right, with an upward cant of the ipsilateral commissure and nasal alar base. The facial soft tissue is less prominent on the right side. | Keogh, I. J., Troulis, M. J., Monroy, A. A., Eavey, R. D., & Kaban, L. B. (2007). Isolated Microtia as a Marker for Unsuspected Hemifacial Microsomia. Archives of Otolaryngology–Head & Neck Surgery, 133(10), 997–1001. https://doi.org/10.1001/archotol.133.10.997

OMENS classification

  • O.M.E.N.S. indicates one of the 5 major manifestations of HFM:
    • O: Orbital distortion
    • M: Mandibular hypoplasia
    • E: Ear anomaly
    • N: Nerve involvement
    • S: Soft tissue deficiency
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OMENS Classification System | Keogh, I. J., Troulis, M. J., Monroy, A. A., Eavey, R. D., & Kaban, L. B. (2007). Isolated Microtia as a Marker for Unsuspected Hemifacial Microsomia. Archives of Otolaryngology–Head & Neck Surgery, 133(10), 997–1001. https://doi.org/10.1001/archotol.133.10.997

Case study:


Diagnosis

Clinical diagnosis

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Frontal view of the patient biting on a tongue depressor. A, This photograph demonstrates the upward occlusal cant on the right side that is a result of the short mandibular ramus and secondary vertical growth inhibition of the maxilla. B, Anteroposterior cephalogram demonstrates the asymmetry of the mandible, with a short right ramus, antegonial notching, and a flat contour. The piriform aperture is elevated on the right, also indicative of deficient vertical midface growth on that side. | Keogh, I. J., Troulis, M. J., Monroy, A. A., Eavey, R. D., & Kaban, L. B. (2007). Isolated Microtia as a Marker for Unsuspected Hemifacial Microsomia. Archives of Otolaryngology–Head & Neck Surgery, 133(10), 997–1001. https://doi.org/10.1001/archotol.133.10.997

OMENS classification:

2-Figure1-1
Global Assessment of the modified pictorial OMENS-Plus classification system | Gougoutas AJ, Singh DJ, Low DW, Bartlett SP. Hemifacial microsomia: Clinical features and pictographic representations of the OMENS classification system. Plast Reconstr Surg. 2007;120:112e–120e.

Imaging

Orthopantomogram (OPG):

X-ray skull:

3D CT scan:

jcdr-7-2383-g008
3D CT scan showing facial asymmetry and a small hypoplastic ramus on the right side | Mishra, L., Misra, S. R., Kumar, M., & Tripathy, R. (2013). Hemifacial microsomia: a series of three case reports. Journal of Clinical and Diagnostic Research : JCDR, 7(10), 2383–2386. https://doi.org/10.7860/JCDR/2013/5773.3532


Management

 

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