hemifacial microsomia

Hemifacial microsomia (HFM) is the second most common congenital facial anomaly after cleft lip/palate. The condition may vary from mild to severe. Goldenhar syndrome has been described as a variant of HFM, in which vertebral anomalies and epibulbar dermoids were present.

Terminology

HFM is also known as craniofacial microsomia, first and second branchial arch syndrome, otomandibular dysostosis, and lateral facial dysplasia. 

Pathology

HFM results from the abnormal development of the first and second branchial arches, hence it primarily affects the ear (aural), mouth (oral cavity), and jaw (mandible).

Associations

As many as 55% of patients with HFM also have extracranial anomalies, which may include central nervous system (CNS), skeletal, cardiac, lung, gastrointestinal, and kidney defects .

Classification

 A classification which graded mandibular deficiency was given by Pruzansky in 1969 :

• grade I: minimal hypoplasia of the mandible
• grade II: functioning but deformed temporomandibular joint with anteriorly and medially displaced condyle
• grade III: absence of the ramus and glenoid fossa

Radiographic features

CT is the usual imaging modality of choice to assess the extent of the mircosomia.   There are a number of features:

• ear: hypoplasia, aplasia, or malformation of the external ear, and middle ear. Hypoplastic mastoid process with partial or complete lack of pneumatization of the mastoid air cells
• mandible: hypoplastic mandibular condyle, reduced height of the mandibular ramus with the chin deviated towards the affected side. The temporomandibular joint deformity can range from mild hypoplasia of the condyle with normal joint anatomy to a grossly disorganized joint anatomy and pseudo-articulation of the condyle at the cranial base
• maxilla: may be normal or reduced in height with delayed eruption of the mandibular and maxillary molars
• zygoma: may be hypoplastic with short or absent zygomatic arch
• orbit: maybe reduced in dimensions and frontal bone can be flattened
• soft tissues: facial musculature, facial nerve supply, and other adjacent soft tissues may be hypoplastic

The CT dataset may also be used to produce 3D models using advanced printing techniques popular for pre-surgical planning.

Differential diagnosis

• Pierre Robin syndrome: micrognathia, glossoptosis, and cleft palate
• Treacher Collins syndrome: hypoplasia of facial bones, especially malar and mandibular bones, malformation of external, middle, and internal ear, macrostomia, and high palatal arch
• Parry-Romberg syndrome (facial hemiatrophy): progressive wasting of subcutaneous fat, sometimes accompanied by atrophy of skin, cartilage, bone and muscle

Siehe auch:

• Goldenhar-Gorlin-Syndrom
• Moeschler-Claren-Syndrom

und weiter:

• mandibuläre Retrognathie
• Mikrognathie