Hemifacial Microsomia - Evaluation of Hemifacial Microsomia patients
1. Clinical evaluatioin of HFM
Clinical examination is the first and foremost investigation and should always include testing of hearing, vision, and for spinal abnormalities. The spectrum of abnormalities is so large that the pediatric investigations have to cover almost all systems.
2. Head and neck findings
Patients with HFM may demonstrate aplasia, hypoplasia, reduced function or malposition of:
- Mandible (especially ramus)
- Occlusion (cant)
- Teeth (crowding, missing or ectopic)
- Ear (Microtia, accessory ear tags)
- Maxilla
- Malar
- Temporal bone
- Frontal bone
- Vertebrae (40-60%)
- Facial nerve (22%)
- Hearing
- Conduction loss, 75%
- Sensorineural loss, 11%
- Macrostomia
- Dermoid cysts (especially epibulbar)
- Muscles (of mastication)
- Fat
- Temporal fascia
- Parotid gland
- Colobomas
- Microphthalmia
- Lateral facial cleft
- Rarely occipital encephalocoele
- Rarely mental retardation
Other systemic findings include:
- Cardiac (VSD, patent ductus, Fallot’s etc)
- Renal/ureteric
3. Radiologic evaluation
To avoid unnecessary radiation it is recommended to delay radiological investigation until they will have an impact on treatment. Similarly an OPT has to be delayed until such time as the child is able to cooperate.
Radiographic evaluation of the head and neck abnormalities of HFM is by CT especially 3D-CT and a panoramic X-ray (OPT). Young children, sometime require general anaesthetia or sedation for CT acquisition . The current generation of multi slice CT-scanners will aquire the relevant data in less than one second.
4. Diagnosis and differential diagnosis of HFM
Other conditions which show facial asymmetry and which can sometimes be mistaken for HFM are Torticollis and Plagiocephaly. By contrast Treacher Collins Syndrome (TCS) is a genuine deformity of the first and second branchial arches but is essentially symmetrical and the autosomal dominant gene has been identified. Diagnosis of TCS can however sometimes be difficult because 65% of births are new mutations.
Lateral facial clefting (Tessier No. 7) is effectively one extreme of Hemifacial microsomia. Most cases are incomplete and show macrostomia and involvements of the ear and mandible on the affected side.
