Micrognathia or mandibular hypoplasia means a small mandible (lower jaw). It is common in infants, but is usually self-corrected during growth, due to the jaw's increasing in size. Many times it’s congenital (present from birth) and it appears as part of a syndrome, which is a condition where more than one body system is involved. A syndrome may be inherited (passed down from the parents) or come about spontaneously.
Patients can be seen by Texas Children's experts in Craniofacial and Craniosynostosis Clinic.
Causes & Risk Factors
Micrognathia may be genetically inherited or spontaneous. There are several causes why the jawbone may not develop properly:
• Positional deformation (the chin is pressed against the chest of the baby)
• Neurologic or neuromuscular problems (reduced movement related to muscle or nerve involvement)
• Connective tissue disorder (reduced movement related to connective tissue problems of the jaw)
• Inherited disorders and syndromes.
• Medications taken during pregnancy (ask your health care provider)
Some of the syndromes that are usually associated with micrognathia are:
• Russell-Silver syndrome
• Seckel syndrome
• Cri du chat syndrome
• Marfan syndrome
• Pierre Robin syndrome
• Hallerman-Streiff syndrome
• Trisomy 13
• Trisomy 18
• XO syndrome (Turner syndrome)
• Treacher-Collins syndrome
• Smith-Lemli-Opitz syndrome
Symptoms & Types
In some cases, the jaw is small enough to cause breathing problems or interfere with an infant's feeding. Infants with this condition may need special nipples and positioning in order to feed properly.
Children may also present with obstructive apnea (one or more pauses in breathing while sleeping).
Diagnosis & Tests
Micrognathia might be diagnosed before birth with ultrasound. It can also be detected by examining the infant at birth. Special tests such as CT scans, sleep studies, and endoscopy of the airway may be needed.
Treatment & Care
The majority of micrognathias corrects itself during growth. The overall prognosis is highly variable dependent on the presence of other associated anomalies.
Distraction osteogenesis is a surgical procedure that may be helpful. This is the slow movement apart (distraction) of two bony segments in a manner so that new bone is allowed to fill in the gap created by the separating bone segments.
Living & Managing
You may need to use special feeding methods for a child with this condition. Most hospitals have programs where you can learn about these methods.
If micrognathia interferes with feeding, you'll need to use special feeding techniques and equipment. You can learn these techniques through special programs that are available at most hospitals.
Micrognathia can cause the teeth not to align properly. This can be seen in the way the teeth close. Often there will not be enough room for the teeth to grow. Children with this problem should see an orthodontist when their adult teeth come in. Because children may outgrow the condition, it often makes sense to delay treatment until a child is older.