Micrognathia is a smaller than normal jaw, often the lower jaw or chin. Micrognathia may be 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.
Pierre Robin (Pee-air; Ro-ban) sequence refers to a combination of small jaw, a normal tongue that is crowded at the back of the throat and difficulty with breathing. Sometimes there is a wide cleft palate (hole in the roof of the mouth). It is not clear why this occurs, but it may happen because of some problem with development early in pregnancy.
There are several reasons why the jawbone may not develop normally:
- Positional deformation (the chin is pressed against the chest of the baby)
- Intrinsic hypoplasia (restricted growth)
- 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)
The most important issue is that the airway may be blocked. Sometimes it is difficult to appreciate it in the early days after birth, and the struggle with breathing becomes more apparent a few days or weeks later. These babies often have difficulty gaining weight because they are using so much energy just to breath.
There are mild cases and severe cases. In mild cases, the airway may be improved by placing the baby on his or her stomach, and having gravity move the tongue a little forward. Even a small amount often helps. In more severe cases, a number of tests can be employed to help understand the severity of the problem, and make sure there are no other issues in the airway. Ultimately, some children may require surgery, including tongue-lip adhesion, mandibular distraction or tracheostomy. In every case, the child requires intensive care until the full extent of the problem is understood.