What is Micrognathia? Symptoms, Causes & Treatment Options

Micrognathia Definition

When you say Micrognathia it simply means an abnormality in the physical anatomical condition of the person’s lower jaw. The person who has this diagnosis is presented or has a smaller size of the lower mandible or jaw. The smaller size of the mandible or jaw is considered to be abnormal. It is the result of the underdevelopment of the chin or mandible. Some health professionals would term it as a craniofacial anomaly.

Micrognathia Symptoms & Signs

Micrognathia usually is evident during infancy. It is the mother who notices this craniofacial anomaly. It is usually noticed when the baby is not feeding well. Along with that are some of the symptoms that the infant may manifest such as:

  1. Chin Deformity
  2. Apnea or absent breathing
  3. Difficulty breathing of Dyspnea
  4. Abnormally Rapid Breathing pattern
  5. Abnormal Teeth Alignment

When an infant is diagnosed with this condition, one problem that the infant or newborn baby will reflect is the breathing difficulties or problem with breathing. What happens is that the tongue, because the lower jaw is small, is prevented from growing normally. With that, the small jaw is unable to hold the infant’s tongue in a forward position. There is a retroposition of the infant’s tongue into the oropharynx or what is medically termed as glossoptosis. With these two problems, regarding the tongue and the small jaw, there is a much likely blockage of airway. Hence, the reason why there is Dyspnea and a possibility of Apnea, if it progresses. In addition to that, it may also lead to abnormally aligned teeth of the infant because of the small space that the small jaw provides.

Micrognathia Causes

There are two probable causes why an infant or a newborn has Micrognathia or small jaw. First as being caused by heredity and second, which is associated with other syndromes. There are no other causes of Micrognathia. Person who have been surgically operated or have acquired accidental trauma with their jaw leading to its alterations, such as shortening of the jaw, may not mean that the person can be diagnosed with Micrognathia. This disease condition should occur naturally and not by accidental trauma.
The Micrognathia, as mentioned, can be brought about due to other genetic syndromes such as:

Cri du chat Syndrome

It is a genetic syndrome wherein there is a missing chromosome, particularly chromosome number 5. It has a symptom of Micrognathia.

Marfan Syndrome

This kind of syndrome is a connective tissue disorder that aids in the strengthening of the structure of the person’s body. It also have symptom of Micrognathia.


This is a rare genetic syndrome that has a symptoms resembling of a normal human aging that occurs in younger children. It also possesses the symptom of Micrognathia.

Russell-Silver Syndrome

It is a disorder of newborn babies having low birth weight, poor growth, short height and abnormally different sizes of the sides of the body. It is has also a symptom of having Micrognathia.

Trisomy 13

It is also called Patau Syndrome. It is a genetic syndrome that has three copies of chromosome 13 instead of the normal, which are two copies. There extra chromosome may be attached to other chromosomes which can be termed as translocation. Infants who are diagnosed with this disease condition also manifest Micrognathia.

Trisomy 18

It is a genetic disorder of having three copies of the chromosome 18 instead of the normal, which are two copies. Babies who manifest this disease condition will have small jaw or Micrognathia.

Turner Syndrome or XO Syndrome

This genetic condition only occurs in the female babies wherein she lacks the normal two copies of X chromosomes. She only has one copy of the X chromosome. The symptoms of the female baby will manifest having Micrognathia.

Pierre Robin Syndrome

This kind of syndrome which is genetically present at birth manifests a baby having Micrognathia.

Treacher Collins Syndrome

It is a genetic hereditary condition that manifests facial structure problems. It also possesses a symptom of having Micrognathia.

Seckel Syndrome

It is a hereditary disease condition that is characterized with having an unusually small mandible or Micrognathia.

Smith- Lemli- Opitz Syndrome

This is another hereditary syndrome that manifests malformation of the face especially in the mandible which is smaller than normal.

Micrognathia Treatment

The management of Micrognathia with regarding the respiratory compromise of the infant is very much controversial. In managing this kind of disease condition, you can have many non surgical modalities such as:

  1. nasopharyngeal airways
  2. tongue lip adhesion
  3. prone positioning
  4. tracheostomy
  5. mandibular distraction

It is mandatory that before undergoing surgical options, one must undergo nonsurgical options. As mentioned, this disease condition can be treated either by surgical intervention or through rehabilitative intervention. Basically the treatment of this disease condition will focus in relief of the symptoms particularly targeting:

  1. Breathlessness
  2. Speech Difficulties
  3. Teeth Misalignment

Micrognathia Surgery

The orthodontist is the one that is best physician to go to when an infant or a patient has been diagnosed with this kind of disease condition. For this craniofacial anomaly, there is a need for reconstructive surgery. The extent of the surgery will depend on the configuration degree of an underdevelopment with regards to the surrounding facial bones and muscles.

Upon surgery, what happens is that the mandible or the lower jaw of the patient will go through a bone graft or series of grafting. With this kind of surgical procedure, it is known to rebuild the structure of the abnormal mandible into a normal mandible. The oral surgeon or the maxillofacial surgeon is the only one qualified to do such surgical procedure.

Prior to surgery, preoperative planning, which is an important part in the treatment, must be done by the surgeon himself. In the preoperative planning, the surgeon will determine the distraction area regarding to the location and anatomy of the osteotomies. Usually the curvelinear kind of mandibular distraction is preferred by many.

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