What is midface hypoplasia?

In midfacial hypoplasia, the center of the face develops more slowly than the eyes, forehead, and lower jaw. When it is mild, it is generally considered a normal and harmless genetic variation. However, in more severe cases, the condition is so pronounced that both appearance and health can be affected. In these cases, hypoplasia is often a symptom of other health problems or genetic disorders.

Human genetics allows for infinite variations in facial construction. In individuals with mild benign midfacial hypoplasia, normal differences in appearance cause features in the middle of the face to be smaller, in comparison, than features in the upper and lower face. The effect is a forehead, lower jaw, and eyes that appear unusually large. In more pronounced cases, the jaw may protrude noticeably forward and the eyes may appear bulging.

When midfacial hypoplasia is marked or easily identifiable at birth, it usually indicates a medical problem that affects the underlying structures of the face. In Crouzon Syndrome, for example, the condition occurs when the skull plates fuse before full skull growth is complete. Treatment of this genetic condition usually involves removal or fracture of the skull bones.

Midface hypoplasia has also been associated with achondroplasia, the most common type of dwarfism. This disorder primarily affects the long bones of the legs and arms, but can also lead to abnormal craniofacial development. In dwarfism, the extent of hypoplasia is generally mild and requires intervention only when it is severe enough to cause complications.

Regardless of its cause, severe midfacial hypoplasia can often lead to obstructive sleep apnea (OSA). OSA patients experience intermittent interruptions in breathing while sleeping, often suffering from symptoms such as severe headache, insomnia, and high blood pressure as a result. Obstructive sleep apnea is most often treated by applying enough air pressure to keep the airway open through a continuous positive airway pressure (CPAP) machine worn by the patient while they sleep. For those patients who have dangerously long periods of not breathing, most other options are surgical. In jaw surgery, excess tissue in the airway is removed or a breathing tube is inserted directly into the throat.

Pronounced midfacial hypoplasia can also lead to misalignment of the jaws and eyelids. In the former, the upper and lower jaws do not meet, resulting in difficulties with chewing and speaking. Subsequently, the eyelids cannot close completely, and vision problems and persistent dry eyes are common. Both of these conditions require plastic surgery to completely correct.

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