Facial nerve palsy due to birth trauma is the loss of controllable (voluntary) muscle movement in an infant's face due to pressure on the facial nerves just before or at the time of delivery.

The infant's facial nerve (also called the seventh cranial nerve) can be damaged just before or at the time of delivery.

Most of the time the cause is unknown. However, a difficult delivery, with or without the use of instruments called forceps, may lead to this condition.

Some factors that can cause birth trauma (injury) include:

• Large baby size (may be seen if the mother has diabetes)
• Long pregnancy or labor
• Use of epidural anesthesia
• Use of a medication to cause labor and stronger contractions

However, most of the time these factors do not lead to facial nerve palsy or birth trauma.

The most common form of facial nerve palsy due to birth trauma involves only the lower part of the facial nerve. This area controls the muscles around the lips. The defect is seen mainly when the infant cries.

The newborn infant may have the following symptoms:

• Eyelid may not close on affected side
• Lower face (below eyes) appears uneven during crying
• Mouth does not move down the same way on both sides while crying
• No movement (paralysis) on the affected side of the face (from the forehead to the chin in severe cases)

A physical exam is usually all that's needed to diagnose this condition. Rarely, a nerve conduction study is needed. Such a test can pinpoint the exact location of the nerve injury.

Brain imaging tests are not needed unless the health care provider suspects another problem (such as a stroke).

In most cases, the infant will be closely monitored to see if the paralysis goes away on its own.

Infants with permanent paralysis need special therapy.

The condition usually goes away on its own.

Occasionally the facial muscles on the affected side become permanently paralyzed.

The health care provider will usually diagnose this condition while the infant is in the hospital. However, mild cases involving just the lower lip may not be seen at birth. A parent, grandparent, or other person may notice the problem later.

If the movement of your infant's mouth looks different on each side when he or she cries, you may want to call your health care provider.

There is no way to prevent pressure injuries in the unborn child. The proper use of forceps and improved childbirth methods have reduced the rate of facial nerve palsy.