Facial nerve palsy in children can come from a variety of causes, some congenital and some acquired in nature.
Congenital facial nerve palsy is defined as palsy of the 7th cranial nerve that is present at birth or that occurs shortly afterward. It is believed to result from birth trauma, intrauterine posture, intrauterine compression, or congenital aplasia of the facial nerve nucleus. This can occur as an isolated abnormality or, less commonly, as part of a syndromic condition such as:
The most recent estimate of the incidence of congenital facial palsy in the United States was found to be 2.1 per 1,000 live births.
Facial nerve palsy can also be acquired later in development, as a result of trauma, stroke, tumor surgery, Bell’s palsy, Lyme disease, herpes zoster infection, or other inflammatory conditions. Although some of these patients may undergo spontaneous recovery, the recovery is often incomplete. Faulty or incomplete regeneration of the damaged facial nerve can result in paresis (slight paralysis) or synkinesis (involuntary facial movements), and can leave these patients with abnormal or even distorted facial motion.
Whether congenital or acquired, facial nerve dysfunction can cause significant functional and social problems for affected children. The inability to generate normal facial motion, including the essential act of smiling, can be psychologically debilitating. In addition to facial animation, these patients can have difficulty with feeding, swallowing, chewing, speaking, and closing their eyes (which can lead to acquired eye disease).
Early evalaution for facial nerve injuries is important because timely medical or surgical treatment can significantly improve outcomes. Supportive treatment during recovery is also important. Eye lubrication, protection and close monitoring by an ophthalmologist are necessary to prevent corneal injuries. And occupational therapy may help speed and strengthen muscle recovery after acute facial nerve injuries or reconstructive surgery. Patients with partial paralysis can learn to strengthen alternative muscles on the weakened side and suppress forceful normal motions to improve facial balance and symmetry. Other techniques, such as electrostimulation, surface EMG biofeedback, and exercise regimens may also aid recovery.
Surgical treatment for facial palsy is used to improve facial symmetry, balance and motion, as well as to correct oral problems and incomplete eye closure. Eye closure can be improved with a variety of procedures including lid loading, temporalis muscle transfer, or fascial or tendon slings. There are many techniques to improve the appearance and function of the midface, and they range in complexity from static slings to functional muscle transfer. Adjunctive treatment with Botox injections can also improve facial symmetry by reducing unwanted forceful contractions.
The current gold standard for dynamic reconstruction of facial motion is microneurovascular muscle transfer. During this procedure, a segment of muscle from elsewhere in the body, typically the gracilis muscle in the leg, is brought to the face with its vascular and neural supply. This surgery may be used for patients who have facial paralysis on one side of the face (unilateral) or both sides (bilateral).
When cases are unilateral, a two-stage procedure usually is preferred using a cross facial nerve graft technique to innervate the free muscle transfer. This procedure can restore spontaneous and emotionally driven motion, such as smiling, to children affected with facial palsy.
When paralysis is bilateral, the motor nerve to the masseter muscle may be used bilaterally to innervate the muscle transfer in separate single stage procedures. After facial reanimation surgery, exercise therapy strengthens and speeds muscle recovery and is essential to the success of this surgery.