When treatment is necessary, therapeutic methods tend to be mild, usually no more than a course of corticosteroids, which can reduce nerve inflammation. In rare cases, though, newborn children are left facing a life of facial paralysis or muscle weakness.
How Facial Paralysis Works
All of our facial expressions are controlled by a single nerve, known as the seventh cranial nerve, or cranial nerve VII. Alongside the motion of our lips, eyes and brow, the seventh cranial nerve plays an important role in transmitting taste signals from our tongues to the brain.
It should be clear that the seventh cranial nerve is crucial in our enjoyment of life, as it is essential in our ability to communicate with others. When this nerve sustains injury, doctors often diagnose Bell’s palsy, referring to the most common form of facial paralysis.
Bell’s Palsy In Adult Patients
Bell’s palsy isn’t just a condition prevalent in newborns. Adults can develop the disorder, too, losing muscle function on one side of the face or, in rare cases, both sides. This form of Bell’s palsy, in general terms, occurs when the seventh cranial nerve becomes “swollen, inflamed or compressed,” according to the National Institute of Neurological Disorders and Stroke.
Why the nerve sustains injury, however, is still unclear. The current theory is that most cases of Bell’s palsy in adults are caused by viral infections, such as meningitis, which can irritate the nerve.
What Causes Cranial Nerve Paralysis?
When cranial nerve paralysis affects a newborn child, however, the situation is somewhat different. In many cases, facial (or “cranial”) nerve paralysis is the result of injuries sustained during childbirth.
We now know, through decades of medical research, that children who experience difficult deliveries are more likely to suffer cranial nerve injuries, since their heads are subjected to the extraordinary pressure and compression of contractions in the birth canal for longer periods of time. Thus, facial nerve palsies can occur spontaneously, as an effect of the rigors of childbirth that all infants must endure.
At the same time, several obstetric interventions, things obstetricians do to make labor quicker or easier, can also result in significant facial nerve damage. In fact, birth injuries related to the use of forceps is almost certainly the leading cause of cranial nerve palsy in newborn babies.
The Role Of Forceps In Infant Facial Nerve Damage
Researchers have known that the use of forceps during an assisted delivery can lead to cranial nerve injuries since at least 1839, when the French neurologist Louis Landouzy described one such incident in his doctoral thesis.
Since Landouzy’s initial description, obstetricians have come to undertand that “facial nerve palsy caused by forceps use is a common occurrence,” according to physicians at the American Medical Association, who published a Journal of the American Medical Association article on the subject in 2009.
How Common Is Bell’s Palsy In Newborn Babies?
While the condition is technically rare, facial nerve palsy may occur in up to 7.5 out of every 1,000 births. The risk increases to 8.8 in 1,000 births when forceps are used to assist the delivery. That’s rare, but not extraordinarily rare.
Fortunately, most cases of facial nerve palsy don’t require treatment. “Most cases will resolve spontaneously,” the American Medical Association authors write; the child will gradually regain control over their facial muscles as the cranial nerve heals over time. The average recovery time, they report, comes in at 24 days after a child’s birth, though some cases won’t resolve until a few months later than that.
Cranial Nerve Palsy Symptoms
Most cases of cranial nerve palsy will be diagnosed based on a visual examination alone, although very mild cases, in which only the lower lip is affected, may not be noticed immediately after the child’s delivery. In newborn infants, facial paralysis is generally accompanied by one or more of the following symptoms:
- no movement on one or both sides of the face (paralysis)
- mouth moves in asymmetrical (uneven) way when crying
- eyelid closes partially or does not close on affected side
In severe cases of paralysis, a nerve conduction velocity test can be performed to measure the amount of electrical signal passing through the seventh cranial nerve. To perform the test, doctors use electrodes, applied to a child’s face, to stimulate the nerve using a mild electrical impulse. The electrical activity in the nerve can then be measured using a separate set of electrodes.
Nerve conduction velocity tests are usually paired with electromyography, the National Library of Medicine reports. In this second test, physicians place thin needles into the facial muscles to gauge the electrical impulse in another way.
Treatments For Bell’s Palsy
Treatment for a facial nerve palsy is generally conservative at first. Since the vast majority of children heal on their own, doctors and parents should closely monitor babies for improvement in face muscle function.
In most cases, treatment isn’t necessary. In cases when one of the child’s eyelids is unable to close completely, eye drops and a special eye patch can be used to keep the eye moist and protected from the outside world.
Surgical interventions have been attempted and, in severe cases, may become necessary, but their efficacy in treating mild or moderate cases of facial nerve paralysis is uncertain. Surgeons can attempt to decompress the nerve by carefully cutting away portions of bone or soft tissue that may be impinging on the nerve. Again, surgery is rare and many doctors believe that it poses more risks than benefits, especially for pediatric patients.
Severe facial nerve damage can result in permanent paralysis. Some children will require lengthy courses of physical therapy, which can help keep their facial muscles strong despite relative immobility. Massage and facial exercises can prevent muscle atrophy.