Facial paralysis – weakness of the facial muscles responsible for eye blinking and facial expression – can be partial or complete. There are a variety of causes, but regardless of the cause, it is a devastating condition. In most cases of facial paralysis, one side of the face is affected and the other is spared. As a result, the appearance of the face is not symmetric (asymmetric). This lack of symmetry (asymmetry) is accentuated whenever the person moves the face as part of normal facial expression. For example, the smile is uneven, one side of the face droops, or the eyebrows aren’t the same level.
Correcting facial paralysis is a field within reconstructive surgery that is evolving, as new approaches and techniques continue to evolve, offering hope now to almost every patient who suffers from this difficult condition. However, there is much progress to be made, and we feel we will see great advances in the management of facial paralysis in the coming years.
We will start by reviewing the important anatomy and functions of the face. Specifically we will discuss the important aspect of the facial nerve. We will then describe some of the most common causes of facial paralysis, including the latest philosophies on early management. We will provide an overview of some of the important challenges facing the patient with facial paralysis. We will then describe the contemporary treatment options available today, for both partial and complete facial paralysis.
Complete facial paralysis means that on the involved side, there is no movement at all. There is no muscle tone on that one side of the face. These cases are more serious, because the longer the paralysis persists, the less likely the facial nerve and muscles on that side of the face will ever function again. In incomplete paralysis, there is diminished movement. There is some tone to the muscles that protects them from wasting away and becoming useless. In this scenario there is no rush to perform any particular procedure. So the options to treat complete facial paralysis are usually different than the options to treat incomplete paralysis.
Humans have 12 cranial nerves. These are nerves that start in the brain and exit the skull to control functions within the head and neck. The facial nerve is the 7th cranial nerve. One will often see it referred to as CN (cranial nerve) VII. The nerves are numbered in the same order that they are found in the brain, from top to bottom. Therefore, the facial nerve is close anatomically to cranial nerve number 8 (CN VIII), which is in control of hearing and balance. This is important because some tumors (such as the benign acoustic neuroma) can grow from the covering of CN VIII and impinge on CN VII (the facial nerve) as the tumor grows. As the tumor impinges on CN VII it impairs the functions of the facial nerve.
The facial nerve has very important functions of which controlling all of the muscles of the face is most significant. The right and left facial nerves normally always work together, to control the raising and lowering of eyebrows, blinking of eyelids, smiling, grimacing, kissing, much of speaking, etc. All emotions that we ever experience are expressed through movements of our face working simultaneously on both sides. During conversation, facial expressions give subtle but important information to the other person or people with whom we are speaking. In some cases our facial expression even alters the meaning of the words we say. Other important functions of the facial nerve include lubricating our eyes through the release of tears (and eye blinking), stimulating the flow of saliva into our mouths to help with eating, and even slightly modifying how we hear loud sounds.
When the facial nerve is injured, all of these complex functions are disrupted. As a result two significant problems arise. First, the function declines and the surface of the eye can become chronically dry, speech and swallowing can be affected, and breathing through the nose on the involved side can be obstructed. The second, and perhaps more devastating problem is the visible facial deformity. The face on the affected side droops and sags, appearing lifeless and immobile. This deformity is distracting to others, and interferes with ones ability to communicate with others. The inability to smile normally and the uneven appearance of the face contribute to anxiety and distress in the patient. The ability to smile is something we all take for granted. When this is taken away, it is extremely difficult for the patient to adjust. The majority of patients with complete facial paralysis will say that, more than anything, they want to be able to smile again.
Most people think of facial paralysis as resulting from a stroke, but in reality most patients who suffer from facial paralysis have other causes.
The most common cause of facial paralysis is Bells Palsy. This is also called Idiopathic Facial Paralysis, meaning that there is no proven known cause or risk factor. It typically affects younger, otherwise healthy adults with no warning. It is thought to be caused by a viral infection of the facial nerve, but that has yet to be proven. Affected patients suddenly develop a complete paralysis of one side of the face. Sometimes it is associated with other symptoms, such as ringing in the ears or hearing loss on the affected side. Fortunately, most patients with Bells Palsy regain function of the nerve, beginning a few weeks after the onset. This is true whether or not any treatment is provided. The odds for complete recovery may be highest, though, in those who are given oral steroids and antiviral medication early after the onset of symptoms.
Unfortunately, this complete return of function does not occur in everyone. Some patients (less than 10% of Bells Palsy patients) have no return of movement for several months, and are left with permanent dysfunction. Not all movement returns, resulting in the inability to form a normal smile. Such patients will also have disorganized movement (synkinesis). In such cases, when the patient speaks or smiles, the eye also partially closes. Another example of synkinesis is twitching of the mouth when the person blinks. This group of patients who have had Bells Palsy and are left with long-term asymmetry and dysfunction – tends to have a different set of challenges (and thus treatment options) than others with a facial nerve that was damaged by a tumor, surgery, or trauma. Bells palsy patients usually regain tone, and their problems are related to having some areas of the face that have no movement, too much tone, or poorly controlled movement. They very rarely are left with long-term complete paralysis. The rest of the groups below are more frequently left with long-term facial paralysis.
This is a benign tumor of the hearing and balance nerve. These tumors can damage the hearing and balance system. Removing them surgically sometimes results in damage to the facial nerve. The damage may result in a partial or complete weakness of the facial nerve. The dysfunction of the facial nerve is typically noticed early in the recovery, soon after the acoustic neuroma has been removed. When this happens, the team of surgeons that removed the acoustic neuroma tumor is often hopeful that the facial nerve function will return completely. In many cases it does but not always. Moreover, many of these patients wait for many months for recovery to return. There is no widespread agreement as to how long it is appropriate to wait before intervening with any surgical procedure that will help “reanimate” the face. Many surgeons suggest waiting one year.
The parotid glands are the largest salivary gland and sit in front of each ear. The facial nerve exits the skull base very near the parotid gland and then branches as it passes right through the substance of the gland. Tumors can grow within the parotid gland – both benign and malignant. Thus, these tumors and the surgery to remove them can result in injury to the facial nerve.
Another major cause for facial paralysis is trauma. Blunt and penetrating trauma from motor vehicle accidents, altercations, and animal bites can on occasion cut or crush the facial nerve. In such cases, prompt identification of any facial nerve injury with timely management is key to minimizing the resulting deformity and dysfunction.
What is the first and most important thing to be concerned about? Dryness of the eye and the importance of eye protection
This is the most important medical concern of facial paralysis. The inability to blink normally may be also accompanied by a diminished tear production. If the surface of the eye remains dry for extended periods, severe damage can occur that can threaten ones vision. It is imperative that the patient with facial paralysis employs a regimen of eye lubrication and protection. This must be started right away, and continued indefinitely. It is very important to see an ophthalmologist for regular checkups. There are a variety of procedures that can be effective to protect and soothe the eye. However, they do not take the place of lubrication regimens. They will be described in the treatment section.
The process by which human beings perceive the faces of others is a funny thing. We all encounter faces all day long, and virtually never pay attention to normal asymmetries that all faces have. Yet they are there, and once pointed out, one can typically see them fairly easily. Our brains are designed to ignore facial asymmetry in others, until it becomes markedly asymmetric. This is a really important observation for patients with facial paralysis. For other deformities such as scars, or skin cancers, it is not the asymmetry that stands out – it is the tumor or scar that is seen. However, with facial paralysis it is not the paralysis that others see, as they do not readily perceive which side is dysfunctional. What they notice is simply that the two sides of the face don’t match well enough. This is very important for patients with facial paralysis and their surgeons to understand. Though there are no magical cures for facial paralysis, we also know that the human brain is designed to ignore some level facial asymmetry. Therefore, by doing whatever we can to improve symmetry we can often achieve a dramatic overall improvement.
The first part of the section will comment on Bells Palsy patients. The remainder will address those patients who have no movement on the involved side. We will also describe reinnervation options. A discussion of muscle transfers will then be followed by a description of a variety of additional procedures that can be very beneficial to patients.
The initial management of Bells Palsy typically involves the use of steroids and antiviral medication. This is based on the theory that Bells Palsy is caused by a viral infection that causes edema (swelling) of the nerve, which then is damaged within the rigid confines of the nerve’s canal. Steroids reduce swelling, and the antivirals are thought to limit the duration of the effect of the virus in the body.
Many studies have looked at whether or not these treatments are beneficial. The studies have not always come to the same conclusion. It is clear that whether or not any treatment is provided, most patients will spontaneously recover and regain a fully functional, normal nerve. A small percentage (less than 10%) will regain some function (tone returns to the face, and some movement) but still be left with asymmetry of the facial movements.
This asymmetry tends to follow certain patterns. The smile is not as strong on the involved side. Often the fold between the nose and lip is deeper, though (indicating too much tone). The eye may partially close with mouth movements.
Treatment options do exist. Many believe that facial retraining through physical therapy is helpful. This has the dual goals of enhancing normal movement, and lessoning synkinesis. The use of “chemodenervation” – the injection of Botox or Dysport – can minimize synkinesis. Some practitioners will even use these injections to lesson movement on the other side of the face in order to improve symmetry.
Reinnervation refers to the attempt to reestablish a nerve impulse to the facial muscles so that eventually the patient will be able to smile naturally and blink. When there is complete paralysis, there is a window of opportunity to accomplish this. Soon after the nerve is injured, the muscles that now lack normal nerve stimulation will start to atrophy and lose tone and mass. Ultimately, scarring (fibrosis) of the connections between the nerve branches and muscle occurs. Eventually, the muscles lose their ability to ever move, and will waste away. This window of opportunity to reinnervate existing facial muscles of expression is probably about one year.
In cases where the facial nerve is severed, either as a result of trauma or surgery, then the nerve can be sutured back together under a microscope with meticulous technique. Though this is the best option, in reality if the facial nerve is transected it will not be possible to achieve completely normal facial nerve function. Good symmetry at rest can often be achieved, but there will be some noticeable asymmetries seen with movement.
If the facial nerve is missing a segment, but the surgeon can gain access to both the closer and farther ends of the nerve, then a replacement graft is sewn in as a “cable” to replace the missing segment of the nerve. This is often done in cancer cases, where the nerve has to be partially removed along with the tumor.
When tumors affect the facial nerve very near the brain, it may not be possible for the surgeon to gain access to the part of the nerve near its take off point from the brain. So a replacement cable graft is not an option. In those cases an alternative cranial nerve can be used to provide nerve impulses to the facial nerve that still remains in the face. The most common nerve to use is the 12th cranial nerve, known as the hypoglossal nerve. The hypoglossal facial nerve transfer can be done a few different ways. In each case, the hypoglossal nerve is connected to the facial nerve. As a result of the surgery, tone is returned to the face. The patient usually can learn to use the tongue to produce a smile. (this is often accomplished by pushing the tongue against the back of the teeth).
In this strategy, the source of input to the paralyzed facial nerve is branches of the facial nerve on the other side of the face. First, a long donor nerve graft is harvested, usually from the lower leg. On the normal, functioning side of the face, one or more branches are chosen to be purposefully cut. The harvested nerve graft is then attached to the normal facial nerve branch, tunneled across the face and connected to the facial nerve on the paralyzed side. At a later date, (after allowing time for the regenerating nerve to grow from the cut ends of the sacrificed branches on the normal side, across the face to the paralyzed side), the nerve is connected to the chosen branch or branches on the paralyzed side. This technique can lead to spontaneous and symmetric movementof the face. The procedure does not always work, however.
The reinnervation options described above are designed to coax movement and function out of the facial muscles, to get the natural smiling and blinking muscles to work again. After a prolonged period of inactivity (typically after a year or so), these facial muscles permanently lose their ability to function. Atrophy and scarring set in, and reinnervation procedures can no longer work. In these cases, muscles must be brought into the face from elsewhere to provide movement. There are two choices – regional muscle transfer (adjacent muscles are moved to the mouth or eyelids), and free tissue transfer (distant muscles are transplanted onto the face).
The most popular and effective muscle for this purpose is the temporalis muscle. It is the largest of the chewing muscles. It arises in the temple, and travels downward to connect into the jaw. Its job is to pull the jaw upward to chew. Fortunately, there are several chewing muscles on both sides of the jaw. Thus, one can detach the temporalis muscle and reroute it to the mouth to achieve some movement – a smile. There are different techniques described to transfer this muscle. Some surgeons take a slip of the muscle from the temple and swing it down over the cheekbone to connect to the corner of the mouth. This can cause a bit of a bulge over the cheek. Recently, many surgeons have opted instead to detach the part that inserts into the jaw, and stretch it down to the corner of the mouth and lips. In either case, the patient needs to deliberately create the smile movement by clenching the jaw. This takes practice, and does not always become spontaneous.
Microvascular free tissue transfer involves the transplantation of tissue (skin, muscle, bone) from one area of the body to another distant site. It requires complete detachment of the tissue. The blood supply must therefore be re established into the “flap” of tissue. This requires suturing the artery and veins of the transplanted tissue to arteries or veins in the face or neck. It is a technically advanced procedure that requires highly specialized expertise.
The muscle most commonly used for facial reanimation is the gracilis muscle. This delicate muscle is located in the thigh and its removal typically has minimal effects on the leg function.
The procedure is often performed in two stages. In the first stage, a cross facial nerve graft is performed as described above. This provides a way to grow one or more branches of the facial nerve from the normal side of the face over to the paralyzed side. After the first stage, a prolonged waiting period allows time for the facial nerve to grow across the face through the cross face nerve graft. This takes up to a year. In the second stage, the gracilis muscle is transplanted from the leg to the face. This requires a stay in the hospital for several days. Microvascular free tissue transfers can fail if a clot forms in the artery or vein. At advanced centers, this failure rate is about 5%.
Most patients with complete facial paralysis develop drooping of the eyebrow. This can obstruct vision somewhat, and also create a very noticeable asymmetry. Browlifts can be very effective to help with this. There are a variety of browlifting procedures, and may be performed on just the paralyzed side, or, if desired, on both sides. Please refer to the browlift content on this site to learn more.
It is often not possible to restore a normal blink in facial paralysis. Thus the upper eyelid, while it opens normally (this is controlled not by the facial nerve but by another cranial nerve), cannot blink or even close completely. Upper eyelid loading involves the placement of an eyelid weight – gold, or more recently platinum chains – to help the eye close more completely. A true blink is not restored, but eye protection (particularly while sleeping) is improved.
The paralyzed lower eyelid may become droopy (lid retraction) or turn out away from the eye ball (ectropion). This can contribute to eye exposure problems and discomfort. A number of procedures exist to elevate and/or tighten the lower eyelid to improve its position.
A simple and safe strategy to suspend the sagging tissues of the face, slings can lift the corner of the mouth and drooping nose. A number of materials are used – either the patients own tissue from the leg or commercially available skin substitutes such as acellular dermis.
This involves the use of Botox or Dysport to relax specific facial muscles. The goal is to improve facial symmetry. It is performed for two reasons. First, to suppress abnormal movement (synkinesis) that often exists after a facial nerve injury. The other is to suppress movement on the other side of the face, in an attempt to make the face more symmetric. These injections are quick and easy to perform. The effects begin in a few days, and last typically for three to four months. Please refer to the chapters on Botox and Dysport for more specific information.
Many patients with facial paralysis benefit from additional procedures to help make them look more youthful, attractive, and symmetric. These include eyelid surgery, face and neck lifting, volume restoration (fat transfer, injectable fillers), and other procedures. More information on these procedures is found elsewhere on this site.