Chronic Facial Paralysis
Facial paralysis is the loss of facial muscle movement due to a weakened or damaged facial nerve, usually occurring on one side of a patient’s face. Causes of facial paralysis or facial weakness include trauma to the face or skull, a tumor in the head and neck, among other causes. “Chronic” facial paralysis refers to long-standing weakness or immobility of the muscles of the face (for example, an inability to smile). In general, facial paralysis is considered “chronic” if it has lasted for longer than 1 year since initial symptom onset.
Diagnosis of chronic facial paralysis is performed by a clinician, and may include electrodiagnostic testing in some cases. Following a severe facial nerve injury, it may be helpful to undergo electrodiagnostic testing in order to determine the prognosis for recovery of the facial nerve. Small, sterile needle electrodes are used to determine the electrical activity of facial muscles, even when they are not able to move the face in a manner visible to a patient or an observer. This is analogous to an electrocardiogram (EKG) that is used to test the muscles of the heart. Similarly, facial electrodiagnostic testing can provide clinical information that may guide treatment. This testing is best performed and interpreted by an integrated team of providers who can work together to accurately interpret the results and then craft an appropriate treatment plan.
Commonly offered surgical treatment for chronic facial paralysis
Chronic Facial Paralysis may be treated through a variety of surgical approaches (see diagram above). All techniques, however, share a common goal: to restore facial symmetry, improve essential functions of the face (such as speech and drinking liquids). Some procedures also offer, if successful, the ability to produce a smile.
Nerve transfer surgery for facial paralysis
In cases of facial nerve paralysis that have lasted, in general, 1.5 years or less, a nearby motor nerve can be connected to a portion of the facial nerve in order to restore movement.
Nerve to masseter transfer
One of the most common nerve transfer procedures is called the nerve to masseter transfer1. This involves the use of the nerve to the masseter muscle as a donor nerve to supply input to the paralyzed facial nerve in order to restore a patient’s smile.
 Klebuc, M. J. (2011). "Facial reanimation using the masseter-to-facial nerve transfer." Plast Reconstr Surg 127(5): 1909-1915.
In the traditional nerve to masseter transfer, shown above, facelift-type incisions are used to access both the nerve to masseter and the main trunk of the facial nerve. The main trunk of the facial nerve is divided, and mobilized towards the nerve to masseter. The nerve to masseter, in turn, is identified and cut. The nerve to masseter is then connected to the facial nerve, thereby providing nerve input to the paralyzed facial nerve. The function of this input is essentially “bite to smile.” After 6 months, patients will be able to initiate facial movement by biting down (activating the nerve to masseter). Retraining and rehabilitation are then required to practice the use of this new movement. Please refer to the Photo and Video Gallery for examples.
An alternative form of this procedure is the “selective” nerve to masseter transfer. This is similar, but instead the only cut in the facial nerve is made at a buccal branch which is usually responsible for initiating smile. The cut buccal branch is then connected to the nerve to masseter in the same fashion as described above.
Patients usually stay in the hospital for one or two days following this procedure. This is a relatively reliable method to restore movement to the corner of the mouth. It does not, however, provide acceptable resting tone to the paralyzed face. For this purpose, a fascia lata sling or hypoglossal nerve transfer may be performed simultaneously (see below).
Hypoglossal nerve transfer
In order to restore resting symmetry or “tone” to the face, the hypoglossal nerve may be used as a donor nerve. The hypoglossal nerve assists with movement of the tongue. The method most commonly employed by the Stanford Facial Nerve Center involves identification of the paralyzed facial nerve within the mastoid bone, behind the ear. This is done by a Neuro-otologist, with specialized training in lateral skull base surgery. The paralyzed facial nerve is then cut and moved to the hypoglossal nerve in the neck.
Due to the importance of tongue movement to speech and swallowing, the hypoglossal nerve is not cut completely, but is instead partially cut to allow nerves to grow into the facial nerve without sacrifice of the entire hypoglossal nerve. This typically preserves normal tongue mobility.
Combined nerve transfer surgery for facial paralysis
The main advantage of the nerve to masseter transfer is that it can restore impressive movement to the corner of the mouth. Its main weakness is that it does not provide sufficient resting tone or symmetry at rest. By contrast, the advantage of the hypoglossal nerve transfer is that it restores symmetry at rest, but movement or smile is extremely limited. Taking advantage of these strengths and limitations, the two nerve transfers may be combined together in one surgery to provide both smile reanimation and restoration of tone. In the combined hypoglossal nerve and nerve to masseter transfer, both the hypoglossal nerve and the nerve to masseter are employed simultaneously.
Gracilis free muscle transfer for chronic facial paralysis
Background: The gracilis muscle transplant procedure has the ability to restore moving, functional muscle to the face. This is particularly useful in cases of long-standing facial paralysis, also called chronic facial paralysis. The procedure involves harvest of muscle from the inner thigh through a surgical incision. The gracilis muscle is detached, including its blood vessels and nerve. The muscle is then transplanted to the paralyzed side of the face, and connected to a nerve and blood vessel.
Once the gracilis muscle is transplanted to the paralyzed side of the face, it must be connected to a new nerve, so that it can move the paralyzed side of the face. The gracilis muscle may be connected to the nerve to master (which is normally used for biting/chewing), to a cross-facial nerve graft harvested from the leg, or to both nerves simultaneously. These options are decided based on a discussion between the surgeon the patient. In general, the gracilis may be performed in a single surgery if connected to the nerve to masseter, or in two surgeries if connected to a cross facial nerve graft. Patients usually stay in the hospital for approximately five days after this surgery. The advantage of the gracilis free tissue transfer surgery is that it can, if successful, restore movement to the corner of the mouth in any patient with facial paralysis, regardless of the duration of paralysis. Nerve transfers, discussed above, are typically used only within 1-2 years from the onset of paralysis and their effectiveness is believed to decrease with time.
Static sling (Facelift and sling to support the corner of the mouth)
The most time-tested treatment for facial paralysis involves a facelift on the paralyzed side of the face, combined with a soft tissue “sling” used to pull up the corner of the mouth. In this procedure, tissue from the leg (fascia) is removed from the thigh through a surgical incision. Fascia is a form of connective tissue that wraps our muscles in a fibrous sheath. Following a facelift on the paralyzed side of the face, this tissue is then sewn to the corner of the mouth and used to lift it. This provides relatively quick improvement in facial symmetry, speech, and helps keep food in the mouth.
The fascia lata can also help to recreate the crease in the skin that separates the cheek from the lip. Most patients experience initial “over-correction,” but this relaxes with time. This means that immediately after surgery, the corner of the mouth is elevated into a prominent smile that relaxes with time. This surgery is relatively quick, and the benefits of it are realized rapidly after surgery once swelling subsides. The downside of this surgery is that no movement is restored to the face. Also, the fascia will stretch with time and therefore the benefits are not permanent. The fascia lata sling may be used in combination with other facial reanimation techniques, such as the nerve to masseter transfer. It may also be used with a facelift in order to provide more firm support to the corner of the mouth or redefine the crease between the lip and the cheek.
Temporalis tendon transfer and lengthening temporalis myoplasty
The temporalis muscle is situated on the side of one’s head, and is one of four major muscles used for chewing. It attaches to the jaw bone (mandible), and helps to close the jaw when chewing. The muscle, and its bony attachment, can be cut through a skin incision that is placed in a natural skin crease between the lip and cheek. The tendon and bone are then sutured to the corner of the mouth. This results in the corner of the mouth being pulled upwards in a smile. In many patients, they may then use the temporalis muscle to produce a smile. In general, the amount of movement with this smile is small and somewhat subtle. However, this procedure provides a very long-lasting suspension of the face, and immediately results in improved symmetry at rest, and often improves speech and eating. There is mild to moderate discomfort in the jaw after this procedure, but this improves with time. This is also a relatively quick procedure that can last for years in some patients.
A variation of the temporalis tendon transfer is the Lengthening Temporalis Myoplasty. In this surgery, a more extended scalp incision allows for release of the temporalis muscle. After freeing the temporalis muscle from adjacent attachments, it is then advanced to the corner of the mouth in a similar fashion to the temporalis tendon transfer. Movement of the mouth can be more impressive with this procedure, but it is offered typically only in patients who have no prior radiation or significant scarring in the region. Please see the Photo and Video Gallery for examples.
Some patients with facial weakness may benefit from a facelift (rhytidectomy) on the side of their facial paralysis. The goal of this facelift, as in all facelifts, is the elevation of redundant and drooping soft tissue near the jawline and neckline. This is not a facial reanimation surgery, but can improve resting symmetry and have a pleasing effect on the appearance of the face. Facial incisions for a facelift are shown below.
The deep tissue of the face that is often repositioned in a facelift is called the superficial superficial muscular aponeurotic system (SMAS). The SMAS is released and repositioned, in a manner called a “SMAS flap facelift” which is a well-established technique 2. The SMAS flap facelift may be combined with other procedures.
 Pepper, J.-P. and S. R. Baker (2011). "SMAS flap rhytidectomy." Arch Facial Plast Surg 13(2): 108-108.