Masseteric Nerve Transfer Surgery
One of the most common nerve transfer procedures for facial paralysis is the masseteric nerve transfer.1 In this procedure, the masseteric nerve is re-routed to the injured facial nerve in order restore a patient’s smile.
In a masseteric nerve transfer, as shown in Figure 1, facelift-type incisions are used to access both the masseteric nerve and the branch of the facial nerve that initiates smile, called the buccal branch of the facial nerve. The masseteric nerve is then surgically connected to the buccal branch of the facial nerve. After about 6 months, patients will be able to smile by biting down (activating the masseteric nerve). Retraining and rehabilitation are then required to practice the use of this new movement, which is called “bite to smile.”
If successful, the masseteric nerve transfer may be quite successful in restoring a smile. The main drawback to this procedure is that patients must bite down in order to smile, therefore retraining and practice is required in order to get the most out of the procedure.
An example of a patient using the masseteric nerve to smile is shown in Figure 2 and the video.
 Klebuc, M. J. (2011). "Facial reanimation using the masseter-to-facial nerve transfer." Plast Reconstr Surg 127(5): 1909-1915.
Is this procedure for me?
In general, patients must have facial paralysis for no more than two years prior to this procedure. After two years of facial paralysis, the nerve may scar shut and no longer accept a new nerve supply. Patients must also have a masseteric nerve that works normally. In some cases of tumor or trauma, the masseteric nerve or the trigeminal nerve (this is the nerve that feeds into the masseteric nerve) may not work normally. In these cases, the masseteric nerve may not be usable for nerve transfer surgery.
Patients who have partial function of their face, such as a weak smile, may not be good candidates for this procedure. Typically, other surgeries or procedures are used for patients with a partial or weak smile.
Patients usually stay in the hospital overnight following this procedure. Swelling and bruising typically go away in 2-3 weeks. Noticeable facial movement from this procedure usually takes about 6 months to show, and the movement will typically get stronger over the first year after surgery. Overall, the masseteric nerve transfer is a relatively reliable method to restore smile. It does not, however, restore the symmetry of the face at rest (when not smiling). In order to restore facial symmetry at rest, a fascia lata sling or hypoglossal nerve transfer may be performed simultaneously.
All patients must undergo rehabilitation exercises after surgery, as learning to “bite to smile” requires practice. We are fortunate to have world-class facial rehabilitation treatment to assist with this at the Stanford Facial Nerve Center.