Dual Nerve Transfer Surgery
Dr. Pepper recently described the surgical technique for Dual Nerve Transfer for facial paralysis treatment. This procedure combines a hypoglossal nerve transfer with a massetric nerve transfer. The main advantage of the masseteric nerve transfer is that it can restore smile very effectively. The primary drawback of the masseteric nerve transfer is that it does not always provide sufficient facial tone or symmetry at rest. In contrast, the hypoglossal nerve transfer often improves facial symmetry at rest, but movement or smile is extremely limited with a hypoglossal nerve transfer. Taking advantage of these complementary strengths and limitations, the two nerve transfers may be efficiently combined together in one surgery to provide both smile reanimation and restoration of facial tone. An example of a patient who underwent a Dual Nerve Transfer is shown in Figure 1 and the Video.
In a Dual Nerve Transfer surgery, as shown in Figure 2, facelift-type incisions are used to access both the masseteric nerve and the hypoglossal nerve. The masseteric nerve is surgically connected to the buccal branch of the facial nerve. The facial nerve is dissected free in the bone behind the ear (the mastoid bone) and then moved towards the hypoglossal nerve in the neck. The facial nerve is then connected to the side of the hypoglossal nerve. After about 6 months, patients will be able to initiate a 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.” Facial tone gradually improves over the first year after surgery through the new nerve supply from the hypoglossal nerve. Note that facial tone takes longer to improve than smile. This is due to the longer distance that nerve fibers from the hypoglossal nerve must travel in order resupply the facial muscles. See Figure 2.
 Pepper, Jon-Paul. "Dual Nerve Transfer for Facial Reanimation." JAMA facial plastic surgery (2019).
Is this procedure for me?
In general, patients must have facial paralysis for no more than two years prior to this procedure. After about two years of facial paralysis, the nerve may scar shut and no longer accept a new nerve supply. Patients must also have functioning masseteric and hypoglossal nerves. In some cases of tumor or trauma, the masseteric nerve or the trigeminal nerve may not work normally and therefore may not be usable for nerve transfer surgery. In addition, patients who have difficulty swallowing are typically not good candidates for hypoglossal nerve transfer surgery and therefore are also not good candidates for Dual Nerve Transfer surgery.
Patients usually stay in the hospital overnight following this procedure and return home the following day. Swelling and bruising from the procedure takes about 3 weeks to resolve.
All patients must be committed to rehabilitation 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.