What are nerve transfers for facial paralysis?
When facial paralysis treatment is initiated early (less than 12 months), then nerve transfers are possible to restore facial movement. The technique involves borrowing a nerve on the paralyzed side of the face to stimulate the facial nerve itself and all its downstream branches. These donor nerves are chosen because they are not affected by facial nerve palsy.
In some conditions, they may be affected and nerve transfers may not be possible. The possible nerves for use include the masseter nerve (fifth cranial nerve), hypoglossal nerve (twelfth cranial nerve), or the spinal accessory nerve (eleventh cranial nerve). It is also possible to use a cross-face nerve graft from the non-paralyzed side of the face. Refer to Cross-Face Nerve Graft for details.
Early paralysis means that the critical connections that the facial nerve has with its target muscles (motor endplates) are still preserved and recoverable. However, in congenital facial paralysis, the facial nerve, its nucleus, or its branches may be absent. Therefore, nerve transfers may not be possible in this group of facial paralysis patients, as the facial nerve itself may be deficient or absent.
The masseter-to-facial nerve transfer is the most commonly practiced nerve transfer because of its reliability and analogous function to smiling. Triggered when biting, the masseter nerve delivers excellent power to the masseter muscle. Its power can be harnessed with great efficacy for the regeneration of the facial nerve. Muscle re-training is typically required because of the alternate pathway used to smile.
How are nerve transfers for facial paralysis performed?
Incisions are planned on the paralyzed side of the face in a facelift fashion. This allows for excellent exposure of the facial and masseter nerves. Both nerves are located using a high-powered microscope and loupe magnification. The masseter nerve sits deep behind the masseter muscle and is dually innervated. One of its branches is isolated and readied for the transfer. Similarly, the facial nerve trunk is identified as it exits the skull and enters the parotid gland. Depending upon the degree of facial paralysis, either the entire trunk or only a selected branch is divided and prepared for connection to the masseter nerve. Any existing facial nerve function is lost during surgery when the nerve is cut. For this reason, it is critical that a surgeon who is an expert in facial paralysis evaluate the patient beforehand to determine if further recovery is not achievable.
The masseter nerve is then connected with very fine sutures to the facial nerve using a high-powered microscope to ensure perfect approximation. The incisions are then closed with absorbable sutures. The steps for the other types of nerve transfers (hypoglossal-to-facial and spinal accessory-to-facial) are similar with nuances in the harvesting of the donor nerves.
What is the recovery for nerve transfers?
Surgery requires general anesthesia and takes approximately 3.5 to 4.5 hours to complete. This is most often performed on an outpatient basis, although some individuals elect to stay in an aftercare facility overnight for comfort or if there is no assistance at home. A small rubber drain is placed underneath the skin to draw away extra fluid. It is removed on the second postoperative day. A soft diet is started immediately after surgery. This includes soft foods such as soups, yogurt, well-cooked chicken, rice or pasta. Hard foods such as hard fruits, vegetables, steak, chips, and other similar items are to be avoided for 3 weeks.
Swelling of the face can occur, but typically resolves over the first week. Bruising is not always present, but it will also improve during the same time period. Activity is restricted during the first 4 weeks to light walking and stationary activities. Heavy lifting, contact sports, and aerobic exercises are to be avoided during this time. Most adult patients elect to take approximately 7 days off (or less) from work. During this time, make up can be used to mask any bruising.
Physical therapy is started when there’s evidence of innervation in the paralyzed face. It can take between 2-4 months to begin seeing movement. A therapist skilled in facial paralysis will initiate exercises, biofeedback, and massage techniques to encourage innervation and strengthening. Scar management is initiated to ensure excellent scar healing. Therapy may need to be continued for several months in order to improve mobility of the muscle and for developing spontaneity of the smile.
What are the risks and complications of nerve transfers for facial paralysis?
Complications are rare with cross-face nerve graft. Standard risks associated with all surgeries apply. These can include bleeding (hematoma), infection, or adverse reactions to anesthesia. In adults, uncontrolled diabetes and smoking may affect healing and overall results. As a dynamic procedure, there is always a risk of minor asymmetry and excessive scarring underneath the skin, causing decreased movement of the lips. There is also a small risk failure to achieve full nerve regeneration, which can result in decreased motion or no function at all.
To minimize your risk, pay close attention to your surgeon’s instructions before and after surgery. The Facial Paralysis Center staff is available at all times to clarify any pre- or postoperative instructions that you were given. Please refer to the Pre- and Postoperative General Instructions for further details.