What is a cross-face nerve graft?
The cross-face nerve graft is a technique used in facial paralysis surgery to bring in nerve stimulation from the non-paralyzed to the paralyzed side of the face. It is similar to the concept of an extension cord. It involves obtaining a nerve graft, most commonly from the lower leg, and implanting it into the non-paralyzed part of the face.
The nerve graft is then connected to working branches of the facial nerve and tunneled to the paralyzed side of the face for innervation. It is used in one of two ways. First, in the setting of early paralysis (less than 12 months), the cross-face nerve graft can be used to reinnervate paralyzed branches of the facial nerve directly. It is used in this capacity when the neural connections (motor endplates) to the facial muscles are still intact, and when it is expected that the entire nerve regeneration process can take place before the permanent loss of these connections. Nerve regeneration occurs at an average rate of one millimeter per day. This slow rate must be taken into account when using the cross-face nerve graft for the purpose. A cross-face nerve graft will typically take 9-12 months to reach its target on the paralyzed side of the face.
Second, in long standing, or late, paralysis, the cross-face nerve graft can be used as an initial step in facial reanimation. In this first stage, the nerve graft is laid down andallowed to regenerate over the course of 6-12 months. A second stage of surgery is required to transfer a muscle to the face for innervation with the cross-face nerve graft. The muscle used most commonly is the gracilis muscle from the thigh (see Gracilis Muscle with Cross-Face Nerve Graft for further details). An additional 6-9 months is necessary in order to innervate the transplanted muscle before it can begin moving.
How is a cross-face nerve graft performed?
A nerve graft is harvested most commonly from the lower leg. This nerve is called the sural nerve, and it is responsible for a minor sensory function in the foot. Specifically, it supplies sensation to a quarter-sized patch along the outer and upper part of the midfoot. Using the nerve for grafting purposes has little downside, as it does not affect the ability to walk or run normally. The nerve is long and has minimal branching, making it an ideal candidate for nerve grafting purposes. Three small incisions are placed along the back of the lower leg to retrieve the nerve. Through these incisions, the full length of the nerve can be harvested without significant scarring.
A facelift-type incision is then placed along the non-paralyzed side of the face. The facial nerve is carefully dissected with with the help of a nerve stimulator. The exploration continues until the major branches of the facial nerve are isolated. Next, the desired branch of the facial nerve is traced further into the face until additional branches are discovered. These additional branches are verified to produce the same type of facial contractions that are desired.
Once the donor branch is isolated, it is then divided and made ready for the sural nerve graft. The sural nerve is then connected to this branch using a high-powered microscope. The graft is then tunneled underneath the skin and across the upper lip. Depending upon the intended use of the cross-face nerve graft, it can then be banked in the upper lip for future use as innervation to a gracilis muscle transplant, or it can be connected to the same nerve branch on the paralzyed side of the face. To perform the latter, an identical facelift-type incision is placed and the individual nerve branches are meticulously identified with a nerve stimulator. Once again, an operating microscope is used to make the connection with sutures that are 70 percent thinner than human hair. All incisions are closed with absorbable sutures.
What is the recovery for a cross-face nerve graft?
Surgery requires general anesthesia and takes approximately 3.5 hours to complete and can be done on an outpatient basis. Some patients elect to stay in an aftercare facility overnight for comfort or if there is no assistance at home. The surgery can combined with other procedures, such as eyelid or brow surgery. A rubber drain is used under the facial skin flap for two days. The drains prevent extra fluid from accumulating underneath the skin. A bulky soft dressing and a facial support garment may be used. Direct pressure on the face should be avoided for the first three weeks. 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.
The leg dressings consist of a simple tape dressing with a mildly compressive wrap. The wrap can be removed in three days. Normal walking is allowed immediately, but heavy lifting, exercising, and running are avoided for 3-4 weeks.
There may be mild swelling of the face, but this 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 four 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 7-10 days off 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 case of cross-face nerve graft to a facial nerve branch on the paralyzed face. This includes a visit to a facial paralysis therapist to 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.
In the case of a first stage smile reconstruction, there will be no movement of the paralyzed face until the second stage of surgery is complete with triggering of the transplanted gracilis muscle. This can be 12-18 months after the initial surgery. Therapy is then initiated to maximize muscle activity and facial movement.
What are the risks and complications of a cross-face nerve graft?
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 of graft failure or failure to achieve full nerve regeneration, which can result in decreased motion or no function at all. In the setting of a two-stage smile reanimation, the degree of motion is difficult to predict and is believed to be somewhat diminished in comparison to a single-stage gracilis muscle to masseter nerve transplant.
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.