Reconstructions are tailored to each person’s unique circumstance. It is important to realize that facial nerve reconstructions rarely result in an appearance identical to the pre-injury state or similar to a person unaffected by facial paralysis, although this is the goal. While it is not possible to recreate all of the intricate movements of facial expression, many excellent techniques are available for smile reconstruction. Reconstructions do typically improve facial function, balance, and appearance, although success is never guaranteed. Achieving greater symmetry and the individual’s personal goals are emphasized.
Reconstructions performed early after facial nerve injury are often able to preserve the original muscles of facial expression. Other nerves may be used to power the muscles if the facial nerve is not available.
Direct Nerve Repair
If the facial nerve has been cut, it may be able to be directly repaired, particularly if managed within a few days from the injury. These injuries often require a nerve graft, or a segment of another nerve, usually the sural nerve from the calf, to span a gap between the two cut ends.
Cross-Facial Nerve Grafts
(See Figure A) In cases of paralysis affecting only one side of the face, the normal, unaffected facial nerve on the opposite side may provide a source of nerve fibers. Specific extra facial nerve branches from the healthy side of the face can be identified and connected to the paralyzed side of the face with a nerve graft. The nerve fibers then grow from the healthy facial nerve, across the nerve graft, and to the dysfunctional nerve and paralyzed muscles. The nerve graft acts somewhat like an extension cord, however, it takes time (months) for the nerve fibers to grow across the face to reach their target.
Typically the sural nerve in the calf is used as the nerve graft (See Figure B). The sural nerve is an expendable sensory nerve. It is removed from the leg via two or three small incisions. A numb patch on the outer side of the foot remains after the sural nerve is removed from the leg. This nerve is not required for walking.
In cases of paralysis affecting both sides of the face, there is not a healthy facial nerve available to borrow from. Other nearby nerves can be used to provide a nerve source for the facial muscles. A branch of a nerve utilized in chewing, the masseteric nerve, is commonly utilized (See Figure C). This nerve branch is expendable, and its use does not result in chewing difficulties. The masseteric nerve branch can be connected to the affected facial nerve. This nerve transfer does not require use of a nerve graft, meaning no surgery is required in the leg. Therapy is required after surgery for the child to learn how to use this nerve for facial movement.
For people with long-standing facial paralysis (greater than 12-24 months), substitution of the nerve supply alone is not sufficient. In these circumstances the original muscles of the face can no longer accept a nerve, and alternative muscles are also required for movement. Muscles from other regions of the body may be utilized. Static reconstructions may be performed to provide support to the face.
Static reconstructions act as an internal sling for the face. They provide support, but not movement. Static support slings may be constructed from other regions of the body, such as fascia from the thigh, forearm, or temple, or from surgical products. Static techniques are sometimes used in combination with dynamic reconstructive techniques.
There are many techniques for reconstructions that provide movement to the paralyzed face. Some examples are listed below:
Regional Muscle Transfers
Functioning muscles on the paralyzed side of the face, such as muscles involved in chewing that are innervated by the trigeminal nerve (cranial nerve V), can sometimes be partially moved to provide facial movement.
Free Functional Muscle Transfers
Advances in microsurgical techniques have made free functional muscle transfers reliable and more elegant. A segment of a muscle from another body region can be transferred to the face to provide movement. The gracilis muscle is an expendable muscle from the inner thigh which is well-suited for transfer to the face (see Figure D). Removal of this muscle from the thigh does not decrease leg movement as four additional muscles perform its same task. The muscle segment is transferred with its blood vessels (so that it is alive) and its nerve (so that it may move). The blood vessels and nerve are then connected to blood vessels and a nerve within the face. The muscle is positioned so that when it contracts, it provides a smiling movement to the corner of the mouth and upper lip.
This procedure is technically very demanding and requires the use of microsurgery to connect vessels with sutures (stitches) several times thinner than human hairs. This reconstruction may be performed in one or two surgical stages, depending on the nerve supply that will be used. We most commonly use this technique in combination with a cross-facial nerve graft and the facial nerve on the opposite face (two stages) with CFNG/VII (see Figure E) or a masseteric nerve transfer (one stage) (see Figure F). For both of these nerve sources, the donor nerve (either the graft or the masseteric nerve) is connected to the nerve to the gracilis muscle (the obturator nerve). The nerve fibers then slowly grow into the transferred gracilis muscle to allow it to contract over time, usually in 4-9 months or more. For bilateral reconstructions, a gracilis muscle can be transplanted to each side of the face. We prefer to do this in two separate surgeries, usually at a minimum of 3 months apart.