Smile Restoration for Facial Paralysis Surgery & Functional Restoration
Is a Smile Restoration the Procedure for You?
Restoration of an active smile and normal resting position of the cheeks and lips is a major goal in facial rehabilitation with functional, cosmetic and social significance. Paralysis of the mid-face often leads to sagging and asymmetry producing a loss of oral competence and drooling.
Eating and speech are frequently impaired and collapse of the external nasal passage can result in obstructed breathing.The loss of facial symmetry and ability to communicate emotion with a smile can create far reaching cosmetic and social problems.
The goal of restorative “smile” surgery is to reestablish facial balance and harmony both at rest and in motion while simultaneously correcting the associated functional problems. The surgical approach is tailored to the individual and is influenced by the cause and duration of the paralysis along with the condition of the facial nerve and muscles.The patient’s age and medical history also influence the decision making process.
A large number of procedures are available to restore position, tone and motion to the cheeks and lips.The technique best suited to the individual and their situation is carefully selected after detailed analysis. The surgical procedures can be viewed as performing five general functions:
1. Restoring the continuity of the facial nerve (microsurgical repair & nerve grafts)
2. Transferring nerve fibers from adjacent nerves to reinnervate the facial nerve (nerve transfers)
3. Replacing damaged or atrophied facial muscles (functional free muscle flaps & local muscle transfers)
4. Providing facial support without movement (static suspension)
5. Further enhancing facial appearance and balance (refinement procedures)
Restoring the continuity of a divided facial nerve is the procedure of choice if circumstances permit. A facial nerve that has been sharply transected during trauma or sacrificed during surgery can be repaired utilizing microsurgical techniques. Under the magnification of an operating microscope the cut ends of the nerve can be reunited with stitches finer than a hair (10-0 nylon). Fig. 3&4 The repaired nerve now begins the regeneration process re-growing from the site of injury at a rate of approximately 1mm/day or one inch a month. It is imperative that the nerves are united without tension. If the gap between the nerve ends is too large to permit a tension free repair then a interposition graft must be used to guide the regenerating nerve fibers (axons).
Fig. 5 An expendable segment of sensory nerve harvested from the calf (sural nerve graft) or neck (great auricular nerve) is frequently used to bridge the gap (nerve graft). Alternately, short nerve gaps can be spanned utilizing a segment of vein or a collagen tube (nerve tube).
Nerve transfers are indicated when the main trunk of the facial nerve is damaged or unavailable but the distal nerve branches and facial muscles remain viable. These techniques are best suited to cases of facial paralysis less than 2 years in duration. Adjacent functioning nerves can be divided and connected to the damaged facial nerve. Over time the fibers from the donor nerve will repopulate the facial nerve and produce facial movement. Nerve transfers however, require the surgeon to “rob Peter to pay Paul.” There is a loss of function produced by sacrificing the donor nerve. For example, the hypoglossal nerve (CN XII)innervates half of the tongue and is frequently transferred to the facial nerve. The technique can provide good facial tone and motion at the expense of tongue atrophy and possible problems with speech and eating. These difficulties are reduced but not ameliorated utilizing a jump graft technique. The spinal accessory nerve (CN XI)innervates several muscles of the neck and shoulder. When this nerve is transferred to the face, shoulder weakness can result. One must also consider the voluntary activity that will need to be performed to produce a smile. With hypoglossal to facial nerve transfers the tongue must be pushed against the roof of the mouth to produce facial movement and unwanted motion can occur with eating and speaking. The spinal accessory (CN XI-VII) transfer requires motion of the shoulder to generate facial movement and troublesome grimacing can be produced by heavy lifting.
In our reconstructive institute the motor nerve branch to the masseter muscle has evolved into the donor nerve of choice for reinnervating the muscles of the midface and lips (masseter-to-facial nerve transfer).
A nerve branch to one of the chewing muscles (masseter muscle) is redirected to selected branches (buccal) of the facial nerve. The surgery is performed through a limited facelift incision and has frequently produced a strong, natural appearing smile without disturbing the individual’s ability to chew. Biting down is initially required to produce a movement, however, many patients will undergo cerebral adaptation and in time develop an effortless smile. Fig. 6&7 (For more information please see V-VII transfer).
Facial nerve fibers from the undamaged side can also be redirected to the injured facial nerve utilizing long nerve grafts that traverse the face (cross-face nerve grafts). fig. 8 This technique has the ability to produce true, spontaneous, emotion-mediated facial movement. Unfortunately, the motion is usually weaker than the uninjured side. In our practice cross face nerve grafts are usually reserved as an adjunctive technique or utilized to power free muscle flaps.
Nerves and muscles have an important interdependent relationship. The nerve carries signals from the brain telling the muscle when and how much to contract. The nerve and muscle communicate with each other utilizing biochemical signals. The nerve also secrets factors that help maintain the muscles strength and health. If the connection between the nerve and muscle is severed then the muscle begins to waste away. After a period of two years the denervated facial muscles develop extensive scarring and deterioration of their biochemical messaging system. If the nerve and muscle are reconnected at this stage little functional recovery is anticipated.
Once irreversible muscle atrophy has developed a new source of healthy muscle must be imported to restore movement. Facial muscle replacement can be achieved by transferring local chewing muscles (masseter & temporalis) or with microneurovascular free muscle transplantation. The central segment of the temporalis muscle can be redirected to the corner of the mouth to provide support and motion. fig. 9&10 A smile is produced by biting down. However, over time motivated individuals can learn to smile without clenching their teeth. Although seldom used alone, the anterior segment of the masseter muscle can also be combined with the temporalis muscle to improve strength and symmetry.
Microneurovascular free muscle transplantation (free muscle flap) is an effective method of smile restoration. A segment of expendable muscle is usually harvested from the inner thigh (gracilis muscle) along with its associated nerves and blood vessels. The muscle is implanted beneath the skin and secured to the cheek and corner of the mouth.
Circulation is re-established by creating microvascular connections with the aid of an operating microscope and stitches that are finer than a hair. Nerve input is achieved by creating microsurgical connections to the masseter nerve(chewing nerve) or to nerve grafts from the opposite facial nerve (cross-face nerve graft). Additional segments of soft tissue and bone can be incorporated as part of the functioning muscle flap and utilized to restore facial contour after trauma or tumor removal. Fig. 11 &12
Sometimes a patient’s poor health will limit their ability to tolerate anesthesia and a complex reconstruction. In this situation an expendable tendon or strip of fascia is utilized to support the cheek and corner of the mouth.fig. 13 These procedures are referred to as static slings because no active movement of the face is produced. Despite the adynamic nature of the procedure it is often effective in preventing drooling and achieving facial symmetry at rest.
There are a large number of restorative procedures available to assist with rehabilitation of the paralyzed face. It is essential to find an experienced team that can provide all the possible treatment options and help you select the surgery that is right for you.
For more information on Smile Restoration, Please contact the Center for Facial Paralysis Surgery & Functional Restoration
The Methodist Hospital
6560 Fannin Street, Suite 800
Houston. TX 77030