You are in: eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > RECONSTRUCTIVE SURGERY Dynamic Reanimation for Facial ParalysisArticle Last Updated: Mar 25, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Steven M Parnes, MD, Head, Professor, Department of Otolaryngology-Head and Neck Surgery, Albany Medical College Steven M Parnes is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Laryngological Association, American Laryngological Rhinological and Otological Society, American Medical Association, American Society for Head and Neck Surgery, Association for Research in Otolaryngology, and Medical Society of the State of New York Editors: Jennifer P Porter, MD, Assistant Professor, Department of Otorhinolaryngology, Division of Communicative Science, Chevy Chase Facial Plastic Surgery; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Dominique Dorion, MD, MSc, FRCSC, Program Director and Division Chair, Professor of Surgery, Division of Otolaryngology, University of Sherbrooke, Canada; Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders; Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine Author and Editor Disclosure Synonyms and related keywords: dynamic reanimation for facial paralysis, paralysis of the face, direct facial nerve anastomosis, interpositional grafts, anastomosis to other motor nerves, dynamic musculofascial transpositions, static musculofascial transpositions, facial nerve, facial paralysis, nerve grafts INTRODUCTIONSection 2 of 12
  Facial paralysis severely hinders mastication, speech production, and eye protection. Numerous reanimation techniques are available to restore function and are based on the cause of the facial paralysis, type of injury and its location, and the anticipated duration. These methods are broadly classified into 4 types as follows: (1) neural methods, (2) musculofascial transpositions, (3) facial plastic procedures, and (4) prosthetics. The most desirable procedures to reestablish the mimetic control of the face generally are based on a sequence of operations that start with the most favorable operation to produce the best results, both functional and cosmetic. The procedures for total unilateral facial paralysis are as follows:
The first 4 are dynamic procedures that restore some voluntary movement and, thus, are more desirable. The latter procedures are reserved for patients in whom the motor end plates are not viable. Combinations of the above procedures may be appropriate depending on the circumstances. History of the ProcedureAttempts to correct facial paralysis date back to 200 AD, when Galen actually discussed the possibility of nerve regeneration. However, the first documented suture repair of a nerve is attributed to Paul of Argina in 600 AD. A. Waller, who recognized that peripheral nerves could regenerate, rediscovered this work in the 1850s. With experience from World War II, H.J. Seddon is credited with introducing the use of cable grafts after it was noted that the primary repair would lead to unacceptable tension and poor results. With the introduction of magnification, including the operating microscope and loupes in peripheral nerve repair, results greatly improved. Evidence of this improvement was reflected in many other papers published after this time. As early as the turn of the century, Alexer in Eden recognized the transposition of muscles in lieu of primary nerve anastomosis. Reuben, Baker, and Connelly repopularized this intervention in the late 1970s by using either the temporalis or masseter muscle. Techniques for facial reanimation have a long and protracted history, but it was not until the modern era with the advent of finer sutures, magnification, and better understanding of physiology that results from reanimation techniques dramatically improved. ProblemTotal disruption of the facial nerve does not permit restoration to complete normalcy. Therefore, realistic expectations must be established at the initial encounter and candidly discussed between the physician and the patient. INDICATIONSSection 3 of 12
If the duration of the paralysis is less than 24 months and no chance of recovery exists, attempt a neural procedure. If the motor end plates are not viable, or immediate restoration of some movement is desirable, a muscle transposition technique may be used. For a description of this procedure, see the Techniques section. RELEVANT ANATOMYSection 4 of 12
To perform the reanimation procedures, the surgeon must have a thorough knowledge of the anatomy of the facial nerve. The facial nerve originates within the pons and exits between the olive and inferior cerebellar peduncle. At this location, the nerve forms a 12-14 mm intracranial portion within the cerebellopontine angle (see Image 1). The facial nerve then enters the temporal bone, where it is confined within a bony conduit. As it enters the internal meatus, the nerve lies medial to cranial nerve VIII. The nerve travels about 10 mm before reaching the lateral end of the meatus superior to the crista transversalis and anterior to the vertical crista (Bill's bar). Exiting the internal auditory canal, the nerve gradually curves anteriorly around the basal turn of the cochlea where it enters the infratemporal portion and travels 2-4 mm (the narrowest portion). The greater petrosal nerve arises from the facial nerve at the geniculate ganglion. At the geniculate ganglion, the greater superficial petrosal nerve leaves anteriorly, while the facial nerve itself makes a 40-80° turn (the external or first genu). The facial nerve courses posteriorly and slightly inferiorly, traveling 11 mm across the tympanic cavity. This horizontal course lies superior to the fossula at the vestibular fenestra (oval window). The nerve makes its second genu as it leaves the oval window niche, passing anteriorly and caudal to the lateral semicircular canal. It then passes lateral to the sinus tympani and the stapedius muscle to form the vertical (mastoid) portion within the temporal bone. At the end of this 13-mm segment, the facial nerve exits from the stylomastoid foramen, where it becomes the extracranial segment. The nerve first innervates the posterior belly of the digastric muscle and then travels 15-20 mm to enter the parotid gland. In the parotid gland, it divides at the pes anserinus into 2 main branches, namely, the temporofacial and cervicofacial. Terminal ramifications of these branches to the temporal, zygomatic, buccal, mandibular, and cervical regions are variable (see Image 2). The nerve fibers travel in groups called fascicles, which vary according to the level. The fibers are surrounded by 3 types of connective tissue, namely, the endoneurium, perineurium, and epineurium. The structure of the fascicles varies considerably throughout the course of the nerve. For this reason, direct repair of the fascicles is not feasible and may be counterproductive. CONTRAINDICATIONSSection 5 of 12
No contraindications exist for restoring facial reanimation in a patient, except inability to tolerate general anesthesia; however, specific guidelines must be followed. If the possibility of spontaneous facial nerve recovery exists, then any procedure that involves transsection of the nerve must be avoided until lack of recovery is a certainty. Any attempt to restore facial function by reestablishing nerve continuity requires intact motor end plates. Nerve continuity can be re-established by direct facial nerve anastomosis, interpositional grafts, or anastomosis to other cranial nerves. Selection of these procedures cannot be considered after 3 years following the original insult. The possibility still exists for motor end plates to survive from 1-3 years after the original insult. An EMG can be obtained to determine viability of the motor end plates. Crossover technique cannot be used if the donor nerve is essential to the overall function of the patient. WORKUPSection 6 of 12
Lab Studies
TREATMENTSection 7 of 12
Medical therapyBefore attempting any surgical repair, the surgeon must consider eye protection. The conservative measures that afford this protection include the use of moisture chambers, artificial tears, and ointments. Irrigations and artificial eye closure techniques may be necessary. These techniques include taping or providing hermetically sealed chambers to protect the eye until a more effective procedure is used. Immediate eye procedures can be considered an alternative regardless of the prognosis. Physical therapy (mechanical versus electrical) and steroids most likely are beneficial. Most authors recommend these interventions, particularly in patients with The duration of facial paralysis also determines the choice of technique. Neural techniques depend heavily on the survival of the motor end plates. These techniques are not used if the paralysis has been present for at least 3 years. If any doubt exists regarding the integrity of the facial nerve, wait for a period of at least 12 months before attempting a surgical interruption that may result in irreversible damage to the facial nerve. Surgical therapySurgical therapies include facial plastic surgical techniques (rhytidectomy, blepharoplasty, brow lift), the prosthetic gold implant, canthopexy, and lid-tightening techniques. Although these therapies have similar indications as the transposition techniques, they can be used to supplement the transposition techniques, particularly to protect the eye during the facial recovery period. This is particularly true as an alternative to tarsorrhaphy, which is standard care in patients who have facial nerve preservation, but in whom recovery is not expected for several months to a year. Intraoperative detailsThe gold implant is a very simple procedure that consistently offers satisfactory results. Initially, corneal protection is used. A small incision is made in the supratarsal crease or 8-10 mm cephalad to the upper lid margin. Using a sharp scissor, the tarsal plate is exposed directly. Prefabricated gold implants ranging in size from 0.6-1.6 g are available. Most of the time, 1- to 1.2-g implants are sufficient and do not have to be sized preoperatively. With the tarsal plate exposed, 8-0 nylon sutures are used directly on top of the plate in order to secure the implant in place. The wound is closed in 2 layers with 5-0 chromic sutures followed by 6-0 mild chromic sutures. This affects very good eye closure in most cases. If incomplete closure is anticipated, a mullerectomy may be performed just prior to placement of the gold weight. Müller's muscle that originates from the levator muscle provides tonic elevation to the lid and adheres tightly to the conjunctiva. The muscle can be incised easily through the conjunctiva with a sharp blade, after which the conjunctiva is closed with a 5-0 plain suture (see Image 11). Patients with a great laxity of the lower eyelid and resulting ectropion may benefit from the lateral tarsal strip procedure. Performing a lateral canthotomy followed by an inferior cantholysis begins the relatively simple technique. The lateral portion of the lower eyelid is divided into musculocutaneous and tarsoconjunctival layers. The tarsoconjunctival layer is grasped with a skin hook, and the overlying conjunctiva is abraded with a sharp blade to promote adherence and to avoid the formation of epithelial deposits. The resulting tarsal strip is sutured to the periosteum inside the lateral rim of the orbit. This is performed in order to shorten and elevate the lower eyelid. The resultant excess tissue of the musculocutaneous layer is removed, followed by wound closure using mild chromic sutures (see Image 9 and Image 12). Free Muscle FlapsThe indications for the use of free muscle flaps are the same as for muscle transfers. Examples of muscles that can be used for muscle flaps include the gracilis, serratus anterior, latissimus dorsi, and extensor digitorum brevis. Additionally, the gracilis muscle has been used as a compound flap to include a skin paddle for repair of skin defects to help reanimate the eye. This procedure has shown good results.1 The procedures are often performed in 2 stages. First, a nerve graft is harvested and attached to the opposite normal side. A free muscle flap with intact neurovascular bundle is anastomosed 6-9 months later with the appropriate nerve and vessels for reanimation. Nutrient vessels for the gracilis muscle are not particularly long; therefore, the gracilis muscle is best used when the superficial temporal, facial vessels, or both are available. Otherwise, the latissimus dorsi pedicle is long enough to reach vessels in the upper neck. A one-stage procedure using the abductor hallucis muscle can also be performed. The results are good to excellent; however, only experienced surgeons with extensive knowledge of microvascular techniques should perform these technically difficult procedures. TechniquesENoG can help determine prognosis, because 90% or greater degeneration implies a poor prognosis. Facial nerve anastomosis When the facial nerve is disrupted, either due to trauma, benign tumors, or an iatrogenic condition, re-approximating the nerve without tension is important. Rerouting the nerve within the temporal bone or releasing it in the area of the parotid gland, which would lengthen the nerve, may help re-approximate the nerve. The best time to perform this technique is within the first few days after the disruption, if feasible, because degeneration has not occurred yet, and the surgeon can stimulate the distal ends of the nerve for assistance in identification. Use the microscope or loupes for magnification while performing this repair. The nerve endings are freshened, and sutures of 8-0 nylon or a smaller size are applied, with 2 or 3 sutures applied to the epineurium. If the injury occurs in the temporal bone, sutures are unnecessary. Placing the ends of the nerve in contact with one another is sufficient to facilitate anastomosis (see Image 10). Repair a nerve injury involving one of the major branches in a similar fashion; however, as a general rule, if a plumb line is dropped from the lateral canthus, and the injury is distal to this line, repair of the injury usually is unnecessary. Spontaneous recovery generally occurs without surgical intervention (see Image 13). Facial nerve repair with grafts Patients who undergo facial nerve repair with grafts differ from patients who have direct repair of the facial nerve in that patients who undergo repair with grafts have a loss of nerve tissue. Most commonly, patients who undergo repair with grafts have undergone some type of tumor resection, such as a malignant parotid tumor, and part of the nerve has been sacrificed. For these patients, direct nerve repair would result in too much tension at the anastomosis. The most commonly used graft is the great auricular nerve due to its proximity to the facial nerve and minimal loss of function. All these nerve grafts are sensory in function; their purpose is to minimize the functional deficit. Drawing an imaginary line between the mastoid tip and the angle of the mandible aids in locating the great auricular nerve. The nerve usually bisects this distance perpendicular to the line, lying on the superficial surface of the sternocleidomastoid muscle (see Image 3). Other cervical nerves in this area can also be used for interposition grafts. If more nerve tissue is required, making an incision on the lateral aspect of the leg can harvest the sural cutaneous nerve. The sural cutaneous nerve lies 1-2 cm lateral to the saphenous vein, medial and posterior to the lateral malleolus of the ankle (see Image 4). Crossover technique Crossover techniques have the advantage of consistently providing some type of restoration, although results are often unpredictable. Three techniques are available—hypoglossal to facial, spinal accessory to facial, and facial to facial. All techniques require the following conditions:
The hypoglossal to facial technique is the most popular and commonly used technique. This technique is indicated most commonly in patients who lose their facial nerve during excision of otoacoustic neuromas. Many patients have synkinesis or mass movement with unappealing results. As a result, some authors advocate the use of this technique in only one of the major branches; ancillary techniques are used for other parts of the face. Biofeedback and the judicious use of botulinum toxin also are used to improve the results. Only the hypoglossal-to-facial crossover will be discussed in detail. The spinal accessory-to-facial technique causes greater morbidity because loss of the trapezius muscle is a very significant disability. For some authors, the facial-to-facial anastomosis is successful, but the results often are inconsistent. More sophisticated free muscle flaps or a second donor nerve usually are required in conjunction with this technique in order to improve the results. In performing the hypoglossal-to-facial nerve anastomosis, the 2 nerves almost always are long enough to preclude exposing the facial nerve within the temporal bone; instead, the nerve is transected as it exits the sternomastoid foramen. To identify the facial nerve, the surgeon proceeds as with a parotidectomy. A Blair or lazy-S incision generally is used, but an extended facelift incision can be substituted. Once the appropriate flaps are raised, the anterior border of the sternocleidomastoid muscle is identified and separated from the parotid gland. A cartilaginous auditory canal is skeletonized and further delineated to identify the pointer. With visualization and palpation, the facial nerve can be identified as it exits the sternomastoid foramen, usually several millimeters inferior to the tragal pointer. By palpating the mastoid and styloid process, the precise location of the facial nerve can be determined. The nerve is skeletonized up to the pes anserinus and, if necessary, to the 2 major branches to provide further mobility and lengthening. The surgeon then directs attention to the hypoglossal nerve, usually found just inferior to the digastric muscle. The fibers of the digastric muscle run perpendicular to the sternocleidomastoid muscle and are located deep to the muscle. Once the nerve is identified and confirmed by nerve stimulation, it is further skeletonized distally towards the tongue for lengthening. The nerve then is transected as distal as possible and sutured directly to the main trunk or, if necessary, to a secondary division of the facial nerve. Techniques similar to those of direct anastomosis are used (see Image 5 and Image 14). Some authors advocate splitting the hypoglossal nerve to reduce the degree of hemiglossal atrophy; nevertheless, no significant morbidity is associated with transecting the entire hypoglossal nerve. Occasionally, a patient may experience some subtle articulation problems; patients must be warned of this possible sequela. Muscle transposition techniques Muscle transposition techniques are used when the neural techniques are unsuitable. Reasons for this include the following:
The trigeminal nerve innervation to the temporalis and masseter muscle must remain intact. Early rehabilitation of the patient may be desirable if prolonged recovery with the neural technique is anticipated. Temporalis muscle transposition The temporalis is a fan-shaped muscle radiating from the narrow coronoid process of the mandible to the broad temporal fossa of the temporal bone. Because of its large area, the temporalis can be used for multiple areas of the face. Obtain additional length by using the fascia and suturing it to the edge of the muscle. Because eyelid procedures have proved to be superior, use the temporalis mainly for the reanimation of the corner of the mouth. Making an incision in the preauricular crease and extending the incision into the superior temporal line exposes the temporalis muscle and fascia (see Image 6). The plane of dissection is above the superficial muscular aponeurotic system in order to avoid injuring the peripheral nerve. After obtaining a wide exposure of the temporalis muscle, an incision is made down to the periosteum, elevating the muscle fibers. As the middle one third of the muscle is elevated and folded on itself towards the corner of the mouth, a large tunnel is made over the zygomatic arch. This tunnel must be able to admit at least 2 finger-breadths to prevent bunching up, causing a large mass in the face. A second incision is made in the vermilion border at the oral commissure to expose the orbicularis muscle. As an alternative, this incision can be placed in the melolabial line to produce a symmetrical crease. The edge of the temporalis muscle then is attached to the orbicularis muscle with a permanent 2-0 chromic suture and is pulled up superiorly and laterally in an overcorrected position. In some patients, a temporoparietal fascial flap may be rotated in the temporalis fossa to fill the defect created by the harvested muscle. The vermilion incision can be closed with 4-0 chromic sutures and running 6-0 nylon sutures. The preauricular incision may be closed with 3-0 chromic sutures and staples. The dressing must contain Steri-strips that will continue to pull up the corner of the mouth for overcorrection (see Image 15). Masseter muscle transposition The masseter muscle transposition technique is used when the temporalis muscle is unavailable due to either resection, such as temporal bone resection, or reconstruction. This technique may be a surgeon's preference because a large facial incision can be avoided in the intraoral application. The disadvantage of this technique is that less muscle is available to use, and the vector force of the muscle is in a more horizontal plane. This provides less superior angulation to the corner of the mouth. In the intraoral approach, the masseter muscle is exposed by making a large incision in the gingival mucosa along the sulcus of the mandible (see Image 7). Creating a plane between the mucosa and the muscle exposes the muscle. The muscle then is freed immediately by raising it off the mandible with periosteal elevators. Once the masseter muscle is freed medially and laterally, it is detached from its insertion at the inferolateral edge of the mandible with curved right-angle scissors. Do not extend this vertical incision of the masseter muscle too far superiorly or posteriorly; otherwise, the nerve supply to the muscle could be jeopardized. The anterior half is split again to fashion 2 slips of the masseter muscle. These slips ultimately are tunneled into the small external incisions made along the vermilion border. The external incisions, each measuring 1 cm, are placed in the lateral inferior lip half the distance between the melolabial line in the upper lip and the vermilion border. Using a pair of sharp scissors, a lateral tunnel then is created in a plane just above the masseteric fascia and medial to the soft tissues of the face. Two clamps are passed through the lip incisions to the intraoral area. The slips of the masseter muscle are grasped and guided into place. The muscles are fixed to the lips and the commissure, pulling the commissure upward and laterally for overcorrection. The lips and muscles are secured in place with permanent sutures directly into the deep dermal layers of the skin to avoid later relaxation. The wounds are closed with dressing that contains Steri-strips, which support the overcorrection (see Image 12). The masseter muscle also may be exposed through an extraoral approach, usually through a rhytidectomy or Blair incision. This is used as an adjunct technique along with some other reanimation procedure. COMPLICATIONSSection 8 of 12
Complications can occur with all of these techniques; however, they are rare. Always be on guard for either infection or hematomas. A most disconcerting complication would be lack of effect. Examples of lack of effect include no movement noted after a dynamic procedure or an undesirable result, such as continued eye exposure and problems with mastication. The outcome of the procedure is very technique dependent. If the nerve actually is transected, the prognosis is poor, and the best result one can expect when a neuro-technique is used is a grade 3 on the House-Brackman scale. This is due to anticipated synkinesis and residual paresis. Muscle transpositions and other ancillary techniques are helpful in improving the aesthetics and, perhaps, can effect eye protection; however, these techniques cannot reproduce the voluntary symmetric and discreet facial movement. OUTCOME AND PROGNOSISSection 9 of 12
To evaluate facial nerve function, the House-Brackman Scale is used. Classification includes the following:
Keep in mind that this is a dynamic scale, and the patient's facial nerve status can change depending on the etiology. FUTURE AND CONTROVERSIESSection 10 of 12
Conclusion When the patient presents with total facial paralysis, particularly when the nerve is disrupted entirely, total restoration with a natural spontaneous expression, full motor power, and perfect congruent movement may be impossible. The techniques described above can provide marked cosmetic improvement and can restore function, particularly in the areas of eye protection, mastication, and articulation. As these procedures evolve, patients will be afforded the possibility of leading normal lives without the stigma of facial disfigurement. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Dynamic Reanimation for Facial Paralysis excerpt Article Last Updated: Mar 25, 2008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
