TITLE: Rehabilitation of the
Paralyzed Face
SOURCE: Grand Rounds Presentation, UTMB, Dept. of Otolaryngology
DATE:
RESIDENT PHYSICIAN: Elizabeth J. Rosen, MD
FACULTY PHYSICIAN: Karen H. Calhoun, MD
SERIES EDITORS: Francis B. Quinn, Jr., MD and Matthew W. Ryan, MD
"This
material was prepared by resident physicians in partial fulfillment of
educational requirements established for the Postgraduate Training Program of
the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended
for clinical use in its present form. It was prepared for the purpose of
stimulating group discussion in a conference setting. No warranties,
either express or implied, are made with respect to its accuracy, completeness,
or timeliness. The material does not necessarily reflect the current or past
opinions of members of the UTMB faculty and should not be used for purposes of
diagnosis or treatment without consulting appropriate literature sources and
informed professional opinion."
Introduction
The diagnosis of a permanent facial paralysis can be
devastating to a patient. The emphasis
that our society places on physical beauty contributes to this perception and
often leads to isolation of these patients who are embarrassed by their
appearance. However, these patients are
plagued not only by a cosmetic defect but also by the functional deficits
caused by loss of facial nerve function.
Lagopthalmos with ocular exposure, loss of oral competence with resultant
drooling, alar collapse with nasal airway obstruction, and difficulties with
mastication and speech production are all potential consequences of facial
paralysis.
The reconstructive surgeon attempting to rehabilitate the
paralyzed face must attempt to address both the cosmetic and functional losses
of the patient. The main functional
goals are to protect the eye and reestablish oral competence. The primary cosmetic goals are to create
balance and symmetry of the face at rest and to reestablish the coordinated
movement of the facial musculature. No
single technique will achieve these goals for every patient and the treating
physician should be familiar with the variety of options available so that an
individualized plan can be developed based on each patients’ clinical picture.
Patient Evaluation
A complete discussion of all of the etiologies of facial
paralysis is beyond the scope of this paper.
The diagnostic evaluation of a facial nerve injury has been nicely
covered in recent grand rounds and will not be reiterated again here. That being said, it is of utmost importance
that a thorough evaluation be performed in every patient prior to the
consideration of any rehabilitative procedure.
When seeing a patient with a facial paralysis for
potential rehabilitation, areas of particular interest in the history taking
include the etiology and the duration of the paralysis. Valuable information about the remaining
facial nerve can be elicited from the etiology of the paralysis and this
information will directly influence the choice of rehabilitative surgery. For instance, a case in which the proximal
facial nerve is missing after tumor extirpation will be addressed with a
different technique than in a case where the nerve is transected but without
tissue loss.
Similarly,
the duration of the paralysis will directly influence the type of procedure
selected for rehabilitation. Although
reports in the literature vary, most authors agree that neural grafting
techniques should be performed within 3 years of the injury. After this time frame significant neural
fibrosis and loss of motor end plate integrity will occur and surgical outcome
is much less predictable. EMG can be a
useful study to differentiate between cases in which denervated but otherwise
normal muscle is present and cases in which irreversible muscle atrophy has
occurred. Those cases in which the
facial nerve is potentially intact and may recover must be observed for a
minimum of 1 year prior to committing to rehabilitative surgery.
Additional
history taking should elicit the general health of the patient and the presence
of any other neurological abnormalities.
An elderly patient with advanced neoplastic disease will obviously
benefit from different therapies than will the young healthy patient with a
congenital facial paralysis. Some
rehabilitative procedures utilize other nerves to reestablish neural input to
the distal facial nerve or local muscle transfer to replace nonfunctioning
facial musculature. Therefore, these
donor tissues must be carefully evaluated to confirm normal function. Additionally the use of a donor nerve or
muscle will necessarily result in donor site morbidity and one must consider
how this will be tolerated by the patient.
Methods of Facial Rehabilitation
There are many procedures that have been described for
surgical rehabilitation of the paralyzed face.
These procedures can be grouped into those that restore neural input,
those that replace nonfunctional facial muscles, those that statically
resuspend facial tissues and adjunctive procedures that address specific
defects.
Restoration of Neural Input
In those cases in which the proximal and distal segments
of the facial nerve are present and free of disease, direct reanastomosis is
the procedure of choice. This should be
performed immediately in the case of obvious intraoperative facial nerve
transection or as soon as possible after a traumatic nerve injury. The ability to stimulate distal nerve
branches remains for approximately 72 hours post-injury and greatly assists
intraoperative identification and reanastomosis. Authors generally agree that neurorrhaphy
should be performed under magnification with small nylon suture after
freshening the nerve endings. However,
whether epineural or perineural repair is performed or whether 8-0, 9-0 or 10-0
nylon suture should be utilized seems to be surgeon’s choice. It is universally accepted that the nerve
must be reapproximated under absolutely no tension. This may be facilitated by rerouting of the
facial nerve in the temporal bone which will typically provide as much as 1cm
of additional length. If this is
inadequate then it is preferable to place a nerve interposition graft than to
place excessive tension on the neurorrhaphy.
When the proximal and distal facial nerve are present but
there is loss of intervening nerve tissue or the reapproximation cannot be
performed without tension, then interposition or cable grafting of the nerve
should be performed. This procedure
utilizes a donor sensory nerve to bridge the gap between the nerve ends. The most commonly used graft is the great
auricular nerve which will typically provide a graft 10cm in length. The advantages of this nerve are that it can
often be harvested through the existing incision, it can be traced to its three
terminal branches which can then be anastomosed to distal facial nerve branches
and the donor site morbidity is minimal.
The sural nerve can be used when a longer segment of nerve tissue is
missing. This nerve supplies as much as
35cm in length and again its harvest has little donor site morbidity.
Nerve crossover techniques are utilized when the proximal
facial nerve is anatomically or functionally disrupted. In this case, a donor motor nerve is used to
reestablish neural input to the distal facial nerve branches. This procedure has been described with
several donor nerves—the hypoglossal, spinal accessory, ansa hypoglossus,
trigeminal and phrenic—although the most commonly used are the hypoglossal and
accessory. The advantage of a nerve crossover
procedure is that it will reliably reestablish neural input to the distal
facial nerve, often providing good resting facial tone and symmetry. The disadvantages include donor site
morbidity, development of synkinesis or hypertonia and the unpredictable
ability to restore voluntary facial movements.
Donor site morbidity from the use of CN XII includes
hemitongue atrophy with resultant difficulty with speech articulation and
manipulation of the food bolus in the oral phase of swallowing. Nerve crossover using CN XI results in
shoulder girdle weakness, reduction in range of motion and occasionally chronic
shoulder pain. Modifications of these
techniques have been described in an attempt to minimize donor site morbidity. This would include splitting the hypoglossal
nerve distally so that some nerve fibers are preserved to the tongue or using
the branch of the accessory nerve to the sternocleidomastoid while preserving
the branch to the trapezius. Synkinesis
or mass movement results from the loss of individualized innervation of specific
facial muscles. Instead, all muscle
groups receive stimulation simultaneously, resulting in an unnatural mass
contraction of all facial muscles.
Hypertonia of the facial muscles results in a grimace expression and is
due to the fact that the regenerating axonal fibers from the donor nerve can
actually be greater in number than in the native facial nerve. This causes an increase in baseline neural
input and increased resting muscle tone.
Finally, the unpredictability of the functional outcome complicates
preoperative patient counseling. Two
patients with essentially identical clinical pictures, treated with identical
crossover procedures, could have two very different results in terms of
voluntary facial movements. The
explanation for this type of variability is unclear. However, it is clear that intensive physical
therapy and training exercises will result in improved voluntary function. Despite these disadvantages, nerve crossover
techniques are widely utilized and large outcome studies report up to 80% of
patients achieving “good” results, defined as a House-Brackman score of III.
The cross-facial nerve grafting technique involves the
sacrifice of some distal nerve branches on the normal side of the face with
placement of a sural nerve interposition graft to the corresponding facial
nerve branch on the paralyzed side. The
idea of using the normal facial nerve to rehabilitate the paralyzed nerve has
the theoretical advantage of providing symmetric voluntary facial
movements. It also, in many cases, has
been shown to reestablish good resting tone and symmetry while producing
minimal donor site deformity. However,
it has the disadvantage of a significantly reduced number of regenerating
neurons compared to other crossover techniques, resulting in much weaker facial
muscle contraction. This procedure is
not typically used on its own, but rather in combination with a subsequent free
muscle grafting procedure which will be discussed in more detail later.
Replacement of Nonfunctional Facial Muscles
Indications for muscle transfer techniques in facial
rehabilitation include long-standing paralysis (greater than 3-4 years) with a
small chance of recovery using nerve grafting procedures, lack of intact facial
neuromuscular units due to fibrosis, atrophy or congenital absence and patient
contraindications to nerve crossover techniques. Options for muscle transfer include regional
muscles pedicled on their native neurovascular supply or free muscle transfers
with microneurovascular reanastomosis.
Regional muscle transfers utilize the temporalis and
masseter muscles. Prior to undertaking
one of these procedures, the normal strength of the muscles and function of the
motor supply from the trigeminal nerve must be confirmed. The transfer of either of these muscles
primarily addresses paralysis in the lower third of the face and the resultant
drooping of the oral commissure.
Patients with a complete facial paralysis who choose to undergo a
regional muscle transfer will require additional procedures to correct the
paralysis of the upper face.
Temporalis muscle transposition has the advantage of
being a technically straightforward procedure that provides immediate
restitution of midface symmetry. It can
be performed through a hemicoronal incision or preauricular incision that is
extended superiorly. A 2cm strip of
muscle is harvested from the middle third of the muscle body and elevated off
of the underlying skull inferiorly to the superior aspect of the zygomatic arch. A tunnel is created over the zygomatic arch,
taking care to preserve the frontal branch if facial nerve recovery is
possible, and the muscle is rotated over the arch, through the tunnel toward
the oral commissure. If additional
length is required, the superficial layer of the deep temporal fascia can be
elevated off of the underlying muscle from inferior to superior, leaving it
attached to the superior extent of the muscle.
An alternative to this would be to harvest a strip of pericranium with
the muscle. A second incision is created
in the nasolabial fold or along the vermillion border to allow access to the
orbicularis oris muscle. The muscle or
fascia is then sutured to the orbicularis with permanent suture and the oral
commissure elevated in an overcorrected position. The disadvantages of this technique include
the bulkiness of the muscle where it crosses over the zygomatic arch, the
temporal depression that results from muscle harvest and the potential for
chronic TMJ pain from loss of support of the temporalis. The voluntary movement that can be achieved
with the temporalis transposition is not spontaneous like the normal side of
the face. The patient will require
training exercises to learn to produce a smile by biting or clenching the
teeth.
Masseter muscle transposition can be used in place of the
temporalis if for some reason that muscle is unavailable. Perhaps more commonly it is used in
conjunction with a temporalis transfer to improve reanimation of the lower lip
at the corner of the mouth. This muscle
can be harvested through an incision along the inferior border of the mandible
or an intraoral incision along the sulcus of the mandible. The anterior aspect of the masseter is
elevated and incised at its insertion along the inferior border of the
mandible. The muscle is rotated
anteriorly toward the oral commissure and secured to the orbicularis oris in a
similar fashion to that described above.
The disadvantage of the masseter transposition is that less muscle mass
is available compared to the temporalis and the vector of pull is more lateral
than superior resulting in a less desirable position of the oral commissure.
Microneurovascular free muscle transplantation is another
option for the rehabilitation of long standing facial paralysis and has
recently gained popularity in use for patients with congenital facial paralysis
and complete lack of normal facial neuromuscular units. In the past, this procedure was performed
with neural reanastomosis but without microvascular reanastomosis. Experience has shown that this will result in
significant muscle atrophy with weakening of muscle contraction. Today these free muscle flaps are harvested
with their native nerve and blood supply and both are reanastomosed in the
recipient site.
Several donor muscles have been described for facial
reanimation including the extensor digitorum brevis, gracilis, latissimus
dorsi, pectoralis minor, rectus abdominis and serratus anterior. An ideal donor muscle has a single dependable
vascular pedicle of sufficient length to allow for harvesting and
reanastomosis. The muscle body needs
sufficient bulk without being overly bulky and the excursion of the muscle in
contraction should be as close to that needed in the face as possible. Additionally, harvest of the donor muscle
should result in minimal morbidity.
Unfortunately, none of the above-mentioned options for donor muscles
display all of these characteristics, so the choice of one versus the others
will be dictated by each individual patient.
The most commonly used recipient vessels are the facial
or superficial temporal arteries and veins.
These most often will be of an adequately matched caliber to the donor
pedicle. The choice of recipient nerve
will be dictated by the status of the ipsilateral facial nerve. Most often native facial nerve is not
available, but if it is, it should be utilized either by direct anastomosis or
interpositional grafting. Crossover
grafting from the hypoglossal or accessory nerves to the nerve stump of the
muscle graft is another option. As
mentioned previously, this leads to donor site morbidity and has the
disadvantages of mass movement and movement that is not coordinated with the
other side of the face. The most
commonly utilized recipient nerve is the facial nerve from the nonparalyzed
side of the face via the placement of a cross-facial sural nerve interposition
graft. This technique is most often
described as a staged procedure with the initial placement of a cross-facial
sural nerve graft followed by muscle transplantation after 10-12 months, although
recent reports have found that this can be performed in a single stage with
similar outcomes.
The advantages of the free muscle graft over the use of a
regional muscle transfer include its ability to be reinnervated with input from
the native facial nerve if it exists, its ability to augment soft tissue
defects in the face if necessary, and its potential for coordinated movement
with the contralateral face if a cross-facial sural nerve graft is used. Disadvantages of this technique include its
technical difficulty and long operating room time, the extended time commitment
required for a staged procedure and the potential for unsatisfactory results
despite a well-performed procedure.
Static Resuspension of Facial Tissues
Patients who do not desire extensive rehabilitative
surgery, those with a poor prognosis or those who are unable to undergo the
previously mentioned techniques may be candidates for static resuspension
procedures. Although, as the name implies,
these techniques do not restore facial movement, they can be very effective in
improving facial symmetry by elevating the corner of the mouth or a ptotic
brow. The elevation of the oral
commissure results in functional improvement as well by reestablishing oral
competence and preventing drooling.
Static slings also tighten the cheek against the teeth, an action which
benefits the oral preparatory phase of swallowing and speech articulation. Elevation of a ptotic brow can reverse
lateral visual field defects caused by drooping facial tissue.
The majority of static sling procedures address the
paralyzed lower face, specifically the oral commissure. However, as mentioned some authors are also
beginning to use these same techniques to improve the paralyzed forehead with a
ptotic brow. Fascia lata had been the
most commonly used material in the past.
It had the advantage of being a native tissue, which reduces the chances
of infection or extrusion. However, its
disadvantages included donor site morbidity, increased operating time and the
tendency for the tissue to stretch over time, leading to recurrence of facial
drooping and need for revision.
Synthetic suspension materials are widely utilized today and include
Gore-Tex and Alloderm. Both of these
materials are safe, easy to work with, available in a variety of sizes, exhibit
good tensile strength with little stretch over time and avoid the increased
time and morbidity of harvesting fascia.
Advantages of facial suspension using Gore-Tex include the technical
ease of the operation, which can often be performed under local anesthesia, the
avoidance of a donor site and the ease of revision or reversal if needed. Additionally, the effect of improved facial
symmetry is immediate and this technique can be used in conjunction with neural
grafting procedures while awaiting axonal ingrowth. The two primary disadvantages of Gore-Tex
include the potential for stretch with loss of suspension requiring revision
and the fact that it is a foreign material and therefore at higher risk for
infection or extrusion.
The technique for
resuspension of the corner of the mouth, as mentioned previously, is
technically straightforward. The process
is quite similar to that described for temporalis or masseter transfer only
with the use of fascia or synthetic materials instead of muscle. And, unlike muscle transfer in which the
muscle is pedicled from its origin, the sling is fixed to the zygomatic arch
and this serves as the support for the suspension. The corner of the mouth is elevated into a
desirable position with a small amount of overcorrection to offset any early
stretch of the sling.
Forehead suspension with Gore-Tex employs essentially the
same idea. An incision is made in a
natural skin crease in the forehead between .5 and 1.0cm superior to the
lateral aspect of the brow. From this
incision, the superior fibers of the orbicularis oculi are identified. A vertical incision in made behind the
hairline, through the galea and a tunnel is dissected in a subgaleal plane
toward the first incision. The sling is
then sutured to the orbicularis, placed under tension until the brow is
elevated to the desired position and then secured to the skull with titanium
screws.
Adjunctive Procedures
Numerous additional procedures have been described to
augment the major rehabilitative procedures outlined above or to address
specific defects not repaired with those procedures. Except for the reinnervation techniques, the
other surgeries often will correct only a portion of the paralyzed face and for
optimal rehabilitation, more than one procedure will be required.
Adjunctive procedures to correct the lagopthalmos and
ectropion that occur in the upper third of the paralyzed face will often be
performed in conjunction with muscle transfers, free muscle grafts or static
slings which are primarily helpful in addressing the lower third of the
face. The loss of function of the
orbicularis oculi muscle leads to an unopposed action of the levator palpebrae
and subsequent inability to close the upper lid. Inadequate eye closure puts the cornea at
risk for exposure, drying, and ulceration, possibly leading to irreversible
damage. For these reasons,
reestablishing complete upper lid closure is of utmost importance. Several techniques have been described to
achieve this goal, but the most commonly utilized is the gold weight
implant. This is a technically easy
procedure that consistently results in correction of lagopthalmos. The disadvantages of a gold weight include
its visibility beneath the thin upper lid skin and the occasional occurrence of
extrusion. An alternative technique to
improve upper lid closure is the palpebral spring. Although this is technically more
challenging, it may be a better option for those concerned about the visibility
of the gold weight or for patients that have compromised levator function with
ptosis in addition to loss of orbicularis function.
Ectropion of the lower lid follows paralysis of the
orbicularis as the tissues become more lax and fall away from the globe with
the pull of gravity. This deformity can
be satisfactorily repaired with a variety of techniques. The wedge resection and lateral canthopexy is
probably the quickest and easiest to perform although a tarsal strip procedure
is also very straightforward. A bit more
complex form of ectropion repair is the temporalis fascia sling. In this case, a strip of deep temporal fascia
is harvested, placed through a tunnel in the lower lid and secured to the
medial and lateral orbital periosteum.
The sling is tightened, thereby pulling the lower lid against the globe.
Tarsorrhaphy had been the procedure of choice to address
the eye in facial paralysis. This has
largely been replaced with the techniques mentioned above, however should
remain in the armamentarium of the reconstructive surgeon. The benefit of tarsorrhaphy is that it is
simple, effective and addresses both the upper and lower lid problems with one
procedure. Disadvantages include the
narrowing of the palpebrae fissure with visual field restriction and the
potential for lid deformity after release of the tarsorrhaphy.
Drooping of the lower lip may persist after other
rehabilitation procedures and can be addressed with a wedge resection of the
redundant, drooping orbicularis oris.
This can be performed alone, in a standard V or W shaped excision, or in
conjunction with transposition of the opposite, nonparalyzed orbicularis. In this technique, a tunnel is created from
the wedge excision to the modiolus on the paralyzed side. The normal orbicularis is then advanced
across the wedge defect and through the tunnel where it is secured to the
modiolus. The direction of pull can be
directed more laterally or superiorly as directed by the individual patient's
deformity.
Many cosmetic procedures designed to rejuvenate the aging
face can also be quite helpful in rehabilitating the paralyzed face as
well. Brow ptosis, as previously
mentioned, may be corrected with a Gore-Tex sling. Other options include a formal brow lift
performed via a direct, mid-forehead or pretrichial incision. Endoscopically assisted lifting procedures
have also been described as useful adjuncts and have the benefit of being able
to address both the ptotic brow and midface in the same setting. The classic rhytidectomy with SMAS plication
is a reasonable adjunct to improve the appearance of the lower third of the
face, while deep plane rhytidectomy with subperiosteal dissection can provide
lifting of the upper lip and midface as well.
Finally, the use of botulinum toxin injection after
reinnervation techniques can be very beneficial in the treatment of synkinesis
or hypertonia. Overactive muscles can be
treated with Botox to reduce resting tone.
Mass facial movements can be improved by selectively targeting those
muscles contributing to the abnormal expression for chemical denervation. The benefits of Botox therapy for these
purposes include its ease of administration, its temporary effect if the
patient is unhappy with the result and its ability to selectively target
abnormal muscles. The disadvantages are
the need for repeat treatments every 3-4 months and the potential for
over-injection with the recurrence of the facial paralysis that was the issue
to begin with.
Summary
There are many possible treatment options for the patient
desiring facial rehabilitation. No
single procedure will address the cosmetic and functional deficits of every
patient. Therefore, carefully tailoring
the treatment plan to each individual’s clinical picture will facilitate
successful rehabilitation and lead to satisfied patients.
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