Facial Paralysis

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					 69                          F A C I A L

                             P A R A L Y S I S


                            F  acial nerve paralysis produces a severe cosmetic and
                            functional deformity. The most common cause of facial
                            paralysis is Bell’s palsy, a diagnosis that should only be
                            made after treatable conditions such as neoplasms or in-
                            fections have been excluded. The aims of this chapter are
                            to (1) describe some of the causes of facial paralysis other
                            than Bell’s palsy, (2) outline the anatomy and physiology
                            of the facial nerve, and (3) describe the causes of facial
                            paralysis that require medical or surgical therapy.

CASE 1                                                        showed a contrast enhancing lesion in the middle ear,
FACIAL NERVE SCHWANNOMA                                       near the second genu of the facial nerve.
                                                                  The left middle ear was explored through a combined
A 38-year-old female noted a gradual onset of left facial     mastoidectomy and transcanal approach, and the acoustic
paralysis over the 3 months before evaluation. She also       tumor was excised. Resection of the tumor resulted in a 14-
described a progressive hearing loss of a year’s duration.    mm facial nerve gap. A greater auricular nerve graft was
She denied having tinnitus, vertigo, ear pain, or otorrhea.   placed to bridge the defect, with one interrupted 10–0
    She had no history of serious illnesses. She had under-   nylon suture placed at the distal anastomosis.
gone a previous tonsillectomy and appendectomy.                   One year following the procedure, the patient had re-
    On examination, she appeared healthy. There was           gained significant tone in the facial musculature and fair to
incomplete left facial paralysis with sparing of some func-   good volitional movement on the operated side. An MRI
tion in the muscles supplied by the ramus mandibularis        scan demonstrated no recurrence of the tumor.
branch of the nerve. The patient had incomplete eye clo-
sure, but there was no evidence of corneal injury. The        CASE 2
tympanic membranes were normal in appearance. On              HERPES ZOSTER OTICUS
tuning fork examination, the Weber’s test, with the tuning
fork placed on the forehead, lateralized to the left ear.     A 35-year-old male presented to the otolaryngology clinic
The Rinne test indicated that bone conduction was better      with a 5-day history of a painful rash involving the left au-
than air conduction for the left ear. The remainder of the    ricle. He also described a 1-day history of near total left
head and neck examination was normal.                         facial paralysis. He denied previous surgery or trauma in-
    An audiogram demonstrated a 30-decibel conductive         volving the ear or temporal bone. His past medical history
hearing loss in the left ear. An MRI scan with gadolinium     was noncontributory.

5 0 2       H E A D       A N D       N E C K        S U R G E R Y

On examination, the left ear demonstrated multiple vesic-                       DIAGNOSIS
ular skin lesions, approximately 2 mm in size, involving the
cartilaginous canal, concha, and antihelix. The tympanic                     he most important part of the evaluation of a patient
membrane was normal. The Weber’s test was midline. The                with facial paralysis is a thorough history and physical ex-
Rinne test revealed air conduction better than bone con-              amination focusing on the head and neck region and neu-
duction bilaterally.                                                  rologic system. It is especially important to evaluate the
     There was a complete paralysis of the left face with in-         ear canal, eardrum, and mastoid for evidence of infection
complete eye closure. Bell’s phenomenon, in which the                 or neoplasm. The parotid gland should be palpated care-
globe rotates superiorly with attempted eye closure, was              fully for evidence of tumor. Mastoid tenderness should be
present in the left eye. The nose, oral cavity, oropharynx,           elicited if present. A complete neurologic examination
and larynx were normal.                                               should be performed to exclude associated deficits and lo-
     An audiogram demonstrated a mild high frequency                  calize the site of the lesion.
sensorineural hearing loss in the left ear. Hearing in the                 The interview should be detailed: the history of
right ear was normal. An MRI scan performed with gado-                adenopathy, rash, trauma, ear infection, or tick bite should
linium contrast was normal.                                           be elicited, the latter raising the possibility of Lyme dis-
     The patient was treated with oral acyclovir, 200 mg 5            ease. The onset, duration, associated symptoms, and rate
times per day for 10 days. He experienced gradual recov-              of progression of the paralysis should be sought.
ery of facial function over 3 months. The vesicles gradu-                  An audiogram is always performed for patients with
ally resolved. His facial function 1 year later was excellent,        facial paralysis. This allows assessment of both hearing
except for weakness of the forehead musculature. There                and stapedial reflex. Some causes of facial paralysis, in-
was also mild postherpetic neuralgia of the left auricle.             cluding tumors of the cerebellopontine angle, may af-
                                                                      fect both the 7th and 8th cranial nerves. An MRI scan of
                                                                      the temporal bone is currently an important part of the


       hese cases illustrate two possible etiologies for facial
paralysis and demonstrate the importance of investigating
the cause of facial paralysis. Idiopathic (Bell’s) facial paral-
                                                                      evaluation of facial paralysis. This is especially true if
                                                                      the history and physical examination do not support the
                                                                      diagnosis of Bell’s palsy or when the paralysis is gradual
                                                                      in onset or associated with other neurologic findings.
                                                                      The scan should be performed with gadolinium, which
ysis is a diagnosis of exclusion.
                                                                      is helpful in detecting small tumors such as acoustic and
     After entering the internal auditory canal, the nerve
                                                                      facial neuromas.
courses within the fallopian canal. The intratemporal por-
tion of the nerve has three branches: (1) the greater super-
ficial petrosal nerve, which supplies the lacrimal gland, (2)
                                                                       K E Y       P O I N T S
the nerve to the stapedius muscle, which contracts and sta-            • MRI of temporal bone important part of evaluation of facial
bilizes the stapes during loud noise exposure, and (3) the             paralysis, especially if history and physical examination do not
chorda tympani nerve, which supplies taste and sensation               support diagnosis of Bell’s palsy or when paralysis gradual in
                                                                       onset or associated with other neurologic findings
to the anterior two-thirds of the tongue and parasympa-
thetic supply to the submandibular gland. The function of
the greater superficial petrosal nerve can be evaluated by
Schirmer’s test, which measures lacrimation. The stapedius

branch of the nerve is routinely tested when a complete                            DIFFERENTIAL DIAGNOSIS
audiologic profile is obtained by an audiologist. The func-
tion of the chorda tympani is usually assessed by history                         any illnesses can present with facial paralysis
only, but electrogustometry and submandibular gland flow               (Table 69.1). A history of a sudden loss of facial function,
may be measured in certain situations.                                without evidence for another cause, suggests the diagnosis
     The main extratemporal branches of the facial nerve are          of Bell’s palsy. Some authorities believe that this disorder
the cervical, mandibular, buccal, zygomatic, and temporal.            is caused by a virus of the herpes family, but this hypothe-
These branches course within the substance of the parotid             sis is yet to be proved. When the nerves of patients with
gland after the nerve exits at the stylomastoid foramen.              Bell’s palsy are surgically explored, erythema and swelling
                                                                      may be observed. The site of lesion remains controversial,
 K E Y        P O I N T S                                             although the geniculate ganglion and tympanic portion are
                                                                      believed to be the most frequently affected. Bell’s palsy
 • Most common cause of facial paralysis is Bell’s palsy; diagno-
 sis should only be made after treatable conditions such as neo-
                                                                      can also involve other cranial nerves, particularly the 5th
 plasms or infections excluded, that is, idiopathic (Bell’s) facial   (30%) and 8th.
 paralysis is diagnosis of exclusion                                       Herpes zoster oticus (Case 2) has a worse prognosis
                                                                      than Bell’s palsy. It is clinically distinguished by the pres-
                                                                               F A C I A L        P A R A L Y S I S            5 0 3

TABLE 69.1       Causes of facial paralysis                          Many lesions of the brain can cause facial paralysis.
                                                                 These include infections, tumors, or cerebrovascular le-
Trauma                                                           sions of the brain or brain stem. Lesions of the cortex pro-
  Forceps delivery                                               duce contralateral facial paralysis because the upper divi-
  Temporal bone trauma                                           sion has bilateral representation.
  Penetrating trauma                                                 Some infants are born with congenital facial paralysis.
                                                                 Birth trauma is an infrequent cause of facial paralysis,
  Iatrogenic: parotid/mastoid surgery
                                                                 sometimes seen in difficult forceps deliveries. Congenital
                                                                 paralysis occurs in many syndromes, including the Möbius
  Parotid malignancies                                           syndrome, in which infants present with multiple cranial
  Schwannoma                                                     neuropathies.
  Parotid tumor
  Carcinoma                                                       K E Y        P O I N T S
  Fibrous dysplasia                                               • Bell’s palsy can also involve other cranial nerves, particularly
                                                                  5th (30%) and 8th
  Von Recklinghausen’s disease
                                                                  • When acute ear infection present on same side as facial
                                                                  paralysis, immediate treatment, including intravenous antibi-
  External otitis                                                 otics and drainage of middle ear is mandatory
  Otitis media
  Herpes zoster oticus

                                                                 T         TREATMENT AND PROGNOSIS
  Coxsackie virus
  Lyme disease                                                         reatment for patients with facial paralysis varies ac-
Idiopathic                                                       cording to its etiology. Patients with trauma to the facial
  Bell’s palsy                                                   nerve, especially when the nerve is completely severed,
  Guillain-Barré syndrome                                        are best treated with immediate exploration and nerve re-
                                                                 pair. When the nerve is severed, a primary reanastomosis
  Myasthenia gravis
                                                                 produces the best functional recovery.
                                                                      Many infections of the temporal bone that produce fa-
  Amyloidosis                                                    cial paralysis require surgical treatment. For example, pa-
                                                                 tients with cholesteatoma and concurrent 7th nerve weak-
                                                                 ness require a mastoidectomy, facial nerve decompression,
                                                                 and control of the cholesteatoma.
ence of painful vesicles, which often precede the onset of            The therapy for other causes of facial nerve paralysis is
facial paralysis.                                                somewhat controversial. There is evidence that short-term
     Infections of the ear and temporal bone, such as otitis     steroid therapy is beneficial for patients with Bell’s palsy.
media and mastoiditis are important causes of facial paral-      Most physicians use a rapidly tapering course of oral pred-
ysis in which rapid intervention can favorably alter its         nisone over a period of 10 days. In herpes zoster oticus,
course. When an acute ear infection is present on the            acyclovir is a rational treatment approach, but proof of its
same side as a facial paralysis, immediate treatment, in-        efficacy is lacking. Ideally, it should be initiated during the
cluding intravenous antibiotics and drainage of the middle       avascular eruption, before onset of facial paralysis.
ear, is mandatory. Both chronic and acute infections of the           Neoplasms that cause facial paralysis are generally
mastoid can be responsible for facial paralysis. A chronic       treated with surgical excision. In the parotid area, malig-
ear infection may be complicated by cholesteatoma, which         nant tumors are usually resected in continuity with the fa-
can destroy the fallopian canal and injure the facial nerve      cial nerve, which is then repaired with a graft. When graft-
directly.                                                        ing is not possible, the nerve can be rehabilitated in
     Neoplasms of the temporal bone, ear canal, and              selected cases with a hypoglossal to facial transfer. After
parotid can cause facial paralysis. In the parotid, the facial   reinnervation takes place, patients can be trained to move
paralysis associated with a malignant tumor carries a poor       the tongue to produce specific facial movements.
prognosis. Facial nerve schwannomas (Case 1) are rare,                Patients with permanent facial paralysis generally re-
but may produce paralysis late in the course of their            quire rehabilitation. For eye closure, gold weights are a
growth. Acoustic neuromas can cause facial paralysis, but        popular method of eye protection. The weight is placed in
usually late in the course of the disease, when they are         the upper lid just anterior to the tarsus. The weight is light
very large.                                                      enough so that the eye can be opened by the levator
5 0 4      H E A D       A N D      N E C K       S U R G E R Y

palpebrae superior, which are innervated by the 3rd cra-                      FOLLOW-UP
nial nerve.
     The facial nerve has a significant level of resistance to             lose repeated evaluation of patients with facial
insult. The prognosis of facial nerve paralysis varies accord-    paralysis is critical, particularly to detect complications
ing to its etiology and the general condition and age of the      such as ocular exposure keratitis. It is also important to be
patient. Young, healthy patients tend to recover faster and       certain that patients with presumed Bell’s palsy do not
more completely than older and debilitated individuals.           have an unsuspected neoplasm. Such patients usually will
     Bell’s palsy has a recovery rate between 85% and 90%.        have some other evidence on history or physical examina-
Approximately 10% of patients will have only partial re-          tion that suggest the possibility.
covery and in 5%, no volitional movement may return, ex-
hibiting significant flaccidity. Prognosis for herpes zoster
oticus is less favorable, with some series showing only 50%       SUGGESTED READINGS
of patients achieving full recovery. Tics and synkinetic
movements are a common occurrence in all patients with            Adour KK: The diagnosis and management of facial paralysis. N
incomplete functional recovery, regardless of the original            Engl J Med 307:348, 1982
cause of the paralysis.                                                An excellent review concerning the approach to the patient
     Patients with facial nerve paralysis secondary to tem-            with facial paralysis.
poral bone infections have an excellent prognosis if
treated early and aggressively. When paralysis becomes            May M: The Facial Nerve. Thieme-Stratton, New York, 1986
complete and fails to show recovery in approximately 12                A comprehensive textbook for those interested in a compre-
weeks, significant fiber degradation may be assumed. This                hensive description of facial nerve function, anatomy, paral-
is also true when the paralysis is secondary to trauma.                ysis, injury, and repair.
     Reanastomosis, decompression, and grafting work ex-
ceptionally well when they are properly performed. The
degree of functional recovery depends upon the patient’s          QUESTIONS
age, degree of nerve injury, length of the damaged seg-
ment, and the technical ability of the surgeon.                   1. Bell’s palsy, the most common cause of facial paralysis?
                                                                      A. Is a diagnosis of exclusion of causes of treatable
                                                                          facial paralysis.
 K E Y       P O I N T S                                              B. Is suggested by a sudden loss of facial function.
                                                                      C. May also involve the 5th facial nerve as well.
 • Patients with trauma to facial nerve, especially when nerve
 completely severed, are best treated with immediate explo-           D. All of the above.
 ration and nerve repair                                          2. Infectious causes of facial paralysis where rapid inter-
 • There is evidence that short-term steroid therapy is benefi-    vention can favorably alter its course are?
 cial for patients with Bell’s palsy                                  A. Otitis media.
 • Bell’s palsy has recovery rate between 85% and 90%; approx-        B. Mastoiditis.
 imately 10% of patients will have only partial recovery and in       C. Herpes zoster.
 5%, no volitional movement may return                                D. All of the above.
                                                                  (See p. 604 for answers.)

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