Congenital facial nerve palsy
Incidence
 0.23-1.8% of live births.
 78-90% are associated with birth trauma. Of the patients with palsies related to
birth trauma, 91% are associated with forceps delivery.
 Congenital unilateral lower lip palsy is the most common of the developmental
lesions, occurring in 1 out of 120-160 live births.
Embryogenesis
 facial nerve develops early in fetal life from the facioacoustic crest in the second
branchial arch.
 The facial nerve develops close to the vestibulocochlear nerve and both of the
internal and external ears. Therefore, any abnormality of these structures often
accompanies facial nerve deficits
 At term, the anatomy of the facial nerve approximates the adult anatomy, with the
exception of its superficial location within a poorly pneumatized mastoid.
 Development of the mastoid bone occurs from age 1-3 years and displaces the
facial nerve medially and inferiorly.
Anatomy
 The facial nerve is a mixed nerve containing motor, sensory, and
parasympathetic fibers.
 motor nucleus lies deep within the reticular formation of the pons, where it
receives input from the precentral gyrus of the motor cortex.
 The upper motor neuron tracts supplying the upper face cross once and then cross
again in the pons; thus, bilateral innervation is present, whereas tracts to the lower
face cross only once.
Parasympathetic
 The parasympathetic fibers originate in the superior salivatory nucleus and are
responsible for lacrimation and salivation via the greater superficial petrosal nerve
and the chorda tympani, respectively.
Sensory
 Afferent taste fibers are carried from the anterior two thirds of the tongue to the
nucleus tractus solitarius via the lingual nerve, chorda tympani, and nervus
intermedius.
 The facial nerve also provides some sensory innervation of the external auditory
canal.
Segments of the facial nerve
 The intracranial segment travels from the brain stem at the level of the caudal
pons to the internal auditory canal (IAC), a distance of 23 mm.
 The meatal segment includes the portion of the nerve between the fundus of the
IAC and the meatal foramen. The facial nerve occupies the anterior/superior
quadrant within the IAC.
 The labyrinthine segment is 3-5 mm in length and travels to the geniculate
ganglion. The first branch of the facial nerve (ie, greater superficial petrosal
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nerve) is within this segment. Importantly, the bony fallopian canal is narrowest
within the labyrinthine segment of the nerve.
tympanic segment (horizontal) begins at the geniculate ganglion where the nerve
turns 40-80° posteriorly (first genu) to enter the middle ear and ends at the
pyramidal eminence. Traumatic causes of facial nerve paralysis are found most
commonly in the perigeniculate region.
The nerve turns inferiorly (second genu) below the horizontal semicircular canal
and continues as the mastoid (vertical) portion, which is 10-14 mm in length and
travels to the stylomastoid foramen.
Upper motor neuron lesions of the facial nerve occur at any point from the motor
cortex proximal to the facial nucleus. Clinically, upper motor neuron lesions result
in muscle sparing in the upper portion of the face but involvement of the lower
two thirds of the facial mimetic musculature.
Lower motor neuron lesions of the facial nerve occur at the level of the facial
nucleus or distal to the nucleus. These lesions involve all the motor branches,
which results in total hemiparesis. Lesions near the geniculate ganglion lead to
paralysis, hyperacusis, and alteration of lacrimation, salivation, and taste.
Lesions distal to the greater superficial petrosal branch cause paralysis
associated with alteration in taste; however, lacrimation is normal.
Extracranial injuries lead to individual deficits depending on the involved branch.
Aetiology
Syndromic
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Möbius syndrome: A broad spectrum of clinical and pathological findings
characterize this syndrome. Presentation ranges from bilateral paralysis of the
facial nerve (usually) with unilateral or bilateral palsy of the abducens nerve. This
syndrome may also affect cranial nerves IX, X, and XII, as well as other
extraocular motor nerves. It often involves abnormalities of the extremities,
including absence of the pectoralis major muscle in Poland syndrome.
Hemifacial microsomia: Several subcategories exist that fall under the spectrum of
oculoauriculovertebral disorders. Vertebral anomalies and epibulbar dermoids
characterize Goldenhar syndrome. Lower facial weakness occurs in 10-20% of
cases, which is likely related to bony involvement in the region of the facial
canal.
Poland syndrome: This syndrome includes Möbius syndrome with congenital
absence of the pectoralis major muscle.
DiGeorge syndrome
Albers-Schönberg disease: Osteopetrosis, a rare cause of paralysis at birth, may
manifest later in childhood.
Trisomy 18, trisomy 13
CHARGE syndrome: This acronym stands for colobomata, heart disease, atresia
of choanae, retarded growth, genital hypoplasia, and ear anomalies. Multiple
cranial nerves may be involved in this condition. At least 1 cranial nerve is
involved in 75% of cases, and 2 or more cranial nerves are involved in 58% of
cases. Of patients who have cranial nerve involvement, 60% involve cranial nerve
VIII, 43% involve cranial nerve VII, and 30% involve cranial nerves IX and X.
Melkersson-Rosenthal: This condition involves recurring attacks of unilateral or
bilateral facial paralysis, swelling of the lips, and furrowing of the tongue.
Angiotensin-converting enzyme is elevated during attacks.
9. Muscular dystrophy: This condition is a steadily progressive familial distal
myopathy associated with weakness of the face, jaw, neck, and levators of the
eyelid. At birth, infants present with facial diplegia; however, lateral gaze is
intact (in contrast to Möbius syndrome). Later in childhood, distal progressive
myopathy develops.
8.
Infectious conditions
 Poliomyelitis
 Infectious mononucleosis
 Varicella
 Acute otitis media
 Mastoiditis
 Meningitis
 Bell palsy
Teratogens
1. Thalidomide embryopathy: This sedative is administered at 28-42 weeks'
gestation and is associated with phocomelia, arrested development of the ear, and
paralysis of the facial and abducens nerves.
2. Misoprostol: This synthetic prostaglandin E1 analogue is used to prevent and
treat gastric ulcers and gastrointestinal lesions induced by nonsteroidal antiinflammatory drugs (NSAIDs). It may stimulate uterine contractions and has been
used with mifepristone or methotrexate to induce abortion. When used alone, up
to 80% of pregnancies continue to term. In a study of 96 infants with Möbius
syndrome and 96 infants with neural tube defects, 49% of infants with Möbius
syndrome were exposed to misoprostol in utero compared to 3% of infants with
neural tube defects. The cause of Möbius syndrome associated with misoprostol
may be vascular disruption of the subclavian artery in week 4-6, causing an
ischemic brain event.
Pathophysiology
Congenital unilateral lower lip paralysis
 A patient with CULLP presents with drooping of the lower lip toward the
unaffected side when laughing or crying and normal appearance of the face at rest.
 CULLP can appear in clusters with cardiac anomalies, which should provoke an
evaluation for VCF. In VCF, microcephaly is present in 40% of cases, malar
flatness is present in 70% of cases, vertical maxillary excess is present in 85% of
cases, and Robin sequence is found in 15% of cases.
 The most common cardiac anomaly is ventricular septal defect (VSD), which
occurs in 65% of cases.
 The etiology of CULLP is most often is attributed to hypoplasia or congenital
absence of the depressor anguli oris or the depressor labii inferioris muscle.
A second theory proposes that a primary brainstem infarction occurs and causes
secondary hypoplasia of the musculature.
Trauma
 Facial palsy is caused by compression of diploic bone of the mastoid process
where the facial nerve is located superficially in infants.
 Complete transection caused by birth trauma is rare; therefore, surgical
exploration is not indicated immediately. The site of injury may be intracranial,
intratemporal, or extratemporal.
Clinical
 Congenital facial nerve paralysis can be diagnosed based on
1. birth history, family history
2. physical examination
3. radiologic and neurophysiologic tests.
 Often, a mild paresis of the facial nerve is not noted at birth, especially if the
injury is bilateral.
 When facial nerve paralysis is associated with hemifacial microsomia or other
craniofacial abnormalities, the facial nerve is often not noted to be weak until the
child grows and a more pronounced asymmetry develops, prompting closer
evaluation of the facial nerve.
 Obtain a thorough birth history in congenital facial paralysis is important. When
the etiology is traumatic, evidence often supports difficult labor caused by
cephalopelvic disproportion (CPD). Risks for difficult labor from CPD include
primiparity and birth weight more than 3500 g. The use of middle forceps delivery
(as opposed to low forceps) also increases the risk of injury to the facial nerve, as
does prolonged second-stage labor.
 Physical examination often reveals ecchymosis, hemotympanum, facial swelling,
and severe head molding—all of which support difficult labor. These findings
may be an indication that trauma caused the facial paralysis.
 In addition to obtaining a birth history, a family history is important. A family
history positive for facial paralysis or other congenital anomalies can increase the
suspicion for a developmental cause of the facial paralysis. Hemifacial
microsomia, Möbius syndrome, and oculoauriculovertebral dysplasia are some of
the developmental causes of facial paralysis that would have additional findings
on physical examination.
 Physical examination may reveal other cranial nerve abnormalities, abnormal
auditory brainstem response (ABR) (waves I-III or I-V), and any other congenital
anomaly.
 Bilateral facial palsy is frequently incomplete, with the lower portion of the
face usually less affected than the upper part. This distinguishes developmental
causes of congenital facial paralysis from traumatic causes, which often involve
the upper and lower face equally and are often unilateral. No evidence of birth
trauma is present.
The House-Brackmann grading system is used to grade facial nerve paralysis as
follows:
 Grade I - Normal
 Grade II - Mild dysfunction, slight weakness on close inspection, normal
symmetry at rest
 Grade III - Moderate dysfunction, obvious but not disfiguring difference
between sides, eye can be completely closed with effort
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Grade IV - Moderately severe, normal tone at rest, obvious weakness or
asymmetry with movement, incomplete closure of eye
Grade V - Severe dysfunction, only barely perceptible motion, asymmetry at
rest
Grade VI - No movement
Medical therapy
 Eye protection: Instill artificial tears in the eyes of a child every hour while the
child is awake. Use ointment when the child is sleeping. Care must be taken when
taping the eye and using patches to prevent the eyelashes from abrading the
cornea. Frequent ophthalmologic evaluations are indicated to evaluate for corneal
abrasions, epiphora, and entropion.
 Harris et al (1983) recommended treating traumatic facial paralysis in the
newborn with observation and corticosteroids. This approach is similar to
treatment of adult acute facial paralysis. No prospective randomized studies are
available that evaluate the efficacy of steroid use in the newborn with facial
paralysis caused by birth trauma; however, it is reasonable to give steroids during
the 5-week observation period before decompression or exploration of the nerve is
undertaken.
Surgical therapy:
 more than 90% of traumatic facial nerve palsies recover spontaneously.
 Conversely, no procedures are available that can enable an infant to develop
normal function of the facial nerve when the palsy is developmental in origin.
 Surgical exploration in the newborn with facial paralysis is controversial.
 Issues regarding timing of facial rehabilitation are complex. The factors that are
involved include ability of the infant to tolerate a surgical procedure, the unknown
potential for recovery, and whether early surgical intervention can prevent future
psychosocial problems for the child. After Wallerian degeneration has occurred,
the nerve regenerates at approximately 1 mm per day.
 Some medical professionals advocate initial surgery during preschool to avoid the
psychosocial problems associated with a physical abnormality. However, waiting
until adolescence when facial growth is mature and the child is able to understand
the risks and benefits of surgery also has merit.
Preoperative details: A general preoperative guideline is to determine if clinical and
electrophysiologic tests reveal (1) complete unilateral paralysis (H-B grade VI), (2)
evidence of temporal bone trauma based upon CT scanning and physical examination,
(3) complete loss of function of the facial nerve at age 3-5 days, and (4) absence of
improvement by age 5 weeks.
Neurorrhaphy
The best situation for repair of the facial nerve is when primary reanastomosis is
possible between the transected ends; however, this is an uncommon occurrence in
congenital paralysis. In developmental paralysis, a fibrotic remnant of the nerve or
total absence of the nerve and traumatic paralysis is often caused by a crush injury
rather than transection. Nerve ends may need to be debrided before anastomosis of the
epineurium with 8-0 or 9-0 nylon sutures. The key factor in neurorrhaphy is
reapproximation without tension.
Cable grafts
In situations in which the nerve has been crushed and neurorrhaphy cannot repair it, a
cable graft may be indicated. The most common donor nerves are the greater auricular
and sural nerves. Cable graft anastomosis is accomplished using 8-0 or 9-0 nylon
sutures to reapproximate the epineurium.
Cross-face grafts
This procedure offers the potential to provide specific divisional innervation to its
counterpart on the contralateral face. This technique may be combined with
microvascular muscle grafts. It is not applicable in patients with developmental
palsies because the distal peripheral nerve and muscle are often impaired. Ysunza et al
(1996) performed cross-face grafts using the sural nerve in children (aged 2 mo to 10
y) with hemifacial microsomia. Of the 9 patients younger than 1 year, 7 had symmetry
at rest and voluntary movement and spontaneous facial expression at 18 months
postoperatively. As the age of the child increased, the percentage of satisfactory
outcomes decreased.
Nerve transposition
This procedure is indicated when no known proximal facial nerve is available based
upon MRI evaluation, physical examination, and topodiagnostic studies. The
hypoglossal nerve provides the best crossover graft with minimal resultant lingual
atrophy. Facial nerve-hypoglossal nerve grafts are not indicated in developmental
palsy because of the impairment of the distal peripheral nerve and neuromuscular
junction (may be shown on muscle biopsy). An ideal outcome of this technique is
good symmetry at rest, some voluntary movement with synkinesis, and mass
movement; however, no emotional facial expression is expected.
Muscle transfer
This procedure is indicated when distal nerves or neuromuscular junctions are absent
or when significant atrophy is present. Children often have good facial tone at rest,
and the risk of the surgery must be weighed carefully against the potential benefit of
muscle transfer. The usual donor muscles include the masseter and temporalis
muscles. Ideal results are good symmetry at rest and some voluntary motion;
however, no emotional movement is expected. The masseter muscle is ideal for
suspending the lateral oral commissure and lower face because of the vector of pull.
The temporalis muscle can be split and used to suspend the upper and the lower face.
Often, a combination of temporalis and masseter muscle transfers is used to
rehabilitate the upper and lower face. The trigeminal nerve innervates these muscles;
thus, voluntary movement can be achieved with rehabilitation training. A free gracilis
muscle transfer may be indicated when no normal musculature is present.
Static sling
Children often have good facial symmetry at rest and do not significantly benefit from
a static sling until the skin and subcutaneous tissue have matured and relaxed. Using a
fascia lata sling to suspend the lower face from the zygoma provides symmetry at rest,
but no voluntary or spontaneous movement is achieved. This procedure is rarely
performed in children and probably is of historical interest only when considering
surgical intervention in infants.
Eye protection
When eye protection is inadequate and corneal abrasions result, tarsorrhaphy, gold
weights, and palpebral springs should be considered. Gold weights are likely the best
option because they are simple to insert and easily removed. This procedure is rarely
performed in the newborn because parents are often very capable of protecting the
infant's eyes.
Treatment for CULLP
Several options are specific to CULLP. Most parents do not notice any defect except
when the child is crying; therefore, surgical intervention in the isolated CULLP
deformity is rarely indicated. Surgical procedures to weaken the nonaffected side with
selective marginal mandibular neurectomy or botulinum toxin injections provide
symmetry at rest. Other plastic-reconstructive options include wedge resection and
fascia lata sling or cheiloplasty, plication or transposition of the orbicularis oris
muscle, and digastric muscle transfer.
Mobius
 Von Graefe first described bilateral facial paresis in 1880.
 Möbius(1888), classified various congenital cranial nerve palsies and singled out
combined VIth and VIIth nerve weakness;
 Both von Graefe and Möbius accepted only cases with both congenital facial
diplegia and bilateral abducens nerve palsies as constituting Möbius syndrome.
 In 1939, Henderson broadened the definition and included cases with congenital
unilateral facial palsy.
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 Minimum clinical sign most commonly and classically associated with Möbius
syndrome is bilateral involvement of cranial nerves VI and VII manifesting as
either partial or complete weakness of each
 Möbius syndrome can also involve anomalies of the face, limbs, chest wall, and
spine.
Epidemiology
 Autosomal dominant inheritance with variable expression and incomplete
penetration has been suggested as a cause of Möbius syndrome; however, most
cases are sporadic (95-98%)
Associations
 Malformations of the limbs and other cranial nerves are often associated with this
syndrome.
 associated with other disorders - Poland anomaly, Klippel-Feil, autistic
behavior,Kallmann syndrome, and hypopituitarism
Pathogenesis
 Etiologically heterogeneous.
 Defect may lie in peripheral nerve, brainstem, or muscle
 Simultaneous disruption of normal flow in developing facial arterial networks
could account for hypoplasia of the eye, ear, and jaw. Concomitant disruption of
the subclavian artery, around the sixth week of embryonic development, could
cause the terminal transverse limb defects and Poland anomalies. Why are the
vessels in the second pharyngeal arch affected and not those in the first? BouwesBavinck and Weaversuggest that obstruction or premature regression of the
primitive trigeminal arteries and/or delayed formation of the basilar/vertebral
system damages the developing cranial nerve nuclei
 Theories:
1. Aplasia or hypoplasia of cranial nerve nuclei
2. Nuclear destruction
Peripheral nerve abnormality
Primary myopathy
Vascular disruption
o disruption of flow in the basilar artery or premature regression of the
primitive trigeminal arteries.
o Disruption sequence in vascular territory of subclavian artery
Autopsy studies have supported all of the causes listed above. The wide range of
presentations can be attributed to the variable causes. Pathologic studies have
shown defects in cranial nerve nuclei with normal musculature and primary
hypoplasia of muscles but a normal central nervous system.
Other anomalies found in Möbius spectrum are likely to be secondary in origin,
such as cleft palate secondary to micrognathia, temporomandibular joint
dysfunction secondary to muscular weakness or diminished intrauterine
movement, and micrognathia secondary to cranial nerve and/or muscle weakness.
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Classification
 CLUFT (Abramson 1998)
o C = cranial nerve, L = lower limb, U = upper limb, F = facial structure,
and T = thorax). Each structural or functional deficit was graded by degree
of involvement: 0, 1, 2, 3 for each region
Clinical
 Characteristic mask-like faces with adducted eyes and downturned mouth
angles, and usually no voluntary facial movements are possible.
 facial paralysis may be incomplete or asymmetric, but it is usually bilateral.
 When paralysis is complete, the lower face is frequently spared.
 Anomalies of the lower extremities or other cranial nerves may be variably
expressed
o VII always, VI in 75%, also IX, X, XII
o second, fifth, ninth, tenth, eleventh, and twelfth cranial nerves described
o The least involved is the XI; III,IV,V and VIII is rare.
 Relevant clinical findings are mask-like faces, drooling, incomplete eye closure,
convergent strabismus, swallowing, and speech difficulties.
 The inability to show happiness, sadness, or anger frequently results in severe
introversion and a reclusive personality.
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Mulliken PRS 1998
 The facial anomalies found in our Möbius patients included cleft palate,
micrognathia, microtia, and microphthalmia.
 auricular hypoplasia in this disorder involved primarily the second pharyngeal
arch, the most severe form being anotia. In contrast, microtia in hemifacial
microsomia may or may not be associated with facial nerve weakness and almost
always spares the lobule.
 Möbius patients with microtia or microphthalmia were more likely to have
micrognathia and/or cleft palate. This is analogous to hemifacial microsomia,
where ocular and auricular deformities correlate with mandibular hypoplasia.
 The most common isolated truncal abnormality in our Möbius patients was
scoliosis (19 percent). In five patients it was severe enough to require brace
therapy; one patient needed surgical correction.
 Other chest abnormalities ranged from hypoplastic pectoralis muscles, abnormal
mammary development, and shoulder girdle deficiency to absent scapula. These
findings confirmed the overlapping of Möbius and Poland syndromes.
Management
 Goals
1. spontaneous facial expression
2. facial symmetry with animation
3. facial symmetry at rest
 Static procedures are not advocated if the main goal in Möbius patients is to bring
movement to the face.
 Dynamic restoration is strongly advocated.
Timing (Sick Kids Toronto)
 Preferred commencement of surgery is at age 4-5, assuming that the child is
healthy and fit enough to undergo prolonged, 8-hour procedure.
 The use of microsurgery in children has been firmly established as a safe and
effective tool for reconstruction
Regional muscles
 local transfer of masseter muscle bilaterally by Webster in 1944
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In 1976, Rubin published his approach for bilateral facial paralysis with bilateral
temporalis muscle transfers
Edgerton (1975) reported two cases of Möbius syndrome in which dynamic
restoration was pursued by the use of the platysma and the temporalis muscles
Free muscle transfer is the workhorse for dynamic reanimation.
Benefits over pedicled options:
1. the muscle can be placed precisely in the desired location and direction
2. Contour deformities at donor sites in the temple and cheek are avoided.
3. Greater active excursion of the oral commissure
4. muscle can be sculpted to the desired size and shape, thus avoiding the
earlier criticisms of excess bulk.
Terzis’ preferred nerve donors
1. Contralateral facial nerve
o If the contralateral facial nerve was minimally
o involved, it was preferred as a motor donor nerve even if it was not
completely normal
2. Hypoglossal nerve
o In severe circumstances in which the hypoglossal nerve was judged to be
intact, this nerve became the second choice for harvesting motor fibers
o should be used only rarely because speech and swallowing are severely
impaired in the vast majority of Möbius patients.
3. Accessory nerve
4. Trigeminal nerve – used infrequently to preserve fifth nerve targets and not to
downgrade further oral functions.
 In rare cases when all three nerves (the fifth, eleventh, and twelfth) are involved in
the developmental lesion, ipsilateral C7 motor fibers has been used as motor
donors for dynamic restoration.
Benefits of reanimation in Mobius children
1. improvemen in self-esteem and social interaction.
2. Treats issues with drooling and fluid loss with drinking
3. speech improvements
Adjunctive procedure
1. Lower lip
a. Plastysma often not involved and can be used as a pedicled transfer for
lower lip reanimation
b. Anterior belly of digastric has been used
2. Eyelid
a. fascial sling for lower eyelid paralytic ectropion (Terzis)
b. Gold weight for upper lid
c. Free platysma muscle for eyelid sphincter (Terzis)