Congenital Facial Paralysis

Updated: Mar 04, 2016
  • Author: Alan D Bruns, MD, FACS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Overview

Background

Congenital (present at birth) facial paralysis is uncommon and, when present, may cause multiple problems for the newborn, such as difficulty with nursing and incomplete eye closure. If the paralysis does not resolve, it may affect the child’s future speech, expressions of emotion, and mastication. This article discusses the etiologies, evaluation, diagnostic testing, and treatment options for this disorder. [1]

Congenital facial paralysis is classified as traumatic or developmental, unilateral or bilateral, and complete or incomplete (paresis). Determining the etiology is important because the prognosis and treatment differ, depending on the underlying pathophysiology. An appropriate history and physical examination usually resolve the origin, but radiographic imaging and neuromuscular testing may be necessary for treatment planning.

An extended physical examination is needed to exclude other congenital malformations. Associated anomalies may include microtia, inner ear abnormalities, extraocular muscle paralysis, facial hypoplasia, other cranial nerve deficiencies, cleft palate, internal organ disorders, and extremity deformities.

A child with Möbius syndrome is depicted below.

Child with Möbius syndrome, eyes open. Image court Child with Möbius syndrome, eyes open. Image courtesy of M.J. Biavati.
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Epidemiology

Frequency

Congenital facial paralysis accounts for 8-14% of all pediatric cases of facial paralysis. [2] The incidence of facial paralysis in live births is 0.8-2.1 per 1000 births, and, of these, 88% are associated with a difficult labor. Of patients with birth trauma, 67-91% are associated with forceps delivery. [3, 4, 5] Developmental causes include those associated with syndromes and teratogens. An example of a development cause is Möbius syndrome, which has an incidence of 1 per 50,000 births. [6] A common disorder that resembles a unilateral partial nerve paralysis is congenital unilateral lower lip palsy (CULLP), also known as neonatal asymmetric crying facies, that occurs in 1 out of 160 live births. [7]

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Etiology

The cause of congenital facial paralysis is associated with either a traumatic injury or developmental deformities of the brain or facial nerve (cranial nerve VII). [8]

Trauma  The most frequent cause of unilateral congenital facial palsy is birth trauma related to a difficult delivery. Risk factors include forceps delivery, birth weight of more than 3500 g, and primiparity. [3] The injury from forceps is induced by the pressure of the posterior blade that compresses the bone overlying the vertical segment of the facial canal. [6] The facial nerve is also susceptible to trauma as it exits the stylomastoid foramen, where soft tissue compression can lead to a transient facial neurapraxia. Complete transection of the facial nerve caused by birth trauma is rare. Intrauterine trauma can also occur from pressure on the infant's face by the sacral prominence during labor. [9]

Developmental causes The causes of developmental facial paralysis are numerous and may be associated with syndromes and teratogens.

Möbius syndrome

A broad spectrum of clinical and pathological findings characterize this syndrome. The patient usually presents with bilateral paralysis of the facial nerve with unilateral or bilateral palsy of the abducens nerve (cranial nerve VI). This syndrome may also affect other cranial nerves, with XII being the next most common. It often involves abnormalities of the extremities, including absence of the pectoralis major muscle in Poland syndrome. [10, 11]

A few families with Möbius syndrome have been described, but most cases are sporadic. Associations have also been made with fetal exposure to misoprostol, cocaine, ergotamine. [12, 13, 14] Malformations of the limbs and other cranial nerves are often identified with this syndrome. Several theories regarding the pathogenesis of Möbius syndrome are as follows:

  • Aplasia or hypoplasia of cranial nerve nuclei
  • Nuclear destruction
  • Peripheral nerve abnormality
  • Primary myopathy
  • Disruption sequence in vascular territory of subclavian artery

Autopsy studies have supported all of the causes listed above. A neurophysiologic study of patients with sporadic Mobius syndrome demonstrated 2 distinct groups characterized by 1) increased facial distal motor latencies (DML) and poor recruitment of small neuropathic motor unit action potentials (MAUP) and 2) normal facial DMLs and neuropathic MAUPs. The functional impairment of facial movements appears to be caused by a nuclear or peripheral site of lesion without brainstem interneuronal involvement. [15]

Hemifacial microsomia

Several subcategories exist that fall under the spectrum of oculo-auriculo-vertebral disorders that consists of anomalies of the first and second branchial arches. This is a common craniofacial disorder characterized by a wide spectrum of anomalies, including a conductive hearing loss due to external and middle ear deformities.

The prevalence of sensorineural hearing loss (SNHL), as well as facial nerve dysfunction, is underappreciated. One recent study states that, in these children, hearing loss was present in 74 of 99 patients (75%), with a conductive component in 73 patients. Sensorineural hearing loss was present in 11 patients (11%), with mixed hearing loss in most patients. Nearly a quarter of the patients (22 of 99 [22%]) had facial nerve dysfunction, but only 1 patient had facial palsy on the same side as the SNHL. [16] Lower facial weakness occurs in 10-20% of cases and is likely related to bony involvement in the region of the facial canal. A nonhereditary variant of hemifacial microsomia is Goldenhar syndrome, which has vertebral anomalies and epibulbar dermoids.

A literature review by Cline et al indicated that 10-45% of patients with hemifacial microsomia/oculu-auriculo-vertebral spectrum have facial weakness and that in most of these cases, all facial nerve branches or just the lower branches are involved. The investigators suggested that facial weakness in hemifacial microsomia results from the effect of temporal bone dysmorphogenesis on the facial nerve. [17]

22q11.2 deletion syndrome (22qDS)

This syndrome may include patients with velocardiofacial syndrome or DiGeorge syndrome. Association of facial nerve palsy and congenital heart disease versus cardiofacial syndrome are different only on clinical grounds, so both conditions can be genetically identical and form part of the spectrum of defects associated with chromosome 22q11 deletions. [18]

Albers-Schönberg disease

Osteopetrosis, a rare cause of paralysis at birth, may also manifest later in childhood.

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. [19]

Facioscapulohumeral muscular dystrophy

An autosomal dominant condition marked by 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. Intelligence and life span are normal and the spectrum of disability is broad. Flaccid dysarthria results from the facial muscle paralysis. A pair of siblings had FSH MD that was accompanied by the unusual finding of sensorineural hearing loss. [20]

Congenital unilateral lower lip paralysis/asymmetric crying facies

This is not usually considered a true congenital facial paralysis, but these patients present with drooping of the lower lip toward the unaffected side when laughing or crying and normal appearance of the face at rest. Congenital unilateral lower lip paralysis (CULLP) can appear in clusters with cardiac anomalies, which should provoke an evaluation for VCFS. The etiology of CULLP is most often 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. [7, 21, 22] Almost 10% (9.4%) of cases are associated with major malformations, most commonly heart defects. Many of those patients with the cardio facial syndrome have the 22q11.2 deletion. Chromosomal analysis for these patients is recommended. [20]

Teratogens associated with facial nerve paralysis

See the list below:

  • Thalidomide: This sedative and antiemetic is associated with phocomelia, arrested development of the ear, and paralysis of the facial and abducens nerves. This medication is currently used in patients with leprosy, multiple myeloma, other cancer treatments. [12]
  • Misoprostol: This synthetic prostaglandin is used to prevent and treat gastrointestinal lesions induced by nonsteroidal anti-inflammatory drugs. It may stimulate uterine contractions and has been used with mifepristone or methotrexate to induce an 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 with 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. [23]
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Presentation

Newborn children with facial paralysis may present with noted asymmetric facial movement, incomplete eye closing, and difficulties feeding. They may have other more significant symptoms from other congenital defects.

Determine the etiology of congenital facial nerve paralysis based on birth history, family history, physical examination, radiologic studies, and neurophysiologic tests.

Obtaining a thorough birth history in congenital facial paralysis is important. When the etiology is traumatic, the evidence often supports difficult labor caused by cephalopelvic disproportion. Risks for difficult labor 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. [3]

A family history positive for facial paralysis or other congenital anomalies increases the suspicion for a developmental cause of the facial paralysis.

Examine the infant bilaterally and evaluate both the upper and lower portions of the face. Looking at forehead wrinkling, eye closure, and lip movement. A bilateral facial palsy is frequently incomplete, affecting either the lower or upper portion of the face. This helps to distinguish developmental causes of congenital facial paralysis from traumatic causes that often involves the upper and lower face equally and are often unilateral.

A traumatic etiology often reveals a unilateral facial paralysis with ecchymosis, hemotympanum, facial swelling, and severe head molding. Documenting these findings during the immediate neonatal period assists in establishing an etiology. [24]

The examination needs to evaluate the other cranial nerves and rule out other congenital anomalies.

Often, a mild paresis of the facial nerve is not noticed 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.

To grade the severity of the facial paralysis, many grading systems exist, such as the Terzis-Noah scale. [25] The most commonly used scale is the House-Brackmann listed below. [26] The higher the grade, the least likely full recovery will occur.

Table. The House-Brackmann Scale (Open Table in a new window)

Grade Characteristics
I. Normal Normal facial function in all areas
II. Mild dysfunction  



Gross



Slight weakness noticeable on close inspection



May have slight synkinesis



At rest, normal symmetry and tone



Motion



Forehead - Moderate-to-good function



Eye - Complete closure with minimal effort



Mouth - Slight asymmetry



III. Moderate dysfunction  



Gross



Obvious but not disfiguring difference between sides



Noticeable but not severe synkinesis, contracture, or hemifacial spasm



At rest, normal symmetry and tone



Motion



Forehead - Slight-to-moderate movement



Eye - Complete closure with effort



Mouth - Slightly weak with maximum effort



IV. Moderately severe dysfunction  



Gross



Obvious weakness and/or disfiguring asymmetry



At rest, normal symmetry and tone



Motion



Forehead - None



Eye - Incomplete closure



Mouth - Asymmetric with maximum effort



V. Severe dysfunction  



Gross



Only barely perceptible motion



At rest, asymmetry



Motion



Forehead - None



Eye - Incomplete closure



Mouth - Slight movement



 



VI. Total paralysis



No movement
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Indications

Traumatic congenital facial nerve paralysis usually resolves spontaneously and does not require surgery. A general guideline when considering surgery in a traumatic facial paralysis patient 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.

Surgery in patients with developmental facial paralysis is usually delayed until later in life.

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Relevant Anatomy

Embryogenesis

The facial nerve (cranial nerve VII) develops early in fetal life from the facioacoustic crest in the second branchial arch. All facial muscles are identifiable in the embryo by the 14th week. The facial nerve develops close to the vestibulocochlear nerve (cranial nerve VIII). 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 complex mixed nerve containing motor, parasympathetic, special sensory (taste), and sensory components.

The motor nucleus lies deep within the reticular formation of the pons, where it receives input from the precentral gyrus of the motor cortex. The motor fibers innervate the muscles of facial expression, posterior belly of the digastric muscle, stylohyoid muscle, and stapedius muscle. The upper motor neuron (supranuclear) 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.

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.

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 to the external auditory canal.

The intracranial segment of the facial nerve travels 23-24 mm from the brain stem at the level of the caudal pons to the internal auditory canal (IAC). The meatal segment includes 7-8 mm 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 superior to the cochlea and vestibule to the geniculate ganglion.

The first branch of the facial nerve, the greater superficial petrosal nerve, is within this segment. The tympanic segment is 12-13 mm in length and begins at the geniculate ganglion, where the nerve turns 40-80° posteriorly (first genu) to enter the middle ear on the medial wall of the tympanic cavity superior to the oval window and inferior to the lateral semicircular canal and ends at the pyramidal eminence.

The nerve turns inferiorly (second genu) below the horizontal semicircular canal and continues as the mastoid (vertical) portion 15-20 mm and exits the stylomastoid foramen. The extratemporal portion of the facial nerve is distal to the stylomastoid foramen and supplies the muscles of facial expression. The facial nerve divides the parotid gland into superficial and deep lobes. Within the gland, branching of the nerve is variable. Most commonly, the nerve divides into an upper temporozygomatic and lower cervicofacial division. Five terminal branches innervate the mimetic musculature of the face, namely the temporal, zygomatic, buccal, marginal mandibular, and cervical branches.

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. [27]

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