You are in: eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > RECONSTRUCTIVE SURGERY Congenital Facial ParalysisArticle Last Updated: Jun 8, 2006AUTHOR AND EDITOR INFORMATIONAuthor: Kim Lundstrom, MD, Consulting Staff, Department of Otolaryngology-Head and Neck Surgery, Longmont Clinic Kim Lundstrom is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery and American Medical Association Coauthor(s): Gregory C Allen, MD, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine Editors: Michael J Biavati, MD, Clinical Assistant Professor, Department of Otolaryngology, University of Texas Southwestern; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Gregory C Allen, MD, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine; 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: congenital facial paralysis, facial paralysis in the newborn, isolated facial paralysis, Möbius syndrome, neonatal paralysis, congenital unilateral lower lip palsy, CULLP, velocardiofacial syndrome, VCF syndrome INTRODUCTIONFacial paralysis in the newborn is uncommon, occurring in 0.23-1.8% of live births. In patients with congenital facial paralysis, it is important to determine the etiology of the paralysis because prognosis and treatment differ for traumatic and developmental causes. History and physical examination can often resolve the origin; however, radiographic imaging and tests of neuromuscular function may be necessary in planning treatment. ProblemCongenital facial paralysis may cause multiple problems for the infant. Isolated facial paralysis causes difficulty with eye closure, potentially leading to corneal ulcerations. Difficulty with the orbicularis oris, depressor anguli oris, and depressor labii inferioris can lead to feeding difficulties. Associated anomalies include abnormalities of the external ears, severe inner ear abnormalities, maxilla and mandible hypoplasia, and cleft palate and vocal cord dysfunction with subsequent aspiration. When evaluating infants with facial paralysis, performing an extensive physical examination to exclude any other congenital malformations and to guide further care is important. FrequencyThe prevalence ranges from 0.23-1.8% of live births. Of these births, 78-90% are associated with birth trauma. Of the patients with palsies related to birth trauma, 91% are associated with forceps delivery. However, Smith et al evaluated 94 cases of neonatal paralysis and found that 25% occurred in either vaginal or cesarean section deliveries. Congenital unilateral lower lip palsy (also referred to as velocardiofacial [VCF] syndrome in some references) is the most common of the developmental lesions, occurring in 1 out of 120-160 live births. EtiologyCongenital facial paralysis can be associated with traumatic or developmental causes. The traumatic causes are related primarily to a difficult labor. Intrauterine trauma can occur from pressure on the infant's face by the sacral prominence during the birthing process. Supranuclear palsy has been shown to be associated with intracranial hemorrhage during the perinatal period. Injury most often results from the narrowing of the vertical segment of the facial canal. 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. The causes of developmental facial nerve paralysis are numerous and include mononeural agenesis, congenital paralysis, and congenital unilateral lower lip paralysis (CULLP). When CULLP occurs with cardiac anomalies, the condition is referred to as VCFl syndrome in some references. Deficits associated with facial nerve paralysis
Systemic or infectious conditions associated with facial nerve paralysis
Teratogens associated with facial nerve paralysis 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. Misoprostol: This synthetic prostaglandin E1 analogue is used to prevent and treat gastric ulcers and gastrointestinal lesions induced by nonsteroidal anti-inflammatory 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. PathophysiologyMöbius syndrome Autosomal dominant inheritance with variable expression and incomplete penetration has been suggested as a cause of Möbius syndrome; however, most cases are sporadic. Four patients with Möbius syndrome reported peripheral neuropathy and hypogonadotropic hypogonadism. Malformations of the limbs and other cranial nerves are often associated with this syndrome. Several theories regarding the pathogenesis of Möbius syndrome are as follows:
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. 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. ClinicalCongenital facial nerve paralysis can be diagnosed based on birth history, family history, physical examination, and 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:
RELEVANT ANATOMYEmbryogenesis The facial nerve 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 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. 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 the stapedius muscle. 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. 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 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 nerve) is within this segment. Importantly, the bony fallopian canal is narrowest within the labyrinthine segment of the nerve. The tympanic segment 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. 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, temporal, zygomatic, buccal, marginal mandibular, and cervical. 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. WORKUPLab Studies
Imaging Studies
Other Tests
TREATMENTMedical therapyMedical treatment of congenital facial paralysis requires attention to eye care. 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 therapyIn general, 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 detailsA 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. Postoperative detailsThe postoperative care of the newborn after facial rehabilitation is similar to any other surgical procedure. The child (if age appropriate) and parents should be instructed on exercises to improve facial rehabilitation. Follow-upAfter facial reanimation, return of function has been found to occur within 18 months. Long-term treatment involves evaluating for any donor site morbidity, including tongue atrophy in patients with facial nerve–hypoglossal nerve transposition, difficulty with mastication in patients with masseter or temporalis transfer, and examination of the donor sites for greater auricular or sural nerve grafts. Routine ophthalmologic examinations and physical therapy for facial expression exercises are included in the long-term treatment of patients. As the child ages, biofeedback can be used to facilitate training of the mimetic musculature after cable grafts, facial nerve–hypoglossal nerve transposition, and muscle transfers. In children with developmental facial nerve paralysis who often have other congenital abnormalities, attention to appropriate weight gain and developmental milestones is necessary. COMPLICATIONSThe primary physician should routinely observe infants with congenital facial paralysis to ensure adequate growth and development. The facial nerve is responsible for providing oral competence in the oral phase of swallowing through the orbicularis oris muscle. When deficit in innervation of this muscle is present, the infant may have great difficulty with feeding because the ability to suck is impaired. As the child ages, speech impediments may become more obvious because of difficulty with oromotor tone; therefore, speech therapy should be considered. Routine ophthalmologic examinations are also indicated to ensure that the eyes are adequately protected. The complications of facial reanimation in the early postoperative period include infection, hematoma, and the production of facial paralysis on the unaffected side in the case of a cross-facial graft. Long-term complications relate to the failure of the reanimation technique and lingual atrophy when a facial nerve-hypoglossal nerve transfer has been performed. OUTCOME AND PROGNOSISMore than 90% of patients with facial nerve paralysis caused by trauma recover without treatment. When the palsy is of congenital origin, the parents should be informed that the child will never have an entirely normal appearance. The best outcome expected in these cases is facial symmetry at rest, symmetry with voluntary movement, and spontaneous emotive movement. FUTURE AND CONTROVERSIESMuch controversy exists regarding the timing of facial reanimation and the need for surgical exploration in children with congenital facial paralysis. Issues regarding the timing of reanimation are complex. Some health professionals advocate initial surgery during preschool to prevent the psychosocial aspects 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 and participate in the decision making process also has merit. MULTIMEDIA
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Congenital Facial Paralysis excerpt Article Last Updated: Jun 8, 2006 | ||||||||||||||||||||||||||