Facial nerve palsy in children

INTRODUCTION — Facial nerve palsy is a common malady in children that may be congenital or acquired. The underlying etiology often remains unclear despite extensive investigation.

In 1830, Sir Charles Bell first described unilateral facial weakness secondary to facial nerve dysfunction. His description of acquired, idiopathic facial paralysis is often termed Bell's palsy [1]. This topic will review clinical aspects of facial nerve palsy in children.

The clinical features and management of Bell's palsy in adults is discussed elsewhere. (See "Bell's palsy: Pathogenesis, clinical features, and diagnosis in adults" and "Bell's palsy: Treatment and prognosis in adults".)

FACIAL NERVE ANATOMY — The facial nerve has a complex anatomy and function that render it susceptible to multiple neurologic disorders based upon the location of the lesion (figure 1). Cranial nerve VII originates from multiple brainstem nuclei that are functionally specialized [2,3].

●The motor component of VII, which accounts for movement of the facial musculature, arises from the motor nucleus of VII in the pontine tegmentum. Fibers innervating the forehead receive bilateral input via the corticobulbar tract, whereas the contralateral corticobulbar tract innervates the remaining facial muscles.

●The superior salivatory nucleus is the origin of preganglionic parasympathetic fibers that innervate the lacrimal, sublingual, and submandibular glands. Innervating fibers of the submandibular and sublingual gland travel via the chorda tympani nerve, whereas the lacrimal gland fibers travel through the greater petrosal nerve.

●Taste for the anterior two-thirds of the tongue and sensory fibers from the external acoustic canal travel to the solitary tract nucleus.

The fibers of the facial nerve emerge from the ventrolateral aspect of the brainstem at the caudal border of the pons and enter the petrous portion of the temporal bone via the internal auditory canal. The sensory fibers travel as the nervus intermedius portion of cranial nerve VII and run between cranial nerve VIII and the motor component of cranial nerve VII. In the temporal bone, the greater petrosal nerve arises from the labyrinthine segment of the facial nerve and carries preganglionic parasympathetic fibers to the pterygopalatine ganglion. The nerve then synapses and sends fibers to the lacrimal gland; lesions affecting the facial nerve prior to the greater petrosal nerve may cause decreased lacrimation. The facial nerve then courses along the medial wall of the anterior epitympanic recess; it is here that the facial nerve may be affected by cholesteatomas.

The mastoid segment of the facial nerve courses inferiorly, lateral to the jugular fossa, allowing lesions there to affect the facial nerve. The stapedius nerve arises from this segment and innervates the stapedius muscle. Lesions of the facial nerve prior to the stapedius nerve result in hyperacusis.

The chorda tympani arises distally in the mastoid segment and enters the middle ear via the canaliculus chordae tympani. It exits via the petrotympanic fissure and supplies afferent fibers for taste to the anterior two-thirds of the tongue. It also provides efferent parasympathetic fibers to the submandibular and sublingual glands that synapse in the submandibular ganglion. The facial nerve exits the skull via the stylomastoid foramen and courses through the parotid gland to divide and supply the muscles of facial expression.

ETIOLOGY AND EPIDEMIOLOGY — The possible causes of facial nerve palsy are many and may be congenital, infectious, neoplastic, traumatic, or idiopathic (table 1) [4,5]. Approximately one-half of all cases qualify for the label "Bell's palsy," previously defined as an acute facial nerve palsy of unknown cause. An estimated 20 per 100,000 people per year are affected by Bell's palsy, rendering it one of the more common referrals for neurologists [6].

Bell's palsy is the appellation commonly used to describe an acute peripheral facial palsy of unknown cause. However, the terms "Bell's palsy" and "idiopathic facial paralysis" may no longer be considered synonymous [6,7]. A peripheral facial palsy is a clinical syndrome of many causes, including herpes simplex virus activation; axonal spread and multiplication of a reactivated neurotropic virus leading to inflammation, demyelination, and dysfunction is the likely cause of Bell's palsy in many adult and some pediatric cases (see 'Herpes simplex virus' below). Nevertheless, most patients with peripheral facial palsy are labelled as having Bell's palsy because there is no established or widely available method of confirming herpes simplex virus as the mechanism in clinical practice [8].

No racial, geographic, or sex-based predilection exists for Bell's palsy, but there is a threefold greater risk during pregnancy (especially in the third trimester or in the first postpartum week) [9] and a fourfold greater incidence in diabetics [6]. The risk of Bell’s palsy may also be elevated in children with an elevated body mass index (>90^th percentile) [10].

The most common cause of acute-onset facial nerve palsy in children has in the past been acute otitis media. However, Lyme disease may be a more common cause in endemic areas than otitis media, as illustrated by a study of 50 children with facial nerve palsy in Delaware [11]. The most common etiology was Lyme disease (50 percent), followed by acute otitis media (12 percent), varicella (6 percent), herpes zoster (4 percent), and coxsackievirus (2 percent). Idiopathic disease (Bell's palsy) was the diagnosis in 26 percent. At least one European study also found Lyme disease to be the most frequently identified cause of acute facial palsy in children, accounting for 16 of 27 cases [12]. Bilateral facial palsy occurred only in children with Lyme disease in this study. However, mumps may be a frequent infectious cause in countries where it is endemic, as parotiditis produces a localized distal compressive neuropathy [13].

Congenital facial nerve palsy — Congenital facial nerve palsy may be the result of developmental defects or of traumatic etiology (table 1). Birth weight greater than 3500 grams, forceps-assisted delivery, and prematurity are all risk factors associated with traumatic facial palsy.

Developmental defects such as congenital dysinnervation syndromes are rare causes of congenital facial palsy. The presence of multisystem dysmorphia and multiple cranial nerve abnormalities tend to favor developmental abnormalities. One well-recognized syndromic form of congenital facial palsy is Moebius syndrome, which is typically accompanied by impairment of ocular abduction and often clubfoot. Hereditary congenital facial paresis 1 and 2 are rare syndromes of isolated facial nerve dysfunction associated with genetic variants on chromosomes 3q21-22 and 10q21.3-22.1, respectively [14-16]. Other syndromes are also associated with facial palsies (table 1), including branchial arch malformation sequence disorders such as Goldenhar syndrome [17,18]. (See "Syndromes with craniofacial abnormalities", section on 'Craniofacial microsomia'.)

In distinguishing developmental from traumatic facial palsies in the perinatal period, some or complete recovery of function favors traumatic lesions. Early motor nerve conduction study can help distinguish an acute from chronic facial palsy and can assist in differentiating these etiologies. (See 'Electrodiagnostic studies' below.)

Moebius syndrome — Moebius (Mobius) syndrome, sometimes called Moebius sequence, is a congenital facial palsy (unilateral or bilateral) with abnormalities of abducens (cranial nerve VI) function, though other cranial nerves (III, IV, V, VIII) may be involved [19,20]. Other orthopedic malformations, including clubfoot, are also common [21]. Postmortem analysis has shown hypoplasia of the motor nucleus of the facial nerve with small or absent facial nerve rootlets exiting the brainstem [22]. A genetic cause has not yet been identified [23], but linkage points to a distinct locus at 13q12.2-13 [24]. There is some overlap with the hereditary congenital facial paresis syndromes.

Otitis media — As mentioned above, otitis media is a relatively common cause of acute facial nerve palsy. One group found that the incidence of facial nerve palsy was 0.16 percent, which was decreased from about 2 percent in the pre-antibiotic era [25]. (See "Acute otitis media in children: Epidemiology, microbiology, and complications", section on 'Other intratemporal complications'.)

Bacterial infection of the middle ear usually is easily diagnosed by simple inspection of the external meatus and tympanic membrane. Computed tomography (CT) scan may allow for better visualization of the course of the facial nerve through the petrous portion of the temporal bone. (See "Acute otitis media in children: Clinical manifestations and diagnosis", section on 'Diagnosis'.)

The management of acute otitis media is discussed separately. (See "Acute otitis media in children: Treatment".)

Herpes simplex virus — Herpes simplex virus (HSV) activation is accepted as the likely cause of Bell's palsy in some pediatric cases [8,26] and most adult cases [27,28]. In one study, for example, HSV-1 genomes were identified in facial nerve endoneurial fluid and auricular muscle in 11 of 14 patients undergoing decompression surgery for Bell's palsy; the HSV-1 genomes were not found in controls [29]. In a prospective case-control study of children presenting with acute unilateral facial nerve palsy, a positive polymerase chain reaction (PCR) for HSV-1 was significantly more common in affected children (10 of 47 [21 percent]) compared with controls (4 of 45 [9 percent]) [8]. Similarly, a positive enzyme-linked immunosorbent assay (ELISA) for HSV-1 was significantly more frequent in affected children (33 of 42 [79 percent]) compared with controls (16 of 41 [39 percent]).

Varicella-zoster virus — In societies where primary herpes zoster regularly occurs due to low immunization rates, varicella-zoster virus reactivation has been identified by PCR or serology in pediatric acute facial paralysis in up to 37 percent of cases [30]. Most such cases are characterized by acute peripheral facial nerve palsy in the absence of rash (ie, zoster sine herpete), while a few are notable for the presence of typical zoster lesions in the auditory canal and auricle, termed the Ramsay Hunt syndrome as discussed in the next section.

Ramsay Hunt syndrome — The Ramsay Hunt syndrome is caused by reactivation of varicella-zoster virus (herpes zoster oticus); the virus lies dormant in the sensory ganglion after primary infection. Ramsay Hunt is characterized by facial paralysis associated with a painful vesicular eruption within the external auditory canal and vestibulocochlear dysfunction. (See "Epidemiology, clinical manifestations, and diagnosis of herpes zoster", section on 'Ramsay Hunt syndrome (herpes zoster oticus)'.)

Lyme disease — As mentioned above, Lyme disease has become the most common cause of acute facial nerve palsy among children in areas endemic for this infection [11,12]. Facial nerve palsy is the most common cranial neuropathy associated with Lyme meningitis [31,32]. Involvement of the facial nerve can be unilateral or bilateral and usually lasts less than two months [33]. (See "Lyme disease: Clinical manifestations in children", section on 'Cranial nerve palsy'.)

The mechanism by which Lyme disease causes facial nerve palsy may be related to direct invasion of the nerve by Borrelia burgdorferi. This possibility is suggested by retrospective studies showing that nearly all children who presented with neuroborreliosis, facial palsy, and a tick bite or erythema migrans in the head and neck region developed ipsilateral facial nerve palsy [12,34].

Patients with Lyme disease and facial nerve palsy may have other clinical features of Lyme disease, but many have no other symptoms nor a history of tick bite or erythema migrans [35]. Painless, nontender swelling and erythema of the face preceding the facial palsy are distinctive features that may be present and help confirm the clinical diagnosis [36]. The likelihood that Lyme disease is the cause of a seventh nerve palsy diminishes in either nonendemic areas or at a time of year when Lyme disease is not prevalent.

In contrast with adults, most children with isolated Lyme disease facial palsy have abnormal cerebrospinal fluid findings, including an elevated white blood cell count, protein, or both [12,37]. However, the clinical significance of these abnormalities is not clear [38]. (See 'Lumbar puncture' below.)

The evaluation of suspected Lyme-induced facial palsy is discussed separately. (See "Lyme disease: Clinical manifestations in children", section on 'Cranial nerve palsy'.)

HIV infection — HIV infection rarely causes facial palsy. If it does, onset is at the time of seroconversion, when a CSF lymphocytosis usually is present [39]. In the later stages when cellular immunity wanes, the facial palsy is typically caused by another infection such as zoster, chronic demyelinating polyradiculopathy, or meningeal lymphomatosis [40].

Other infections — Other probable infectious causes of Bell's palsy include cytomegalovirus, Epstein-Barr virus, adenovirus, rubella virus, mumps, influenza B, echovirus, and coxsackievirus [1,40,41], although they have been implicated less conclusively. In addition, there are case reports of children with facial nerve palsy and serologic evidence of Rickettsia conorii infection (Mediterranean spotted fever) [42] and severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) [43].

Other conditions — Several other disorders should be considered in the differential diagnosis of facial nerve palsy.

●Cholesteatoma should be suspected if the onset of facial palsy is gradual [6]. (See "Cholesteatoma in children".)

●The Melkersson-Rosenthal syndrome is characterized by facial paralysis, episodic facial swelling, and a fissured tongue, typically beginning in adolescence but with recurrent episodes of facial palsy [44]. Abortive forms outnumber the classic triad. Perivascular tuberculoid granulomas are seen in the edematous tissue [45], but the cause is unknown and treatment is unproven.

●Sarcoidosis should be considered, especially in patients with bilateral facial palsy. Acute or subacute onset of bilateral facial nerve palsy may be caused by numerous other disorders, including neuroborreliosis (see 'Lyme disease' above), mumps, and Guillain-Barré syndrome [46]. (See "Neurologic sarcoidosis" and "Lyme disease: Clinical manifestations in children", section on 'Cranial nerve palsy' and "Mumps", section on 'Neurologic complications' and "Guillain-Barré syndrome in children: Epidemiology, clinical features, and diagnosis", section on 'Clinical features'.)

●Severe systemic hypertension has been linked to unilateral primary facial nerve palsy in children and adolescents and rarely in adults [47]. Hypertension should be suspected in a pediatric patient if facial palsy is associated with headache, altered level of consciousness, vomiting, convulsions, or focal central nervous system deficit.

●Acute leukemia and primary brain tumors have been diagnosed infrequently mostly in younger children with acute peripheral facial palsy [48-50]. Fever and otitis media accompanied facial nerve symptoms in some but not all cases. (See "Overview of the clinical presentation and diagnosis of acute lymphoblastic leukemia/lymphoma in children" and "Involvement of the central nervous system (CNS) with acute myeloid leukemia (AML)".)

●Congenital myopathies, congenital myotonic dystrophy, congenital myasthenic syndromes, Guillain-Barré syndrome, and infantile botulism can also have profound facial weakness but often are accompanied by other features including ophthalmoplegia, respiratory insufficiency, or generalized weakness. (See "Congenital myopathies" and "Myotonic dystrophy: Etiology, clinical features, and diagnosis", section on 'Congenital DM1' and "Neuromuscular junction disorders in newborns and infants", section on 'Congenital myasthenic syndromes' and "Guillain-Barré syndrome in children: Epidemiology, clinical features, and diagnosis" and "Neuromuscular junction disorders in newborns and infants", section on 'Infant botulism'.)

Congenital unilateral lower lip palsy, also referred to as asymmetric crying facies or congenital hypoplasia of the depressor angularis oris muscle, is a typically benign cosmetic deformity that can mimic congenital facial nerve palsy [51]. It is best identified on examination of the crying infant. The affected angle of the lower lip will fail to depress, resulting in marked asymmetry compared with the normal depression of the opposite angle of the lower lip. It is distinguished from facial nerve palsy and stroke by preservation of other functions of the facial nerves, such as pursing the lips, eye closure, and nasolabial fold depth. Although typically a benign condition, it can occur with congenital heart disease in Cayler syndrome or may be associated with renal developmental abnormalities [52,53].

CLINICAL FEATURES — Patients with idiopathic facial nerve palsy (Bell's palsy) typically present with the sudden onset (usually over hours) of unilateral facial paralysis. Common findings include decreased forehead movement, sagging of the eyebrow, inability to close the eye, disappearance of the nasolabial fold, and drawing of the mouth to the unaffected side [4]. Decreased tearing, hyperacusis, and/or loss of taste sensation on the anterior two-thirds of the tongue may help to site the lesion in the facial canal but are more useful as an indicator of severity than of anatomic diagnosis. The presence of an ipsilateral abducens (ie, cranial nerve VI) palsy suggests the possibility of a brainstem lesion as the cause of the facial palsy, since the abducens nucleus is in close proximity to the fibers in the brainstem that exit as the facial nerve.

Facial movement is assessed by observing the response to commands for closing the eyes, elevating the brow, frowning, showing the teeth, puckering the lips, and tensing the soft tissues of the neck. For children unable to cooperate with examination instructions, facial movement may be assessed by observing the facial appearance during laughing or crying. The examination also includes a general physical examination and neurologic examination; particular attention should be directed at the other cranial nerve functions, external ear for vesicles or scabbing (which indicates zoster), and for mass lesions within the parotid gland. Testing of taste is also helpful in localizing lesions of the facial nerve.

Peripheral versus central lesions — Sparing of the forehead muscles is suggestive of a central (upper motor neuron) lesion because of bilateral innervation to this area. However, this finding does not exclude a peripheral site of pathology in all cases.

Central activation of the facial nerve is both volitional and automatic or emotional in origin, and the facial nerve is the final common pathway. Thus, dissociation of movement of the face to command from spontaneous movement, as in smiling, indicates an upper motor neuron lesion. Lack of dissociation indicates a lower motor neuron (peripheral) lesion.

DIAGNOSIS — The diagnosis of Bell's palsy is based upon the following criteria:

●A diffuse involvement of all of the distal branches of the facial nerve is present.

●Onset is acute, over a day or two; the course is progressive, reaching maximal clinical weakness/paralysis within three weeks or less from the first day of visible weakness; recovery of some degree of function usually occurs within six months.

●Associated prodrome, such as ear pain or hearing impairment, may be reported.

Accurate diagnosis begins with a thorough history and physical examination. The history should address the time of onset, rapidity of progression, associated symptoms (eg, hyperacusis, lack of taste), and any systemic diseases such as diabetes mellitus or chronic otitis media. A careful history should also include exposure to tick bites, history of rash, and HIV risk factors.

As mentioned, the primary etiologies of congenital facial nerve palsy include trauma and developmental abnormalities. In traumatic cases, a history of prolonged labor, forceps delivery, periauricular ecchymoses, or hemotympanum may help with diagnosis, but it is not diagnostic. It is important to look for associated dysmorphic features or multisystemic syndromal pathology. As an example, Goldenhar syndrome (craniofacial microsomia) has associated malar and maxillary hypoplasia and hemifacial microsomia, in addition to congenital facial paralysis [54].

The physical examination should include a careful assessment of facial musculature paralysis as well as careful examination of the ear, mastoid region, parotid gland, and neck. Examination of other cranial nerves, hearing, taste, salivation, and lacrimation may help localize the lesion.

Diagnostic tests — Serologic testing for Lyme disease is recommended for all children with acute-onset facial palsy when there is the possibility of exposure. Patients who have a typical incomplete facial palsy and who recover do not need further study.

Other adjunctive investigations, such as electrodiagnostic studies, neuroimaging, or lumbar puncture, are reserved for patients with atypical clinical features to help identify an underlying etiology for facial nerve dysfunction. Atypical features include the presence of any of the following [4]:

●Additional cranial neuropathies or neurologic signs

●Systemic signs (eg, otitis media, acute mastoiditis, rash, trauma)

●Sudden onset of symptoms (without progression)

●Insidious progression of symptoms beyond three weeks

●No improvement within four months

Diagnostic tests may also be used to help determine prognosis for patients with severe clinical features.

Lyme serologies — Serologic testing for Lyme disease is recommended for all children with acute-onset facial palsy when there is the possibility of exposure in Lyme-endemic areas during the spring through autumn seasons. With the exception of the first four to six weeks of infection, serologic testing is highly sensitive and specific for the diagnosis of Lyme disease. Occasionally the cranial neuropathy occurs before the patient has become seropositive; in such patients, follow-up serologic testing in several weeks is typically diagnostic.

When serologic testing for Lyme disease is indicated, two-tier testing is recommended, using an enzyme-linked immunosorbent assay (ELISA) followed by a Western blot as the tests of choice (See "Nervous system Lyme disease", section on 'Facial nerve palsy' and "Diagnosis of Lyme disease".)

Electrodiagnostic studies — In the first days after symptoms onset, the blink reflex (stimulation of the supraorbital nerve) can confirm the peripheral origin of weakness and assess the degree of axonal conduction block [55].

The simplest electrodiagnostic test is electromyography (EMG). Even in patients who have a clinically complete lesion, needle EMG may show some potentials on active volition, which allows one to conclude that at least some axons in the nerve are still in continuity with a potential for regrowth.

Motor nerve conduction study (motor NCS, also called electroneurography or evoked electromyography) is another electrodiagnostic test used for the evaluation of facial nerve palsy. It is usually obtained in patients with complete lesions for prognostic purposes. Motor NCS involves stimulating the main branch of the facial nerve near the stylomastoid foramen and recording the compound muscle action potential (CMAP) in millivolts.

CMAP amplitudes reach their minimum level between 7 and 14 days after the onset of weakness in most patients. At approximately 10 days after the onset of symptoms, the amplitude of the CMAP on the paralyzed side compared with that on the normal side yields an estimate of the degree of axonal loss [55]. The amplitude of the paralyzed side is compared with that of the normal side and is expressed as a percentage. This percentage is presumed to correspond to the number of surviving motor neurons [56]. Thus, a CMAP value of 10 percent of normal corresponds with a degeneration or loss of 90 percent of the motor axons on that side [57]. In normal individuals, a 5 to 20 percent difference between the two sides can exist [58].

At approximately 20 to 30 days after onset, needle EMG may provide confirmation of muscle denervation and the degree of axonal damage [55]. In patients with axonal loss, needle EMG at about three months after onset may be used to assess for evidence of subclinical reinnervation from the facial nerve.

Imaging studies — Imaging is necessary if the physical signs are atypical, if chronic otitis media, acute mastoiditis, temporal bone trauma, or a neoplasm is suspected as the etiology, if progression is slow and beyond three weeks, or if no improvement has occurred at six months. The initial imaging technique of choice for facial nerve palsies is debatable.

●One group recommends high-resolution CT in the axial and coronal planes for patients with an otoscopically demonstrable mass, history of chronic otitis media, or previous mastoid surgery [2]. Fractures of the temporal bone also are best viewed with CT scanning.

●Patients should otherwise undergo pre- and post-contrast enhanced magnetic resonance imaging (MRI) including the brainstem, temporal bone, and parotid gland. MRI is the best study to evaluate the intraparotid facial nerve for inflammation, edema, or neoplasm. Contrast enhancement of the geniculate ganglion within the labyrinthine segment of the facial nerve is common in Bell's palsy [6]. However, contrast enhancement of the first genu and proximal tympanic segment is typically normal [2]. Enhancement of the inner ear structures occurs only in herpes zoster facial palsy and can be taken to suggest this diagnosis even without a vesicular eruption [59].

Lumbar puncture — Lumbar puncture is recommended for children with cranial nerve palsy when there is clinical suspicion of meningitis (eg, severe or prolonged headache, fever, papilledema, or nuchal rigidity); cerebrospinal fluid analysis may reveal an increased white blood cell count or protein in cases of facial palsy associated with central nervous system infection [60]. A slight increase in monocytes and lymphocytes is compatible with Bell's palsy but does not definitively diagnose the condition nor exclude an inflammatory process. The cerebrospinal fluid concentration of antibody to B. burgdorferi is highly specific for the diagnosis of central nervous system Lyme disease. (See "Lumbar puncture in children" and "Lyme disease: Clinical manifestations in children", section on 'Cranial nerve palsy'.)

Cerebrospinal fluid analysis is of limited utility for the diagnosis of Lyme disease when involvement is restricted to the peripheral nervous system, (eg, isolated facial nerve palsy and no signs of meningitis). Therefore, we suggest that children who have facial nerve palsy and Lyme disease undergo lumbar puncture only if they have clinical evidence of central nervous system infection. This suggestion is in agreement with the recommendations of the Infectious Diseases Society of America and the American Academy of Neurology [61,62]. (See "Nervous system Lyme disease", section on 'Facial nerve palsy' and "Lyme disease: Clinical manifestations in children", section on 'Cranial nerve palsy'.)

TREATMENT — The treatment of facial nerve palsy in children is guided by the etiology and the severity of the condition [4].

The treatment of facial nerve palsy due to a specific cause (eg, Lyme disease or acute otitis media) involves treatment of the underlying disorder. (See "Treatment of Lyme disease" and "Acute otitis media in children: Treatment".)

Treatment options for congenital or permanently acquired lesions include muscle transfers and nerve grafts. In both acquired and congenital facial palsies, care must be taken to protect the cornea of the affected side. Congenital unilateral lower lip palsy can be treated with botulinum injections to the unaffected side.

Eye care — Appropriate eye care is required to help avoid corneal abrasions if the patient with facial palsy is unable to close the eye. This care generally entails administration of artificial tears during the day with ophthalmic ointment and patching at night; tape should not be placed directly on the eyelid because the patch could slip and abrade the cornea. Rarely, tarsorrhaphy or temporary implantation of a gold weight into the upper lid is required.

Drug therapy for Bell's palsy — Given the established benefit of glucocorticoid treatment for adults with Bell's palsy, we recommend early treatment with oral glucocorticoids for all children with Bell's palsy. This recommendation is consistent with guidelines from the American Academy of Neurology [63]. Treatment should preferably begin within three days of symptom onset. Our suggested regimen is prednisone 2 mg/kg daily (up to 60 to 80 mg) for five days, followed by a five-day taper. At least two studies have found that doses of 1 mg/kg may be similarly effective [64,65].

Early combined therapy with oral glucocorticoids plus valacyclovir (20 mg/kg per dose three times daily, maximum 1000 mg per dose) for one week for children with severe Bell's palsy (ie, a House-Brackman (table 2) grade IV or higher) may marginally reduce risk of long-term sequelae, as discussed below. However, there is no consensus among experts regarding the use of antivirals combined with glucocorticoids to treat Bell's palsy in children.

Patients with Ramsay Hunt syndrome should be treated with prednisone plus acyclovir or valacyclovir. (See "Treatment of herpes zoster", section on 'Ramsay Hunt syndrome'.)

●Efficacy of glucocorticoids – The mainstay of pharmacologic therapy for Bell's palsy in adults is early short-term oral glucocorticoid treatment, which is established as effective by systematic reviews and meta-analyses [66-70] of randomized controlled trials [71-77]. (See "Bell's palsy: Treatment and prognosis in adults", section on 'Glucocorticoids for all patients'.)

The benefit of glucocorticoids in children with Bell's palsy is less well-established, likely partially due to studies including children with mild symptoms as well as the high rates of spontaneous recovery over the long-term in these patients [78]. One placebo-controlled trial of 42 children with severe facial palsy found that the rate of normal nerve function was slightly higher in patients assigned to glucocorticoid at four and six months of follow-up (86 and 100 percent in treated versus 72 and 86 percent untreated controls), but all patients improved by 12 months [79]. However, in another trial of 187 children with symptoms <72 hour duration, recovery of facial function was similar for those assigned either to prednisolone or placebo both at one-month (49 versus 57 percent; adjusted odds ratio [aOR] 0.7, 95% CI 0.4-1.3) and up to final follow-up at six months (99 versus 93 percent; aOR 3.0, 95% CI 0.5-17.7) [80]. Other lower-quality studies have not shown specific long-term benefit of glucocorticoid therapy versus conservative management [81].

●Efficacy of antiviral therapy with or without glucocorticoids – The suspicion that Bell's palsy is frequently caused by herpes simplex virus (see 'Herpes simplex virus' above) led to adult trials of antiviral therapy with or without glucocorticoids [71-77]. These trials found no benefit for antiviral therapy alone compared with placebo and conflicting evidence of additional benefit for antiviral agents when combined with glucocorticoids.

•In a 2009 meta-analysis involving 18 trials and 2786 patients, treatment with glucocorticoids alone was associated with a reduced risk of unfavorable recovery (relative risk [RR] 0.69, 95% CI 0.55-0.87), whereas treatment with antiviral agents alone was not (RR 1.14, 95% CI 0.80-1.62) [66]. In pooled data from eight trials, the same meta-analysis found a trend toward a reduced risk of unfavorable recovery for combined antiviral and glucocorticoid treatment compared with glucocorticoid treatment alone, but the outcome just missed statistical significance (RR 0.75, 95% CI 0.56-1.0).

•In a second 2009 meta-analysis of six trials and 1145 patients, there was no significant benefit of combined antiviral and glucocorticoid treatment for achieving at least partial facial muscle recovery (odds ratio 1.5, 95% CI 0.83-2.69) [67].

•A 2019 meta-analysis of three trials at low risk of bias (n = 766 participants) concluded there was little to no effect in rates of incomplete recovery with combination antiviral and glucocorticoid therapy compared with glucocorticoid therapy alone (RR 0.81, 95% CI 0.38-1.74), even for the subgroup with severe Bell's palsy (RR 0.82, 95% CI 0.57-1.17; 2 trials, n = 98) [82]. However, when all available evidence was included (13 trials, 1729 participants), the rate of incomplete recovery was lower after antiviral and glucocorticoid therapy than glucocorticoid alone (RR 0.59, 95% CI 0.47-0.70).

Surgery — The early surgical management of facial nerve palsy in the pediatric population has not been systematically studied. One uncontrolled study evaluating middle cranial fossa decompression of the labyrinthine segment of the facial nerve demonstrated benefit for patients in whom electrodiagnostic studies show a ≥90 percent reduction of the compound muscle action potential [83]. At least two uncontrolled case series in patients with severe Bell's palsy have shown improvement following facial nerve decompression performed as late as 70 to 89 days after symptom onset [84,85]. Another study suggested that facial nerve decompression prevented further episodes of facial palsy but did not promote facial nerve recovery [86].

However, a 2001 practice parameter from the American Academy of Neurology determined that the surgical treatment of facial nerve palsy could not be recommended due to concerns about the inherent bias of these studies and the potential complication of hearing loss [87]. A 2013 guideline from the American Academy of Otolaryngology-Head and Neck Surgery Foundation made no recommendation regarding surgical decompression because the evidence consisted of low-quality, nonrandomized studies [88]. Thus, the use of early surgery for children with facial nerve palsy should be studied further before considering this as a treatment option.

Surgical reanimation techniques may be considered in children with congenital or permanently acquired facial nerve palsy [89,90]. These techniques do not completely restore normal physiologic function, although they may aid the child psychologically. Surgical procedures are divided into static procedures that provide symmetry of the mouth at rest and reanimation techniques that allow facial expression [90-94]. They may involve regional muscle transfers, nerve crossovers, cable grafts, and free muscle grafts. These procedures are advocated in early school age, when the child may have some understanding of the procedure [54].

PROGNOSIS AND NATURAL HISTORY — The prognosis of individual cases of facial paralysis can be difficult to assess and is based upon the underlying cause.

●Congenital facial palsies have a poor prognosis for recovery of function because of insufficient development of the facial nerve or canal.

●Traumatic facial paralysis in the perinatal period has an excellent prognosis, with 100 percent of patients showing some degree of improvement of function on the affected side.

●Most studies have focused on the prognosis of Bell's palsy and found that the majority of cases recover with minimal, if any, dysfunction [64,95,96]. The Copenhagen Facial Nerve study evaluated the natural history of 2570 cases of peripheral nerve palsy over a 25-year period, including 463 children younger than 15 years old [95]. A full recovery was achieved by 90 percent of these children. Many studies of acquired facial nerve palsy in children show excellent recovery rates of over 97 percent [5,97,98]. In one retrospective cohort of 102 children, 101 made a full recovery, with early recovery (by one month) weakly associated with lower doses of glucocorticoids, faster initiation of steroid treatment, and lesser severity of facial palsy on the 10^th day [64]. Another smaller retrospective cohort of 53 children with Bell's palsy found that children under eight years of age had a higher recovery rate by one month compared with older children [99]. Nearly all the children in these retrospective studies received glucocorticoid treatment, and a minority also received antiviral therapy. In another case series of 32 episodes of Bell's palsy in 29 children, complete recovery occurred in 31 episodes and was unrelated to treatment with glucocorticoids [96].

The prognosis of nerve injury is related primarily to the type and severity of the lesion [100]. A simple rule is that clinically incomplete lesions tend to recover. For facial nerve palsy, the House-Brackmann grading system was devised both as a clinical indicator of severity as well as an objective record of progress (table 2) [101]. On this scale, grades I and II have good outcomes, grades III and IV characterize moderate dysfunction, and grades V and VI portend a poor result, although studies in children show good outcomes even in those with grades IV to VI [64,97]. Limited data suggest that electrophysiologic measures of facial nerve function are more reliable than the House-Brackmann for estimating prognosis in cases with more severe facial nerve injury [102].

Motor nerve conduction studies have proved useful for determining the prognosis of idiopathic facial palsy. One study of facial motor nerve conduction study performed three to seven days after onset showed that 79 percent of those with a frontalis compound muscle action potential (CMAP) amplitude greater than 50 percent of the unaffected side had a good recovery by three months, compared with 48 percent of those with smaller CMAP amplitudes [103]. Another group noted that 84 percent of patients with CMAP amplitude responses greater than 30 percent of normal had complete recovery of facial function [104]. A CMAP response less than 10 percent suggests a poor prognosis and surgical consideration [105], although one-third of patients may have complete recovery even when CMAP amplitudes show 90 to 98 percent degeneration. In one study of patients with 90 percent reduction in CMAP who underwent middle cranial fossa decompression, 50 percent had a better final recovery than did control patients [106].

The prognosis of Bell's palsy is favorable if some recovery is seen within the first 21 days of onset [107]. A diagnosis of Bell's palsy is doubtful if some facial function, however small, has not returned within three to four months, and additional evaluation to determine the etiology is warranted [108].

In severe lesions that recover, the outgrowth of new axons from the injury site is not discretely directed but is disorganized and misdirected; on volitional activation of the facial nerve, a mass action of facial musculature or synkinesis ensues. Thus, on blinking, there is twitching of the angle of the mouth, and, on smiling, the eye may close or wink. Similarly, with misdirected autonomic fibers, a salivary stimulus may result in excess lacrimation, the syndrome of "crocodile tears." Synkinesis can be managed with a combination of botulinum toxin injections for selective chemodenervation of affected muscle groups and facial neuromuscular retraining [109].

The recurrence rate of Bell's palsy in children is less than 10 percent, similar to that in adults, and can occur months to years from the initial occurrence and on the same or contralateral side [110]. One series in children found recurrences in 11 of 182 patients (6 percent), two of which were associated with the Melkersson-Rosenthal syndrome [111]. Recurrence of facial palsy is more frequent, and prognosis is worse in patients with Melkersson-Rosenthal syndrome than in those with recurrent Bell's palsy [112,113]. Facial nerve decompression may be beneficial for recurrent facial nerve palsy associated with Melkersson-Rosenthal syndrome [114].

Recurrence of facial nerve palsy should prompt a search for associated findings that may suggest a diagnosis other than Bell's palsy. Imaging should be performed to evaluate for any structural abnormalities. In addition, the blood pressure should be evaluated, since hypertension has been linked with recurrent facial nerve palsy in children [115].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Bell's palsy".)

SUMMARY AND RECOMMENDATIONS

●Anatomy – The facial nerve has a complex anatomy and function that renders it susceptible to multiple neurologic disorders based upon the location of the lesion (figure 1). (See 'Facial nerve anatomy' above.)

●Etiologies – Approximately one-half of all cases qualify for the label "Bell's palsy," defined as an acute facial nerve palsy of unknown cause. Specific causes of facial nerve palsy include congenital, infectious, neoplastic, traumatic, and idiopathic etiologies (table 1). Important infectious etiologies include otitis media, herpes simplex viral infection, Lyme disease, Ramsay Hunt syndrome, and HIV infection. (See 'Etiology and epidemiology' above.)

●Clinical features – Patients with facial nerve palsy typically present with the acute onset of unilateral facial paralysis. Common findings include sagging of the eyebrow, inability to close the eye, disappearance of the nasolabial fold, and drawing of the mouth to the unaffected side. Decreased tearing, hyperacusis, and/or loss of taste sensation on the anterior two-thirds of the tongue may also occur. (See 'Clinical features' above.)

●Diagnosis of idiopathic facial palsy – The diagnosis of idiopathic (Bell's) facial nerve palsy is based upon the following criteria (see 'Diagnosis' above):

•A diffuse involvement of all of the distal branches of the facial nerve is present.

•Onset is acute, over a day or two; the course is progressive, reaching maximal clinical weakness/paralysis within three weeks or less from the first day of visible weakness; recovery of some degree of function usually occurs within six months.

●Diagnostic testing to evaluate for underlying causes – Serologic testing for Lyme disease is recommended for all children with acute-onset facial palsy when there is the possibility of exposure. Additional testing is warranted for patients with atypical presentations. (See 'Diagnostic tests' above.)

•Imaging – Neuroimaging is warranted if the physical signs are atypical, if alternative diagnoses are suspected, if progression is slow and extends beyond three weeks, or if no improvement has occurred at six months. We perform either high-resolution CT in the axial and coronal planes or MRI of the brain and parotid gland with gadolinium contrast. (See 'Imaging studies' above.)

•Other studies – Adjunctive investigations such as lumbar puncture and electrodiagnostic studies are reserved for selected patients with atypical features or clinical course. (See 'Lumbar puncture' above and 'Electrodiagnostic studies' above.)

●Treatment of idiopathic facial palsy

•Eye care – In both acquired and congenital facial palsies, care must be taken to protect the cornea of the affected side. Appropriate eye care entails administration of artificial tears during the day with ophthalmic ointment and patching at night. (See 'Eye care' above.)

•Pharmacotherapy – For children with idiopathic acquired facial palsy (ie, Bell's palsy), we recommend early treatment with oral glucocorticoids (Grade 1B). Treatment should preferably begin within three days of symptom onset. Our suggested regimen is prednisone 1 to 2 mg/kg daily (up to 60 to 80 mg) for five days, followed by a five-day taper. (See 'Drug therapy for Bell's palsy' above.)

Combination therapy with prednisone plus valacyclovir 20 mg/kg per dose three times daily (maximum 1000 mg per dose) for one week may reduce the risk of long-term sequelae. However, data from adult trials suggest only marginal additional benefit of combination therapy, and high-quality data for children are lacking. (See 'Drug therapy for Bell's palsy' above.)

●Management of other causes – The management of facial nerve palsy due to a specific cause (eg, Lyme disease or acute otitis media) involves treatment of the underlying disorder.

●Prognosis – Most children with Bell's palsy recover with minimal, if any, dysfunction. The prognosis for other causes of facial paralysis varies based upon the natural history of the underlying cause. (See 'Prognosis and natural history' above.)

ACKNOWLEDGMENTS — The UpToDate editorial staff acknowledges Robert P Cruse, DO and Thomas J Geller, MD, who contributed to earlier versions of this topic review.