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Bell’s PalsyStephen G. Reich, MD, FAAN

ABSTRACTPurpose of Review: Bell’s palsy is a common outpatient problem, and while thediagnosis is usually straightforward, a number of diagnostic pitfalls can occur, and alengthy differential diagnosis exists. Recognition and management of Bell’s palsyrelies on knowledge of the anatomy and function of the various motor and nonmotorcomponents of the facial nerve. Avoiding diagnostic pitfalls relies on recognizing redflags or features atypical for Bell’s palsy, suggesting an alternative cause of peripheralfacial palsy.Recent Findings: The first American Academy of Neurology (AAN) evidence-basedreview on the treatment of Bell’s palsy in 2001 concluded that corticosteroids wereprobably effective and that the antiviral acyclovir was possibly effective in increasingthe likelihood of a complete recovery from Bell’s palsy. Subsequent studies led to arevision of these recommendations in the 2012 evidence-based review, concludingthat corticosteroids, when used shortly after the onset of Bell’s palsy, were ‘‘highlylikely’’ to increase the probability of recovery of facial weakness and should be offered;the addition of an antiviral to steroids may increase the likelihood of recovery but, if so,only by a very modest effect.Summary: Bell’s palsy is characterized by the spontaneous acute onset of unilateralperipheral facial paresis or palsy in isolation, meaning that no features from thehistory, neurologic examination, or head and neck examination suggest a specific oralternative cause. In this setting, no further testing is necessary. Even without treatment,the outcome of Bell’s palsy is favorable, but treatment with corticosteroids significantlyincreases the likelihood of improvement.

Continuum (Minneap Minn) 2017;23(2):447–466.

INTRODUCTIONBell’s palsy is a common outpatientproblem, and while the diagnosis isusually straightforward, a long andbroad differential diagnosis exists forperipheral facial nerve palsy, and ap-proximately one-third of cases are dueto another cause. Bell’s palsy is charac-terized by the acute spontaneous onset(72 hours or fewer) of unilateral periph-eral facial paresis or palsy in isolation(no other neurologic or systemic signs),for which no specific etiology is un-covered, and in almost all cases, showsimprovement within several months.1

If a specific cause is found, such asLyme disease or sarcoidosis, it shouldnot be referred to as Bell’s palsy.

HISTORY OF BELL’S PALSYSir Charles Bell (1774 to 1842) isassociated with idiopathic peripheralfacial palsy, not because he was the firstto observe or report this finding, sincedepictions of facial palsy can be tracedto ancient art and texts (Figure 5-1),2

but instead because Bell recognizedthat peripheral facial palsy resultedfrom involvement of the seventh cra-nial nerve (which he referred to as therespiratory nerve). As he demonstratedin a series of clinical and experimentalobservations, the seventh cranial nervecontrolled the muscles of facial expres-sion, as stated by Bell:

On cutting the respiratory nerveon one side of the face of a

Address correspondence toDr Stephen G. Reich, Universityof Maryland School ofMedicine, 110 S Paca St, 3rdFloor, Baltimore, MD 21201,[email protected].

Relationship Disclosure:Dr Reich serves as associateeditor of the Journal ofClinical Movement Disordersand on the editorial board ofParkinsonism & RelatedDisorders. Dr Reich hasreceived publishing royaltiesfrom Informa, has receivedresearch support as aninvestigator for studies fromthe National Institute ofNeurological Disorders andStroke, and has given expertmedical testimony in legalcases related to malpractice.

Unlabeled Use ofProducts/InvestigationalUse Disclosure:Dr Reich discusses the use ofacyclovir and valacyclovir forthe treatment of Bell’s palsy.

* 2017 American Academyof Neurology.

Supplemental digital content:Videos accompanying this ar-ticle are cited in the text asSupplemental Digital Content.Videos may be accessed byclicking on links provided inthe HTML, PDF, and appversions of this article; theURLs are included in the printversion. Video legends beginon page 464.

447Continuum (Minneap Minn) 2017;23(2):447–466 ContinuumJournal.com

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited.

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monkey, the very peculiar activ-ity of his features on that sideceased altogether. The timid mo-tions of his eye-lids and eye-brows were lost, and he couldnot wink on that side; and hislips were drawn to the otherside, like a paralytic drunkard,whenever he showed his teeth inrageIthe conclusion is inevita-ble, that the motions of the lips,nostrils and eye-lids, and fore-head, in expression, have noth-ing to do with the fifth pair ofnervesI A man had the trunk ofthe respiratory nerve of the faceinjured by a suppuration, whichtook place anterior to the ear,and through which the nervepassed in its course to the face. Itwas observed, that in smiling andlaughing, his mouth was drawn

in a very remarkable manner tothe opposite side. The attempt towhistle was attended with a ludi-crous distortion of the lips: whenhe took snuff and sneezed, theside where the suppuration hadaffected the nerve remainedplacid, while the opposite sideexhibited the usual distortion.3

Bell was born in Edinburgh, Scotland,and trained as a surgeon, but he is bestrecognized for his contributions as ananatomist. He was also an accomplishedartist who illustrated many of his owndissections. In 1804 Bell moved toLondon, where he helped found medi-cal schools at University College Londonand Middlesex. Prior to his discovery ofthe innervation of the face, Bell demon-strated that the ventral spinal root ismotor; the Bell-Magendie law attributedmotor and sensory functions to theventral and dorsal roots, respectively. Inaddition to Bell’s palsy and the Bell-Magendie law, he is also eponymizedby Bell’s phenomenon (upward de-viation of the eyeball during forcedclosure of the lids) and by the longthoracic nerve of Bell that innervatesthe serratus anterior.4Y6

ANATOMYOFCRANIALNERVEVIIWhen evaluating a patient with aperipheral facial palsy, the most clini-cally relevant anatomic facts to appre-ciate are the following:

& A peripheral (lower motor neuron)facial palsy weakens the entireipsilateral face, including thefrontalis and orbicularis oculimuscles, which are spared withcentral (upper motor neuron)lesions that cause weakness of onlythe lower two-thirds of thecontralateral face (Figure 5-2). Thefeatures of a peripheral facial palsywere beautifully described byRomberg7: ‘‘The patient is unable

KEY POINTS

h Bell’s palsy is characterizedby the spontaneousacute (72 hours or fewer)onset of a unilateralperipheral facial nervepalsy without anyaccompanying signs, withneither the history norexamination suggestingan alternative diagnosis.

h Sir Charles Belldetermined that theseventh cranial nervecontrolled the musclesof facial expression.

h A peripheral (lowermotor neuron) facialpalsy weakens all theipsilateral facial muscles,including the frontalisand orbicularis oculi. Acentral (upper motorneuron) facial palsyweakens only thecontralateral two-thirdsof the face, sparingthe frontalis.

FIGURE 5-1 Sir Charles Bell (1774 to1842), a native ofEdinburgh, Scotland,

who practiced in London, was asurgeon but is best remembered as ananatomist. His name is attached tofacial palsy because he was the first todemonstrate, both experimentally and byclinical observation, that the muscles offacial expression were innervated by theseventh cranial nerve.

448 ContinuumJournal.com April 2017

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to corrugate his forehead, thefurrows on which disappear at oncewith the paralysis, so that the browof an old man becomes as smoothas that of a child, and no moreeffectual cosmetic is to be found forelderly ladies.’’ Therefore, a helpfulclinical pearl for differentiating acentral versus peripheral facial palsyis that the latter ‘‘gets out thewrinkles.’’ Of course, this is notclinically useful in the young,unwrinkled patient.

& It is distinctly rare to have aparenchymal lesion affect the facialnucleus or fascicle in isolation.The clue that a peripheral facialpalsy is from a central lesion is thepresence of neighborhood signslocalizing to the pons. These includean ipsilateral horizontal gaze palsydue to involvement of theparamedian pontine reticularformation; ipsilateral sixth nervepalsy; internuclear ophthalmoplegia(INO) due to involvement of the

FIGURE 5-2 In the top images, both patients demonstrate weakness of the lower face withpulling of the mouth to the normal side when smiling. The sparing of the leftfrontalis in the left lower image confirms that this is upper motor neuron facial

weakness, whereas the right frontalis cannot be contracted in the patient on the lower right,who has Bell’s palsy.




ipsilateral medial longitudinalfasciculus; ipsilateral facialnumbness due to involvementof the descending tract of cranialnerve V; and a contralateralhemiparesis. The combinationof a peripheral seventh cranialnerve palsy along with an ipsilateralhorizontal gaze palsy and INO isknown as the eight-and-a-halfsyndrome, adding the seventhnerve palsy to the more well-knownone-and-a-half syndrome.8

& The facial nerve innervates morethan just the muscles of facialexpression. Afferent fibers conveysensation from the external auditorycanal, pinna, mastoid, and mucosaof the palate (hence the need tocheck the palate as well as theauditory canal for vesicles insuspected geniculate zoster/Ramsay

Hunt syndrome) as well as tastefrom the anterior two-thirds ofthe tongue. Parasympatheticfibers in cranial nerve VII innervatethe lacrimal gland and minorsalivary glands. The sensory andparasympathetic fibers are carriedvia the nervus intermedius(Wrisberg nerve) (Figure 5-39).1,10Y12

The nucleus of cranial nerve VII isin the tegmentum of the caudal pons.The fascicle ascends, looping aroundthe abducens nucleus, protruding in thefourth ventricle as the facial colliculusbefore exiting the dorsolateral pons(cerebellopontine angle). The parasym-pathetics arise in the superior saliva-tory nucleus; taste fibers terminate inthe nucleus of the tractus solitarius, andthe sensory afferents terminate in thenucleus of the spinal tract of cranialnerve V.

KEY POINT

h In addition to innervatingthe muscles of facialexpression, the facialnerve also conveyssensation from theexternal auditory canal,pinna, mastoid, andmucosa of the palate;innervates the stapediusmuscle and the lacrimaland minor salivaryglands; and carries tastefrom the anteriortwo-thirds ofthe tongue.

FIGURE 5-3 The facial nerve and its branches.

Reprinted with permission from Blumenfeld H, Sinauer Associates, Inc.9 B 2002 Sinauer Associates, Inc.


Bell’s Palsy



The facial nerve travels with thevestibulocochlear nerve in the internalauditory meatus before entering thefacial canal (fallopian canal), a narrowbony canal within the temporal bone.It is because of its course through thisnarrow canal, with little room forexpansion, that inflammation of thenerve (due to any cause) is thought tocause compression resulting in paraly-sis and, as will be discussed, is therationale for the use of corticosteroidsfor Bell’s palsy. The first branch of thefacial nerve to exit, at the level of the ge-niculate ganglion, is composed of thefibers innervating the lacrimal gland, viathe greater superficial petrosal nerve. Iflacrimation is diminished in a periph-eral facial palsy, it suggests a moreproximal lesion. Distal to the geniculateganglion, the fibers innervating thestapedius muscle exit (this explainswhy some patients with Bell’s palsymay have hyperacusis).

The chorda tympani is the finalbranch of cranial nerve VII before itexits the skull at the stylomastoid fo-ramen. The chorda tympani, as previ-ously mentioned, conveys taste fromthe anterior two-thirds of the tongue(as such, taste may be affected in Bell’spalsy and is sometimes the first symp-tom) and joins with the lingual nerve toinnervate the minor salivary glands(their involvement is rarely evident inBell’s palsy). From the stylomastoid fo-ramen, the facial nerve courses throughthe parotid gland before dividing intobranches that innervate all of the mus-cles of facial expression as well as thebuccinator.1,10Y12 It is at this level thatindividual branches of cranial nerve VIIcan be affected by infiltrative or com-pressive lesions, or trauma, and cause apartial lower motor neuron facial palsywith sparing of the frontalis. This is whyit is important to do a careful head andneck examination in the patient with aperipheral facial palsy, with particular

attention to the parotid gland, cervicaladenopathy, or skin lesions, the latterrelevant to perineural invasion by squa-mous or other types of cancer.13

Sparing of the frontalis with a‘‘central (upper motor neuron) facial’’is traditionally thought to reflect bilat-eral supranuclear innervation from theprimary motor cortex, with the lowertwo-thirds of the face receiving pre-dominantly contralateral innervation.In contrast, studies in nonhumanprimates suggest that either there islittle corticobulbar innervation of theVII subnuclei innervating the frontalis14

or that innervation is from corticalareas distinct from those supplyingthe lower two-thirds of the face.15,16 Astudy in humans suggests that sparingof the orbicularis oculi by upper motorneuron lesions is due to its dual inner-vation from cortical regions suppliedby both the middle cerebral artery andanterior cerebral artery in contrast tothe lower face, where cortical innerva-tion is supplied solely by the middlecerebral artery.17

EPIDEMIOLOGYThe incidence rate of Bell’s palsy is 20to 40 out of 100,000 per year, and sexesare equally affected with an average ageof onset of 40 years. The incidence rateis highest in those age 70 years andolder. No difference exists in the side ofthe face affected, nor does there appearto be a seasonal predominance.18,19 Anumber of ‘‘risk’’ factors have been re-ported for Bell’s palsy, including dia-betes mellitus and hypertension, withlittle definitive evidence; however,both have been associated with aworse prognosis for recovery as hasolder age, non-ear pain, completepalsy, and decreased tearing.18Y20 Al-though pregnancy is often cited as arisk factor for Bell’s palsy, this was notfound to be the case in the epidemio-logic study from Rochester, Minnesota,

KEY POINT

h Factors suggesting aworse prognosis forrecovery of Bell’s palsyinclude diabetes mellitus,hypertension, older age,complete paralysis, lackof improvement by1 month, non-ear pain,and decreased tearing.




by Hauser and colleagues.18 In this re-gard, Katz and colleagues21 found thatrisk factors for Bell’s palsy duringpregnancy included chronic hyperten-sion, maternal obesity, and severe pre-eclampsia, but Bell’s palsy had no effecton perinatal outcome (Case 5-1).

ETIOLOGY OF BELL’S PALSYThe cause of Bell’s palsy is not knownand may not be the same in all in-

dividuals. Edema of the facial nervewithin the narrow fallopian canal hasbeen observed during decompressivesurgery for Bell’s palsy22 consistentwith MRI enhancement of the facialnerve in Bell’s palsy.23 The cause ofthe edema may be ischemia in predis-posed patients, such as the elderly orthose with diabetes mellitus or hyper-tension, akin to other known ischemiccranial neuropathies, including the

Case 5-1A 31-year-old woman presented with a history of Bell’s palsy, which had been diagnosed 1 month beforethe visit when she was 32 weeks pregnant, and her pregnancy had otherwise been uncomplicated. Herfirst symptom had been that her taste was ‘‘funny.’’ The following day she had noticed ‘‘drooping’’ ofthe right face and difficulty closing the right eye. By the next day, she had complete right facial paralysis.She was seen by her obstetrician and started on prednisone and valacyclovir. About 1 week after theprednisone was stopped, she experienced 3 to 4 days of pain around the right side of her head and jaw,which she described as severe and that resolved spontaneously. The weakness had improved when shepresented for neurologic consultation. On examination, the patient hadminimal asymmetry of her face atrest; while showing her teeth, no movement of the right side of the face occurred; she could barelyapproximate the lids when squeezing the eyes shut, and the frontalis muscle on the right was weak(Figure 5-4). She reported 80% return of function 6 months later.

Comment. The teaching points of this case include: (1) Bell’s palsy can occur during pregnancy,although it is not clear that this is an actual risk factor; (2) altered or diminished taste can be the initialsymptom of Bell’s palsy; (3) pain is not an uncommon feature of Bell’s palsy, either at presentation orduring recovery; and (4) regarding pregnancy, valacyclovir is category B, suggesting that it is probably safeto use during pregnancy.

FIGURE 5-4 Patient with Bell’s palsy from Case 5-1. A, At rest, the patient has slight widening of the right palpebral fissure.B, When attempting to smile, the patient experiences clear weakness of the right side of her face withpulling of her mouth to the left. C, When closing her eyes, the right lids cannot be completely approximated.D, When asked to look surprised, the right frontalis does not contract.


Bell’s Palsy



abducens and oculomotor nerves.24

But this would not account for themany young people with Bell’s palsy,including children. Herpes simplex vi-rus (HSV) type 1, according to Gilden,1

‘‘is probably the cause of most casesof Bell’s palsyI[and] reflects virusreactivation from latency in the genicu-late ganglion rather than primaryinfection.’’ Supporting evidence in-cludes the isolation of HSV DNA fromendoneurial fluid in Bell’s palsy25;increased salivary shedding of HSVDNA in patients versus controls26,27;polymerase chain reaction (PCR) evi-dence of HSV type 1 in the geniculateganglia28,29; and an HSV type 1 exper-imental animal model of Bell’s palsy.30,31

Despite this evidence, Gilden1 acknowl-edged that ‘‘how the virus damages thefacial nerve is uncertain.’’32,33

EVALUATION OF BELL’S PALSYPatients with Bell’s palsy typicallydevelop facial weakness over 1 to2 days. They may find that toothpaste,liquids, or food leak from the affectedside of the mouth, that the eyeliddoes not close, or that it is moredifficult to speak, which leads manypatients to the emergency departmentfor fear of a stroke.

The key first step in evaluating thepatient is to determine whether thefacial weakness is peripheral or cen-tral. Of note is that, while almost allpatients with a hemiparesis fromstroke have facial weakness, it is rarelythe presenting symptom and is oftennoticed by others rather than thepatient (Case 5-2). As discussed inthe section on anatomy, with a centralfacial palsy, sparing of the upper one-third of the contralateral face occurs.With a peripheral facial palsy, weak-ness of all muscles of facial expressionoccurs. The furrow is lost from thebrow, and the patient cannot elevatethe brow (ie, in response to the

command, ‘‘raise your forehead likeyou’re surprised’’), the palpebral fis-sure is wider, the nasolabial fold isflattened, the cheek cannot be puffedout, and the nares do not flare with ahard inspiration. The patient is unableto whistle, and when smiling or show-ing teeth, the mouth is drawn to theintact side. Having the patient test hisor her ability to whistle is a useful wayto document recovery.

Although most patients with Bell’spalsy do not notice a dry eye (recallthat the lacrimal gland is innervated bycranial nerve VII), nevertheless, asdiscussed in the section on treatment,proper lubrication and eye care isnecessary, particularly when severeweakness of the orbicularis oculi oc-curs to the extent that the upper andlower lids cannot be approximated.Paradoxically, some patients may pre-sent with tears running down the cheek,presumably due to weakness of theinferior portion of the orbicularisoculi, preventing tears from beingdirected toward the lacrimal duct,possibly in combination with ocularirritation. If the stapedius muscle isinvolved, hyperacusis may occur, ascontraction of the stapedius functionsto dampen the ossicles. Despite thefacial nerve innervation of minor sali-vary glands, dry mouth is usually notexperienced. Involvement of the chordatympani causes loss of taste in theipsilateral anterior two-thirds of thetongue; this can sometimes be the firstsymptom noticed by the patient, andimpaired taste may portend a worseprognosis for recovery. Other factorsreported to be associated with a worseoutcome include complete facial palsy,older age, diabetes mellitus, and, asmentioned in the following section,non-ear pain.18Y20

It is not uncommon for patientswith Bell’s palsy to report painVtypicallyaround the ear, mastoid, and faceVand

KEY POINTS

h The cause of Bell’s palsyis not known but maybe due to reactivation ofherpes simplex virustype 1.

h The return of the abilityto whistle can be auseful way to documentimprovement in Bell’spalsy (assuming thepatient could whistlebefore its onset).

h Although typically noobjective sensory lossoccurs with Bell’s palsy,pain around the ear andface may occur, whichat times can be severe.Prolonged pain outsideof these areas may be asign that the patient hasan alternative cause offacial palsy.




non-ear pain has been associated witha worse prognosis. Likewise, patientsmay report facial ‘‘numbness’’ (it isimportant to ask what they mean bynumbness), but sensory testing is usu-ally normal in Bell’s palsy. Yet, someauthors have suggested that patientswith Bell’s palsy in fact have a cranialpolyneuropathy. Adour11 found evi-dence of involvement of cranial nervesV, VIII, IX, and X in patients with Bell’spalsy.34 In a series of 51 patients diag-

nosed with Bell’s palsy, Benatar andcolleagues35 found that 8% had evi-dence of involvement of at least oneother cranial nerve, including the tri-geminal, glossopharyngeal, and hypo-glossal. These findings raise severalquestions: is Bell’s palsy really a cranialpolyneuropathy simply dominated byinvolvement of the facial nerve? Or,should signs of involvement of othercranial nerves ‘‘rule out’’ Bell’s palsy?The important point is that, in an

KEY POINT

h Some have suggestedthat Bell’s palsy is actuallya cranial polyneuropathy.But, anything more thansubtle signs implicatingother cranial nervesshould be viewed as apotential red flag, castingdoubt on the diagnosis ofBell’s palsy.

Case 5-2A 40-year-old woman presented to the emergency department after noticing that her face felt‘‘swollen’’ upon awakening, and she noted that the right side of her face felt ‘‘distorted and weak.’’She noticed toothpaste leaking from the right side of her mouth, tearing of the right eye, andinability to flair the right nostril.

On examination, the patient had mild right peripheral facial paresis with an otherwise normalexamination. As she was initially suspected of having a stroke, she underwent an MRI, whichdemonstrated mild enhancement of the intracanalicular and labyrinthine segments of the right facialnerve (Figure 5-5). She was treated with eye care, corticosteroids, and valacyclovir. She had completeresolution of her symptoms by 3 months.

Comment. Recognition that this patient had a peripheral facial palsy, in isolation, would have steeredthe diagnosis and evaluation from a stroke and toward Bell’s palsy, obviating the need for the MRI.Nevertheless, it does confirm that enhancement of these particular segments of the facial nerve mayoccur in patients with Bell’s palsy.

FIGURE 5-5 Axial MRI of patient in Case 5-2. A, Unenhanced MRI demonstrating a normalfacial nerve (arrow). B, Enhancement of the intracanalicular and labyrinthinesegments of the right facial nerve (arrow), which can be seen in Bell’s palsy.

Courtesy of Robert Morales, MD.


Bell’s Palsy



otherwise ‘‘typical’’ case of Bell’s palsy,patients may have other subtle cranialnerve symptoms and signs, but theirpresence should be a red flag that thecondition might not be Bell’s palsy, andcareful follow-up is warranted.

The majority of patients with Bell’spalsy will not have a recurrence, but arecurrence happens in about 7%, ei-ther on the sameor theopposite side.36Y38

A recurrence should prompt a carefulsearch for an alternative cause, suchas sarcoidosis39,40 or other inflam-matory or infiltrative disorders. TheMelkersson-Rosenthal syndrome is an-other consideration for recurrent pe-ripheral facial palsy; it is characterizedby a fissured tongue and periodic lip orfacial swelling,41 but many patients donot have the entire triad; inspection ofthe tongue can be an important clue.42

By adhering to the definition of Bell’spalsy as a spontaneous, acute, unilat-eral, isolated peripheral facial palsy, andif no red flags suggest an alternativecause, then neither laboratory testingnor imaging is needed43; unfortunately,the majority of patients undergo imag-ing. MRI of patients with Bell’s palsymay show enhancement in the in-tracanalicular and labyrinthine segmentsof the facial nerve (Case 5-2),23,44 andthis should not necessarily suggest analternative diagnosis. As pointed out bySartoretti-Schefer and colleagues,44 thenormal facial nerve may show en-hancement of the geniculate ganglionand the tympanic-mastoid segment.Electrodiagnostic studies have littlerole in the management of Bell’s palsy.43

According to a clinical practice guide-line from the American Academy ofOtolaryngologyVHead and Neck Sur-gery Foundation, based on level Cevidence, electrodiagnostic studies arenot recommended for patients withincomplete facial paralysis, most ofwhom will have a good recovery, butmay be offered to the patient with

complete paralysis for prognostic pur-poses, although it is not likely to changemanagement.43

DIFFERENTIAL DIAGNOSIS ANDRED FLAGSA very long list of causes of peripheralfacial palsy exists (Table 5-1). At least50% of peripheral facial palsies aredue to Bell’s palsy, and when no redflags from the history or examination(Table 5-2) suggest an alternativediagnosis, the percentage is no doubteven higher. Most of the causes listedin Table 5-1 should not be confusedwith Bell’s palsy as long as one adheresto the features of Bell’s palsy previ-ously mentioned: spontaneous, onsetover 72 hours, otherwise normal neuro-logic and systemic examination, improve-ment over several months, and nored flags.

Historic red flags casting doubt onthe diagnosis of Bell’s palsy as thecause of a peripheral facial palsy includegradual onset over weeks to months,concomitant vertigo or hearing loss,constitutional symptoms, cancer, hu-man immunodeficiency virus (HIV)45,46

or risk factors for HIV, and features sug-gesting Lyme disease (eg, endemic area,known tick bite, skin rash).47Y49 Sincethe majority of patients with Bell’s palsyimprove within several months, the lackof any improvement or a gradual pro-gression from facial paresis to facialpalsy should both raise a red flag. About7% of patients with Bell’s palsy willhave a recurrence,37Y39 but when thisoccurs, it should be considered a red flag,prompting an evaluation (to includeimaging and a lumbar puncture) foranother cause.

Some of the red flags from the neu-rologic examination include bilateralfacial palsy,50 involvement of other cra-nial nerves (as mentioned previously,the physician may see subtle signs ofother cranial nerve involvement in Bell’s

KEY POINTS

h About 7% of patientswith Bell’s palsy willhave a recurrence.

h For typical cases of Bell’spalsy, with no red flagsfrom the history orexamination, no furtherworkup, includingimaging, is necessary.

h If a patient with Bell’spalsy is imaged with MRI(typically not necessary),enhancement of theintracanalicular andlabyrinthine segmentsof the facial nerve maybe seen.

h Red flags casting doubton the diagnosis of Bell’spalsy include gradualonset, involvement ofother cranial nerves,concurrent vertigo orhearing loss, bilaterality,risk for Lyme disease orhuman immunodeficiencyvirus, and systemic cancer.




TABLE 5-1 DifferentialDiagnosisof PeripheralFacial Palsy

b Parenchymal Lesion (Pontine)

Multiple sclerosis

Stroke

Abscess

Encephalitisa

Neoplasm

Other

b Congenital

Mobius syndromea

Forceps trauma

b Trauma

Basilar skull fracture

Postoperative/iatrogenic

b Extraaxial Neoplasm

Schwannoma

Neuroma

Meningioma

Metastatic

Cholesteatoma

Parotid

Perineural invasion

Other

b Meningitis

Bacterial (including tetanus)

Virala

Human immunodeficiencyvirusa (including initialseroconversion)

Zika virusa

Epstein-Barr virus

Polio virus

Other

Fungal

TABLE 5-1 Continued

Mycobacteria

Tuberculosis

Leprosy

Spirochete

Syphilis

Lyme diseasea

Sarcoidosisa

Neoplastica

b Infectious (Nonmeningitic),Inflammatory, or Infiltrative

Geniculate zoster (RamsayHunt syndrome)

Guillain-Barre syndromea

Chronic inflammatorydemyelinatingpolyradiculoneuropathy

Osteomyelitis of skull base

Otitis media

Parotitis

Mastoiditis

Amyloidosisa

Granulomatosis withpolyangiitis

Polyarteritis nodosa

Sjogren syndrome

b Other

Idiopathic intracranialhypertension

Melkersson-Rosenthalsyndrome

Paget disease

Hereditary neuropathywith liability to pressurepalsy

Wernicke encephalopathy

Ethylene glycol ingestion

Continued on page 457


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palsy), hemiparesis, hearing loss ornystagmus, ataxia, horizontal gaze palsy,or systemic weakness. Important find-ings on the head and neck examinationto look for include vesicles in theexternal canal, tympanic membrane orpalate, cervical adenopathy, otitismedia, parotid mass, skin cancer, fis-sured tongue, and facial swelling.41,42 Itis important to recognize that a pe-ripheral facial palsy may be the firstsign of an evolving disorder such asneurosarcoidosis, meningeal carcino-matosis, or Guillain-Barre syndrome.51

Several specific causes of peripheralfacial palsy deserve highlighting. It isthe most common neurologic manifes-tation of Lyme disease,47Y49 and thisshould always be considered in pa-tients who live in an endemic area,especially if the facial palsy is bilateralor in a child. Halperin and Golightly49

determined that 25% of facial palsiesduring the summer months in an en-demic area were due to Lyme disease,based on serology. Because no otherclinical features may suggest Lymedisease before or at the time of facialpalsy (eg, erythema migrans), andserologic evidence may lag behind theearliest clinical manifestations,47 thedecision to treat rests largely on the phy-

sician’s index of suspicion for Lymedisease. If no symptoms or signs occurother than facial palsy, such as cranialpolyneuropathy or evidence of paren-chymal involvement, then a lumbarpuncture is probably not indicated.48

Even without antibiotics, the prog-nosis of Lyme disease facial palsy isfavorable,52 and therefore treatmentis aimed at preventing sequelae. Aspointed out by the American Academyof Neurology (AAN) Practice parameter,‘‘no definitive data exist to establishthe superiority, or lack thereof, ofeither oral or parenteral treatment.’’53

For facial palsy presumed to be from

KEY POINT

h Lyme disease is acommon cause ofperipheral facial palsy inendemic areas duringthe summer months,but in the absence ofpotential exposure andwithout othercharacteristic signs,routine testing is notrecommended.

TABLE 5-2 Red Flags CastingDoubt on theDiagnosis ofBell’s Palsy

b Gradual onset

b Vertigo, hearing loss, tinnitus

b No improvement within3 months

b Bilateral facial palsy

b Othercranialnerve involvement

b Limb or bulbar weakness

b Parotid gland enlargement

b Otitis media

b Vesicles in external auditorycanal, tympanic membrane,or oropharynx

b Cervical adenopathy

b Facial swelling/fissured(scrotal) tongue

b Skin rash/other signs ofLyme disease or living in anendemic area

b Risk factors for humanimmunodeficiency virus

b Facial skin cancer

b Systemic cancer

TABLE 5-1 DifferentialDiagnosisof Peripheral FacialPalsy Continued from page 456

b Myopathy or NeuromuscularJunction disordersa

Facioscapulohumeralmuscular dystrophy

Oculopharyngeal dystrophy

Myotonic dystrophy

Myasthenia gravis

a Facial palsy may be bilateral.




Lyme disease, it is reasonable to usean oral agent. If no clinical or serologicevidence confirms the diagnosis of Lymedisease at presentation, then steroidsmay be considered in case the diagno-sis is actually Bell’s palsy; according tothe AAN practice parameter, althoughevidence is limited, a short course ofsteroids is not likely to be harmful whentreating Lyme disease.53

Ramsay Hunt syndrome (Case 5-3) ismanifested by a peripheral facial palsywith erythema and vesicles in the externalauditory canal, the tympanic mem-brane, or the oropharynx. It is due toreactivation of varicella-zoster virus inthe geniculate ganglion.54 Accompanyingsymptoms reflect neighborhood involve-ment of the vestibulocochlear nerve in-cluding vertigo, hearing loss, and tinnitus.

KEY POINT

h A careful head and neckexamination is importantin patients with aperipheral facial palsywith particular attentionfor vesicles on thetympanic membrane,external auditory canal,or soft palate, indicatingherpes zoster (RamsayHunt syndrome).

Case 5-3A 76-year-old man noticedear pain followed byweakness of the rightface. He did not experiencehearing loss or vertigo. Onexamination, he had a rightperipheral facial palsy anderythema and vesicles in theright ear (Figure 5-6). Hewas diagnosed as havinggeniculate zoster, RamsayHunt syndrome, and wastreated with corticosteroidsand acyclovir.

Comment. Although theinvolvement of the ear byzoster was readily apparentin this patient, in others it issubtle, necessitating carefulinspection of the externalauditory canal and tympanicmembrane as well as theoropharynx. The presence ofvertigo, hearing loss, andtinnitus may accompanyRamsay Hunt syndrome andare important red flagspointing away fromBell’s palsy.

FIGURE 5-6 Images of patient in Case 5-3. A,The patient has erythema in theright auricle along with vesicles. B,

When attempting to smile, the patient showsweakness of the right side of his face as well as lesswrinkling of the right frontalis.


Bell’s Palsy



About 5% of patients with sarcoid-osis will have neurologic involvement,and in one-half of those cases, it is thepresenting sign, with a peripheralfacial palsy being the most commonmanifestation. Neurosarcoidosis is par-ticularly important to consider withbilateral peripheral facial palsy. Thediagnosis may be challenging and re-quires a careful search for evidenceof systemic involvement and, ideally,pathologic confirmation.39,40 Anotherimportant consideration, particularlywhen bilateral facial palsy occurs, isGuillain-Barre syndrome, which mayevolve rapidly from facial palsy into amore classic picture with bulbar andlimb weakness with areflexia, but asubtype of Guillain-Barre syndromemanifests by only bifacial weaknessand distal paresthesia.51

MANAGEMENTMost patients with Bell’s palsy areworried they have had a stroke, soreassurance and education are impor-tant parts of treatment along withcounseling that the prognosis is favor-able for most patients, particularlythose with mild or moderate facialweakness at presentation. Because ofweakness of eyelid closure and the riskof corneal exposure, particularly inthose with complete palsy, patientsshould use lubricating drops frequentlyduring waking hours and a lubricatingointment at night. The lid can be tapedclosed at night or a cellophane patchcan be applied with care so that nodirect contact with the cornea occurs.

The use of steroids and antivirals toimprove the recovery of Bell’s palsy isbased on the previously mentioned ob-servations about the possible roles ofedema and HSV type 1 in the patho-physiology and etiology, respectively, inBell’s palsy. Here the author reliesprimarily on the AAN evidence-basedguidelines. The first guideline pub-

lished in 2001 found only five publishedstudies of sufficient rigor upon which todetermine the effectiveness of cortico-steroids (two Class I, two Class II, andone Class III), and nonewere sufficientlypowered to allow for a definitive rec-ommendation.55 By pooling the resultsof the Class I and II studies, coupledwith the safety of a short course ofsteroids, the authors of this guidelineconcluded that: ‘‘steroids are safe andprobably effective in improving facialfunctional outcomes in patients withBell’s palsy’’ (level B recommenda-tion).55 Even less evidence, and noClass I studies, existed upon which tobase a recommendation for acyclovir,which received a level C recommenda-tion of being safe and possibly effec-tive. The lack of unbiased studies and ahigh complication rate precluded anyevidence-based recommendations onsurgical decompression.55

The AAN evidence-based guidelineon steroids and antivirals for the treat-ment of Bell’s palsy was updated in2012,56 and the revised recommenda-tions were based largely on two Class Istudies published since the originalreview. The first study by Sullivan andcolleagues57 compared four treatmentarms: prednisolone alone (25 mg twiceper day for 10 days), acyclovir alone(400 mg twice per day for 10 days), acombination of prednisolone and acy-clovir, and placebo in patients age 16or older who presented within 72 hoursof onset of Bell’s palsy (Figure 5-7).The primary outcome was the degreeof facial weakness observed in digitalphotographs by three blinded review-ers, using the House-Brackmann fa-cial nerve grading system, at 3 and9 months. Of 551 patients who under-went randomization, outcome datawere available for 496 (90%).

The other Class I study by Engstromand colleagues58 was similar, but in-stead of acyclovir, valacyclovir (1000 mg

KEY POINTS

h A peripheral facial palsyis the most commonneurologic manifestationof neurosarcoidosis andis particularly importantto consider if bilateral.

h A peripheral facial palsymay the first sign ofGuillain-Barre syndrome,progressing to limbweakness, but a variantof Guillain-Barresyndrome occurs withonly bifacial palsy.

h To protect the cornea inpatients with Bell’spalsy, lubricating dropsshould be used frequentlyduring the day, and alubricating gel should beused at night along withtaping the lid closed orusing a patch thatdoes not rest onthe cornea.




3 times per day for 7 days) was used.More than 800 patients between ages18 and 75, presenting within 72 hours,were randomly assigned to prednisolone(60 mg/d for 5 days then reduced by10 mg/d) and placebo, valacyclovir andplacebo, placebo and placebo, andprednisolone and valacyclovir. The pri-mary outcome measure was time tocomplete recovery (score of 100) onthe Sunnybrook facial nerve gradingsystem. Similar to the study by Sullivanand colleagues,57 those patients whoreceived prednisolone had a signifi-cantly higher rate of recovery at all timepoints, including the final assessment at1 year compared to placebo and to thecombination of valacyclovir and pred-nisolone (Figure 5-8). The lower ratesof recovery, even for the placebo-placebo group in the study by Engstromand colleagues,58 were attributed to thehigher sensitivity of the Sunnybrookscale for residual weakness. No sig-nificant adverse effects occurred ineither study.

An editorial following the publica-tion of these two trials by Tyler32

concluded that ‘‘antiviral therapyshould not be routinely used in pa-tients with [Bell’s palsy].’’ Tyler did,however, point out the potential ben-efit of antivirals for treatment ofRamsay Hunt syndrome.32 The AANevidence-based review gave a level Arecommendation to the use of corti-costeroids for treatment of Bell’s palsywithin 72 hours of onset. Continuing,they reiterated that adding an antiviralto a corticosteroid offers no significantbenefit regarding facial recovery. How-ever, they pointed out that the 95%confidence interval of the two Class Istudies could not rule out a modesteffect of adding an antiviral and gave aClass C rating to the combination.56

When discussing the combinationwith patients, despite counseling thatadding an antiviral to a steroid doesnot offer significant benefit (when alsotold that a benefit, even modest atbest, cannot be ‘‘ruled out’’), most

KEY POINT

h The American Academyof Neurologyevidence-based reviewgave a level Arecommendation to theuse of corticosteroidswithin the first 72 hoursof onset to increasethe likelihood ofimprovement for Bell’spalsy. Combining anantiviral with acorticosteroid does notsignificantly improve theoutcome of Bell’s palsy,and their use was given alevel C recommendationfor a possible modestbenefit, at best.

FIGURE 5-7 Graph shows rates of full recovery at 9 months for patients withBell’s palsy who were treated with prednisolone and placebo,prednisolone and acyclovir, placebo and placebo, and acyclovir and

placebo. In those patients who received placebo, two-thirds recovered completelyby 3 months, and 85% recovered completely by 9 months. The use of prednisolonesignificantly increased the rate of complete recovery to 83% and 94.4% at 3 and9 months, respectively. Acyclovir, either alone or in combination with prednisolone,showed no additional benefit.

Reprinted with permission from Sullivan FM, et al, N Engl J Med.57 B 2007 Massachusetts MedicalSociety. nejm.org/doi/full/10.1056/NEJMoa072006#t=article.


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patients, in the author’s experience,opt to take an antiviral.

The clinical practice guidelines by theAmerican Academy of OtolaryngologyVHead and Neck Surgery Foundation,developed by specialists in a variety ofrelated fields including neurology, madesimilar recommendations about theuse of corticosteroids and antivirals forBell’s palsy. They went on to addresssome of the other popularly toutedtreatments for Bell’s palsy, findinginsufficient or poor-quality evidenceto make any recommendations aboutthe use of surgical decompression, acu-puncture, and physical therapy to treatBell’s palsy.43

LONG-TERM MANIFESTATIONSAND COMPLICATIONSAs the placebo arms of the previouslymentioned studies demonstrate, up to85% of patients with Bell’s palsy makea complete recovery within 1 year.57,58

Those left with facial weakness maybe candidates for surgical proceduresaimed at improving facial function, par-ticularly when significant eyelid weak-ness occurs, with risk of exposurekeratitis (this complication requiresprompt ophthalmologic referral). Theseinclude implantation of a gold weightin the eyelid and other nerve or muscletransfer procedures that will not bereviewed here; patients should be

FIGURE 5-8 Percent of patients with Bell’s palsy making a complete recovery(Sunnybrook scale score of 100) by time and treatment groups. Patientswho received prednisolone and placebo had a significantly faster rate of

recovery of complete facial function (75 days) compared to those receiving placebo-placebo(104 days) or valacyclovir-placebo (135 days). Similarly, a significantly higher rate ofrecovery was seen at 3, 6, and 12 months in patients who received prednisolone. Nosignificant additional improvement in the recovery rate was shown whenprednisolone was combined with valacyclovir.

CI = confidence interval; HR = hazard ratio.

Reprinted with permission from Engstrom M, et al, Lancet Neurol.58 B 2008 Elsevier. thelancet.com/journals/laneur/article/PIIS1474-4422(08)70221-7/abstract.



http://thelancet.com/journals/laneur/article/PIIS1474-4422(08)70221-7/abstract

http://thelancet.com/journals/laneur/article/PIIS1474-4422(08)70221-7/abstract


referred to a surgeon experienced inthese options.13,59

When residual weakness occurs inpatients with Bell’s palsy, the apparentside of the weakness can be paradox-ical. With an acute peripheral facialpalsy, the nasolabial fold is flattened,and the palpebral fissure is widened.But with chronic weakness, a contrac-ture may develop such that at rest, thenasolabial fold on the weak side isdeeper and the palpebral fissurenarrower (Case 5-4).60 The actual sideof the weakness is readily apparent withmovement, and synkinesia almost al-

ways occurs, confirming an old facialpalsy. The author has been involvedin a few cases where an old case ofBell’s palsy with contracture has beenmisinterpreted as new weakness on thepatient’s good side of the face, leadingto an erroneous diagnosis (usuallystroke) and unnecessary testing beforethe findings are interpreted correctlyand the history clarified. Patients areoften unaware of residual weaknessand synkinesia and may forget abouthaving had Bell’s palsymany years earlier.

There are two types of synkinesiasthat develop after Bell’s palsy due to

KEY POINT

h Residual facial weaknessafter Bell’s palsy cancause a contracture,making it appear at restthat the normal side isweak with a flatternasolabial fold andwidened palpebral fissure.When facial function istested, the weak side isreadily apparent.

Case 5-4A 73-year-old man was seen for Parkinson disease and related a history of remote Bell’s palsy, fromwhichhe reported a good recovery. On examination, at rest (Figure 5-9A) the right nasolabial fold was flatter,and the palpebral fissure was wider, suggesting that was the side of the facial weakness. However,as Figures 5-9B and 5-9C demonstrate, he had a contracture on the left, which is the side of theweakness.

Comment. This case demonstrates that it can be easy to mistake the side of weakness from a previouscase of Bell’s palsy, but the synkinesia is a sure giveaway.

FIGURE 5-9 Images of the patient in Case 5-4. When comparing the sides of the patient’s face at rest, there is flattening ofthe right nasolabial fold and widening of the right palpebral fissure (A), suggesting right-sided facial weakness.But, when smiling (B) or closing his eyes (C ), it is apparent that the weakness is present on the left. Theasymmetry at rest reflects contracture of the left face from a remote Bell’s palsy.

Panel A reprinted with permission from Reich SG, Neurology.60 B 2007 American Academy of Neurology. neurology.org/content/68/2/E1.full.


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misdirection of regenerating fibers.The first is motor: with blinking,particularly if forceful, simultaneouscontracture of the ipsilateral mouth orplatysma occurs, and similarly, whensmiling or showing teeth, contractureof the orbicular oculi and narrowing ofthe palpebral fissure occurs (Case 5-5).This is often asymptomatic but if patientsare bothered, then botulinum toxin is themost effective treatment. Some patientsgo on to develop hemifacial spasm.61

Nonmotor fibers in the facial nervemay also misdirect, producing twotypes of synkinesias. The first is gusta-tory tearing in which salivation may beassociated with lacrimation (so-calledcrocodile tears named for the myththat the crocodile either sheds a tearto attract its victim or sheds a tear asthe victim is being eatenVin eithercase, the implication is that crocodiletears are insincere tears).

When salivation causes facial sweat-ing, this is known as Frey syndrome orgustatory sweating, named for LucjaFrey, one of the first female Polishneurologists, whose productive careerwas cut tragically short by the Nazis.62

Although Frey was not the first torecognize this phenomenon, she iscredited with discerning its physiologyand pharmacology. Frey syndrome is

encountered much more commonlyafter parotid surgery than Bell’s palsy(see the video from Reich and Grill62

for an example of Frey syndrome).

CONCLUSIONBell’s palsy is characterized by the spon-taneous, acute (over 24 to 72 hours)onset of unilateral peripheral facialpalsy in isolationVthat is, no featuresfrom the history, neurologic examina-tion, or general examination suggest analternative diagnosis. Red flags castingdoubt on the diagnosis of Bell’s palsyinclude gradual onset, concurrent ver-tigo or hearing loss, vesicles in theexternal auditory canal, living in an areaendemic for Lyme disease, risk factorsfor HIV, and systemic cancer, amongothers. When no red flags exist, and thediagnostic criteria for Bell’s palsy areused, additional testing is usually notnecessary. Even without treatment,most patients, especially those withfacial paresis rather than palsy, will havea complete recovery. A 10-day course ofcorticosteroids has been shown tosignificantly increase the likelihood ofrecovery; adding an antiviral does notsignificantly improve the likelihood ofrecovery, but the possibility that doingso may have a modest benefit, at most,cannot be ruled out. Residual effects of

KEY POINTS

h A motor synkinesia is acomplication of Bell’spalsy. This is usuallyasymptomatic but, ifbothersome, can betreated withbotulinum toxin.

h Two nonmotorsynkinesias after Bell’spalsy include gustatorylacrimation (crocodiletears) and gustatorysweating, known asFrey syndrome.

Case 5-5A 55-year-old woman had undergone surgery for a large right acousticneuroma 20 years earlier andwas followed by her neurologist for headaches.Postoperatively, she had had moderate facial weakness that graduallyimproved, and she eventually developed an asymptomatic synkinesia. Whenshe blinked, simultaneous movement of the right lips and mentalis occurred,and when she smiled, contraction of the orbicularis oculi occurred(Supplemental Digital Content 5-1, links.lww.com/CONT/A214).

Comment. This case demonstrates one of the complications of facial nervepalsy: the aberrant regeneration of motor fibers. The patient exhibitssynkinesia between the orbicularis oculi and orbicularis oris, so that movingthemouth causes a contraction, which narrows the palpebral fissure, and eyeclosure causes retraction of the mouth. This symptom is often asymptomaticbut, if bothersome, it can be treated with botulinum toxin.



http://links.lww.com/CONT/A214


Bell’s palsy include permanent weaknessand motor and nonmotor synkinesia, thelatter including gustatory tearing andgustatory sweating (Frey syndrome).

VIDEO LEGENDSupplemental DigitalContent 5-1Synkinesia after right facial nerve palsy.The 55-year-old woman in Case 5-5 de-veloped a moderate right facial nervepalsy 20 years earlier as a consequenceof the removal of a large acousticneuroma, which gradually improved.When she blinks, co-contraction of theright orbicularis oris occurs, and whenshe smiles, co-contraction of the rightorbicularis oculi occurs, causing thepalpebral fissure to narrow; these aresigns of aberrant regeneration of thefacial nerve with synkinesia.

links.lww.com/CONT/A214B 2017 American Academy of Neurology.

ACKNOWLEDGMENTThis article is dedicated to Donald H.Gilden, MD, FAAN (1937 to 2016), inrecognition of his many contributionsto Bell’s palsy and with appreciation ofhis friendship.

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Bell’s Palsy



bell’s palsy · the muscles of facial expression, the facial nerve also conveys sensation from...

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