Acute Facial Paralysis

Sarah Mowry, M.D.March 13, 2012

Disclosures

• None

Lecture Objectives

• Review facial nerve anatomy• Identify and classify facial nerve dysfunction• List causes of acute facial paralysis• Describe presumed etiology of Bell palsy• Explain the current treatment

recommendations for Bell palsy

Facial Nerve Anatomy

Right Ear Left Ear

Facial Nerve Anatomy

Patient Work Up

• History• Physical• Audiogram• Electrodiagnostic testing• Imaging

Facial Nerve Exam

• Elicit history/exam findings of intratemporal branches– Dry eye (Schirmer’s test)– Hyperacusis from stapedius dysfunction (reflex testing)– Dysguesia– Decreased sensation in the EAC (Hitselberger’s sign)

• Examine all branches of the nerve in the periphery– Degree of weakness– Presence of synkinesis– Presence of spacticity

• Examine other cranial nerves• Examine the EAC, TM and periauricular area

Classify

• House-Brackmann Scale• Sunnybrook• Sydney• Fisch Detailed Evaluation of Facial Symmetry• Yanagihara

Sunnybrook

House Brackmann ScaleGrade Description Gross function Resting

appearanceDynamic appearance

1 Normal Normal Normal Normal

2 Mild dysfunction Slight weakness with effort, may have mild synkinesis

Normal Mild oral and forehead asymmetry; complete eye closure with minimal effort

3 Moderate dysfunction

Obvious asymmetry with movement, noticeable synkinesis or contracture

Normal Mild oral asymmetry, complete eye closure with effort, slight forehead movement

4 Moderately severe dysfunction

Obvious asymmetry, disfiguring asymmetry

Normal Asymmetrical mouth, incomplete eye closure, no forehead movement

5 Severe dysfunction Barely perceptible movement Asymmetric Slight oral/nasal movement with effort, incomplete eye closure

6 Total paralysis None Asymmetric No movement

Imaging in Bell Palsy

• The literature is filled with case reports of missed diagnoses

• Contradictory evidence in the literature about the prognostic value of MRI– Most studies performed on 1.5 T magnets and

were qualitative in nature• Some advocate imaging all patients. – Is this the best use of scarce resources?– If so, what is the timing of imaging?

Imaging in Bell’s Palsy

• Absolute indications – Any patient with symptoms suspicious for stroke– Palsy that progresses after 3 weeks– Palsy that does not start to improve by 3 months– Recurrent facial palsy– Any patient contemplating surgical intervention

Facial Nerve Testing

• Faradic/galvanic stimulation• NET• MST• ENoG• EMG

• Only used for patients with complete paralysis

Patterns of Injury

Seddon (1940s)• Neuropraxia• Axonontmesis• Neurontmesis

Sunderland (1950s)• 1st degree – conduction

block and demyelination• 2nd degree – axonal loss• 3rd degree – disruption of

the endoneurium• 4th degree disruption of the

perineurium• 5th degree – disruption of

the epineurium

Patterns of Injury

• Neuropraxia– No wallerian degeneration– Axon and supporting tissue remains intact

• Axonotmesis– Loss of continuity of the axon– Wallerian degeneration occurs

• Neurotmesis– Injury involves endoneurium– Wallerian degeneration occurs

Pattern and Prognosis

• Neuropraxia will recover fully• Axonotmesis will recover without synkinesis• Neurotmesis will develop synkinesis and may

not recover fully

Ideal Test

• Be able to distinguish Axontmesis from Neurontmesis– Distinguish 2nd from 3rd degree injury

• All available testing can only distinguish 1st degree injury from higher levels of injury

• Must make inferences about higher degrees of injury from specific testing patterns.

Faradic/Galvanic stimulation

– No longer used– Direct current applied to the stylomastoid

foramen– Assess with visual response– Does not predict prognosis

Nerve Excitability Test (NET)

• Electrode over main trunk and then a ground electrode elsewhere

• Current increased until visual response is elicited from normal side– Threshold testing

• Same done for diseased side• Difference of 3.5mAmp between sides indicates poor

prognosis for full recovery• Drawback is inter-test variability and subjective

nature of response

Maximal Stimulation Test (MST)

• Increase the current on the normal side until “maximal facial twitch” is seen

• Same level of current is then applied to the diseased side

• Difference between the 2 sides is then graded as equal, lesser or no response.

• Drawback is painful exam, very observer dependent

Electroneurography (ENoG)

• Electrodes over the main trunk and then distally• Measures the compound muscle action potential • Suprathreshold stimulus is applied to both sides • Magnitude of the response is compared between

sides• Not useful until Wallerian degeneration has

occurred

Electromyography

• Introduced in the 1960s to replace faradic and galvanic stimulation

• Needle electrodes are placed into the muscle• Measures a compound muscle action potential – Fibrillation potentials and polyphasic action

potentials• Requires 21 days to quantify the degree of

denervation• Evoked and voluntary EMG

Voluntary EMG

• Used to identify a false positive ENoG• Suggests early “deblocking” of the FN• Presence of CMAP on voluntary EMG is a sign

of good prognosis

Acute Facial Paralysis

• Unilateral facial dysfunction is common– 20-30 per 100,000 per year for Bell’s Palsy

• Bilateral facial dysfunction is not common– Less then 2% of acute palsies are bilateral– Typically associated with systemic diseases– Usually other manifestations of systemic diseases

are present

Acute Facial Palsy

• All that palsies is not Bell’s!• 70-85% of acute unilateral facial paralysis is

idiopathic thus can be termed “Bell palsy”

Limb C, Niparko JK. The acute facial palsies. In: Neurotology 2nd Edition. Jackler RK, Brackmann DE Eds. Pg 1231.

Bilateral Acute Paralysis

• Bell palsy• DM• Heerfordt’s

fever (uveoparotid fever)

• PAN• GBS• Myesthenia

gravis• Skull fracture• Bulbar palsy• Prophyria• Leukemia• Myotonic

dystrophy• Meningitis

• Botulism• Leprosy• Polio• Lyme disease• Syphilis• Isoniazid• Post vaccine

neuropathy

Bell Palsy

• Sir Charles Bell first to attribute facial paralysis to dysfunction of the facial nerve in 1821

• Cause has been a source of intense debate• From 1930s-1960s felt to be due to vascular

insufficiency to the distal portion of the nerve• Other theories included autonomic

dysfunction, autoimmune injury and viral infection

Viral Hypothesis

• Murakami et al. Ann Int Med 1996;124(1):27• Performed transtemporal facial nerve

decompression on 14 patients with Bell’s, 9 pts with HZ oticus and 12 controls

• Looked for HSV, VZV and EBV in endoneurial fluid and post auricular muscle (PCR)

• Also drew serological studies on all patients

Viral Hypothesis

• Murakami et al 1996– Identified HSV-1 DNA in the endoneurial fluid and post

auricular muscle of 11 of 14 patients (78%)– Identified VZV in 89% of the Ramsey Hunt patients– No viral DNA was identified in the control patients– No HSV-1 or HSV-2 DNA was found in the Ramsey Hunt

or control patients– HSV-1 antibody was present at higher incidence than

controls– Viral antibody titers were not different between the

groups

Viral Hypothesis

• Murakami et al 1996– Still not definitive– Need to identify replicated viral particles in the

affected nerve

Mouse Model

• Mouse model– Induce a transient facial paralysis by inoculating

HSV-1 onto the auricle or tongue of KOS mice (60%)

– Inflammatory lesion within the facial nerve similar to that seen in human Bell’s palsy• Mixed injury of the facial nerve with extensive

demyelination of the distal nerve

– Electrical testing is similar to that seen in humans

Idiopathic Facial ParalysisAKA Bell Palsy

• 20-40 people/100,000 population per year• 7-12% have recurrent Bell Palsy• <2% have bilateral involvement• Most common between age 20-65 yrs of age• Those over 60 yo have worse prognosis for full

recovery (30%)• Children have very high rates of full recovery

(>90%)

Natural History of Bell Palsy

• Peitersen 1982– 1011 patients in Copenhagen, Denmark over 15 yr

period– Examined at onset and then at 1 week intervals

for 1 month then bimonthly exams until complete resolution or 1 yr

– At presentation, 31% had incomplete paralysis, 69% had complete paralysis (non-standardized scale)

Natural History

• Peitersen 1982– Approximately half of patients presented with

pain in addition to facial palsy• 50% had coincident pain• 25% had pain precede palsy• 25% had pain after palsy manifested

– 83% had taste alteration– 71% had hyperacusis– 12% had lacrimal dysfunction

Natural History

• Peitersen 1982– All patients recovered function to some degree– 71% achieved normal facial muscle function– 80% regained taste function– 97% regained lacrimal function– 86% regained stapedial muscle function

Natural History

• Peitersen 1982– Risk factors for incomplete recovery• Diabetes• Pregnancy• Return of function beginning >3weeks from onset of

paralysis• Postauricular pain

Treatment

• Numerous recommended treatments over the years– Medications, surgery, diet, physical therapy,

acupuncture• Viral etiology treated with antiinflammatory

and antiviral therapies• Current treatment investigations involves

corticosteroids, antivirals and surgery

Medical Therapy

• N Engl J Med. 2007;357(16):1598-607– Prednisolone (85%) better than placebo (63%)– Acyclovir+steroid no improvement over prednisolone

alone• Cochrane Database Syst Rev. 2010 Mar 17;(3):CD00

1942.– >1500 pts in 8 randomized studies– Corticosteroids significantly reduced residual weakness

and synkinesis when compared to placebo• Otol Neurotol. 2011 Jan;32(1):141-6.– Improved outcome if started within 48 hours

Steroids

• Currently no consensus treatment regimen for Bell’s palsy– Prednisone 1mg/kg (QD or divided TID) for 10

days followed by a rapid taper– Other studied regimens are:• Prednisolone 25 mg BID x 10 days (NEJM)• Cortisone 200mg QD x3d, 100mg QD x3d, 50mg QD x2d• Methylprednisolone 1mg/kg/day x 10 day with 3-4 day

taper

Antivirals

• Multiple RCT and meta-analyses have failed to demonstrate improved function with antiviral monotherapy or in combination with steroids– Acyclovir 400mg 5x/day– Valacyclovir 1g BID x3-10days

• Cochrane review of 7 studies and 1987 patients did not demonstrate benefit with the addition of antivirals to steroid therapy

Antivirals

de Almeida, J. R. et al. JAMA 2009;302:985-993

Is Medical Therapy the Only Option?

• 10-15% of patients will have some facial nerve sequelae despite maximal medical therapy

• How do we identify these patients?• Is there anything that we can do to improve

their outcome?

Surgery for Bell’s Palsy

• Controversial• First described distal FN decompression in

1932 by Ballance and Duel.– Distal 1 cm of the mastoid segment– Presumed etiology was vascular congestion at the

stylomastoid foramen• Chorda tympani neurectomy• Progressed more proximally along the nerve

until the mid 1960s

Surgery for Bell’s Palsy

• 1961 William House described the MCF technique to approach the IAC and FN

• 1965 Crabtree and House described the MCF for FN decompression in Bell’s palsy and trauma

• 1972 Fisch and Esslen reported on 12 patients undergoing total FN decompression for Bell’s palsy

MCF approach for Bell’s

• Fisch and Esslen 1972– 11 of 12 had involvement of the labyrinthine

segment and geniculate ganglion– 8 of 12 had involvement of the meatal segment– 5 of 12 had involvement of the tympanic segment– 3 patients tested with intraoperative EEMG

demonstrated conduction block proximal to GG at the meatal foramen• Confirm by Gantz et al (‘82) 15/16 had block at meatal

foramen

Anatomic Findings

• Ge and Spector 1981– Anatomic study of the meatal foramen

demonstrating passage way of 0.68mm at the meatal foramen due to tight arachnoid band

ENoG• Less than 90% degeneration

prognosis for HB 1-2 is excellent (90-95%)

• Greater than 95% degeneration within 21 days prognosis for HB 1-2 is only 40-50%.

• Those who progress to 90% degeneration will continue to worsen to the >95% degeneration more than 90% of the time.

• 85% may be prognostic of poor outcome– Clin Otolaryngol. 2006 Apr;31(2):144-

8.– Otol Neurotol 2011; 32(6):1031-1036

ENoG

• Cannot distinguish between axonontmesis and neurontmesis

• Daily testing until day 14 of paralysis

• Rapid progression of degeneration suggests worse degree of injury

• Progression to >95% degeneration after 3 weeks still have good prognosis

Gantz et al 1999

• 37 patients over 15 yrs• Inclusion criteria– Complete facial paralysis– ENoG >90% degeneration– Absent voluntary EMG CMAP– Presentation within 14 days• Early in study presentation within 21 days

Gantz et al 1999

• 3 arms– Medical controls (n=11)

• Steroids 80 mg prednisone x 7 days with taper from days 8-14

– Surgical controls (n=7)• Group of patients operated on early in the study between

14-21 days from onset of paralysis

– Study group (n=19)• Underwent subtemporal craniotomy with decompression

of the distal IAC, labyrinthine, GG and tympanic segments

Gantz et al 1999

Gantz et al 1999

• Steroids only vs intervention group p=0.0003• Steroids vs surgical controls – not significantly

different• <14 days vs >14 days at time of surgery was

significantly different p=0.001• Patients who meet the inclusion criteria and

undergo surgery have a 91% chance of a good outcome at 7 mo

MCF decompression

Right Ear Left Ear

MCF decompression

Right ear Left ear

MCF decompression

Indications for MCF decompression

• Complete facial nerve paralysis (HB 6/6)• Electroneuronography– >90% difference between the affected side and the

normal side• Voluntary electromyography– Absence of voluntary CMAP

• Presentation within 14 days of onset of complete paralysis

• Patient desires operative intervention

Conclusions

• Differential diagnosis for acute unilateral facial paralysis includes more than just Bell Palsy

• Majority of patients with Bell palsy do well with “masterly inactivity”

• Corticosteroids DO significantly improve facial nerve outcomes (HB 1 or 2) over placebo

• Maybe the jury is still out on antivirals• Surgery significantly benefits a small group of

patients with severe Bell palsy

Thank you!