Facial Nerve Disorders

Sarah Mowry, M.D.University of Iowa Temporal Bone Course

March 22, 2011

Disclosures

• I wish!

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

• List causes of chronic facial paralysis

• Discuss presentation of facial schwannoma and its treatment

Facial Nerve Anatomy

Right Ear Left Ear

Facial Nerve Anatomy

Facial Nerve Anatomy

• Tortuous course through from the brainstem to the periphery

• Root entry zone – Pontomedullary junction• Fibers to the upper division of the face cross the

midline to provide bilateral innervation• Extrapyramidal innervation of the facial motor

nucleus responsible for emotional facial control• Also contributions from the trigeminal and

cochlear nuclei

Facial Nerve Anatomy

• Nervus Intermedius (Nerve of Wrisberg) carries parasympathetic fibers and sensory division of CN VII

• Preganglionic parasympathetic fibers to lacrimal, submandibular and sublingual glands• Sensory fibers include the special visceral afferents of

taste • Chorda tympani carries SVA fibers AND the

preganglionic parasympathetic fibers to the salivary glands

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

Further Classification

Unilateral vs Bilateral• Acute

– Various definitions– Generally weakness occurs

over days– Does not progress after 2-3

weeks

• Chronic– Weakness progresses slowly

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

insuffiency 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– Viral 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– Induce a transient facial paralysis by inoculating

HSV-1 onto the auricle or tongue of KOS mice– Inflammatory lesion within the facial nerve similar

to that seen in human Bell’s palsy

Ideopathic 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):

CD001942.– >1500 pts in 8 randomized studies– Corticosteroids significantly reduced residual

weakness and synkinesis when compared to placebo

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

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

• 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

Indications for MCF decompression

• Complete facial nerve paralysis (HB 1/6)• Electroneuronography– >90% difference between the affected side and the

normal side• Voluntary electromyography– Absence of voluntary CMAP

• Presentation within 12 days of onset of complete paralysis

• Patient desires operative intervention

Chronic Facial Paralysis

• Congenital– Mobieus

syndrome– Birth trauma– Myotonic

dystrophy• Toxic– Thalidomide– Lead

poisoning

• Neoplastic– Schwannoma– Hemangioma– VS– Glomus– Metastasis– Leukemia– Parotid

tumors

• Systemic– DM– EtOH

neuropathy– Osteopetrosis– CMT– MS– Amyloidosis– Paget’s

disease

Congenital Facial Paralysis

• May be due to birth trauma– Shoulder dystocia– Forceps delivery

• Mobeius syndrome– Bilateral dysfunction of CN VI an VII– May have other CN anomalies (V and VIII)– Limb and chest wall abnormalities also occur

Congenital deafness and FN weakness

Facial Nerve Tumors

• 5% of facial palsy is caused by a tumor• Most common cause is a parotid neoplasm– 85% are salivary in origin, 15% are schwannoma

• Most common intratemporal primary FN tumors are:– Schwannoma– Hemangioma– Other rare tumors are granular cell tumor and glomus faciale

• Secondary FN tumors: SCCA, RMS, ELST, metastasis, Langerhan’s cell histiocytosis

FN Hemangioma

• Hamartomatous growth of blood vessels around the FN– First described in 1969 by

Jack Pulec– Geniculate ganglion, IAC and

2nd genu are most common locations

– May cause symptoms even when small• Thought to be a vascular steal

ischemia

Case 1

• MM 82 yo female with sudden onset right facial paralysis approx 6 mo ago

• Paralysis slowly improved but did not return to normal

• Felt that her face was “tight”• Family noticed a “twitch” around the right eye• Also noticed a decrease in hearing during the

same time period

Case 1

• She had a tarrsorphy and canthoplasty when her face did not return to normal function

• On examination she had right facial hypertonicity with mass movement on forceful eye closure

FN Hemangioma

• Symptoms– Recurrent facial nerve paralysis followed by recovery

with hypertonicity and significant synkinesis is suggestive of these lesion

– Other symptoms are hemifacial spasm, recurrent facial paralysis

– Sensorineural hearing loss is out of proportion to the size of the lesion due to early erosion into the basal turn of the cochlea• Brackmann has postulated this due to cochlear vascular

steal

FN Hemangioma

• HEI reviewed their 20 yr experience with geniculate ganglion hemangioma– 18 patients– 89% with progressive facial weakness coexistent

with synkinesis (17%) and twitching (56%)• Degree of palsy was moderate to severe at presentation

(HB 3-6/6 in 62%)

– SNHL was present in 22%

Otol Neurotol. 2010 Jun;31(4):665-70.

FN Hemangioma

• ENoG findings did not correlate well with clinical findings– 2 pts with HB 1/2 had ENoG >90% degeneration• May be due to dysynchronous firing

• 5/6 patients demonstrated both denervation and renervation activity of EMG– This is characteristic of FN hemangioma

Otol Neurotol. 2010 Jun;31(4):665-70.

FN Hemangioma

CT• CT scan demonstrates

erosive lesion centered at geniculate

• Classically have intratumoral calcifications

• Lamellar hemangiomas have layers of calcium depostion in the tumor walls

MRI• MRI will demonstrate an

avidly enhancing lesion at the geniculate

• May demonstrate enhancement of the facial nerve distal and proximal to the geniculate

FN Hemangioma

• Treatment– Observe– Resection• Partial resection with FN preservation• Total resection with FN preservation• Total resection with FN sacrifice

– No evidence to support or condemn radiation– No consensus about the extent of surgical

resection

FN Schwannoma

• Most common neoplastic growth of the facial nerve– True incidence is unknown

FN Schwannoma

• Schwannoma arise from axonal supporting cells (Schwann cells)

• Vast majority are benign, but there are case reports of malignant tumors of the FN

FN Schwannoma

• Arise eccentrically from the nerve trunk• Can arise anywhere along the course of the

facial nerve• Frequently produces multiple areas of swelling

of the nerve– Not necessarily multifocal as tumor can be

identified between the nodules– “beads on a string”

FN Schwannoma

• CPA and IAC lesions– Present with history/physical and radiographic

findings c/w vestibular schwannoma– May be impossible to distinugish FN from VS until

time of operation

Case 2

• SB is a 48 yo woman presented with unilateral tinnitus and mild asymmetric SNHL of the right ear for 1 year.

• On examination, her facial nerve function was completely normal bilaterally

Case 2

• Underwent a MCF approach for hearing preservation resection of a presumed VS

• Intraoperatively it was apparent the tumor arose from the facial nerve as no plane existed between the tumor and FN

• The bulk of the tumor was removed and a small cuff of tumor was left on the nerve

• Post operatively her FN function was 3/6 which had recovered to 1/6 by 1 month post op

FN Schwannoma

• Most common location is extratemporal• Intratemporal locations are: tympanic and vertical

segments and geniculate ganglion• Tumors within the fallopian canal are apt to cause facial

weakness– Progressive and sometimes intermittent facial weakness is

typical• Proximity of the membranous labyrinth results in fistulae of

the cochlea and SSC• Tumors in the tympanic and mastoid segments may cause a

conductive hearing loss by impinging on the ossicular chain

FN Schwannoma

• Evaluation– History and Physical exam– Audiogram• Reflex testing may be helpful

– Radiology– CT and MRI are complimentary

Radiology

CT• HRCT with thin sections• Bony erosion or widening of

the fallopian canal • May demonstrate

labyrinthine or cochlear fistula

• Changes may be subtle in small lesions

MRI• T1WI – heterogeneous and

hypointense to brain• Avidly enhancing with

gadolinium contrast• Dumbbell appearance

– IAC and middle fossa connected via the labyrinthine segment

• Beads on a string

Case 3

• JB is a 62 yo woman with a 4 year history of right blepharospasm and 18 mo of gradual right facial weakness

• Complained of bilateral hearing loss but worse on the right

• She had some mild dysequilibrium but no vertiginous episodes

• She had right sided headaches but no other focal neurologic deficits

Case 3

• HB 3/6 • + spasm of the right obicularis oculi• Rinne + bilaterally; Weber to the left

Case 3

• Underwent a translabyrinthine-transtemporal resection of the lesion

• Tumor penetrated the dura of the middle fossa and was intraparenchymal

• FN stump was positive for tumor at the porus• Had a Greater Auricular nerve graft from CPA

to the tympanic segment

FN Schwannoma Treatment

• 3 factors affect treatment choices– Site of the lesion– Extent of the lesion– Hearing status of both ears

• Treatment options– Observation – Decompression surgery– Surgical resection– Radiation

Schwannoma Surgery

• Depends on the location of the tumor– Transmastoid – descending segment, some parotid

lesions– Transmastoid/middle fossa – labyrinthine

segment, geniculate ganglion, some tympanic segment lesion

– Translabyrinthine – any segment and gives direct exposure of the nerve from brainstem to periphery

Summary

• Bell Palsy most common cause of acute facial paralysis

• Most will recover regardless of treatment

• Small percentage will benefit from surgical decompression

• Must have a high index of suspicion for FN tumors

• Further investigation is warrented in any patient with a nonresolving facial weakness