Post on 17-Dec-2015
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