Facial Nerve Paralysis

Facial Nerve Paralysis
By: Vanessa S. Rothholtz, M.D., M.Sc.
UCI Department of Otolaryngology - Head and Neck Surgery


Chief Complaint
My Starbucks caramel macchiatto dribbled down my chin this morning, and it ruined my white coat. Now my face isn’t working. Do I need a face lift?
History
* Unilateral left-sided otalgia (TMJ)
* Fever, chills
* Headache
* Generalized fatigue
* Conjunctivitis two weeks ago (resolved with antibiotics)
* “My eczema acted up again last week, but it looked a little different.”
* Travel – Sonoma County for a friend’s wedding a last month

Physical
* Eyes: Left eye with injected conjunctiva, pupils equal and reactive
* Ears: EAC patent, TM c/m/i
* Nares: Patent, clear
* OC/OP: Dentition intact, tongue midline / mobile, No tonsillar hypertrophy
* Face:
o Normal tone and symmetry at rest
o Obvious facial asymmetry with effort
o No perceptible forehead movement
o Incomplete eye closure
o Asymmetrical motion of mouth with maximal effort

What grade of paralysis is this based on the House-Brackmann facial nerve grading scale?

House-Brackmann Facial Nerve Grading Scale

I Normal
II Normal tone and symmetry at rest

Slight weakness on close inspection

Good to moderate movement of forehead

Complete eye closure with minimum effort

Slight asymmetry of mouth with movement

III Normal tone and symmetry at rest

Obvious but not disfiguring facial asymmetry

Synkinesis may be noticeable but not severe

+/- hemifacial spasm or contracture

Slight to moderate movement of forehead

Complete eye closure with effort

Slight weakness of mouth with maximum effort


IV Normal tone and symmetry at rest

Asymmetry is disfiguring or results in obvious facial weakness

No perceptible forehead movement

Incomplete eye closure

Asymmetrical motion of mouth with maximum effort

V Asymmetrical facial appearance at rest

Slight, barely noticeable movement

No forehead movement

Incomplete eye closure

Asymmetrical motion of mouth with maximum effort

Differential Diagnosis
V Anomalous sigmoid sinus, benign intracranial hypertension, intratemporal aneurysm of internal carotid artery, embolization for epistaxis (external carotid artery branches)

I Malignant otitis externa, otitis media, cholesteatoma, mastoiditis, meningitis, parotitis, chicken pox, Ramsay Hunt syndrome, encephalitis, poliomyelitis (type I), mumps, mononucleosis, leprosy, HIV/AIDS, influenza, Coxsackie virus, malaria, syphilis, scleroma, TB, botulism, mucormycosis, Lyme disease

T Cortical injuries, basilar skull fractures, brainstem injuries, penetrating injury to middle ear, facial injuries, altitude paralysis (barotrauma), SCUBA diving (barotrauma)

A Temporal arteritis, periarteritis nodosa, Multiple sclerosis, myasthenia gravis, sarcoidosis, Wegener granulomatosis, eosinophilic granloma

M Paget disease, osteopetrosis, diabetes mellitus, hyperthyroidism, pregnancy, alcoholic neuropathy, bulbopontine paralysis, oculopharyngeal muscular dystrophy

I Bell palsy, Melkersson-Rosenthal syndrome (recurrent facial palsy, furrowed tongue), hereditary hypertrophic neuropathy, (Charcot-Marietooth disease, Dejerine-Scottis disease), Landry-Guillain-Barre syndrome, Sarcoidosis, Kawasaki disease, surgery, embolization

N Acoustic neuroma, glomus jugulare tumor, leukemia, meningioma, hemangioblastoma, hemangioma, pontine glioma, sarcoma, hydradenoma, gacial nerve neuroma, teratoma, fibrous dysplasia, von Recklinghausen’s disease, carcinomatous encephalitis, cholesterol granuloma, carcinoma (invasive or metastatic)

C Molding, forceps delivery, myotoic dystrophy, Moebius syndrome

D Vaccine for rabies, Antitetanus serum, mandibular block anesthesia

Course of the Facial Nerve
* Intracranial – Arises at the pontomedullary junction and courses with CNVIII to the internal acoustic meatus - 12mm
* Meatal – Anterior to the superior vestibular nerve and superior to the cochlear nerve – 10mm
* Intratemporal –
o Labyrinthe segment
+ Passes through narrowest part of fallopian canal - 12mm
+ Narrowest part of facial nerve. The most susceptible to compression secondary to edema.
o Tympanic segment
+ From geniculate ganglion to pyramidal turn – 11mm
o Mastoid segment
+ Exits the stylomastoid foramen – 13mm
* Extracranial – From stylomastoid foramen to pes anserinus
The longest segment of the facial nerve is:

A. Vertical of mastoid portion

B. Cisternal portion

C. Tympanic portion

D. Portion in the IAC


Blood supply to facial nerve – clinical relevance
* Courses between the epineurium and periosteum – making the blood supply at risk when mobilizing at the first genu
* Extrinsic
o Stylomastoid artery (branch of the postauricular artery of external carotid artery)
o Greater petrosal artery (branch of middle meningeal artery)
o Internal auditory artery (branch of the AICA)
* Labyrinthe segment - lacks anastomosing arterial cascades thereby making the area vulnerable to ischemia
Work Up

* Basic labs, thyroid function panel, Lyme titers ELISA for antibodies
* Audiogram
* Stapedial reflex
* EKG
* MRI with gadolinium / CT
* Nerve Excitability Test, Maximal Stimulation Test, Electroneuronography (EnoG) - Useful 72 hours post-injury

Topognostic Testing
* Schirmer test for lacrimation
* Stapedial reflex test (stapedial branch)
* Taste testing (chorda tympani nerve)
* Salivary flow rates and pH (chorda tympani)
Schirmer Test
* Greater superficial petrosal nerve
* Filter paper is placed in the lower conjunctival fornix bilaterally
* 3- 5 minutes
* Value of 25% or less on the involved side or total lacrimation less than 25 mm is considered abnormal.
Stapedial Reflex
* Stapedius branch of the facial nerve
* Most objective and reproducible
* A loud tone is presented to either the ipsilateral or contralateral ear  evokes a reflex movement of the stapedius muscle  changes the tension on the TM (which must be intact for a valid test) resulting in a change in the impedance of the ossicular chain
* If intact stapedial reflex, complete recovery can be expected to begin within six weeks
* Absence of the stapedial reflex during the first two weeks in Bell’s Palsy is common


Taste Testing
* Chorda tympani
* Extremely subjective
* Papillae generally disappear within 10 days post injury - middle 1/3 of the tongue is most indicative, because the anterior 1/3 may receive bilateral input.

Salivary flow rates
* Chorda tympani
* Cannulation of Wharton's ducts bilaterally
* 5 minute measurement of output
* Significant if 25% reduction in flow of the involved side as compared to the normal side
* Salivary pH Flow Rate
Nerve Excitability Test (NET)
* Most predictive prognostic factor for recovery of facial nerve function*
* Hilger nerve stimulator over stylomastoid foramen
* Reflects elevated thresholds for neuromuscular stimulation due to degeneration / disruption of axons (comparison to contralateral side)
* Difference > 2.5 milliamps - poor prognosis

Nerve Excitability Test (NET)
* Benefits:
o Easy to perform
o More comfortable for patient
* Drawbacks
o Subjectivity (relies on operator’s visual detection of response)
o May exclude smaller fibers (current thresholds are likely to selectively activate larger fibers with lower thresholds and not those smaller fivers closer to stimulating electrode)

Maximal Stimulation Test (MST)
* Electrical impulse administered to saturate the nerve with current and to compare it to contralateral side
* Test is repeated periodically until definitive response
* Response
o Equivalent to contralateral side
o Minimally diminished (50%)
o Markedly diminished (< 25% of normal)
o Absent
* Symmetric response within first ten days – complete recovery in > 90%
* No response within first ten days – incomplete recovery with significant sequelae
* Superior to NET - test becomes abnormal sooner, but drawback is subjectivity
Evoked electromyography (EEMG) or Electroneuronography (EnoG)
* Records compound muscle action potential (CMAP) with surface electrodes placed transcutaneously in the nasolabial fold (response) and stylomastoid foramen (stimulus)
* Waveform responses are analyzed to compare peak-to-peak amplit`udes between normal and uninvolved sides where the peak amplitude is proportional to the number of intact axons
* Most reliable in first 2-3 weeks post event (as neuropraxic fibers recover or regenerate, they discharge asynchronously and the response is subsequently diminished)
* Response < 10% of normal in first 3 weeks – poor prognosis
* Response > 90% of normal within 3 weeks of onset – 80-100% probability of recovery
* Testing every other day
* Advantages: Reliable
* Disadvantages:
o Uncomfortable
o Cost
o Test-retest variability due to position of electrodes
Electromyography (EMG)
* Measures post-synaptic membrane di/triphasic (polyphasic) potentials with voluntary muscle contraction that are present 6-12 weeks prior to visible return of function
* Assesses reinnervation potential of muscles two weeks after onset
* Limited value early in evaluation because fibrillation potentials indicating axonal degeneration do not appear until 10 – 14 days post onset
* Detection of motor units in 2 of 3 muscle groups – 87% satisfactory outcome
* Detection of motor units in 1 muscle group – 11% satisfactory
More Methods
* Antidromic (retrograde) Conduction – F-waves represent activated motor neurons in facial muscles.
* Transcranial magnetic stimulation – Enables central activation via a transcranial application of induce current via an electromagnetic coil
* Trigeminofacial Reflex – Records action potentials reflexively generated in the orbicularis oculi muscle in response to an electrical stimulus applied to V1
Lyme Disease - Borrelia Burgdorferi

* Ten percent of patients have facial nerve paralysis after 1-4 weeks incubation period
* ELISA to search for IgG and IgM antibodies
* Facial paralysis resolves in 6 to 12 months
* Treatment
o Early antibiotics
# Reduce symptoms
# Event long-term sequelae
o Children - IV penicillin, ceftriaxone or cefotaxime
o Adults - tetracycline
o Muscular therapy
Bell’s Palsy
* 60-70% cases
* Pathophysiology – Impaired “axoplasmic” flow from edema of facial nerve within fallopian canal
* Rapid onset and evolution < 48 hours
* May be associated with acute neuropathies of cranial nerves V- X
* Pain or numbness affecting ear, mid-face, tongue and taste disturbances
* Recurrences are more likely (2.5x) in patients with family history, immunodeficiency or diabetes
Bell’s Palsy Treatment
* Oral antivirals - Acyclovir - 10mg/kg (500mg) q8hrs x 7 days
* Corticosteroid taper 1mg / kg / day for 10 days
* Eye protection - lacrilube
* Follow progression with serial exams
* Facial nerve decompression
+ Progression to > 90% degeneration on ENOG
+ Performed before irreversible injury to the endoneural tubules occurs (two weeks), will allow for axonal regeneration to occur
Treatment of Bell’s Palsy with Steroids: A controversial closer look
* Steroids may have the following effects:
o Reduce risk of denervation
o Preventing / lessening synkinesis
o Preventing progression to complete paralysis
o Hastening recovery
* Controversy:

Ramsay Hunt Syndrome
Herpes Zoster Oticus (Ramsay Hunt syndrome)
* 10-15% of acute facial palsy cases
* Lesions may involve the external ear, the skin of EAC or soft palate
* Associated symptoms – hearing loss, dysacusis and vertigo
* Additional involvement of CN V, IX and X and cervical branches 2, 3 and 4
* Pathogenesis – Neural injury due to edema at point between the meatal foramen and the geniculate fossa in the labyrinthe segment
Acute Otitis Media
* History and physical exam make the diagnosis
* Palsy is progressive over 2 to 3 day period
* Infectious agent – Staphylococcus non-aureus, Propionobacterium
* CT temporal bone
* Treatment
o Myringotomy
o Otic antibiotic drops containing topical steroids
o IV antibiotics and steroids
o If not improved… mastoidectomy
Möbius Syndrome
* Most frequently sporadic
* Congenital facial weakness with impairment of ocular abduction
* Dysfunction of other cranial nerves – III, IV, IX, X, XII
* Skeletal abnormalities (orofacial, limb malformations)
* Pathogenesis – Genetic cause vs. Ischemic cause
Melkersson-Roenthal syndrome
* Triad
* Lips become chapped, fissured and red-brown in appearance
* Biopies identify granulomatous changes
* Facial nerve decompression may be indicated if facial paralysis is severe and recurrent
Neoplastic

* About 5% of cases of facial nerve paralysis are caused by tumors
* Characteristics of facial nerve palsy
+ Slow developing
+ Additional cranial nerve deficits
+ Recurrent ipsilateral involvement
+ Adenopathy
+ Palpable neck or parotid mass
* Most common benign tumor - facial nerve schwanomma
* Most common malignant tumors - mucoepidermoid carcinoma and adenoid cystic carcinoma of the parotid gland.

Temporal Bone Fractures
* Longitudinal fractures
o 80% incidence but 10-20% with facial nerve injury
* Transverse fractures
o 20% incidence, but 50% with facial nerve injury
* Most common site of fracture
o Perigeniculate region
* Penetrating injury to extratemporal facial nerve branches
* Injuries medial to a line perpendicular to the lateral canthus do not need to be explored because they recover spontaneously (draw please)
* Immediate paralysis after injury lateral to this line needs to be explored and repaired with an end-to-end anastomosis 48-72 hours after the initial injury
Sunderland Nerve Injury Classification
* I Neuropraxia
o Conduction block from compression and loss of axonic flow
o Complete recovery
* II Axonotmesis
o Axon disrupted but endoneurium preserved
o Wallerian degeneration occurs distal to site of injury
o Complete recovery
* III Neurotmesis
o Complete disruption of axon including its surrounding myelin and endoneurium
o Wallerian degeneration
o Unpredictable outcome – High risk for synkinesis
* IV Complete disruption of perineurium
* V Complete disruption of epineurium
o Risk of a neuroma from nerve sprouts outside of nerve sheath

A patient with facial nerve injury following a gunshot wound to the temporal bone typically presents with which of the following symptoms?

A. Midface branch paralysis

B. Complete facial paralysis

C. Forehead paralysis

D. Partial weakness of the facial nerve

What if the facial paralysis doesn’t resolve?
* End-to-End Anastomosis
* Cable Nerve Graft
* Hypoglossa-Facial Nerve Anastomosis (Crossover or Jump Graft)
* Muscle transposition (Gracilis)
* Static Suspension (Gortex, Threads)

Complications

* Keratitis
* Emotional/Social Issues
* Synkinesis

Facial Nerve Paralysis.ppt