FACIAL NERVE PALSY

JC FlemingENT Specialty Registrar

OVERVIEW Broad spectrum of pathologies Severe functional and psychological

consequences Rapid investigation and treatment of

reversible causes vital Knowledge of anatomy vital to narrow

differential diagnoses

SOME DEFINITIONS Palsy: Complete or partial muscle

paralysis, often accompanied by loss of sensation and uncontrollable body movements or tremors

Paresis: Muscular weakness

Paralysis: Complete loss of muscle function

ANATOMY Brainstem Nuclei

Motor root emerges from lower pons Intracranial

Runs from brainstem to Internal auditory canal Joined here by Nervus Intermedius

IntratemporalFrom Internal auditory meatus to stylomastoid

foramenLabyrinthine segment is narrowest segment of

facial nerve course – susceptible to compression Extratemporal

Divides within parotid gland (TZBMC)

Cranial nerve VII 7, with facial canal highlightedImage:Cranial_nerve_VII.svg by Patrick J. Lynch, medical illustrator

right-sided middle ear space with the external ear canal, eardrum (tympanic membrane) and hearing bones (ossicles) removed

Right-sided middle ear space with the external ear canal, eardrum (tympanic membrane) and hearing bones (ossicles) removed.

The facial nerve is seen to pass horizontally in a path superior to the middle ear, and then turn in an inferior direction and then pass vertically posterior to the middle ear.

Extratemporal course of the facial nerveCourtesy of Patrick J. Lynch, medical illustrator

DEGREE OF NERVE INJURY Neuropraxia

Compression injury; conduction block; complete recovery likely

AxonotmesisAxonal injury but endoneurium preserved;

axon regeneration 1mm/day Neurotmesis

Nerve transection

MANAGEMENT History

Onset Progression

If no recovery after 4-6 weeks, rule out neoplasm Relevant PMH

Recent infection Trauma Surgery Syphilis/HIV/TB history Toxin exposure

Associated features Fever Otalgia Vertigo

Family History Drug History

EXAMINATION Full head and neck examination Full cranial nerve examination

If other neuropathies present, suspect central or systemic cause

Sparing of forehead movement ->central lesion (UMN) due to cross-innervation

If partial localised palsy, suspect parotid disease

HOUSE-BRACKMANN GRADE GRADE I-VI

Detailed grading system Important for prognosis and to monitor

recovery

Remember: Grade I: Normal function Grade VI: Total paralysis Grades II-III: complete eye closure

possible Grades IV-V: incomplete eye closure

OTHER INVESTIGATIONS Bloods

Look for specific causes (see next slide!) Electrophysiology

ENoG, EMG IMAGING

CT (intratemporal portion), MRI

Schirmer test: look for decrease in lacrimation, due to injury of greater superficial petrosal nerve (preganglionic parasympathetic fibres to lacrimal gland)

Stapedial reflex Electrogustometry RARELY USED

CAUSES Many! Apply surgical sieve e.g. TIN CAN MED DIP Or KITTENS K (c)ongenital

Mobius syndrome; myotonic dystrophy I nfection and idiopathic

Bells palsy; Ramsay-Hunt; Otitis media; Meningitis; Lymes disease; TB; HIV; Syphilis

T oxins and trauma Lead poisoning; surgery; temporal bone trauma

T umour Parotid; acoustic neuroma; Meningioma; Glioma; cholesteatoma

E ndocrine Diabetes mellitus; hyperthyroidism

N eurologic Guillain-Barre; MS; CVA

S ystemic Sarcoidosis; amyloidosis

BELL’S PALSY

By James Heilman, MD (Own work) [CC-BY-SA-3.0 (www.creativecommons.org/licenses/by-sa/3.0) or GFDL (www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

BELL’S PALSY Most common cause of paralysis

Paralysis (2/3) or paresis (1/3) of face Sudden onset Absence of intracranial or ear disease

Often: Viral prodrome Dysgeusia (chorda tympani) Hyperacusis (stapedius)

Cause: HSV, microcirculatory failure implicated 70% full recovery by 6 months Degree of paralysis prognostic Treatment: Corticosteroids, Eye protection, (oral

antivirals [controversial])

RAMSAY HUNT SYNDROME CNVII palsy accompanied by a herpes

zoster induced erythematous vesicular rash on the ear or in the mouth.

Worse prognosis than Bell’s Management: Antivirals, corticosteroids

and eye protection

CONCLUSIONS Severe functional and cosmetic

outcomes Wide range of causes REMEMBER eye protection Bell’s palsy most common BUT

diagnosis of exclusion

Symptoms progressive/non-resolving after 4-6 weeks, rule out underlying

malignancy