facial nerve palsy
TRANSCRIPT
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