Facial Nerve Palsy Flashcards
Where does the facial nerve come from?
The Facial nerve arises from the medulla and emerges between the pons and medulla. It passes through the posterior fossa and runs to the middle ear before emerging from the stylomastoid foramen to pass into the parotid gland.
What functions does the facial nerve have?
Motor control of the muscles of facial expression.
Motor control of submandibular, sublingual, stapedius, and lacrimal glands.
Sensory control of soft palate and taste to anterior 2/3 of the tongue.
What is the route of the facial nerve?
Enters through the internal acoustic meatus into the petrous bone passing very close to the inner ear cavity. Before entering close to the middle ear there is the geniculate ganglion and then the greater petrosal nerves which branch off to the lacrimal glands and nasal/oral mucosal glands. In the middle ear the branch to stapedius is given off. Before leaving through the stylomastoid foramen the chorda tympani branch carrying the parasympathetic to submandibular and sub lingual branches off. After passing through the stylomastoid foramen the facial nerve passes through the parotid gland and then branches into its 5 terminal branches
What are the common causes of facial nerve palsy?
3 groups -
Bilateral
Unilateral LMN
Unilateral UMN
Bilateral/Unilateral
Sarcoidosis
Guillain-Barre syndrome
Bilateral acoustic neuroma (neurofibromatosis type 2)
Bell’s palsy (25% of bilateral but only 1% of all Bell’s palsy)
Unilateral LMN Bell’s palsy Ramsay Hunt syndrome, Lyme’s disease, HIV, TB and meningitis Acoustic neuroma and parotid tumours MS Diabetes Otitis media Cholesteatoma
Unilateral UMN
Stroke
Brainstem tumours
MS
How do UMN and LMN of the facial nerve differ?
Note LMN lesions – complete palsy, UMN lesions are usually forehead sparing are are only really caused by strokes (and MS).
What investigations should be ordered in a patient with a facial nerve palsy?
CRP
Glucose
Lyme disease serology and Herpes zoster serology
Examine parotid
Examine ear for cholesteatoma and Ramsey Hunt Syndrome
CT/MRI if head trauma or suspect SOL
What is Bell’s palsy?
Unilateral facial nerve palsy and represents 70% of all facial nerve palsies. Unclear what the cause is although it is definitely inflammatory causing entrapment of the nerve on its bony canal. Usually 80% recover within 3 months.
What are the main two risk factors for bell’s palsy?
Pregnancy and diabetes
How does bell’s palsy present?
Abrupt – overnight or after a nap Complete weakness by 24-72hours Mouth sag and dribbles Watering or dry eyes Impaired brow wrinkling, whistling, lid closure and cheek pouting Impaired speech and taste Hyperacusis
How is bell’s palsy managed?
Prednisolone PO for 5 days
Protect eye by keeping it well lubricated – drops in day and ointment at night. If eye can’t close, then urgent ophthalmology referral needed.
Prognosis – usually recovered completely within a week if incomplete paralysis occurs. Complete paralysis still has 80% chance of fully recovering.
What is Ramsay hut syndrome?
Herpes zoster oticus, herpes zoster infection of the facial nerve, often in the elderly. Severe otalgia. Other CN also involved sometimes – IX, V and VI.
What are the clinical features of ramsay hunt syndrome?
Otalgia preceding facial nerve palsy Deafness Tinnitus Vertigo Zoster vesicles appears around the ear, in the deep meatus, soft palate and tongue.
How is ramsay hunt syndrome managed?
Aciclovir with prednisolone
