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Otorhinolaryngology > Facial nerve > Flashcards

Facial nerve Flashcards

1
Q

Where does the facial nerve (CN7) originate from within the brain?

A

Lateral surface of the brainstem between the pons and medulla

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2
Q

Through what does the facial nerve pass out out of the cranial cavity?

A

Internal acoustic meatus

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3
Q

Describe the course of the facial canal once it enters the internal acoustic meatus?

A

It follows the facial canal (which is within the petrous part of the temporal bone)

It gives off branches along its course and exits the skull at

the stylomastoid foramen

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4
Q

What branches are given off the facial nerve within the facial canal?

A

1) The greater petrosal nerve
2) Nerve to stapedius muscle
3) Chorda tympani nerve

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5
Q

Describe the course of the facial nerve after exiting the stylomastoid foramen (include the branches)

A

Gives off the posterior auricular nerve (innervates skin behind ear)

It then splits within the parotid into:

To - temporal
Zanzibar - zygomatic
By - Buccal
Motor - marginal
Car - cervical
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6
Q

How do you test the 5 branches of the facial nerve?

A 
To - temporal - Raise eyebrows
Zanzibar - zygomatic - Scrunch up eyes
By - Buccal - Puff out checks
Motor - marginal - clench teeth
Car - cervical - tense neck
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7
Q

What is thought to be the cause of Bell’s palsy?

A

A viral infection of the 7th (facial) nerve

causing swelling of the nerve in the tight facial canal

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8
Q

What % of facial palsies are thought to be due to Bell’s palsy?

A

80%

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9
Q

Describe the onset of Bell’s palsy?

A

Sudden onset

Preceded by URTI

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10
Q

What are Tavener’s criteria?

A

(A way to diagnose Bell’s palsy)

Acute onset

Complete hemifacial palsy (as LMN)

No CNS pathology

No ear pathology

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11
Q

How is Bell’s palsy diagnosed?

A

It’s a diagnosis of exclusion

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12
Q

What is the treatment for Bell’s palsy?

A

If within 48 hrs then treat with:

High dose oral steroids

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13
Q

What is the prognosis for Bells palsy?

A

most resolve

some left with residual weakness

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14
Q

How long before recovery starts with Bell’s palsy?

A

Usually begins with 2 months

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15
Q

What are the most common tumours of the parotid?

A

BENIGN pleomorphic adenomas

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16
Q

How can masses in the parotid affect the facial nerve?

A

It can take out 1, 2, 3, 4 or all 5 of the branches depending on size and location.

Weakness may occur initially

and lead to complete palsy

17
Q

What part of the skull does the facial nerve run across?

A

the posterior cranial fossa

18
Q

Where is a common site of skull base pathology that affects CN 7?

A

the cerebellopontine angle (CPA)

19
Q

If a facial nerve palsy was associated with unilateral hearing loss and tinnitus what would you suspect and why?

A

That there was a mass at the cerebellopontine angle (CPA)

as CN8 (vestibulocochlear) also passes along here with CN7

20
Q

What type of fractures can affect the facial nerve and what is also commonly associated with this and why?

A

Transverse skull fractures (15% affect CN7)

hearing loss and tinnitus are common due to CN8 (vestibulocochlear) involvement

Nerves 9-12 may be affected.

21
Q

What differentiates a lower vs an upper motor neurone lesion of CN 7?

A

If upper motor neurone

the palsy will be contralateral

There will be forehead muscle sparingas each facial nerve supplies both sides

If LMN it is ipsilateral and complete paralysis

22
Q

What is Ramsay Hunt syndrome?

A

shingles causing:

facial palsy and pain

vesicles on ear drum, canal and pinna

23
Q

What are the adverse outcomes of Ramsay Hunt syndrome?

A

Deafness

vertigo

as palsy is severe pt may not recover

24
Q

What is the treatment for Ramsay Hunt syndrome?

A

acyclovir

25
Q

What is the treatment/management for facial palsy?

A

Treat underlying cause

Eye drops as unable to create tear film leading to conjunctival ulceration and blindness

26
Q

What is the job of the greater petrosal nerve?

A

To stimulates the (parasympathetic) secretormotor activity in the lacrimal gland

Convey taste from the palate

27
Q

What is the job of the stapedius muscle

A

To stabilise the stapes

28
Q

What is the job of the chorda tympani nerve?

A

provides taste to anterior 2/3rds of tongue

29
Q

Where is the motor nucleus of the facial nerve located?

A

In the pons

30
Q

What is the counterintuitive way that deep lobe of parotid tumours can present?

A

Oropharyngeal mass which displaces tonsils medially

31
Q

What are the peripheral causes of facial nerve palsy?

A

Trauma (e.g. forceps delivery or penetrating injury)

Iatrogenic (e.g. parotid or submandibular (mannibular nerve) nerve damage from sugery)

Malignant parotid tumours

Inflammatory conditions of the parotid (e.g. sarcoidosis)

32
Q

What are the middle ear causes of facial nerve palsy?

A

Iatrogenic (mastoid and middle ear surgery MUST warn pts of this)

Infection (cholesteatoma, AOM, mastoiditis, herpes zoster)

Tumours

33
Q

What are the signs of cholesteatoma?

A

A MEDICAL EMERGANCY!

Discharging ear and a facial palsy

34
Q

What is the treatment for cholesteatoma?

A

antibiotics

Surgical exploration and excision of cholestiatoma

35
Q

What is the treatment of acute otitis media (AOM)?

A

antibiotics

and often a myringotomy (tiny incision is created in the eardrum) to drain pus

36
Q

What are the petrous temporal bone causes of facial nerve palsy?

A

Trauma (transverse fractures of the skull)

Tumours

37
Q

What are the intracranial bone causes of facial nerve palsy?

A

Tumour (e.g. acoustic neuromas, facial nerve neuromas, meningioma)

Iatrogenic (skull base surgery)

Vascular (stroke)

Neurological (e.g. multiple sclerosis)

38
Q

What are the side variable causes of facial nerve palsy?

A

Bells palsy (lower nerve palsy)

Ramsay-Hunt syndrome

Guillian-Barre syndrome

Otorhinolaryngology (7 decks)

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