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m4 ENT > Facial Nerve Disorders > Flashcards

Facial Nerve Disorders Flashcards

1
Q

Innervations of facial nerve

A

Somatic Motor:
1 . Muscles of facial expression
2. Stapedius
3. Posterior belly of digastric
4. Stylohyoid

Somatic Sensory:
1. External ear (small area around concha of auricle)

Special Sensory:
1. Taste to anterior 2/3 of tongue

Parasympathetic
1. Submandibular and sublingual salivary glands
2. Lacrimal gland

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2
Q

Course of facial nerve

A

Arises from pons
-> Internal acoustic meatus
-> Facial canal
= Labyrinthine segment: 1st branch of facial nerve: greater petrosal nerve (lacrimal gland)
-> Tympanic segment: Runs in middle ear behind TM
= Mastoid segment: Branches of facial nerve: Nerve to stapedius and chorda tympani (anterior 2/3 of tongue, submandibular and sublingual glands)
-> Exits facial canal through stylomastoid foramen
= Branches of facial nerve:
Posterior auricular nerve, nerve to posterior belly of digastric, nerve to stylohyoid
-> Pierces parotid gland
-> Divides into 5 terminal branches:
Temporal
Zygomatic
Buccal
Mandibular
Cervical

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3
Q

What nerve runs with chorda tympani?

A

Lingual nerve

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4
Q

Clinical features of CN7 UMN lesions

A
  1. Contralateral weakness of lower half of face
    - Preserved function in contralateral upper face (spares forehead)
    - Loss of contralateral nasolabial fold
    - Drooping of corner of mouth
  2. Sensation of external auditory meatus
    - Unaffected
  3. Corneal reflex
    - Preserved
  4. Stapedius
    - Unaffected
  5. Taste and tears
    - Unaffected
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5
Q

Clinical features of CN7 LMN lesions

A
  1. Ipsilateral weakness of upper + lower half of face
    - Loss of (IP) frontal wrinkling
    - Inability to fully shut (IP) eye
    - Loss of (IP) nasolabial fold
    - Drooping of (IP) corner of mouth
  2. Sensation of external auditory meatus
    - Decreased sensation
  3. Corneal reflex
    - Loss
  4. Stapedius
    - Hyperacusis
  5. Taste and tears
    - Decreased secretion of saliva and tears: Exposure Keratitis
    - Loss of taste in anterior 2/3 of the ipsilateral tongue
    (If lesion is before chorda tympani branches out)
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6
Q

Causes of CN7 UMN lesion

A

Tumour
Stroke: Bleed, infarct
Demyelination disease
Recovering Bell’s palsy (May look like forehead sparing)

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7
Q

Causes of CN7 LMN lesion

A

Behind the ear
- Mastoid surgery
- Mastoiditis
- Cholesteatoma surgery

On
- Ramsay hunt syndrome
- Malignant otitis externa
- Acute/chronic otitis media

Below
- Parotid tumour
- Parotid surgery
- Bell’s palsy
- Temporal bone fracture

Internal
- Middle ear disesae
- Glomus tumours
- Cerebellopontine angle tumour (acoustic neuroma)

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8
Q

Onset of Bell’s palsy

A
  • Clinical Dx, Dx of exclusion
  • Acute onset over a 48-72 hour period
  • Maximal at onset (HB grading should improve and not worsen after that)
  • Unilateral
  • Isolated CN VII palsy
  • No synkinesis or twitching(?)
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9
Q

Recovery progression for Bell’s palsy

A

Start to improve after a few weeks, with recovery of some/all facial function within 6 months
- Residual muscle weakness may last longer

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10
Q

Management of Bell’s palsy

A

Conservative
- Physiotherapy (Facial exercises)

Medical
- Steroids (Prednisolone - Benefit is within 72 hours of onset)**
- Analgesia

Prevention/ Tx of Cx
- Eye care (Lubricating eye drops, tape eyelids shut at night, eye gels at night)
- Refer to Eye if exposure keratitis to do tarsorrhaphy

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11
Q

Investigations for Bell’s palsy only conducted for

A

Only for recurrence/severe Bell’s palsy

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12
Q

Investigations for recurrence/severe Bell’s palsy

A

MRI
Electroneurography (72 hours to 2 weeks)
Electromyography (>2 weeks)

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13
Q

Pathophysiology of Ramsay hunt syndrome

A

Reactivation of latent varicella zoster virus residing in geniculate ganglion with subsequent spread of inflammatory process to involve CN7

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14
Q

Clinical features of Ramsay hunt syndrome

A
  • Acute, persistent vertigo
  • Unilateral
  • Vesicles in ear
  • SNHL
  • Ipsilateral facial nerve palsy
  • Ear pain
  • Nystagmus
  • History of chicken pox
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15
Q

Management of Ramsay hunt syndrome

A
  • Prednisolone
  • Valacyclovir
  • Analgesia
  • Vestibular suppressants
  • Eye care: eye drops, tape eye
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16
Q

Prognosis of Bell’s palsy vs Ramsay hunt syndrome

A
  • Facial palsy usually severe and often doesn’t recover
  • Prognosis POORER than in Bell’s palsy
17
Q

Malignant otitis externa

A

Rapidly spreading infection by P. aeruginosa or S. aureus to temporal bone, middle ear and inner ear
- Osteomyelitis of bony external ear

18
Q

Risk factors of malignant otitis external

A

DM, elderly, immunocompromised

19
Q

Clinical features malignant otitis externa

A
  • Excessive otalgia OUT OF PROPORTION to ear signs, interferes with sleep and function
  • Purulent otorrhea
  • Affects CN 7 first –> CN 8 –> CN 9, 10 as it spreads along skull base –> Ipsilateral CN signs/ facial palsy
  • Otoscopy: Granulation tissue at bony cartilaginous junction of EAC, intact ear drum
  • Does not improve with abx or ear drops

*can DIE if untreated

20
Q

Investigations for malignant otitis externa

A
  • Swab ear canal +/- Biopsy TRO SqCC
  • CT Temporal/ Blood test for inflammatory marker
  • MRI scan to determine extent of soft tissue involvement and differentiate b/w inflammation and tumour (NPC)
  • Bone scan (Gallium): Taken up by polymorphonuclear leukocytes so areas with active infection i.e. osteomyelitis will be hyperintense (Lights up)
21
Q

Management of malignant otitis externa

A
  • Admit
  • Analgesia
  • Intensive pharmacotherapy: IV empirical ciprofloxacin + ceftazidime for at least 6 weeks
  • Control predisposing conditions e.g. DM
  • Aural toilet (microsuction)
  • Surgical debridement of necrotic tissue or bone
22
Q

Impact of facial nerve palsy

A
  • Dry ears, tearing
  • Eating, drooling, drinking
  • Difficulty communication
  • Change in taste
23
Q

Types of deformity seen in facial nerve palsy

A
  • Static (at rest)
  • Dynamic
  • Synkinesis (development of facial movements that were not intended)
24
Q

Examples of synkinesis

A

Eye closure when chewing/eating
Lifting of lips when eye is closed/blinks

25
Q

Grading system for facial nerve palsy

A
  1. House-Brackmann Grading*
    - Difference between 3 (complete) and 4 (incomplete) is by complete eye closure
  2. Sunnybrook facial grading system

Looks at:
- facial region
- static
- dynamic
- synkinesis

26
Q

Facial nerve palsy results in

A
  • Loss of symmetry at rest
  • Loss of symmetry during movement
  • Overcompensation (synkinesis)
27
Q

Static procedures for resting position

A
  • Brow lift for eyebrow position
  • Upper lid blepharoplasty for upper lid ptosis
  • Eye tape
  • Tarsorrhaphy
  • Canthoplasty for excess scleral show
  • Slings for blunted nasolabial fold and depressed angle of mouth
28
Q

Procedures for dynamic movement

A

2 ends present:
- Close together (<1cm): Stitch
- Further away (>1cm): Find another nerve to join the 2 ends together

Proximal end missing:
- Find another nerve it can join to: Masseteric nerve/ Hypoglossal nerve
- Temporalis, masseter or digastric muscles can take over the function of muscles of facial expression

29
Q

Treatment of synkinesis

A
  • Neuromuscular retraining (physiotherapy)
  • Botox
  • Synkinesis surgery
30
Q

Treatment for flaccid paralysis

A
  • Facial massage
  • Stretching exercises
  • Assistive movement
  • Avoid overactivity of normal side
31
Q

Complications of facial nerve palsy

A

EYE
- Eye pain (Exposure keratopathy due to inability close eyes)
- Corneal ulcers
- Red eye
- Bell’s reflex (Upward movement of eye to protect cornea)
- Bogorad’s syndrome: Crocodile tears (Tearing when eating)

MOUTH
- Leakage/ drooling when drinking or eating (Buccinator paralysis)

FACE
- Facial synkinesis (Excessive abnormal and unintended movements)
- Frey’s syndrome (facial sweating and flushing while eating)

32
Q

Examination for LMN facial nerve palsy

A
  • Cranial nerve PE TRO UMN and neuro PE

INSPECT EAR CLOSELY
- Otoscopy to look at EAC and TM/ middle ear/ vesicular rashes
- Rinne’s and Weber’s tests
CHL –> Middle ear pathology
SNHL –> IAM/CPA/Brain pathology

  • Parotid PE for parotid lumps or post-auricular scar suggesting past parotidectomy
  • Signs of trauma (temporal bone fracture)
  • Grading: House-Brackmann grading
33
Q

Complications of Ramsay hunt syndrome

A

Pinna perichondritis
Meningitis
CN9-12 palsies

m4 ENT (25 decks)

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