Facial nerve (91-101)

Question 1

Name some causes for UMN and LMN facial nerve palsies;

Answer 1

UMN- strokes, tumours, subdural haematoma, multiple scelosis. LMN- 1. Infective causes- acute otitis media, viral infection (HSV1 [Ramsey hunt], CMV, EBV], 2. Neoplasm- acoutic neuroma, parotid malignancy. 3. Other- Bell’s palsy (most common), sarcoidosis

Question 2

Name three salient differences between UMN and LMN facial nerve palsies;

Answer 2

Forehead sparing = UMN palsy. Forehead paralysis = LMN palsy. UMN = increase tone, rigidity, hyperreflexia. LMN = Hypotonia, hyporeflexia, fasculations

Question 3

What does the marginal mandibular branch of the facial nerve supply?;

Answer 3

Lower lip and depressor anguli oris mucles. Injury results in dropping of lower lip and inability to smile

Question 4

What is the nerve supply to the external ear?;

Answer 4

Great auricular (C2-3 branch cervical plexus), Lesser occipital nerve (C2) and auriculotemporal nerve (branch of mandibular CN V3)

Question 5

What is the blood supply to the ear?;

Answer 5

Anterior- superior temporal (branch external carotid). Posterior- posterior auricular (branch of external carotid) Internal ear- maxillary artery (branch of external carotid artery)

Question 6

Which nerve supply the tempanic membrane?;

Answer 6

External surface- predominantly the auriculotemporal (branch of mandibular CN V3).
External surface contributions- vagus (CNX) and Great auricular (C2-3).

Internal surface- glossopharyngeal (CN IX) via Jacobson nerve

Question 7

What pathologies affect the external ear?;

Answer 7

Infections- otitis externa. Trauma- Auricular haematoma -> result in avascular necrosis (cauliflower ear), kleidoid scar. Cancer- skin cancers

Question 8

Name three signs and symptoms of a patient with acoustic neuroma;

Answer 8

Facial nerve symtpoms (CNVII)- LMN facial palsy (Bells palsy), loss of sensation facial nerve distribution, loss of anterior 2/3rd tongue taste. Vesticulo-cochlear nerve symptoms (CNVIII)- sensory neuro-deafness, loss of balance, vertigo

Question 9

How is acoustic neuroma diagnosed & managed?;

Answer 9

MRI is ix of choice. If <2cm usually asymptomatic and may have survaliance with yearly MRI. If 2-3cm or symtomatic treat with localised radiation / gamma knife. If >3cm requires open surgery.

Question 10

What condition is associated with bilateral acoustic neuromas?;

Answer 10

Neurofibromatous type 1

Question 11

What are the main features of Ramsay Hunt syndrome (Type 2)?;

Answer 11

Ipislateral LMN facial palsy. Vesicles in palate & tongue. Vesicles in ear. Low grade fever.