Lecture 12- Integrated cases

Question 1

​Cranial nerve lesions

Answer 1

• damage from the cell body within brainstem or somewhere along its route after its left the brainstem
  
  • Same side of body as the side of the brainstem it comes from (ipsilateral)
  • E.g. left CN III (oculomotor) lesion will manifest itself in the left eye

Question 2

When we think about contra/ipsilateral we are thinking about the

Answer 2

motor cortex nerves which synapse with the cranial nerve (i.e. facial nerve) in the brainste

Question 3

Right motor cortex nerve will synapse with

Answer 3

left cranial nerve and that cranial nerve will supply the left side of the head and neck.

Question 4

when is the forehead spared? In stroke or bells palsy

Answer 4

stroke

Question 5

why is the forehead spared in stroke

Answer 5

• Due to ipsilateral input supplying the forehead
• The right primary motor cortex has a lesion which means there is no signal to the left cranial nerve. However ipsilateral motor cortex (on the right) from the right can supply the forehead- therefore forehead spared.

Question 6

why is the forehead not spared in bells palsy

Answer 6

• Forehead not spared
• No ipsilateral input

Question 7

how was the doctor able to reassure her that her symptoms were not due to a stroke?

Answer 7

• Bells palsy because forehead is not spared
• Left sided palsy
• Left facial nerve

Question 8

to test the integrity of the facial nerve what will the doctor ask the pt to do?

Answer 8

Smile, raise eyebrows, ask to tightly close eyes, purse lips

–> muscles of facial expression

Question 9

other symptoms of facial nerve palsy

Answer 9

• Dry mouth- dry mouth due to parasympathetic supply usually to salivary glands affected
• Tears- lacrimal nerve
• Hearing (nerve to stapedius)- usually dampens hearing- therefore lesion would cause hyperacoustic
• ‘tastes pie, makes you cry, closes your eye, gland’

Question 10

what are the three branches that arise from the facial nerve within the petrous bone (internal acoustic meatus)

Answer 10

• Greater petrosal- salivary glands
• Nerve to stapedius- dampens hearing
• Chorda tympani- taste and parasympathetic

Question 11

why might the doctor want to examine the externala nd middle ear more closely

Answer 11

• Are the vesicles on the outer ear
• Ramsay-hunt syndrome
• Herpes zoster
• To see if there is pathology e.g. infection/ fractured petrous bone that may interrupt facial nerve in middle ear - otoscope
  
  • E.g. blood in the middle ear= Hemotympanum indicates petrous bone fracture
    
    • Tympanic membrane would look blood red

Question 12

giuve 2 reasons why the pts eye might be at risk of drying and injury as a result of a facial nerve lesion? How could this be managed?

Answer 12

• Inability to close eye- palpebral part of orbicularis oculi
• Decreased lacrimation
  
  • Give eye drops
  • Cover eye

Question 13

Answer 13

C- touch on left cornea closure of right eye but not left

• Ophthalmic division of trigeminal (sensory)- she would feel
  
  • shared between eyes - therefore both facial nerves triggered
• Motor output is testing facial nerve