Unit 14 week 2

Question 1

▪ Gross anatomy of auditory and vestibular systems

• Cochlea
• Semicircular ducts of membranous labyrinth (within canals of osseus labyrinth)

Utricle, saccule

• Include pharynx and temporal bone

▪ Mechanisms of sound transmission within the ear

▪ Mechanisms by which vestibular system detects acceleration and orientation

▪ Sensory transduction by hair cells (auditory and vestibular)

▪ Vestibulocochlear nerve (VIII), including testing

▪ Basics of throat anatomy and speech production

▪ Basis of tests to distinguish conductive from sensorineural hearing deficits Identify and explain common deficits

▪ Discuss how sensory deficits can affect learning, social interactions

▪ Discuss how stigma may affect diagnosis and treatment

▪ Communication across a sensory barrier (e.g. people with hearing deficits)

▪ Students should briefly consider (revise) appropriate use of antibiotics

• Selection (informed by diagnosis)
• Importance of the patient completing the course

Question 3

social impact of hearing problems at a young age

Answer 3

▪ Adults may reduce their interactions through lack of feedback from the child

▪ This can then compound problems by delaying/impairing physical and emotional development

▪ Highlights importance of identifying issue early in life

▪ Children may be unlikely to self-advocate, to understand that they have an impairment, or to seek help

▪ Poor language/communication skills can be interpreted as a lack of intelligence

▪ School staff, and parents, may then reduce their expectations of the child, do not expect them to catch up with their peers, and do not imagine possible causes or corrections

Doctors should try to identify underlying causes of impaired language/communication

Question 4

what does the vestinular system do

whci cells allow it to do these things

Answer 4

The vestibular system detects acceleration (linear/rotational) and gravity, using hair cells

Question 5

which age group are most prone for ear infections

Answer 5

children

Question 6

Eustachian / Auditory / Pharyngotympanic Tube

Answer 6

Equalises pressure between atmopshere and middle ear

▪ Opens with yawning/swallowing

▪ Blockage prevents this

▪ Decongestant can help

▪ Descending flight: pinch nose, close mouth, gently try to blow (Valsalva maneouver); forces air to middle ear, equalising pressure

▪ Children have horizontal, narrower tube, reducing drainage and increasing likelihood of infection

Question 7

how does the vestibular system work?

role of utricle and saccule

Answer 7

Rotational acceleration causes fluid in 3 semicircular ducts to move, which deflects CUPULA, which produces RECEPTOR POTENTIALs in hair cells, which activate vestibular nerve

UTRICLE and SACCULE have hair cells embedded in gel, with calcium carbonate otoconia

Otoliths are weights, which respond to linear acceleration/gravity, and so deflect hair cells

hair cells then activate the vestibular nerve (joins cranial nerve VIII, vestibulocochlear), with vestibular projections going to vestibular nuclei in medulla

Question 9

hearing can be one of 2 kinds

which 2 tests should you use to distinguish between them

Answer 9

Hearing impairment may be conductive or sensorineural (can distinguish using Rinne [rhymes with ‘dinner’] and Weber tuning fork tests; will be shown in practical), or both (mixed hearing loss)

Question 10

auditory transduction pathways for conductive and sensorineural conduction pathways

Answer 10

Conduction: Auditory canal → tympanic membrane → ossicles→ cochlea → basilar membrane

Sensorineural: Hair cells → vestibulocochlear nerve → brainstem → auditory cortex

Tympanic membrane detects vibrations in air (within auditory canal) and communicates to ossicular chain in middle ear

Question 11

what is a grommet

Answer 11

a small tube, inserted into the eardrum and drains fluid discharge from the middle ear to the outer ear- this is a grommet (typically self-extrude within 6 months)

Question 12

what is the standard therapy for acute otitis media

Answer 12

Amoxicillin

Question 13

acute otitis media is most likely caused by whichi 2 organisms

Answer 13

• Streptococcus pneumoniae
• Moraxella catarrhalis

Question 14

chronic otitis media is caused by differnet organisms what are they

Answer 14

Pseudomonas aeruginosa and other Gram-negative non-fermenters

these are not affected by amoxicillin

Question 15

cholesteatoma

Answer 15

A cholesteatoma is an abnormal, noncancerous skin growth that can develop in the middle section of your ear, behind the eardrum.

It may be a birth defect, but it’s most commonly caused by repeated middle ear infections.

A cholesteatoma often develops as a cyst, or sac, that sheds layers of old skin.

A cholesteatoma is an abnormal destructive soft tissue mass (non-neoplastic keratinous cyst). There is debate about its precise nature, but it is not a tumour (and occurs as a result of chronic inflammation or trauma).

Question 16

is this a CT or MRI

Answer 16

CT

Question 17

is this a CT or MRI image

Question 18

How does a hearing aid work?

▪ Does it restore conductive hearing loss or sensorineural? Or Both?

Answer 18

• Some have microphones that detect sound and deliver it (amplified) into the auditory canal; this can compensate for conductive deficits
• For people without an auditory canal/ear, a device can conduct vibration through bone to the cochlea

Question 19

cochlear implants

Answer 19

Cochlear implants can bypass various deficits, including loss of hair cells, and work directly on the cochlear nerve

▪ A microphone device transmits to the implant, which electrically stimulates nerve fibres

▪ It exploits the mapping of sound frequencies along the cochlea

▪ You should consider stigma around hearing aids, for children and adults, with some people being more embarrassed to be seen wearing them, than they are to be seen struggling to follow a conversation

Question 20

Significance of tegmen thinning

Why could destruction of the tegmen be dangerous?

Answer 20

The tegmen is a thin (vulnerable) bony plate separating middle ear from intracranial space

▪ The cholesteatoma has damaged it, but not (yet) perforated it

▪ Infection could spread intracranially to meninges or brain.

Question 21

danger of surgery to (parietal bone?)

Answer 21

• Facial nerve is nearby and exposed
• Vestibulocochlear nerve also here
• Further hearing loss may occur if the cochlear part of the facial nerve is damaged
• Facial nerve complications are possible; the chorda tympani is a collateral from the facial nerve that carries nerve fibres from some of the taste receptors
• Vertigo may result from damage to facial nerve that carries fibres from the vestibular system

Question 22

Acute bacterial infection, if it complicates glue ear, can:

Answer 22

1) Resolve without sequelae
2) Resolve after significant local tissue damage

3) Demonstrate repeated bouts of acute inflammation and damage
4) Lead to chronic inflammation, characterised by a triad of continued tissue damage, continued attempts at tissue repair and continued presence of an inciting agent

Question 23

You should understand distinction between extradural and intracranial abscess

Answer 23

Extradural: between thick dura mater and bone of the skull vault; on imaging has a biconvex shape

Intracranial: anywhere within the skull vault

This could be epidural, subdural (between the dura and arachnoid mater) or intracerebral

Question 24

You should consider the pathophysiology of conduction of infection from extra- to intra- dural spaces and the significance of this change

Answer 24

Can happen where infection causesa breach in the dura mater, allowing infection to spread into subdural space

▪ Would be expected to lead to worse prognosis, with higher mortality risk

▪ During surgery, where the Dura is friable (breakable), it may be difficult to assess whether infection has spread further.

No cerebrospinal fluid (CSF) leakage is a good sign that the dura is intact

Question 25

glue ear

Answer 25

• common condition, especially in children under 8
• For most children, the sticky fluid will drain from inner ear and leave no further effects
• However, when glue ear is persistent/re-occurring, children may not receive the input necessary for normal development of language and literacy skills
• These children can have delayed speech, poor auditory perception and slow language processing speeds which can result in difficulties with learning (For instance it will be hard for them to learn phonics to aid their reading and spelling)
• ▪ Difficulties can remain even after the glue ear has gone, resulting in symptoms consistent with dyslexia