Lecture 21: Ear Disease and Hearing Loss Flashcards
Describe the Eustachian Tube
- Tube which links the back of the nose to the middle ear. When you pop your ears (yawning), you get air that travels from back of nose to middle ear.
- Provides environment which equalise pressure in the middle ear compared to the ear canal, so that tympanic membrane is always suspended in neutral.
- Negative pressure in middle ear, ear drum sucked in, hearing might be reduced.
- Positive pressure (over pressure by popping ear too much), ear drum will be sucked out (rare).
Describe the pathway fromt he cochlear to the brain
E COLI
- After the cochlea, sound gets transmitted by eighth nerve to cochlear nucleus (nucleus for hearing), fibres cross over and go to olivary tract up to lateral lemniscus and then to inferior colliculis to cortex
What are the different types of hearing loss?
1) Conductive (e.g. ear canal, ear drum, hearing bones)
2) Sensorinueral (e.g cochlea, hearing nerves)
3) Mixed (conductive + sensorineural)
4) Central disorders
Can range from mild, moderate, severe and profound
What are some consequences to hearing loss?
- Speech and language deficits
- Learning difficulties
- Auditory processing difficulties
- Academic achievement
- Low self-esteem and confidence
- Social isolation
- Reduced employment opportunities
- Safety: alarm etc.
What is this?
- White area is cholesteatoma with infection around it.
- A cholesteatoma is an abnormal, noncancerous skin growth that can develop in the middle section of your ear, behind the eardrum.
- Skin building up on the wrong side of the ear drum, which is a result of eustachian tube dysfunction.
- Negative pressur_e in middle ear, e_ar drum gets sucked into middle ear space. Keratin accumulates and starts to expand causing chronic infection, which destroy structures and cause hearing loss and other complications.
- Patient who came in with a brain abscess due to chronic middle ear disease (can get intracerebral, extradural, subdural but also sigmoid sinus thrombosis) which can lead to death.
What sort of information should you get from taking a history with a patient?
History
- Age
- Severity
- Duration
- Onset: rapid/gradual, constant/fluctuating
- Precipitating factors (e.g. trauma, noise, drugs)
- Past and family history
- Associated symptoms: tinnitus, vertigo, fullness, headaches
What sort of Examinations would you undertake if someone presents with hearing loss?
1) Check inside the ear using a Otoscopy (auriscope).
With the otoscope, you look through the ear canal at the whole tympanic membrane (4 quadrants). Make sure you see pars flaccida which is the top part of the tympatic membrane. Often this is where you wil find middle ear disease and cholestatoma.
2) Whisper Test/Clinical test of hearing
Mask one ear (e.g. by scratching paper in one ear). Then whisper into the ear that is not masked (e.g. 20-30dB, which is normal hearing)
3) 512Hz Tuning Fork Testing (Weber and Rinner Tests)
3a) Weber test is by placing tuning fork on the middle of the forehead (testing via bone conduction). In a normal patient, they can hear the sound equally in both ears. (Use the other hand to push the back of the forehead)
3b) Rinne test is by placing tuning fork behind patient’s ear on mastoid process and in front just next to the pinna.
- Positive (normal) test is when louder in front compared to back since air conduction should be greater than bone conduction.
- Negative (abnormal) test is when the patient hears sound louder at the back (bone conduction greater than air conduction).
- You can stimulate conductive hearing loss by sticking finger into the ear canal, so you couldn’t hear the tuning fork in front but could hear in the back (negative Rinne test).
What sort of investigations would you do if someone presents with hearing loss?
1) Air conduction audiogram (pure tone, visual reinforcement, soundfield)
The audiogram is a chart of hearing sensitivity with frequency charted on the X axis and intensity on the y axis (see images shown above). Intensity is the level of sound power measured in decibels; loudness is the perceptual correlate of intensity.
2) Otoacoustic emissions
- Used as a measure of inner ear health as studies have shown OAE disappear after inner ear has been damaged. More common in children. There are actually sounds produced by the hearing ear. When machine send a sound to ear, get vibration and hair cell movements, recording the echo coming back from the ear which has a specific curve (OAE).
- In kids if they have OAE, we expect them to have normal hearing but there are exceptions. In some cases OAEs are not representative, e.g. neurological problems or brain problems (absent hearing nerve) but still have normal OAE which can be misleading (should never be the only test done on a child).
3) ABR (auditory brainstem response)
Screening test on netonates with electrodes attached, produce sounds and record the brain response)
- Screening test on neonates with electrodes attached, produce sounds and record the brain response
4) CT, MRI
Undergo once established hearing loss.
5) ENG, Electrocochleography
6) Bloods e.g. VDRL
7) Genetic testing
8) Cardiac, renal, ophthalmology consult
- All the regions develop at the same time in the young children, problem in one can indicate problem in others. (Kidneys develop at a similar time to the ears)
- 20~25% of people with hearing loss also have problem with their eyes.
How do you determine between conductive and sensorineural hearing loss?
If someone has Conductive Deafness (impaired ear canal), it shows…
- Air-bone gap
- Rinne test negative, Weber test referred to the deaf ear
- Tympanogram shows low compliance
- Reflexes absent with impedance probe in deaf ear
If someone has Sensorineural hearing loss, it shows…
1) No air-bone gap
Rinne test positive, Weber test referred to better ear
Normal tympanogram
The difference (or gap) between these two lines plotted on your audiogram is the air [conduction] – bone [conduction] gap or air- bone gap for short. For example, if your audiogram showed an air- conduction hearing loss of 70 dB while your bone-conduction test results only showed a 40 dB hearing loss for a given test frequency, then the difference between them in this case would be an air-bone gap of 30 dB (70 – 40 = 30).
Conductive Deafness can be caused by
- Stiffness, scar, bone;
- Laxity, infections, injury;
- Fluid;
- Perforation.
Sensorineural deafness can be caused by _______
- Cochlear problems:
- Congenital (genetic or acquired).
- Stable (manage consequences).
- Sudden or fluctuant (urgent treatment).
- Progressive (pattern may be flat, low tone (recruitment & noise intolerance), high tone, U-shaped)
- Neural problems:
- Poor discrimination
- Reflex decay
- Consider acoustic neuroma (schwannoma) if one-sided or if there is family history.
Briefly describe 6 Clinical examples of Conductive Hearing loss
- Otitis Media With Effusion (“Glue Ear”) (first pic)
Common in children 1-4 years
Infection/inflammation (e.g. upper respiratory tract) causing e_ustachian tube dysfunction_ (negative pressure)
Effusion (thick fluid that never clears). Significant impairment of hearing.
- Mastoiditis (baby pic)
Mastoid cells become infected or inflamed, often as a result of an unresolved middle ear infection (otitis media). Because so many vital structures pass through the mastoid, infection may spread outside of the mastoid bone and cause s_erious health complications_.
Medical emergency (possible surgery and antibiotics)
Hearing loss is secondary. Redness behind the ear, loss of folding behind the ear, ear sticks forwards.
- Sigmoid sinus runs through this (major sinus draining into jugular vein coming from brain), can form thrombus (thrombophlebitis). Penetrating veins and arteries which you can get infections to the brain (subdural, extradural and intracerebral abscesses).*
1. Tympanic Membrane Perforation
Consequence of otitis media, trauma include surgery
- Subtotal perforation, eardrum is missing looking straight into the middle ear.*
- Need repair but not until child is 7 or 8 years old (risk of ear infection), might need hearing aid until it can be repaired.*
1. Microtia/Atresia
Normal cochlea (develops in first 8 weeks in-utero)
External ear has not developed properly (no ear canal), so m_aximum conductive hearing loss_
Can still use the ear by using bone anchored hearing aids that bypass the middle ear by vibrations (use bone conduction).
- If external ear is not normal, there can be possibly something wrong with internal ear sturctures as well.*
1. Pinna, Ear Canal, Middle Ear
9 year old with poor hearing, worse on the right (right maximum conductive hearing loss with normal cochlea)
Weber R, Rinne both –ve
Audiogram shows conductive hearing loss on both sides (worse on right) with normal cochlea reserve (arrow).
- Middle Ear Tumour (Glomus Tumour)
37 year old female with ulsatile tinnitus (e.g. due to carotid arteries (pass cochlear), jugular bulb, or tumour?) and decreasing hearing.
Weber R, Rinne +ve
Normal audiogram! (possibly tinnitis)
Tumour in the middle ear close to the ossicles. Glomus tumour is most vascular tumour you can get. Very good blood supply often directly from the carotid.
Can have hereditary problems, whereas tumours also somewhere else in the neck on the other side as well as in the adrenal glands. (Not common but something you shouldn’t miss!)
Describe Otitis Media With Effusion
(“Glue Ear”) (first pic)
Common in children 1-4 years
Infection/inflammation (e.g. upper respiratory tract) causing eustachian tube dysfunction (negative pressure)
Effusion (thick fluid that never clears). Significant impairment of hearing.
Conductive Hearing Loss
Describe Mastoiditis
Mastoid cells become infected or inflamed, often as a result of an unresolved middle ear infection (otitis media). Because so many vital structures pass through the mastoid, infection may spread outside of the mastoid bone and cause serious health complications.
Medical emergency (possible surgery and antibiotics)
Hearing loss is secondary. Redness behind the ear, loss of folding behind the ear, ear sticks forwards.
Sigmoid sinus runs through this (major sinus draining into jugular vein coming from brain), can form thrombus (thrombophlebitis). Penetrating veins and arteries which you can get infections to the brain (subdural, extradural and intracerebral abscesses).
What is this?
Mastoiditis
Mastoid cells become infected or inflamed, often as a result of an unresolved middle ear infection (otitis media). Because so many vital structures pass through the mastoid, infection may spread outside of the mastoid bone and cause serious health complications.
Medical emergency (possible surgery and antibiotics)
Hearing loss is secondary. Redness behind the ear, loss of folding behind the ear, ear sticks forwards.
Sigmoid sinus runs through this (major sinus draining into jugular vein coming from brain), can form thrombus (thrombophlebitis). Penetrating veins and arteries which you can get infections to the brain (subdural, extradural and intracerebral abscesses).
