Lecture 2 Pathology Flashcards
What is a conductive hearing loss?
This is when external or middle ear conditions lead to a conductive hearing loss. The cochlea is not affected but there are problems conducting sound energy to it. With CHL, there are no issues with speech discrimination so hearing aids work well.
What are sensory hearing losses?
These are normally permanent and result from cochlea damage e.g. reduced number of inner and outer hair cells as you get older. SHL tend to be greater in the higher frequencies and have both recruitment and speech discrimination problems.
What are neural hearing losses?
This is caused by damage to the auditory nerve. Symptoms include no typical hearing loss pattern and speech discrimination is often very poor.
What is otitis externa?
This is an umbrella term for general infections or irritations of the external ear canal.
What are the 5 potential causes of otitis externa?
- Bacteria e.g. swimmer’s ear.
- Viral
- Fungal
- Trauma
- Dermatitis
What are the 4 types of otitis media?
- Acute Suppurative Otitis Media
- Chronic Suppurative Otitis Media
- Serous Otitis Media
- Otitis Media with Effusion (OME) aka Glue Ear
How does Acute Suppurative Otitis Media present?
This is a bacterial infection, possibly resulting from a throat infection and the bacteria has travelled up the eustachian tube into the middle ear.
Initially a mild hearing loss with some pain and then rapidly progresses into increased conductive hearing loss and excruciating pain.
The ear drum is an angry red and in severe cases, white pus in the middle ear causes the ear drum to bulge outwards.
The ear drum can sometimes burst and the pus will drain into the ear canal. If the child goes to ENT, they will put a small slit into the perforation and drain the pus away.
How does Chronic Suppurative Otitis Media present?
This follows on from acute SOM which has not been resolved and the infection becomes chronic because it produces irreversible changes to the middle ear mucosa.
There will be a hearing loss and persistent and smelly discharge.
In pictures, the thickened edge of the infection implies it has been there a long time.
How does Serous Otitis Media present?
This happens when the eustachian tube is blocked and the middle ear cavity is unable to aerated. This causes the middle ear pressure to rise and water clear/straw coloured fluid is seen from the middle ear cleft.
There is a hearing loss and blocked feeling in the ear, clicking or popping type tinnitus.
The ear drum is usually retracted due to the negative pressure in the middle ear cavity.
How does Glue Ear (OME) present?
This is caused by a prolonged blockage of the Eustachian tube and failure to aerate the middle ear cavity. Often developing from a cold or middle ear infection e.g. AOM.
Very common from birth up to 6 years old with a hearing loss. However, mainly characterised by the presence of a thick and sticky mucoid effusion in the middle ear with a retracted ear drum.
What is the management of Acute Suppurative Otitis Media?
Antibiotics for the infection and painkillers for the pain.
In severe cases, when the tympanic membrane is bulging because of the pus under pressure, an incision is made in the ear drum and the pus is drained to relieve the pressure.
What is the management of Chronic Suppurative Otitis Media?
Keep water out of ears to avoid further infections.
The overt infection needs treating with aural toilet, antibiotic drops and suction.
Small central perforations may close spontaneously. However, larger perforations may require a myringoplasty. This is when a small piece of skin from another body part of artificial skin is used to cover the hole of the large perforation.
With marginal perforations, infections need to be treated and monitored for the presence of cholesteatoma.
What is the management of Serous Otitis Media?
“Watchful waiting”.
Allergy tests.
Advice on dust and avoid exposure to cigarette smoke.
What is the management for Glue Ear?
Auto-inflation - a nose balloon that tries to reopen the eustachian tube by blowing air into it.
If problem does not resolve, Grommets are an option. This is a grommets tube inserted into the ear drum to keep the middle ear aerated. They prevent the reoccurrence of glue ear and stay in place for 3-18 months. As the ear drum grows, the grommets tube grows outwards towards the ear canal and falls out.
Hearing aids and classroom management are good options too.
What are the characteristics of a safe perforation?
A central perforation in the pars tensa of the tympanic membrane which doesn’t involve the attic region/annulus.
They do not spread the ear infection to other parts of the body.
Can be pinhole in size or cover the total central area of the ear drum.
How do you manage a safe perforation?
Keep the ear dry.
Infection may need antibiotic treatment.
Small perforations often heal themselves or larger perforations may require tympanoplastic surgery (using a piece of skin to cover the hole of the perforation).
What are the characteristics of an unsafe perforation?
A perforation that involves the annulus or attic region of the ear drum.
They are considered ‘unsafe’ because they can lead to the spread of infection e.g. cholesteatoma.
Can be very small or cover the whole of the ear drum.
What is Otosclerosis?
This is a progressive disease where an overgrowth of the spongy bone around the stapes footplate causes the stapes to lock in place, meaning it cannot vibrate back and forth to deliver sound energy to the cochlea.
What is the presentation of Otosclerosis?
A typically bilateral hearing loss.
May be tinnitus and sometimes vertigo.
The person is often conscious they hear better in noisy environments.
What is Presbycusis?
This is an acquired sensory hearing loss, most common in older people.
It is caused by the loss of sensory hair cells, nerve cells and other aging processes within the cochlea.
How does Presbycusis present?
- Bilaterally
- Symmetrically
- Sensory hearing loss
- Loss of high frequency sounds initially
- Slowly progressive
What is noise induced hearing loss?
This is when a person experiences prolonged exposure to loud noises e.g. working in a factory or a nightclub. It damages the stereocilia on your IHC + OHCs so over time they no longer stand up straight and become bent.
Why is most noise induced hearing damage seen at 4,000Hz on audiograms?
Our outer ear resonances are boosting the decibels between 2-5,000 Hz which includes speech but also if you’re working in a noisy factory at 4,000 Hz, your outer ear is also boosting this sound so the noise is even more intense. Hence why the most damage is caused at 4,000Hz.
What is recruitment of hearing?
Recruitment is a reduced dynamic working range of hearing.
Typically the working range of hearing is from about 0dB to 100dB as 100dB is when sounds get uncomfortably loud.
So if someone can only begin hearing sounds at 40dB and up to 100dB, they have recruitment of hearing because their working hearing range is decreased to only 60dB.
