Ear disorders and testing ear function Flashcards
What causes Ramsay Hunt syndrome?
Reactivation of VZV
in the geniculate ganglion of the CN7 facial nerve
What happens to the ear in Ramsay Hunt syndrome?
Vesicular rash on upper pinna
and external auditory meatus
Why is there a vesicular rash on the upper pinna and external auditory meatus in Ramsay Hunt syndrome?
Due to the facial nerve carrying sensory information from this part of the ear
What is a pinna haematoma?
Bleeding between the cartilage and perichondrium of the pinna
What causes a pinna haematoma?
Trauma
What are the complications of a pinna haematoma?
Necrosis of the cartilage in the pinna
Cauliflower deformity
What causes necrosis of cartilage in the pinna in a pinna haematoma?
Cartilage is avascular, perichondrium carries it blood supply
if blood accumulates between the two, separates the two
cartilage suffers avascular necrosis
What causes a cauliflower deformity of the pinna?
After necrosis of cartilage in pinna
fibrosis occurs
new asymmetrical cartilage may form
both as part of healing
How is a pinna haematoma treated?
Drain the blood from the pinna
re-align the cartilage and the perichondrium to give it back its blood supply
How can wax in the external auditory meatus affect ear function?
If it builds up and blocks the external auditory meatus
prevents sound vibrations reaching tympanic membrane
loss of hearing
What is otitis externa?
Inflammation of the external auditory meatus
What are the signs and symptoms of otitis externa?
External auditory meatus is red swollen painful contains exudate, discharge
What are the causes of otitis externa?
Infection
Allergy
What can predispose to otitis externa?
Swimming
Skin problems e.g. dermatitis (eczema)
What can cause perforation of the tympanic membrane?
External pressure
Inernal pressure due to infection of middle ear
increased pressure in middle ear
pushes against tympanic membrane
How is a perforated tympanic membrane treated?
It resolves itself
What can cause bulging of the tympanic membrane?
Infection of middle ear
increased pressure in middle ear
What is otosclerosis?
Ossicles fuse with each other where they normally articulate with each other
Which ossicle is most commonly affected by otosclerosis?
Stapes
What does stapes fuse with in otosclerosis?
Its base plate fuses with the oval window
How does otosclerosis of stapes with the oval window affect ear function?
Reduced vibration of stapes against oval window
loss of hearing
What is hyper-acusis?
Sensitivity to loud noises
What is one of the causes of hyper-acusis?
Problems with nerve to stapedius of facial nerve
reduced function of stapedius muscle
doesn’t control vibrations of stapes base plate against oval window when loud sounds are heard
What causes otitis media with effusion?
Reduced function of eustachian tube
increased negative pressure in middle ear cavity
draws transudate fluid out of mucosa lining middle ear cavity
What does otitis media with effusion predipose to?
Acute otitis media
How does otitis media with effusion affect ear function?
Reduced vibrations of tympanic membrane, ossicles
loss of hearing
How does otitis media with effusion affect the tympanic membrane?
Is retracted
because the negative pressure in the middle ear cavity draws it inwards
How is otitis media with effusion treated?
May resolve itself in a few months
Or use grommets
How do grommets treat otitis media with effusion?
Drain away fluid
Ventilate middle ear cavity to equilibriate pressure in it with atmospheric pressure
What causes acute otitis media?
Infection of the middle ear
What age group is acute otitis media more common in?
Children
Why is acute otitis media more common in children?
Eustachian tube is shorter and more horizontal
easier for infection to travel from nasopharynx to middle ear
also easier for tube to become blocked, leading to otitis media with effusion, increased risk of acute otitis media
What causes blockage of the eustachian tube in children?
Enlarged adenoids, pharyngeal tonsils
What are the signs and symptoms of acute otitis media?
Otalgia, pain of ear
Tympanic membrane is red, bulging
Fever
What are the complications of acute otitis media?
Tympanic membrane perforation
Facial nerve damage
Mastoiditis
Intracranial problems
Why can acute otitis media damage the facial nerve?
Because the facial nerve passes through the internal auditory meatus, facial canal
near the middle ear
Why can acute otitis media lead to mastoiditis?
Because the middle ear is within the petrous part of the temporal bone
continuous with the mastoid air cells
infection can spread from the middle ear into these mastoid air cells
Why can acute otitis media lead to intracranial problems?
Because the middle ear is within the petrous part of the temporal bone
close to the meninges, sigmoid sinus
infection can spread from middle ear into them
What are the signs of symptoms of mastoiditis?
Behind the ear, it is
red
swollen
painful
Ear is pushed forwards
What is choelasteatoma?
Abnormal skin growth in a retracted pouch of the tympanic membrane
What are the causes of a cholesteatoma?
Reduced function of Eustachian tube
negative pressure in middle ear
draws tympanic membrane and skin inwards
Chronic ear infections
How does a cholesteatoma affect ear anatomy?
Erodes structures it comes into contact with
e.g. ossicles
mastoid process
What are the signs and symptoms of cholesteatoma?
Painless otorrhea
Hearing loss
Why does cholesteatoma give painless ear discharge?
Cholesteatoma predisposes to infection of middle ear
Why does cholesteatoma give hearing loss?
Prevents vibrations in external auditory meatus reaching tympanic membrane
Reduces vibrations of tympanic membrane
What is otorrhea?
Ear discharge
What causes Meniere’s disease?
Increased fluid in inner ear
affects the stereocilia on the hair cells in the spiral organ of Corti and sterocilia on hair cells in vestibular apparatus
What are the symptoms of Menier’s disease?
Vertigo
Tinnitus
Hearing loss
What is vertigo?
Sensation of room spinning
What is tinnitus?
Ringing in the ears
What causes benign paroxysmal positional vertigo?
Calcium crystals in the fluid of the vestibular apparatus
What is the main symptom of benign paroxysmal positional vertigo?
Short episodes vertigo every time the person moves their head
What is the explanation for the main symptom of benign paroxysmal positional vertigo?
Every time move head
calcium crystal in semicircular duct moves due to effect of gravity
this keeps moving stereocilia on hair cells even after head is still
What is meant by labyrinthitis?
Inflammation of the vestibular apparatus of the inner ear
What is meant by conductive hearing loss?
Hearing loss due to problem in external auditory meatus, tympanic membrane, ossicles
What is meant by sensorineural hearing loss?
Hearing loss due to problem in cochlea, cochlear part of CN8 vestibulocochlear nerve, primary auditory cortex
What examinations are done for a patient with hearing loss to determine what type of hearing loss it is?
Tuning fork tests
What are the types of tuning fork tests?
Rinne’s test
Weber’s test
How is Rinne’s test done?
Tuning fork ringing next to ear
Tuning fork ringing with base at mastoid process
How is Weber’s test done?
Tuning fork ringing with base at top of head
What is meant by air conduction?
Conduction of sound through air in external ear, middle ear to cochlea
What is meant by bone conduction?
Conduction of sound through temporal bone to cochlea
How does air conduction compare to bone conduction normally?
Air conduction is louder than bone conduction
What are the results of Weber’s test with conductive hearing loss in one ear?
Sound is louder in affected ear
What are the results of Weber’s test with sensorineural hearing loss in one ear?
Sound is louder in unaffected ear
What are the results of Rinne’s test with conductive hearing loss in one ear?
Bone conduction is louder than air conduction
What are the results of Rinne’s test with sensorineural hearing loss in one ear?
Air conduction is louder than bone conduction
What are some examples of causes of conductive hearing loss?
Wax
Otitis externa
Otitis media with effusion
Otosclerosis
What are some examples of causes of sensorineural hearing loss?
Meniere’s disease
Presbyacusis
What is meant by presbyacusis?
Sensorineural hearing loss in people older than 55 years
What are the complications of mastoiditis?
Meningitis
Temporal lobe abscess
Sigmoid sinus thrombosis