Session 7 Flashcards
What are symptoms and signs of ear pain?
- Otalgia - ear pain, can be referred
- Discharge
- Hearing loss (conductive or sensorineural)
- Tinnitus - perception of hearing sound with no external source
- Vertigo - hallucination of movement
- Facial nerve palsy - facial nerve runs through petrous bone
What makes up the external ear?
- Pinna seen on outside of head
- External auditory meatus (ear canal)
- Skin-lined
What makes up the middle ear?
- Air filled cavity
- Ossicles
- Lined with respiratory epithelium (pseudostratified columnar ciliated epithelium with goblet cells)
What is the tympanic membrane?
- Boundary between external and middle ear
What connects the middle ear to the nasopharynx?
- Pharyngotympanic tube (Eustachian tube)
What are the names of the ossicles found within the middle ear?
- Stapes
- Malleus
- Incus
What makes up the inner ear?
- Cochlea
- 3 semi-circular canals orientated at 90o to each other
- Fluid filled
Which nerve carries special sense for hearing and balance?
- Vestibulocochlear nerve
Why is the ear a common site of referred pain?
- Many nerves that carry general sensation from the ear also carry general sensation from other parts of the body
- Pathology of these sites can be interpreted by the body as ear pain
Branches of which nerves can cause referred pain to the ears?
- Cervical spinal nerves (C2/C3)
- Vagus
- Trigeminal (auriculotemporal)
- Glossopharyngeal (tympanic)
- Small contribution from CN VII
What other conditions could be responsible for otalgia if the ear is normal on examination?
- TMJ dysfunction (trigeminal nerve branch C)
- Diseases of oropharynx (glossopharyngeal nerve)
- Diseases of larynx and pharynx including cancers (glossopharyngeal and vagus nerves)
What is the role of the external ear?
- Collects, transmits and focuses sound waves onto the tympanic membrane
- Tympanic membrane vibrates
What can cause pinna abnormalities?
- Congenital
- Inflammatory
- Infective
- Traumatic
If a patient presented with facial palsy and a painful red ear with vesicles, what would your diagnosis be?
- Ramsay-Hunt syndrome
What is perichondritis?
- Occurs due to infection involving cartilage of ear
- Provides blood supply to cartilage
- Caused by ear piercing or insect bites
- Ear can be painful, red or swollen
- Treat with antibiotics
What is pinna haematoma?
- Accumulation of blood between cartilage and its overlying perichondrium
- Due to blunt injury so common in contact sports
What kind of haematoma is a pinna haematoma?
- Sub perichondral haematoma
- Blood strips perichondrium off cartilage
- Deprives cartilage of blood supply
- Blood pushes against cartilage
- Leads to pressure necrosis of tissue
How is pinna haematoma treated?
- Drainage (aspirate with a needle)
- Prevent reaccumulation of blood/ re-apposition of two layers
What happens if a pinna haematoma is left untreated?
- Fibrosis
- New asymmetrical cartilage development
- Cauliflower deformity
What epithelium lines the external acoustic meatus?
- Keratinising, stratified squamous epithelium
- Continuous onto lateral surface of tympanic membrane
Describe the structure of the external acoustic meatus
- Outer 1/3 is cartilaginous
- Inner 2/3 are bony
- Sigmoid shape
Describe the cartilaginous part of the external acoustic meatus?
- Hair, sebaceous and ceruminous glands line cartilage part
- Acts as a barrier to foreign objects
- Ceruminous glands produce ear wax
Outline the self-cleaning function of the external acoustic meatus
- Desquamation and skin migration
- Laterally off tympanic membrane out of canal
- Keeps ear canal free of debris
What should you see on a normal otoscopic view?
- Cone of light
What common conditions can affect the external acoustic meatus?
- Wax/foreign bodies
- Otitis externa
What causes otitis externa?
- Also known as swimmer’s ear
- Moisture in external acoustic meatus becomes a breeding ground for bacteria
- Treated with antibiotics
What is malignant otitis externa?
- Very rare
- Potentially life-threatening
- Infection becomes invasive and erodes bone of ear
What are common abnormalities of the tympanic membrane?
- Bulging secondary to bacterial acute otitis media
- Build-up of pus and exudate in middle ear causes tympanic membrane to bulge into external acoustic meatus
- Otitis media with effusion
- Tympanic membrane retracted (sucked inwards) due to air bubbles when fluid accumulates in middle ear cavity
What is cholesteatoma?
- Retraction of pars flaccida of tympanic membrane forms a sac/pocket
- Traps stratified squamous epithelium and keratin
- This proliferates
- Forms cholesteatoma
- This slowly grows and expands
What leads to cholesteatoma?
- Chronic eustachian tube dysfunction
- Negative pressure created
- Pulls pocket into middle ear
What are the symptoms of cholesteatoma?
- Painless, often smelly otorrhea (ear discharge)
- Hearing loss
What are the more serious consequences of cholesteatoma?
- Enzymatic bony destruction
- Erode ossicles, mastoid process, petrous bone, cochlea
What is the middle ear?
- Air filled cavity
- Between tympanic membrane and inner ear
- Contains ossicles
How are ossicles connected?
- Via synovial joints
What is the function of the middle ear?
- Amplifies and relays vibrations from tympanic membrane to oval window of cochlea
- Transmits vibration to waves in a fluid medium
What tampers ossicle movement?
- Tensor tympani
- Stapedius
- These muscles contract if excessive vibration due to loud noise
- Protective
- Acoustic reflex
What is otosclerosis?
- Ossicles fused at articulations due to abnormal bone growth
- Particularly occurs between base plate of stapes and oval window
- Sound vibrations cannot be transmitted effectively to cochlea
- One of the most common causes of acquired hearing loss in young adults
What causes otosclerosis?
- Both genetic and environmental causes
- Exact cause unknown
How does otosclerosis present?
- With gradual unilateral or bilateral conductive hearing loss
What controls the pressure of the middle ear?
- Mucous membrane of middle ear continuously reabsorbs air in middle ear causing negative pressure
- Eustachian tube allows equilibration of pressure within middle ear cavity with atmospheric pressure
- Also allows ventilation and drainage of mucus from middle ear
What is otitis media with effusion (glue ear)?
- Not an infection
- Due to Eustachian tube dysfunction
- Fluid and negative pressure in middle ear
- Decreases mobility of tympanic membrane and ossicles
- Hearing affected
How is otitis media with effusion treated?
- Most resolve spontaneously in 2-3 months
- If it affects speech and language development or school performance, grommets are used
What is acute otitis media?
- Acute middle ear infection
- More common in infants/children
- Mostly viral aetiology
What are the signs and symptoms of acute otitis media?
- Otalgia (infants may pull/tug on the ear)
- Other non-specific symptoms e.g. temperature
- Red bulging tympanic membrane
- Loss of normal landmarks
What bacteria can cause acute otitis media?
- Streptococcus pneumoniae
- Haemophilus influenzae
Why are children more susceptible to getting acute otitis media?
- Eustachian tube is shorter and more horizontal in infants
- Easier passage for infection from nasopharynx to middle ear
- Tube can block more easily e.g. due to adenoid enlargement in children
- Compromises ventilation and drainage of middle ear
What are the complications of acute otitis media?
- Tympanic membrane perforation
- Facial nerve involvement
- Mastoiditis (rare but potentially life-threatening)
- Intracranial complications (meningitis, sigmoid sinus thrombosis, brain abscess)
What is mastoiditis?
- Middle ear cavity communicates with mastoid air cells via mastoid antrum
- Middle ear infections can spread into mastoid bone via this route leading to mastoiditis
- Swollen area seen behind ear
- Ear turns forward
Which parts of the brain can be affected by ear infection?
- Temporal lobe
- Meninges
What structures are found within the inner ear?
- Cochlea
- Vestibular apparatus
What is the function of the cochlea?
- Fluid movement is generated by footplate of stapes
- Converted into action potentials in CN VIII
- Perceived as sound at temporal lobe
What is the function of the vestibular apparatus?
- Fluid movement is generated by position and rotation of head
- Converted into action potentials in CN VIII
-Perceived as position sense and balance
How does inner ear pathology present?
- Sensorineural hearing loss
- tinnitus
- Disturbances in balance and vertigo
What is the cochlea?
- Fluid filled tube
- Specialised hair cells generate action potentials when moved
Where are the specialised cilia of the cochlea found?
- Organ of corti
Outline how we hear
- Auricle and external auditory canal focuses and funnels sound waves towards tympanic membrane
- Membrane vibrates
- Vibration od stapes at oval window sets up vibrations/movement in cochlear fluid
- Sensed by stereocilia in cochlear duct
- Movement of stereocilia in organ of Corti trigger APs in cochlear part of CN VIII
- Primary auditory cortex
What is the vestibular apparatus?
- Fluid-filled tubes with specialised hair cells (stereocilia) that generate action potentials
- Includes semi-circular ducts, saccule, and utricle
How does vestibular apparatus allow us to perceive and maintain our sense of balance?
- Moving position pr rotation of head moves fluid
- Stereocilia bend
- Action potentials generated via CN VIII
- Brain perceive signals as sense of balance
What is presbycusis?
- Sensorineural hearing loss associated with old age
- Bilateral
- Gradual
- Corrected with hearing aids
What is benign proximal positional vertigo?
- Vertigo only
- Short-lived episodes
- Triggered by movement of head
- Caused by crystals forming in vestibular apparatus - when these dislodge they cause movement of fluid in canals
- Dix-Hallpike manoeuvre (diagnosis)
- Epley manoeuvre (treatment)
What is Meniere’s disease?
- Vertigo, hearing loss and tinnitus (typically unilateral)
- May also describe ‘aural fullness’, and nausea and vomiting
- Symptoms longer lasting (30 mins up to 24 hrs)
- Recovery in between recurrent episodes
- Hearing may deteriorate over time and dip during episodes
Compare acute labyrinthitis and acute vestibular neuronitis
- History of URTI
- Acute labyrinthitis involves all inner ear structures and is associated with hearing loss, tinnitus, vomiting and vertigo
- Acute vestibular neuronitis usually causes no hearing disturbance or tinnitus
- Sudden onset of vomiting and severe vertigo (lasting several days)
What is a gross hearing assessment?
- Whispering a word or number
- Patient repeats it back
- Ear not being tested is masked
Which tuning fork tests are used to test hearing?
- Weber’s and Rinne’s test
- Determines if hearing loss is sensorineural or conductive
What is conductive hearing loss?
- Pathology involving external or middle ear
E.g. - wax
- acute otitis media
- otitis media with effusion
- otosclerosis
What is sensorineural hearing loss?
- Pathology involving inner ear structures or CN VIII
E.g. - Presbycusis
- Noise-related hearing loss
- Meniere’s disease
- Ototoxic medications (furosemide, gentamycin, vancomycin)
- Acoustic neuroma
