ENT Flashcards
Describe the physiology of the outer ear
the outer ear is air-filled, composed of auricle and auditory canal
Describe the physiology of the middle ear
the middle ear is air-filled and consists of the tympanic membrane (eardrum) and a chain of bones (auditory ossicles) called the malleus, incus, and stapes
Describe the physiology of the inner ear
The inner ear is fluid-filled and consists of three semicircular canals and the cochlea (a spiral-shaped series of three tubular canals containing the organ of Corti/organ of sound)
How do all three parts of the ear work to enable us to hear sound?
The outer ear functions to direct sound waves into the auditory canal
Sound waves traveling through air amplified by tympanic membrane
Sound waves must be converted into pressure waves in fluid in inner ear (cochlea)
Describe the physiology of the cochlea in the inner ear
consists of a series of ducts called the scala vestibuli, scala tympani and scala media
What is the organ of Corti?
The organ of Corti contains inner and outer hair cells, which are the sites of auditory transduction
The bodies of the hair cells are in contact with auditory nerve fibres, and the cilia of the hair cells are in contact with the tectorial membrane
What happens when the hair cells in the inner ear are depolarised?
excitatory neurotransmitter is released to activate afferent cochlear auditory nerves
What happens when the hair cells in the inner ear are hyperpolarised?
afferent cochlear auditory nerves are inhibited
What is the vestibular system?
The vestibular system is used to maintain equilibrium or balance by detecting angular and linear accelerations of the head
What detects the angular rotation of the head in the vestibular system?
Semicircular canals. Mad up of the superior, posterior and horizontal
What detects the liner accelerations of the head in the vestibular system?
detected by the otolithic organs. Made up of the saccule and utricle
Describe how the hair cell causes depolarisation and activation of the nerve fibre
Each hair cell has 50 to 70 small cilia called stereocilia, plus one large cilium, the kinocilium
When the stereocilia bend in the direction of the kinocilium, ion channels open to cause membrane depolarization and activation of the nerve fibre
Describe how the hair cell causes hyperpolarisation and inhibition of the nerve fibre
Each hair cell has 50 to 70 small cilia called stereocilia, plus one large cilium, the kinocilium
Bending the stereocilia backward to the kinocilium closes the ion channel causing membrane hyperpolarization and inhibition of the nerve fibre
What are the three groups of ear infections?
- Outer ear inflammation (otitis externa): conductive hearing loss
- Middle ear inflammation (otitis media): conductive hearing loss
- Inner ear inflammation (labyrinthitis): sensorineural hearing loss causing ‘inner ear dizziness’
What is Otitis Externa ususally caused by?
Bacterial :
Pseudomonas aeruginosa
Proteus mirabilis
Staphlococcus aureus
Fungal:
Candida
Aspergillus
What are the treatment options for ACUTE otitis externa?
- Thorough cleaning with anti-inflammatory corticosteroid ear drops, anti-infective chloramphenicol ear drops, or
astringent such as aluminium acetate.
2% acetic acid solutions (e.g. EarCalm® spray) also used. - Anti-infective (antibiotics): topical antibiotic plus glucocorticosteroid: neomycin/polymyxin plus butamethasone/ dexamethasone/ hydrocortisone
(= otic ear-drop solutions or ear sprays e.g Otomize ® spray)
flumetazone plus clioquinol (e.g. Locorten-Vioform® ear-drops
What are the treatment options for CHRONIC otitis externa?
oral flucloxacillin (or clarithromycin if penicillin-allergic).
IV cephalosporin can be used if patient is systemically unwell.
Antifungal agent: polysorbate, gentian violet, nystatin
What are the BNF cautions with the treatment of otitis externa?
when otitis externa is accompanied by perforated eardrum, aminoglycoside antibiotics (such as gentamicin and neomycin) are contra-indicated as they may cause ototoxicity, although some specialists do use (with caution)
How to treat ear wax?
Using cerumenolytic products such as olive oil, almond oil and sodium bicarbonate drops
How does Otitis media present?
Acute otitis media (AOM) typically presents as a sudden onset of otalgia (ear ache), fever, and hearing loss.
Often preceded by an upper respiratory tract infection lasting for several days.
What is otitis media usually caused by?
Bacterial:
Streptococcus pheumoniae, Hemophilus influenza
Fungal:
Candida
Aspergillus
Viruses
What are the treatment options for ACUTE otitis media?
a) Local cleansing
b) Anti-infective (antibiotics):
a systemic antibacterial is used such as oral amoxicillin (or clarithromycin if penicillin-allergic)
What are the treatment options for CHRONIC otitis media?
oral amoxicillin or IV cephalosporin
What does the BNF guidelines say about the pus present in otitis media infections?
the pus in the middle ear associated with otitis media carries a higher risk of ototoxicity than the drops themselves. Ciprofloxacin or ofloxacin ear drops [both unlicensed; available on named-patient basis from a specialist importing company] or eye drops used in the ear [unlicensed indication] are an effective alternative to aminoglycoside ear drops for chronic otitis media in patients with perforation of the tympanic membrane
What is labyrinthitis and what is it caused by?
Inflamed labyrinth (inner ear)
Associated with vertigo, balance disorder, tinnitus in addition to hearing loss
Caused by bacterial/viral disease but also by stress/ototoxicity
What are the treatment options for Labyrinthitis?
Anti-viral agents: valacyclovir
Treatment of vertigo and nausea: prochlorperazine (dopamine D2 receptor antagonist)
Treatment of symptoms: anxiety (benzodiazepines) and/or depression (selective serotonin re-uptake inhibitors)
Vestibular rehabilitation therapy (VRT)
What are ototoxic drugs the major cause of … (give examples)
Hearing loss
Analgesics - salicylates
Anti-microbials - Gentamicin, Vancomycin
Loop diuretics - Furosemide
What are the three types of nasal conditions?
- Nasal allergy - rhinitis
- Nasal congestion
- Nasal staphylococci
Define Rhinitis and Rhinorrhea
Rhinitis: allergic acute or chronic inflammation of the nasal mucosa (e.g. hay fever)
Rhinorrhea: the production of excessive watery nasal secretions by the nasal mucosa
Why do Rhinitis and Rhinorrhea occur?
Both occur mainly as the result of either:
a) viral infection of the nasal mucosa.
b) an interaction between antigens and tissue-bound IgE antibodies within the nasal mucosa.
