ENT 1 Flashcards
what is the outer ear consisted of?
The outer ear is air-filled
Composed of auricle (Pinna) and the auditory canal
what does the middle of the ear consist of?
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 (hammer, anvil and stirrup)
-and eusthachian tube
what does the inner ear consist of
The inner ear (labyrinth) is fluid-filled and consists of the vestibular system (three semicircular canals and the vestibule) and the cochlea (a spiral-shaped series of 3 tubular canals containing the organ of Corti / organ of sound)
what is the ear physiology and how does it effect hearing
The outer ear functions to direct sound waves into the auditory canal
Sound waves travelling through air amplified by tympanic membrane
Sound waves transmitted from air-filled middle ear must be converted into pressure waves in fluid in inner ear (cochlea)
Cochlea controls hearing whilst vestibular system controls balance – both work by mechanical to electrical signal transduction
The Organ of Corti contains inner and outer hair cells, which are the sites of auditory transduction
Inner hair cells are responsible for signalling to the brain via the cochlea nerve, outer hair cells act as amplifiers
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
Vibration of basilar membrane activates inner and outer hair cells (sensory receptors) by causing bending of stereocilia (next slide)
When inner hair cells are depolarized, excitatory neurotransmitter (glutamate) is released to activate afferent cochlear auditory nerves
When inner hair cells are hyperpolarized, afferent cochlear auditory nerves are inhibited (next slide – also true for hair cells in vestibular system - later)
what does cochlea consist of?
The cochlea consists of a series of ducts called the scala vestibuli, scala tympani and scala media
Scala vestibuli and tympani are filled with perilymph, whilst scala media filled with endolymph, and which contains the organ of corti
what is the Hair cell function
Hair cells have stereocilia (left) – largest known as kinocilium (vestibular system)
Hair cells typical resting membrane potential more depolarized than neuron (from ~-45/-50mV to -60/-65mV)
High potential difference between endolymph (+80mV) + perilymph (0mV)
Bending stereocilia towards the largest stereocilium / kinocilium mechanically opens ion channels causing influx of K+
This causes hair cell depolarization that leads to influx of Ca2+ via Voltage-gated calcium channels (VGCC)
This leads to neurotransmitter release (glutamate, shown in white) and activation of the afferent nerve fibres
Bending the stereocilia backward away from the largest stereocilium /kinocilium closes the ion channels, leading to hair cell hyperpolarization and inhibition of the afferent nerve fibres
Activation leads to signals to the brain (synapses to nuclei in brainstem then from there to other brain regions such as cortex (e.g. auditory cortex for cochlea hair cells), cerebellum and cranial nerves (vestibular) – see later
Afferent and efferent connections. Different for inner and outer hair cells of cochlea
what is the vestibular system used for
The vestibular system is used to maintain equilibrium or balance by detecting angular and linear accelerations of the head
- Angular acceleration is detected by semicircular canals
- Linear acceleration & gravity is detected by the otolithic organs (utricle (horizontal) and saccule (vertical) acceleration)
what does the movement of stereocilia cause?
Semicircular canals and otolithic organs have specialized epithelium with hair cells that function much as described for cochlea
Movement of stereocilia leads to downstream signalling to the brain with information on position and movement
what are possible conditions of the ear?
Ear wax build up (not infection/condition)
Outer ear inflammation (otitis externa): conductive hearing loss
Middle ear inflammation (otitis media): conductive hearing loss
Inner ear inflammation (labryinthitis and vestibular neuronitis/neuritis): sensorineural hearing loss causing inner ear dizziness
what are the common drugs used in the management of ear disorders?
Antibiotics (neomycin, flucloxacillin, amoxicillin, clarithromycin, erythromycin – see also Autumn term PM2A2)
Anti-histamines (cinnarizine, cyclizine, promethazine teoclate – see also Autumn term PM3A)
Anaesthetics (lidocaine – see also Autumn term PM3B)
Analgesics (paracetamol, ibuprofen – see also Autumn term PM3B),
Anti-fungals (clotrimazole – see also Autumn term PM3A)
Anti-infectives (clioquinol)
Anti-inflammatories (corticosteroids – dexamethasone, flumetasone; NSAID – phenazone [also analgesic and anti-pyretic] – see also Autumn term PM3A)
Astringents and acids (aluminium acetate and acetic acid)
Cerumenolytic agents (olive oil, almond oil, sodium bicarb, sodium chloride, arachis oil, urea hydrogen peroxide)
D2 receptor antagonists (prochlorperazine – see also Spring term PM3B)
how is the ears examined?
Otoscopes used to examine ear canal and tympanic membrane
Usually monocular
Can visualise e.g., bulging or perforation of tympanic membrane
what is the symptoms, diagnosis, treatment and advice for ear wax(outer year)
Symptoms: Impacted ear wax can cause: earache, hearing loss (common), discomfort, tinnitus, itchiness etc. and make examination of ear difficult
Diagnosis: By examination of ears with otoscope
If need to remove:
Cerumenolytic products act by softening ear wax (cerumen)
Usually 3-5 days of ear drops as first option (soften, help remove)
Simple remedies – olive or almond oil 3-4x daily; sodium bicarbonate (5%) or sodium chloride (0.9%) ear drops (off-label use)
If unsuccessful can try irrigation (drops and irrigation can be repeated)
Don’t insert anything else into ear to remove (e.g. cotton buds)
Other commercial options but not in NICE guidelines: Urea Hydrogen Peroxide 5% w/w
Regular use of drops can prevent build-up
- which bacteria/fugus causes otitis externa
2.what are the signs and symptoms
3.what is the diagnosis
4.what is the treatment options (acute) - what are the cautions
- Inflammatory disease typically caused by:
Bacteria (**P. aeruginosa & S. aureus most common, others e.g. S. epidermidis, P. mirabilis) or
Fungal (Candida and Aspergillus) infection.
- Signs: red, swollen ear canal, cellulitis, erythema of tympanic membrane
Symptoms: pain or tenderness tragus/pinna (can be jaw pain), itching (canal), discharge, hearing loss (less common)
- Diagnosis: on signs (2+) & symptoms (1+)
- Treatment - Self-care advice: For all cases, if necessary remove ear wax, keep clean and dry
Acute otitis externa
Often mild and self-limiting. Any pain can be treated with simple analgesia (paracetamol or ibuprofen)
Analgesia for pain (paracetamol/ibuprofen), rarely requires oral antibiotics
Consider OTC 2% acetic acid solution (e.g. EarCalm® spray) anti-fungal + anti-bacterial action
Other preparations such as astringent aluminium acetate (8% or 13% drops)
Anti-inflammatory corticosteroid ear drops (0.5% prednisolone sodium phosphate (less potent) or 0.1% betamethasone sodium phosphate)
Anti-infective: can use clioquinol (antifungal and antiprotozoal)
- In combination with flumetasone pivalate
Topical antibiotics may be considered: can use 7-14 days topical antibiotic with/wo topical corticosteroid:
- e.g. Gentamicin drops 0.3% (Genticin®)
- neomycin sulfate +/- dexamethasone (such as Otomize® spray – also has 2% acetic acid POM)
Anti-fungals: can use 1% clotrimazole solution
- cautions
If there is a perforated eardrum, aminoglycoside antibiotics (e.g. gentamicin and neomycin) are contra-indicated (can cause ototoxicity), although some specialists do use with caution
what is chronic otitis externa
signs and symptoms
treatment depending on cause
Chronic otitis externa
Signs: conductive hearing loss; dry scaly skin or red moist skin in ear canal; fluffy debris, hyphae, dots of black debris in the ear canal if fungal
Symptoms: constant itching in ear
If fungal infection suspected: topical antifungal e.g., clotrimazole 1% solution; OTC acetic acid 2% drops or spray (off label); corticosteroid + clioquinol drops (see previous slide)
If bacterial infection suspected: treat as acute otitis externa
If no signs infection: topical corticosteroid (see previous slide for examples)
what is the treatment for systemic otitis externa infection
- If systemic/infection spread beyond ear canal (cellulitis), may prescribe oral antibiotics, e.g., 7-d oral flucloxacillin (or clarithromycin if can’t have penicillin)
what is the treatment for severe infection of otitis externa
- For severe infection may take swab to ID organism(s).
If spreading cellulitis or systemically unwell, can consider oral flucloxacillin 7 days (or clarithromycin if penicillin-allergic).
May need e.g. ciprofloxacin if Pseudomonas
- what is the cause of otitis media ACUTE (middle ear)
- symptoms
3.diagnosis - treatment
- Cause: Acute otitis media (AOM) occurs when eustachian tube become swollen/inflamed or blocked (common in young children)
Inflammation typically caused by viruses but can be bacterial (e.g. - Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes, Moraxella catarrhalis, can also be e.g., Staph. Aureus, Proteus spp)
- Traps fluid in middle ear which can become infected - Symptoms: Typically presents as a sudden onset of otalgia (earache), fever, and hearing loss, often preceded by URTI lasting for several days. Also vomiting, discharge, diarrhoea, fullness/pressure in the ear…
- Diagnosis: Acute onset of symptoms (e.g., earache in older children/adults)
On otoscopic exam – red/yellow/cloudy tympanic membrane, mod-severe bulging of tympanic membrane, perforation or discharge in canal - Acute otitis media usually self-limiting (~3 days, can be up to 1 week. Simple analgesia can be used for pain (paracetamol or ibuprofen). In most cases, antibiotics not necessary.
May advise delayed-prescribing or back-up prescription for if symptoms do not improve (NICE - within 3 days) or worsen. Seek medical help if symptoms worsen rapidly or become significantly unwell.
If no antibiotic is prescribed, an option for children or <18yrs: anaesthetic and analgesic eardrops (if no otorrhea/perforation): Phenazone 40 mg/g with lidocaine 10 mg/g (4 drops 2-3 times/day, up to 7 days, available as Otigo®
Antibiotics are considered in some cases:
- Patient is systemically unwell
- High risk of complications
- <2 yrs old bilateral AOM
- With perforation or discharge ear canal
If Abx, first line 5-7 days of oral amoxicillin (clarithromycin if allergy, erythromycin if allergy and pregnant) at appropriate dose.
when is antibiotics considered in acute otitis media?
Antibiotics are considered in some cases:
- Patient is systemically unwell
- High risk of complications
- <2 yrs old bilateral AOM
- With perforation or discharge ear canal
what is chronic otitis media?
Chronic otitis media (chronic supporative CSOM):
Chronic inflammation, perforated ear drum and otorrhea
Referred to specialist ENT
Usually require antibiotics and topical steroids
- what is Labryinthitis & vestibularneuritis/neuronitis (inner ear)
2.causes
3.symptoms
4.signs - diagnoisis
6.treatment
7.what is option for chronic cases?
- Inflammation of inner ear (labyrinthitis) or vestibular nerve (vestibular neuritis)
- Cause: Usually caused by viral infection (more rarely by bacterial infection). Also by stress and ototoxicity
3.Symptoms: Inner ear dizziness associated with vertigo, balance disorder, nausea, tinnitus (both) in addition to hearing loss (labyrinthitis only)
- Signs: Nystagmus, may use head impulse test in diagnosis
- Diagnosis on clinical signs/symptoms
- Treatment – symptomatic
Self-care – e.g. rest. Expect to resolve with time, even without treatment
Severe nausea or vomiting with vertigo: to relive rapidly can be given buccal prochlorperazine (dopamine D2 receptor antagonist) or IM prochlorperazine or cyclizine
Less severe nausea or vomiting with vertigo: short course oral prochlorperazine or anti-histamines cinnarizine, cyclizine, or promethazine teoclate are options – up to 3 days
Corticosteroids, benzodiazepines or anti-virals generally not recommended
- For chronic cases: vestibular rehabilitation therapy (VRT)
what are the different levels of hearing loss?
Different degrees or levels of hearing loss (e.g. mild, moderate, severe, profound)
what are the different types of hearing loss and what it is caused by?
Sensorineural hearing loss is caused by damage to the hair cells of the cochlea or the damage to the auditory nerve: this is permanent as human hair cells cannot regenerate
Conductive hearing loss is due to sounds not being transmitted from outer to inner ear – e.g. due to blockage. Can be permanent or temporary
what are the possible causes of hearing loss
There are a range of possible causes of hearing loss such as:
-Genetic hearing loss/deafness
-Noise-induced: Loud noises with high dB(A) can damage hair cells
-Age-related: Gradual loss with age due to ‘wear and tear’ of cochlea hair cells. Permanent. Can benefit from hearing aids. Common as we age
- Otosclerosis (conductive hearing loss) – bony growth
Sudden hearing loss can have different causes including (but not limited to):
- Ototoxic drugs (cause damage to the inner ear)
- Infections: viral such as Rubella (congenital), measles, mumps and others. Other non-viral such as bacterial meningitis (can spread to the cochlea and damage hair cells or sometimes can be due to inflammation and damage of auditory nerve). Sensorineural hearing loss. Hearing loss can be permanent.
- Trauma/injury (including infection, noise etc.)
- Meniere’s disease (sensorineural hearing loss): due to changes in fluid pressure in inner ear (endolymph)
what are examples of ototoxic drugs?
Analgesics and antipyretics
Salicylates (e.g. aspirin in high doses), quinine (malaria)
Antimicrobials:
Aminoglycosides
e.g. Gentamicin, neomycin
Glycopeptide antibiotics
Vancomycin (less risk)
Macrolide antibiotics
Erythromycin (less risk)
Antineoplastics (platinum-based)
Cisplatin, carboplatin (less)
Loop diuretics
e.g. Furosemide (esp. in high doses, parenteral)
what are hearing aids
Hearing aids: there are many types, such as behind the ear, in ear and in canal. Can be used for conductive and sensorineural hearing loss (depending on the case). Amplify sounds to aid hearing.
what are implants
Implants: such as bone anchored hearing aid, cochlear implant, auditory brainstem implant, middle ear implants.
what are cochlear implants
Cochlear implants, typically for more severe sensorineural hearing loss (damage/loss of hair cells) and in profound deafness. Directly stimulate the cochlea nerve (bypass ‘upstream’ signalling through the ear).
