Ear Flashcards
Describe the structure of the External Auditory Meatus
Sigmoid shaped tube
External 1/3 Cartilage
Internal 2/3 Temporal Bone
Describe the structure of the Tympanic Membrane
Skin on the external surface and mucous membrane on the inside
Connected to surrounding temporal bone by cartilagenous ring
Parts include: Pars Tensa, Pars Flaccida, Anterior and Posterior Malleolar fold
Describe the blood supply to the External Ear
Branches of ECA (Posterior Auricular, Superficial Temporal, Occipital, Maxillary)
Name the four nerves innervating the External Ear
Auriculotemporal
Greater Auricular Nerve
Lesser Occipital
Auricular branch of vagus
How would bites of the external ear be managed?
Wounds left open, irrigated, abx given
Why does a Pinna Haematoma require urgent ENT referral?
Disrupts overlying vessels in the Perichondrium which can lead to avascular necrosis (and cauliflower ear)
How is Tympanic Membrane perforation managed?
Traumatic - Watch and wait for 6 weeks, avoid water, after this if persisting then refer for myringoplasty
Non traumatic (eg post OM) - Antibiotics, water avoidance, and review in 6 months
What is a Haemotympanum?
Blood in the middle ear often associated with Temporal Bone Fracture
Conservatively managed but followed up to check for residual damage
Name the two parts of the middle ear
Tympanic Cavity (containing Malleus, Incus, Stapes)
Epitympanic Recess (superior to Tympanic Cavity near mastoid air cells)
Where does Stapes connect to?
Oval Window of middle ear
What is the purpose of Mastoid Air Cells?
Buffer system of air
Release air if pressure becomes too low
Two muscles are involved in the Acoustic Reflex. What is this and name the muscles involved.
Protective muscles contract in response to loud noises
Tensor Tympani and Stapedius
What is the role of the Eustacian Tube?
Connects middle ear to Nasopharynx, equalising pressure
Otitis Media can be Acute or Chronic. How can Chronic Otitis Media be subclassified?
- Active Mucosal (discharge through perforation)
- Inactive Mucosal (perforation but no discharge)
- Active Squamous (cholesteotoma)
- Inactive Squamous (retraction pocket)
What are the two main roles of the Inner Ear?
Converts mechanical signals into electrical
Maintains balance by detecting position and motion
There are two main components of the Inner Ear. Describe the Bony Labyrinth
Cochlea, Vestibule and three Semicircular Canals
Lined internally with Periosteum and contains Perilymph
There are two main components of the Inner Ear. Describe the Membranous Labyrinth
Lies within the Bony Labyrinth
Contains Endolymph
Cochlear duct, Semicircular Ducts, Utricle, Saccule
Describe the structure of the Vestibule
Central part of the bony labyrinth
Separated from middle ear by oval window
Contains Saccule and Utricle
Describe the structure of the Cochlea
Twists around a central portion of bone called the Midiolus
Spiral lamina bone attaches to cochlear duct
Two perilymph filled chambers (Scala Vestibuli, Scale Tympani)
Describe the structure of the Semicircular Canals
Anterior, Lateral and Posterior
Swelling at one end known as Ampulla
What is the Cochlear Duct?
Sits within the Cochlea and is the organ of hearing
Epithelial cells of hearing - Organ of Corti
What are the Saccule and Utricle?
Two membranous sacs which are organs of balance
Utricle connects to Semicircular Canals and senses position side to side
Saccule recieves cochlear duct and senses upwards and downwards movement
Endolymph drains from here
Describe the distribution of CNVIII
Forms Vestibular Ganglion which splits into superior and inferior parts to supply: Saccule, Utricle, Semicircular Canals
Cochlea portion: Enters at base of Mediolus to supply receptors of Organ of Corti
What is the time frame description for Otitis Externa?
Acute <3 weeks
Chronic >3 months
Describe the protective mechanisms of the External Ear
- Elastic cartilage has protective hairs
- Self cleansing via Epithelial Escalator
- Ear wax
Ear wax is composed of Epithelial Cells, Lysozymes and Oily Secretions. Name four roles
- Cleaning and lubrication
- Protection from bacteria/dust/insects
- Acidic coat inhibits microbial growth
- Hydrophobic coat prevents water reaching canal skin
Name four risk factors for Otitis Externa
Hot and Humid Climates
Swimming
Immunocompromised
Insufficient or Excessive wax
What organisms are implicated in Otitis Externa?
90% Bacterial (S.Aureus, Pseudomonas)
10% Fungal (aspergillous - after prolonged abx)
Herpes Zoster
Name four non infective causes of Otitis Externa
Acne
Eczema
Psoriasis
Ear Plugs (irritants)
Name four symptoms of Otitis Externa
Pain
Itching
Hearing Loss
?Discharge
Name three signs OE of Otitis Externa
Inflamed External Canal
Scaly Skin
Pre-auricular LN
Necrotising Otitis Externa is a subtype of Otitis Externa. Define it
Extension into Mastoid or Temporal Bones (often in immunocompromised, elderly or diabetic)
How does Necrotising Otitis Externa present?
Discharge
Jaw Pain
Headache of great intensity
Facial nerve palsy - if osteomyelitis
How would you investigate Necrotising Otitis Externa?
Bone Scan
CT
How would you manage Necrotising Otitis Externa?
Prolonged Abx
Piperacillin- Tazobactam
Ciprofloxacin if pen allergic
You would only investigate Otitis Externa if it was atypical or non responding. How would you do this?
Ear Swab
Test integrity of membrane - can they taste something put in ear, can they blow out when nose is pinched
How is Otitis Externa managed?
Remove any debris
First line topical Abx (Cipro)+/- Steroids
Severe - Oral Flucloxacillin (if systemically unwell)and Topical Abx
What general advise should you give patients with Otitis Externa?
Use ear plugs when swimming
Keep ears clean and dry
Avoid swimming for 7-10d
What is Recurrent AOM?
> 3 distinct episodes of AOM in the past 6 months
Name the common organisms implicated in AOM
Haemophilus Influenza
Strep Pneumoniae
Rhinovirus
RSV
Name four risk factors for AOM
Smoking
URTI
Eustacian Tube Dysfunction
Craniofacial Abnormalities
Name three presenting features of AOM
Otalgia (tugging at ear)
Fever
Hearing Loss
Give three differentials for AOM
Trigeminal Neuralgia
TMJ dysfunction
GCA
What might you see on Otoscope of AOM
Red/Cloudy TM
Air fluid level
How would you immedately managed AOM?
Simple analgesia
Delayed Abx (5d Amoxicillin - not delayed if systemic sx or at risk)
When would you admit patients with AOM?
Severely systemically unwell
Suspected complications
<3m with temp >38
When would you refer a patient with AOM to ENT?
If recurrent in the present of persistant symptoms/persistent cervical lymphadenopathy/unilateral epistaxis
Name three complications of AOM
Tympanic perforation
Hearing loss
Labyrinthitis
What is Otitis Media with Effusion?
Results from either incomplete resolution of AOM or non infective obstruction of Eustacian Tube
Relative negative pressure in the ear canal drops leading to fluid accumulation
Name four risk factors for Otitis Media with Effusion
Chronic allergy
Sinusitis
Deviated septum
Enlarged tonsils
Name four presenting features of Otitis Media with Effusion
Rarely Otalgia
Fullness
Pressure popping
Poor speech development
What would you see on Otoscopy of Otitis Media with Effusion
Retracted Straw Coloured Tympanic Membrane