Eileen - upper respiratory tract, otitis media with efusion Flashcards
Name the four tonsils.
- Pharyngeal
- Tubal
- Lingual
- Palatine
What are the two folds surrounding the palatine tonsils?
- Palatopharyngeal
- Palatoglossal folds
What is the arterial supply of the palatine tonsils?
Facial artery
What is the epithelium of the palatine tonsil?
Non-keratinised squamous epithelium
What is another name for the pharyngeal tonsil?
Adenoids
Where is the pharyngeal tonsil located?
The upper posterior nasopharynx
What is the epithelial lining of the pharyngeal tonsil?
Pseudostratified squamous
Where is the tubal tonsil located?
- Surrounds the opening of the
- Eustachian tube into the pharynx -tubal elevation
What is the epithelial lining of the tubal tonsil?
Pseudostratified squamous epithelium
Where is the lingual tonsil located?
The posterior aspect of the tongue
Describe the epithelium of the lingual tonsil.
Non-keratinised squamous epithelium invaginated to form a single crypt
What is Waldeyer’s ring?
An uninterrupted ring formed by the tonsil around the start of the respiratory tract
How do the tonsils protect against respiratory infections?
They hold a lot of micro-organisms that are around the throat area and mount an immune response against them- protect respiratory tract from infections
Which bone does the external auditory canal lie in?
The temporal bone
What is the epithalamus lining for the tympanic membrane?
Simple cuboidal epithelium
What are ceruminous glands?
Specialised sweat glands that secrete cerumen- helps prevent dust and foreign objects from entering the ear
Which window in the middle ear does the stapes articulate with?
Oval
What is the function and innervation of tensor tympani?
Limits movement and increases tension on the eardrum to prevent inner ear damage by loud noises- innervated by mandibular branch of the trigeminal nerve
What is the function and innervation of the stapedius muscle?
- This is the smallest skeletal muscle
- Dampens large vibrations of the stapes due to loud noise - protecting the oval window Innervated by the facial nerve
When does the Eustachian tube open?
- Closed at the pharyngeal end
- Opens during swallowing and yawning - allowing air to enter and leave the inner ear
What liquid is contained in the bony labyrinth?
Perilymph - surrounds the membranous labyrinth
Describe the bony labyrinth.
A series of cavities in the petrous portion of the temporal bone
Describe the membranous labyrinth.
A series of epithelial sacs and tubes within the bony labyrinth - has same general form as bony labyrinth - contains hearing and balance receptors
What liquid does the membranous labyrinth contain?
Endolymph
What are the two parts of the membranous labyrinth in the vestibule?
- Saccule
- Utricule- connected by a small duct
What are the nerves that make up the vestibular nerve?
- Ampullary nerves
- Urticular nerves
- Saccular nerves
What are the three channels of the cochlea?
- Cochlear duct
- Scala vestibuli
- Scala tympani
Describe the scala vestibuli
- Channel above the cochlear duct
- Ends at the oval window
- Part of bony labyrinth and so filled with perilymph
Describe the scala tympani
- Channel below the cochlear duct
- Ends at the round window
- Part of bony labyrinth and so filled with perilymph
How are the scala tympani and vestibuli connected?
At the apex of the cochlear - helictrema
What is the name of the membrane that separates the scale vestibuli from the cochlear duct?
Vestibular membrane
What is the name of the membrane that separates the scala tympani from the cochlear duct?
Basilar membrane
What rests on the basilar membrane?
The organ of corti
Describe the hair cells of the organ of Corti.
- Each hair cell has 40-80 stereocilia that extend into the endolymph
- At their basal ends, the cells synapse both with first-order sensory neurons and motor neurons from the coho clear branch of the sensory nerve
Where are the cell bodies of the cochlear sensory neurons located?
In the spiral ganglion
Describe acute Ottis media
- An acute infection of the middle ear
- Abrupt onset of signs and symptoms related to middle ear inflammation and effusion
Describe Otitis media with effusion.
- Presence of fluid in the middle ear
- Without signs and symptoms of acute otitis media
- May occur spontaneously due to poor Eustachian tube function or as an inflammatory response following AOM
List the risk factors for otitis media.
- Preschool ages children
- Children between 3 months and 3 years
- Premature birth
- Male gender
- Ethnicity - Native American, Inuit
- Family history of recurring otitis media Siblings in house
- Genetic syndromes
- Low socioeconomic status
- Orofacial abnormalities - cleft lip and palate
- Bottle fed infants
Describe ways in which fluid can easily reach middle ear
- Dysfunction of Eustachian tube allows reflex of fluid and bacteria into ear from nasopharynx
- Children have shorter, wider and more horizontal Eustachian tube
- Infection spreads more easily in infants as they spend most of their day lying down
- Bottle fed infants - angle of feeding allows more milk reflex into middle ear
What is middle ear effusion an expression of?
Underlying mucosal inflammation
Briefly describe the aetiology of acute otitis media and otitis media with effusion.
- Most cases are following an upper respiratory tract infection that had been present for several days
- Respiratory viruses found in middle ear exudates AOM and OCE interrelated aetiologies
- Acute infection often followed by inflammation, effusion and recurrent infection
How do persistent middle ear infections cause hearing problems?
Decreases motility of the the tympanic membrane - barrier to sound conduction
What is the pathophysiology of otitis media with effusion?
- Tubal tonsils hypertrophy in response to infection - blocking the Eustachian tube opening
- New air can’t access middle ear
- Respiratory epithelium in middle ear contains mucous secreting cells
- Mucous builds up in inner ear
Describe conductive hearing loss
- Occurs usually in the external or middle ear
- Interferes with the ability of sound to be transmitted to the inner ear - just makes things sound quieter
- Usually treated successfully with surgery
Describe sensorineuroal hearing loss
- Occurs in the inner ear (sensory) or vestibular nerve (neural)
- Normally permanent as the human inner ear and hair cells only has limited regeneration capacity
What are some causes of conductive hearing loss
Build up of ear wax/fluid
Ruptured eardrum
Otosclerosis of ear ossicles prevent free movement
What can cause sensory sensorineural hearing loss?
- Damage to hair cells in cochlear
- Can occur naturally in ageing (presbycusis)
What happens to sound in sensorineural hearing loss?
It becomes distorted and the quality and volume of sound is affected- speech is hard to understand
What hearing loss is present if there is a negative Rinne’s test?
Conductive hearing loss in that ear
What is a normal Weber’s test called?
Mid-line Weber’s
What is the problem when a Weber’s test indicates sound lateralising towards the right ear?
A right conductive hearing loss or a left sensorineural hearing loss
What is the problem when a Weber’s test indicates sound lateralising towards the left ear?
Either a left conductive hearing loss or a right sensorineural hearing loss
What is the most common treatment for glue ear?
Grommets
Describe the procedure for inserting grommets.
The patient is put under general anaesthetic
A small incision is made in the eardrum and a grommet inserted through it
What is the function of a grommet?
Helps drain fluid away from middle ear and also helps maintain the air pressure in the middle ear cavity
How are grommets removed?
- As the eardrum heals, the grommet is slowly pushed out and eventually falls out of the ear- between 6-15 months
- Some require surgical removal as they don’t fall out
How successful are grommets?
30% of children need further grommets inserted to fully treat the condition
What are the four main ways in which hearing loss affects children?
- Developmental delay in receptive and expressive communication skills (speech and language)
- Language deficit causes learning problems that result in reduced academic achievement
- Communication difficulties lead to social isolation and poor-self concept
- Impact on vocational choices
Describe vocabulary development in children with hearing loss.
- Vocab development is slower
- Learns concrete words (cat, jump) more easily that abstract words (after, jealous)
- Difficulty with function words (and, an, are)
- Vocabulary gap widens with age
- Difficulty understanding words with multiple meanings
Describe sentence structure development in children with hearing loss
- Comprehend and produce shorter/simpler sentences
- Difficulty in understanding and writing complex sentences
- Misunderstandings
Describe speaking development in children with hearing loss.
- Can’t hear quiet speech sounds - s, sh, f, t and k - and so don’t include them in their speech
- May not be able to hear their own voice when speaking
Describe academic achievement in children with hearing loss.
Difficulties in all aspects of school, especially reading and mathematical concepts
Score 1 to 4 grades lower than kids who can hear - gap widens as the children progress through school
When does newborn hearing screening offered?
Within 4-5 weeks of birth
What is the first test offered in the newborn hearing screening programme, and how is it performed?
Automated
Otoacoustic
Emission (AOAE) screening
- soft tipped probe placed into the ear- sound are played
- a normal response (echo) sound be detected from the cochlear
What is the second line test offered in the newborn hearing screening programme, and how and why is it performed?
It’s an automated auditory brainstem response (AABR) test- performed when the AOAE test doesn’t yield a clear response - electrodes are placed on the head and neck of the baby- sounds are played - responses are detected through the electrodes
What is the benefit of the AABR over the AOAE?
Measures auditory pathways as well as integrity of the inner ear - can detect the condition auditory neuropathy - children are deaf, but with normal otoacoustic emissions
What are the organs of balance?
Vestibular apparatus - allows for 3D detection + orientation in a gravitational field
How is balance maintained by the vestibular apparatus?
- 3 Semi-circular canals detect angular acceleration 2. Otolith organs (utricle + saccule) detect linear acceleration
Where in relation to the skull is the vestibular apparatus located?
In the petrous temporal bone of base of skull
What reflex are the semi-circular canals responsible for? What could disturbance in reflex lead to?
Vestibulo-ocular reflex
Nystagmus (involuntary eye movement in the absence of head movement)
Where are the vestibular receptors located?
In the ampulla
Where is the ampulla located?
Within the 3 semi-circular canals
What does the ampulla contain?
Hair cells which have stereocilli
Why does the endolymph initially lag when your head rotates? What is the subsequent effect of this lag?
Due to inertia
The ampulla gets deflected opposite to the side of head movement -> endolymph pushes cilia to bent -> stimulates hair cells
Describe the vestibulo-ocular reflex
Rotation of the head detected by hair cell activation of endolymph lag -> sensory nerve impulse travels to brainstem via vestibule-cochlear nerve -> triggers inhibitory signal for extra ocular muscles on 1 side and excitatory signal for the extra ocular muscles on the other side -> compensatory movement of the eye in response to spinning/movement -> preserves image in the centre of the visual field e.g. if you are spinning clockwise, your left eye’s lateral rectus muscle and right eye’s medial rectus muscle would get activated
How do you test for the vestibulo-ocular reflex?
- Spin patient on the Barany chair: should present with horizontal nystagmus when normal - room moves side to side
- Caloric testing: pour cold/warm water into ear -> heat transferred to semi-circular cancel -> horizontal nystagmus as horizontal canal is closest to external auditory meatus
What is the significance of caloric reflex clinically?
Can test for vestibulo-ocular reflex in UNCONSCIOUS patients, for BRAINSTEM activity.
What tests can be used to determine brainstem death?
- Caloric reflex
- Direct light reflex
- Gag reflex
What’s a weakness of the vestibulo-ocular reflex?
- Dizziness in e.g. fairground rides
- Motion sickness after powerful head spinning
