ENT Flashcards
What are the two main types of hearing loss?
- conductive - problem with sound travelling from environment to the inner ear, sensory working fine but sound not reaching eg: ear plugs
- sensorineural - problem with sensory system or vestibulocochlear nerve in inner ear
- ie defects to oval window in cochlea (sensory), cochlear nerve (neural), rarely more central pathways
What is the physiology of hearing?
- outer ear directs and funnels sound towards the TM, pinna and external acoustic canal amplify sound along the way until it reaches TM which vibrates as a result
- vibration of the of TM spreads through the ossicles (malleus, incus and stapes) and is sent to the oval window setting up vibrations and movement in cochlear fluid of inner ear
- this is sensed by stereocilia in cochlear duct (part called spiral organ of corti)
- movement of stereocilia in organ of corti triggers action potentials in cochlear part of CN 8
- semicircular canals to primary auditory context makes sense of this input as sound
How might hearing loss present?
may be gradual and insidious
- associated sx
- tinnitus
- vertigo
- pain - infection
- discharge - ear infection
- neuro symptoms
What are some common causes of conductive hearing loss?
external canal obstruction
TM perforation
osteosclerosis
infection
trauma
otitis media with effusion
glue ear
cholesteotoma
What are some common causes of sensorineural hearing loss?
ototoxic drugs
post infective
cochlear vascular disease
meniere’s
noise damage
presbycusis
labyrinthitis
acoustic neuroma
neuro causes
How might you assess hearing loss?
rinne’s and weber’s
pure tone audiometry
tympanometry
other methods of hearing tests
What are some common causes of sudden hearing loss?
conductive - ear wax, foreign body, infection, effusion, Eustachian tube dysfunction, perforated TM *cause found commonly
sensorineural - most often unilateral, idiopathic, infection, meniere’s, medication, MS, stroke etc
How might you investigate sudden hearing loss?
- Audiometry to establish diagnosis - loss of at least 30 decibels in 3 consecutive frequencies on audiogram
- MRI or CT head if acoustic neuroma or stroke
How might you manage sudden hearing loss?
- immediate ENT referral for assessment within 24h of patient presenting and within 30 days on onset
- when underlying cause found, treatment as required
- idiopathic SSNHL with steroids under ENT guidance
- oral or intra-tympanic (via injection of steroids through TM)
What causes deafness in childhood?
conductive - genetic abnormalities in canal
sensorineural - autosomal dominant like in alports
non genetic - intrauterine infections, perinatal causes
what intrauterine infections and perinatal causes may lead to deafness in childhood?
- intrauterine infection eg: CMV, rubella, HSV
- perinatal causes eg: prematurity, hypoxia, kernicterus, iVH
What is the universal newborn hearing screening?
- otoacoustic emissions - microphone in external meatus to detect tiny cochlear sounds by outer hair cell movement which occurs in response to sound
- auditory brainstem response - ears covered with earphones that emit series of soft clicks and electrodes on infants forehead and neck to measure brain wave activity in response
How do you test hearing in older children?
distraction testing - 6 to 18m
visual reinforced audiometry - 6m to 2.5y
speech discrimination - 2y to 5y
How is deafness in childhood managed?
cochlear implants
hearing aids
MDT care
What is the pathophysiology of otalgia?
inside the ear, pain fibres in nerve endings are stimulated by distension of skin due to swelling or compression against bony or cartilaginous structures
cervical nerves, trigeminal, glossopharyngeal and vagal nerves involved in referred pain to the ear
What are some differentials for otalgia?
otitis externa
necrotising otitis externa
otitis media
furunculosis
barotrauma
TMJ dysfunction
Ramsay hunt
neoplasia
What is the nerve supply to the ear?
great auricular + auriculotemporal branch of trigem - pinna
facial nerve - lateral ear drum
glossopharyngeal - TM medial
vagus
What are some red flag sx for otalgia?
- oropharyngeal symptoms may suggest a head and neck cancer
- Progressive or sudden onset hearing loss
- Eye symptoms (loss of vision, black spots)
- Immunosuppressed or diabetes mellitus which may allow an infection to rapidly progress
How might you investigate otalgia?
otoscopy + mastoid
TMJ examine
nerve function
neck examination
flexible nasal endoscopy
ear swabs and culture
radiology for MRI
What are the 3 components of the physiology of balance?
- vision
- proprioception - muscles and joints
- inner ear vestibular system
What is vertigo?
a sensation of movement when stationary - unsteady or spinning rotation, “being on a boat” or “fairground ride”
N+V, falling over or bumping into things, holding on when walking
*no consciousness loss
What is the vestibular ocular reflex?
- when gaze forwards, both Vestibular systems send equal strength signals
- when head turned right with gaze still forwards the right VS sends stronger signal than left this makes eye turn towards weaker signal and maintain same direction of gaze vice versa *almost pushes eye away
What are some differentials for loss of balance?
BPPV
vestibular neuronitis
meniere’s
vestibule migraine
acoustic neuroma
Ramsay hunt syndrome
cerebellar lesions
r/o cardiac
What is nystagmus?
abnormal involuntary eye movements that can be caused by problems in the vestibular system or in the cerebellum and brain stem
How might you investigate balance?
*balance clinic
ENT exam - vestibular ocular reflex, dix-hallpike
neuro - gait, eyes, Romberg, cerebellar, joint position
CVS exam
specific - posturography, videonystagmography, calorie testing, VHIT