ENT - Hearing Loss & Vertigo

Question 1

Vertigo

Definition
Central Causes
Peripheral Vestibular Causes
HINTS Examination
Other Causes

Answer 1

1.) Definition - the hallucination of movement

2. ) Central Causes
   - stroke (posterior circulation): cerebellum, brainstem, vestibular nuclei
   - cerebellar dysfunction, migraines, neoplasms,
   - Parkinson’s, demyelination (e.g. MS)
   - ototoxic drugs: furosemide (loop diuretics), aspirin (NSAIDs), gentamycin (aminoglycosides), quinine, chemo (cisplatin, vincristine, cyclophosphamide)
3. ) Peripheral Vestibular Causes
   - BPPV, Meniere’s disease
   - vestibular neuronitis, acute labyrinthitis
   - Ramsey-Hunt Syndrome: herpetic infection of CN VII causing hearing loss and tinnitus +/- vertigo
   - HINTS exam can be used to differentiate between peripheral and central causes

4.) HINTS Examination - differentiates central and peripheral causes
- Head Impulse test: abnormal in peripheral, normal in central
- Nystagmus: unidirectional/none in peripheral, bidirectional/vertical in central causes
- Test of Skew: vertical skew in central

5. ) Other Causes
   - anaemia, postural hypotension

Question 2

Sudden Sensorineural Hearing Loss (SSNHL)

Definition
Sudden Conductive Hearing Loss
Causes of SSNHL
Investigations
Management

Answer 2

1. ) Definition - hearing loss over < 72 hours which is unexplained by other conductive causes
   - otological emergency, immediately refer to ENT
2. ) Sudden Conductive Hearing Loss - must exclude:
   - ear canal obstruction e.g. wax
   - otitis externa, AOM, OME
   - ET dysfunction, perforated TM
3. ) Causes of SSNHL - 90% idiopathic
   - often unilateral, permanent or resolve in days/weeks
   - infection: meningitis, HIV, mumps
   - migraine, stroke, MS, ototoxic medication
   - Ménière’s disease, acoustic neuroma
   - Cogan’s syndrome: a rare autoimmune condition causing inflammation of the eyes and inner ear
4. ) Investigations
   - audiometry: loss of hearing at high frequencies, loss of >30 dB in three consecutive frequencies
   - MRI/CT: if considering stroke or acoustic neuroma
5. ) Management
   - urgent referral to ENT for assessment within 24 hrs when presenting with SSNHL within 30 days of onset
   - treat the underlying cause if found e.g. infection
   - idiopathic: high dose PO corticosteroid (or could have intra-tympanic (injections) corticosteroids)
   - 1/3 recover to normal, 1/3 have no recovery

Question 3

Tuning Fork Tests

Usage
Rinne’s
Weber’s

Answer 3

1. ) Usage - to differentiate sensorineural and conductive hearing loss, using a 256/512Hz tuning fork
   - useful when no access to a pure tone audiogram
2. ) Rinne’s - test conductive hearing (place on mastoid)
   - positive test is normal: air > bone conduction, seen in no hearing loss or sensorineural hearing loss
   - negative test is abnormal: bone > air conduction, seen only in conductive hearing loss
3. ) Weber’s - tests sensorineural and conductive hearing (place on the middle of forehead)
   - negative test is normal (equally loud in both ears)
   - sensorineural: louder in the good ear
   - conductive: louder in the bad ear because conductive loss removes background noise so appears louder

Question 4

Pure Tone Audiometry

Usage
Air and Bone Conduction
Conductive Hearing Loss
Sensorineural Hearing Loss

Answer 4

1. ) Usage - assesses hearing thresholds at different frequencies, performed in a soundproofed booth
   - can be used from age 4 upwards
   - each frequency is tested multiple times and the quietest tone heard is marked on the audiogram
   - anything < 20dB is considered normal
2. ) Air and Bone Conduction
   - air conduction: measured playing a tone through headphones, assesses the whole auditory pathway
   - bone conduction: uses a bone conductor on the mastoid, bypassing the conductive auditory system
   - any discrepancy in hearing between the ears needs to be masked (playing noise in the contralateral ear)
3. ) Conductive Hearing Loss - due to an impedance to hearing in the middle or external ear e.g. wax, infection
   - air-bone gap: ↓air conduction, normal bone conduct…
4. ) Sensorineural Hearing Loss - due to a problem between the cochlear and auditory cortex of the brain
   - no air-bone gap: equally ↓bone and air conduction
   - presbyacusis: bilateral downward-sloping thresholds and high-frequency hearing loss with relative preservation of word recognition scores

Question 5

Tympanometry

Usage
Type-A Tracing
Type-B Tracing
Type-C Tracing

Answer 5

1. ) Usage - measures compliance of the TM by applying pressure in the external ear canal using a probe
   - provides information on the TM, middle ear, and ET
   - pressure on the x-axis, compliance on the y-axis
   - compliance peaks when the pressure in the external ear canal is equal to the pressure in the middle ear
2. ) Type-A Tracing - normal result
   - compliance peak centred on 0daPA on the x-axis
3. ) Type-B Tracing - flat tracing
   - suggests middle ear effusion or perforation
   - effusion: normal canal volume (1cm^3 in adults)
   - perforation: much larger canal volume as it is measuring the middle and external ear volume
4. ) Type-C Tracing - suggests ET dysfunction
   - compliance peak has a negative pressure

Question 6

Benign Paroxysmal Positional Vertigo

Pathophysiology
Clinical Features
Dix-Hallpike Test
Management

Answer 6

1. ) Pathophysiology
   - calcium carbonate crystals (cholelithiasis) are deposited in the inner ear (semi-circular canals)
   - deposits sit at the bottom of the canal when the head is still, head movements cause abnormal stimulation of hair cells giving hallucination of movement
2. ) Clinical Features
   - sudden attacks of rotational vertigo lasting 30-60s
   - provoked by changing the position of the head
   - episodes disappear within weeks but often recur
3. ) Dix-Hallpike Test - used to diagnose the condition
   - sit patient upright then lay them down with their head hanging off the bed then tilt their head to the side
   - positive test triggers nystagmus (rotatory/torsional geotropic)
4. ) Management
   - can last several weeks or longer, but most recover
   - Epley Manoeuvre can help alleviate symptoms (removes crystals from the inner ear)
   - vestibular rehabilitation: e.g. Brandt-Daroff exercises
   - encourage rest, adequate hydration, avoid sudden position changes or looking upwards for long periods
   - advised not to drive whilst symptomatic, consider adjustments to work if occupation involves hazards

Question 7

Meniere’s Disease

Pathophysiology
Clinical Features
Management

Answer 7

1. ) Pathophysiology
   - endolymphatic hydrops causes dilatation of the endolymphatic spaces of the membranous labyrinth
   - affects mainly ages 30-60yrs
2. ) Clinical Features
   - paroxysmal vertigo (mins to hrs) associated w/ N/V +
   - unilateral sensorineural hearing loss AND tinnitus
   - aural fullness
   - episodes last for 12-24hrs
   - hearing deteriorates over time
3. ) Management - need ENT referral for diagnosis
   - prochlorperazine for acute attacks
   - prophylactic betahistine to prevent recurrence
   - surgical: grommet insertion, labyrinthectomy, endolymphatic sac decompression
   - diet: ↓salt, chocolate, alcohol, caffeine, Chinese food

Question 8

Acute Labyrinthitis

Pathophysiology
Clinical Features
Management

Answer 8

1. ) Pathophysiology
   - previous URT infection or vascular lesion causing inflammation of the inner ear (labyrinth) affecting the vestibular nerve and all other inner ear structures
2. ) Clinical Features
   - acute severe vertigo +/- associated N/V
   - can include hearing loss and tinnitus
   - other CN deficits if due to a vascular lesion
3. ) Management
   - vestibular sedatives: prochlorperazine (acute attacks)
   - rehab exercises if suffering from prolonged poor balance from vestibular hypofunction

Question 9

Acute Vestibular Neuronitis

Pathophysiology
Clinical Features
Management

Answer 9

1. ) Pathophysiology
   - previous URT infection causing inflammation of the inner ear only affecting the vestibular nerve
2. ) Clinical Features
   - acute severe vertigo, ataxia, N+V
   - patients may have horizontal nystagmus
   - no hearing loss or tinnitus
3. ) Management
   - vestibular sedatives: prochlorperazine (acute attacks)
   - rehab exercises if suffering from prolonged poor balance from vestibular hypofunction

Question 10

Acoustic Neuroma (Vestibular Schwannoma)

Pathophysiology
Clinical Features
Investigations
Management

Answer 10

1. ) Pathophysiology - benign subarachnoid tumour causing overproduction of Schwann cells
   - occur at the cerebellopontine angle
   - causes local pressure effects on the CN VIII
   - can also compress other cranial nerves
   - usually unilateral, bilateral acoustic neuromas are associated with neurofibromatosis type 2
2. ) Clinical Features
   - CN VIII: vertigo, asymmetric or unilateral sensorineural hearing loss with ipsilateral tinnitus
   - larger tumour can cause ↑ICP –>focal neurology
   - absent corneal reflex (V), facial nerve palsy (VII)
3. ) Investigations
   - audiometry to assess hearing loss
   - MRI of cerebellopontine angle: to visualise tumour
4. ) Management
   - conservative: monitoring if untreatable or asymptomatic
   - radiotherapy to reduce the growth
   - definitive: surgery (CNVIII injury –> permanent hearing loss/dizziness, CNVII –> facial weakness)