DISEASES OF THE INNER EAR 1.3 (AB)

Question 1

What is the key feature of Scheibe dysplasia?

Answer 1

Cochleosaccular dysplasia; only the membranous labyrinth is formed.

Question 2

What is Mondini dysplasia?

Answer 2

Partial bony and membranous labyrinth; arrest at the 6th week leading to a 1.5 coil cochlea.

Question 3

What is Michel’s aplasia?

Answer 3

Complete absence of all bony and membranous structures in the inner ear.

Question 4

What is a key feature of Large Vestibular Aqueduct (VA) Syndrome?

Answer 4

Enlarged vestibular aqueduct, often bilateral and asymmetric.

Question 5

What additional symptom is commonly seen in Large VA Syndrome apart from hearing loss?

Answer 5

Dizziness.

Question 6

What is the leading cause of sensorineural hearing loss (SNHL) in children?

Answer 6

Infections.

Question 7

What causes serous (toxic) labyrinthitis?

Answer 7

Degradation of the tissue fluid environment within the ear due to bacterial toxins and perilymph contamination.

Question 8

What is the key clinical presentation of serous labyrinthitis?

Answer 8

Sudden onset of SNHL with acute vertigo.

Question 9

What is the cause of suppurative labyrinthitis?

Answer 9

Bacterial invasion leading to profound hearing loss and acute vertigo.

Question 10

What is the most common etiology of deafness associated with meningitis?

Answer 10

Suppurative labyrinthitis.

Question 11

How does bacterial infection reach the inner ear in suppurative labyrinthitis?

Answer 11

Via a fistula between the middle ear and the inner ear.

Question 12

What is Ramsay Hunt syndrome?

Answer 12

Herpes zoster oticus with facial paralysis, herpetic skin eruptions, and possible hearing loss and vertigo.

Question 13

What viral infection is a common cause of congenital and progressive SNHL in children?

Answer 13

Cytomegalovirus (CMV).

Question 14

What type of hearing loss is associated with measles?

Answer 14

Bilateral, moderate to profound SNHL.

Question 15

What is the main mechanism of aminoglycoside ototoxicity?

Answer 15

Entry into hair cells leading to cell death.

Question 16

Which aminoglycosides are cochleotoxic?

Answer 16

Kanamycin, Tobramycin, Amikacin, Neomycin, Dihydrostreptomycin.

Question 17

Which aminoglycosides are vestibulotoxic?

Answer 17

Gentamicin, Streptomycin.

Question 18

What is the risk factor for neomycin toxicity?

Answer 18

Renal disease (CKD), prolonged use, increased serum levels, age, loop diuretics.

Question 19

What type of hearing loss do loop diuretics cause?

Answer 19

Reversible SNHL.

Question 20

What are the symptoms of quinine toxicity?

Answer 20

Tinnitus, SNHL, visual disturbances.

Question 21

What is the toxic dose of salicylates that can cause tinnitus?

Answer 21

6-8 g/day.

Question 22

What type of hearing loss does salicylate toxicity cause?

Answer 22

Reversible SNHL within 72 hours.

Question 23

What is Noise-Induced Hearing Loss (NIHL)?

Answer 23

A common occupational disability caused by repeated exposure to loud sounds.

Question 24

What frequency is most affected in NIHL?

Answer 24

4 kHz.

Question 25

What is the typical progression pattern of NIHL?

Answer 25

Progresses most rapidly in the first 10-15 years of exposure.

Question 26

What is acoustic trauma?

Answer 26

Hearing loss caused by a single exposure to a hazardous noise level.

Question 27

What is the key audiometric finding in acoustic trauma?

Answer 27

Permanent Threshold Shift (PTS) without Temporary Threshold Shift (TTS).

Question 28

What is the maximum allowable duration for exposure to 90 dB noise according to OSHA?

Answer 28

8 hours.

Question 29

What is the maximum allowable duration for exposure to 100 dB noise according to OSHA?

Answer 29

2 hours.

Question 30

What is the most common type of temporal bone fracture?

Answer 30

Longitudinal.

Question 31

How does longitudinal temporal bone fracture affect hearing?

Answer 31

It uncommonly extends through the labyrinth and typically affects high-frequency hearing.

Question 32

What is the effect of transverse temporal bone fracture on hearing?

Answer 32

Almost always traverses the labyrinth, leading to complete loss of cochlear and vestibular function.

Question 33

What is labyrinthine concussion?

Answer 33

Blunt trauma to the ear leading to temporary or permanent SNHL.

Question 34

What is a perilymphatic fistula?

Answer 34

A pathologic communication between the perilymphatic space of the inner ear and middle ear.

Question 35

What are the possible causes of a perilymphatic fistula?

Answer 35

Congenital defects (e.g., Mondini dysplasia), barotrauma, direct or indirect trauma to the temporal bone, or complications of stapedectomy surgery.

Question 36

What condition is associated with perilymphatic fistula and CSF leak?

Answer 36

Mondini dysplasia.

Question 37

What clinical presentation suggests a perilymphatic fistula?

Answer 37

Sudden SNHL and vertigo after head trauma, barotrauma, lifting, or straining.

Question 38

What is the main cause of radiation-induced cochlear damage?

Answer 38

Free radicals.

Question 39

What percentage of patients undergoing radiotherapy involving the cochlea develop SNHL?

Answer 39

0.5

Question 40

What radiation dose is considered detrimental to the cochlea?

Answer 40

>45Gy.

Question 41

What factors increase the risk of radiation-induced SNHL?

Answer 41

Advanced age, preexisting hearing loss, and adjuvant ototoxic chemotherapeutic agents.

Question 42

What is the latency period for radiation-induced SNHL?

Answer 42

0.5 to 2 years after treatment.

Question 43

What systemic disorder is associated with 4-10% of SNHL cases?

Answer 43

Multiple sclerosis.

Question 44

What systemic disorder presents with pulsatile tinnitus and SNHL?

Answer 44

Benign intracranial hypertension.

Question 45

What is the typical hearing loss pattern in basilar migraine?

Answer 45

46% of cases present with bilateral low-frequency SNHL.

Question 46

What other symptoms are associated with basilar migraine-related SNHL?

Answer 46

Episodic vertigo, tinnitus, aural fullness, distortion, and recruitment.

Question 47

What vascular condition can lead to SNHL due to AICA involvement?

Answer 47

Vertebrobasilar arterial occlusion.

Question 48

What is Cogan syndrome?

Answer 48

A prototypic autoimmune disorder that affects the inner ear.

Question 49

What is the most common pattern of hearing loss in presbycusis?

Answer 49

Worse for high frequencies.

Question 50

Which gender is more commonly affected by presbycusis?

Answer 50

Men.

Question 51

What is the progression pattern of presbycusis?

Answer 51

Gradual, with an accelerating rate of hearing loss over time.

Question 52

What is Schuknecht’s classification of presbycusis?

Answer 52

Sensory, neural, and strial/metabolic types.

Question 53

What is the characteristic hearing loss pattern in sensory presbycusis?

Answer 53

Steep high-frequency hearing loss with preserved speech perception due to degeneration of the organ of Corti.

Question 54

What is the characteristic hearing loss pattern in neural presbycusis?

Answer 54

Down-sloping high-frequency hearing loss with a disproportionate loss of speech perception due to degeneration of spiral ganglion cells.

Question 55

What is the characteristic hearing loss pattern in strial/metabolic presbycusis?

Answer 55

Flat SNHL with preserved speech perception due to degeneration of the stria vascularis.

Question 56

What are the key auditory tests for diagnosing hearing loss?

Answer 56

Pure tone audiometry, auditory brainstem response, auditory steady-state response evaluation, otoacoustic emission, and impedance testing (tympanometry).

Question 57

What is the gold standard imaging modality for diagnosing potential retrocochlear hearing losses?

Answer 57

MRI with gadolinium enhancement.

Question 58

What imaging technique is used for detailed cochlear evaluation?

Answer 58

High-resolution CT scan with 1 mm cuts.

Question 59

Why are 1 mm cuts used in high-resolution CT scans of the cochlea?

Answer 59

To avoid missing small structures, as standard CT scan cut sizes are 5 mm.