Inner Ear Disorders

Question 1

Presbycusis

Answer 1

The decrease of auditory function that occurs with aging.

○ Reduction in hearing sensitivity, understanding and cognitive function

Question 2

Symptoms of Presbycusis

Answer 2

slow progressive bilateral SNHL (HF), tinnitus, reduction in word rec ability, stable HL, history is very important

Question 3

Incidence & Prevalence of Presbycusis

Answer 3

30-35% of adults 65-76 years with HL

40-50% of adults 70+, slightly more common in males, genetic predisposition

Question 4

Site of Lesion of Presbycusis

Answer 4

Sensory (IHC, OHC) - otoxtoxic substances, NIHL, poor cell repair mechanisms (aging)

Neural: degeneration of spiral ganglion

Strial: stria vascularis: damage from age-related cell loss and oxidative stress, inefficient oxidative pathways or dysfunctional supporting cells

Question 5

Risk Factors of Presbycusis

Answer 5

genetics, smoking, hypertension, diabetes, cardiovascular, cerebrovascular, noise exposure, age, race

Question 6

Noise Induced Hearing Loss

Answer 6

both intensity and duration of sound impact audiologic function

exposure to isolated sudden high intensity signal=acoustic trauma

exposure to elevated noise levels over time=gradual HL onset

Question 7

NIHL symptoms

Answer 7

tinnitus (constant, high pitched, non-pulsatile, develops gradually over time), hyperacusis, gradual onset HL (HF), aural fullness, TTS, vestibular symptoms

Question 8

NIHL Incidence & Prevalence

Answer 8

second most common cause of SNHL, 10 million americans, young adults, workers prior to OHSA workplace noise restrictions

Question 9

NIHL Etiology & Pathology

Answer 9

genetics, smoking, male gender, diabetes mellitus, CVD, toxins, free radicals can damage hair cells and cochlear nerve fibers

dependent on noise level, frequency, time of exposure, use of hearing protection, metabolic exhaustion=source of free radical damage

reticular lamina damage causes intermixing of endolymph and perilymph

Question 10

NIHL Site of Lesion

Answer 10

Organ of Corti-OHC (oxidative stress from free radicals, shearing trauma for high intensity fluid waves through cochlea)

as noise intensity increases, IHC become involved, NT release can damage nerve cells

half-octave shift: max point of displacement of traveling wave along BM more basal direction for high itnensity stimuli

Question 11

NIHL Audiology

Answer 11

Patient history, noise notch (damage thought to occur 5-15 mm from oval window which corresponds to this frequency range), OAEs, ultra-high frequency testing, bilateral damage

Question 12

NIHL Management

Answer 12

Prevention & Conservation

Amplification

Question 13

Sudden HL

Answer 13

Non-fluctuating SNHL of 30 dB within 72 hour period over 3 adjacent frequencies, little is known about etiology or treatment

Question 14

SSHL Incidence & Prevalence

Answer 14

1% of all SNHL, 4000 new cases each year

bilatearly in 4-17% of patients, more common in elderly

Question 15

SSHL Symptoms

Answer 15

Rapid onset of HL (popping sensation, upper respiratory infection), vertigo (~50%), tinnitus (~70%), aural fullness

Question 16

SSHL Etiology & Pathology

Answer 16

Viral Infections: many cases are preceded by infection
Autoimmune
Labyrinthe Membrane Rupture
Vascular: inner ear vasculature can be compromised by microembolism/vasospasm, therapies have focused on improving cochlear blood supply
Neurologic: MS, migrane
Neoplastic: vestibular schwannoma

Question 17

SSHL Site of Lesion

Answer 17

degeneration of cochlear duct structures near basal turn, VIII and central sites can be involved

Question 18

SSHL Audiology

Answer 18

case history–differential diagnosis (retrocochlear vs. SSHL, suddenly noticed HL vs. SSHL, Meniere’s vs. SSHL)

acoustic reflexes, WRS and OAEs are variable – may provide information about etiology and prognosis

Question 19

Michel Aplasia

Answer 19

complete failure of development of inner ear and auditory nerve

Question 20

Mondini Aplasia

Answer 20

incomplete development and malformation of inner ear (cochlea and vestibular)

Question 21

Transverse Temporal Bone Fracture

Answer 21

head trauma in anterior-posterior plane

directly damage VIII or VII or vestibular structures–compromise inner ear, cause hemorrhage

Question 22

Meningitis

Answer 22

suppurative labyrinthitis due to direct spread of infection from subarachnoid space through cochlear aqueduct

symptoms: stiff neck, headache, high fever, nausea, vomiting

HL: bilateral SNHL symmetrical and permanent

may have ossification of cochlea 3 months-1 year

Question 23

Diabetes

Answer 23

autoimmune disease where insulin cells are destroyed (I) or managed with diet (2)

vascular pathology–defects in structure or function of blood vessels, relevant to inner ear

progressive, bilateral SNHL (abnormal ABR)

Question 24

Autoimmune Inner ear Disorders

Answer 24

not well understood

bilateral fluctuating SNHL – quicker onset than associated with other pathologies, tinnitus may be present

Question 25

DFNB1

Answer 25

over 50% have profound deafness
autosomal recessive, mutation disrupts potassium flow to inner ear

usually congenital, usually stable

Question 26

meniere’s disease

Answer 26

episodic vertigo, tinnitus, fluctuating unilateral SNHL, aural fullness

begins in early to mid adulthood–progressive

early stages=episodic and unilateral, LF HL
late stages=chronic symptoms, become bilateral, HL spreads across frequency

Question 27

Meniere’s disease etiology

Answer 27

endolymphatic hydrops: overextension of membranous labyrinth due to excessive endolymph