audiology ch. 18, 10-11

Dizziness, vertigo, & imbalance

Considered as top complaints in doctor’s offices, responsible for 5-8 million US visits yearly: 

vestibular input

Which sense aids balance most? 

locate position

Main job of balance system? 

five sensory receptors

Membranous labyrinth contains what? 

Superior canal 

Which canal is vertical? 

excitation

Kinocilium deflection causes?

inhibition

Stereocilia away from kinocilium causes… 

endolymph flow

What bends the cupula? 

hair cells

Crista ampullaris houses…

horizontal motion

Utricle primarily senses…

vertical motion

Saccule mainly detects…

calcium carbonate

Otoconia are composed of…

cochlear nerve

VIII nerve includes the

Opposite side

Horizontal VOR eyes move? 

head movement

VOR stabilizes gaze during: 

illusion of motion

Which best defines vertigo? 

high blood pressure

Non-vestibular cause of imbalance? 

illusion of motion

Vestibular system mismatch leads to

posterior canal

BPPV most commonly affects? 

head position changes

What triggers BPPV episodes? 

Autophony, conductive loss

SCD key symptom pair? 

sound-induced vertigo

Tullio phenomenon involves? 

oscillopsia

Classic vestibulotoxicity complaint? 

Gentamicin

Ototoxic medication example? 

Hearing loss in labyrinthitis 

Neuritis versus labyrinthitis difference? 

aging, head trauma

BPPV common precipitating factors?

world bouncing

Oscillopsia feels like? 

Direction-changing nystagmus

Central balance signs include? 

Vertigo, aural fullness, tinnitus 

Meniere’s classic symptom trio? 

motion sensitivity

Vestibular migraine may present with? 

meniere’s disease

Endolymphatic hydrops relates to? 

true

true/false: fall risk rises with age

hospitalization, fractures

Common outcomes after falls include: 

Age-related unsteadiness 

Presbyapondera mainly describes

vestibular cause

Primary vestibular question is: 

angular acceleration

Semicircular canals primarily sense

linear acceleration

Otolith organs primarily sense

stabilize gaze

VOR purpose during head turns: 

0.1 - 3 Hz

Vestibular sensitivity peak range

0.003 Hz range

Calorics mainly probe

Guide test choice

Case history first helps

Flag BPPV

Bedside screens can

eye movements

VNG/ENG primarily records

rotary chair

Best for bilateral hypofunction

saccule pathway

cVEMP predominantly assesses: 

Dix-Hallpike

Which test triggers BPPV nystagmus? 

Present low-threshold

cVEMP in SCD is typically…

reduced calorics

Bilateral vestibulotoxicity often shows…

vHIT

Which test reflects high-frequency VOR? 

vestibular neuritis

Unilateral hypofunction suggests what condition? 

inflammation resolved

Neuritis tests can appear normal when

false

true/false: calorics test high-frequency function

epley

Which maneuver treats posterior BPPV? 

Unilateral caloric weakness

Meniere’s often shows these tests

reduced or absent

In Meniere’s, cVEMP may be…

highly variable

Vestibular migraine testing is typically…

Direction-changing nystagmus

Central disorders often show…

inconsistent

VOR in central disorders is…

low-sodium diet

Diet often advised for Meniere’s? 

balance

The role of the ____ system is to provide accurate information about our position in space and about the direction and speed of our movement

falling

the balance system serves to prevent ____ by rapidly correcting for any changes that might occur in body position with respect to gravity

eye

The system functions to control ____ movement to maintain accurate vision during head movement

vary

The contributions of the visual, vestibular, and somatosensory systems ____ as a function of what we are doing at the moment

vestibular

The ____ portion of the inner ear consists of a fluid-filled membranous labyrinth within the bony labyrinth of the temporal bone

five sensory receptors

The membranous labyrinth contains ____ ____ ____:

• Otolith organs

  • Utricle

  • Saccule

• Semicircular canals

  • Superior (anterior)

  • Horizontal (lateral)

  • Posterior canals

hair cells

The vestibular system uses ____ ____, similar to the auditory system, each with many stereocilia and one taller kinocilium

opposite

When the head or body moves, fluid shifts in the ____ direction, stimulating vestibular hair cells and increasing activity in the vestibular branch of the VIII nerve

motion and gravity

Vestibular hair cells respond to both ____ & ____, helping the body detect changes in position & movement

increases; excitatory

Movement of stereocilia toward the kinocilium ____ electrical activity & creates an ____ neural response

decreases; inhibitory

Movement of stereocilia away from the kinocilium ____ electrical activity & creates an ____ neural response

angles

The semicircular canals are positioned at right ____ to each other, allowing them to detect angular and rotational head movements

ampulla

Each semicircular canal contains an _____ at its entrance, which houses sensory hair cells 

cupula

These hair cells extend into a gelatinous structure called the ____

• When the head moves, fluid inside the semicircular canals shifts, pushing against the cupula & bending the embedded cilia.

• This bending of the cilia stimulates the hair cells, enabling the detection of rotational motion

horizontal; vertical

The utricle and saccule detect head tilt & linear acceleration, with the utricle responding mainly to ____ acceleration & the saccule to ____ acceleration

otoconia

In both structures, hair cells extend into a gelatinous membrane that contains calcium carbonate crystals called ____

more

The added weight of the otoconia makes the membrane ____ sensitive to gravity, allowing the hair cells to detect changes in head position & movement

vestibular

____ Nerve: 

• Vestibular nerve division → Formation of Scarpa’s ganglion → Central connections

superior; inferior

Vestibular nerve division

• Nerve fibers from the otolith organs & semicircular canals exit through two branches: the ____ (from the superior semicircular canal (SCC), lateral SCC, and utricle) & the ____ vestibular nerve (from the posterior SCC & saccule)

scarpa’s

Formation of _____ ganglion

• These nerve fibers converge at the lateral end of the internal auditory canal, forming ____ (vestibular) ganglion

ascending and descending

Central connections

• After entering the brainstem, the vestibular nerve splits into _____ & _____ branches, which synapse in multiple vestibular nuclei & the cerebellum

gaze; vestibulo-ocular

The vestibular system helps stabilize ____ during head movement through a built-in connection between the vestibular & ocular motor systems

• This connection produces a reflexive eye movement called the ____-____ reflex, which sends excitatory or inhibitory signals from the horizontal semicircular canal to the vestibular nuclei after head motion

compensatory

The vestibular nuclei then signal the eye muscles to create _____ eye movements

• Horizontal VOR

• Vertical VOR

horizontal VOR

Eyes move left when the head turns right

vertical VOR

Up/down eye movements maintain stable vision

eye

Understanding the VOR is essential because many vestibular tests measure ____ movements as an indicator of vestibular system function

medical

Balance problems can arise from non-vestibular causes, including ____ conditions such as high blood pressure, diabetes, neurological disorders, & certain medications

vertigo

a key sign of a vestibular disorder, involving an abnormal sensation of motion

mismatch

When the vestibular system is damaged, it sends inaccurate signals about head or body movement to the brain, creating a ____ between actual movement & perceived movement, resulting in an illusion of motion

vestibular

Disorders of the _____ System:

• BPPV

• Superior Canal Dehiscence (SCD) 

• Vestibulotoxicity

• Vestibular Neuritis/Labyrinthitis

• Ménière’s Disease

• Vestibular Migraine

• Central Balance Disorders

Benign Paroxysmal Positional Vertigo (BPPV)

A peripheral vestibular disorder caused by dislodged otoconia that migrate into a semicircular canal (most commonly posterior).

Benign Paroxysmal Positional Vertigo (BPPV)

Causes:

• Aging, head trauma, viral illness, idiopathic

Benign Paroxysmal Positional Vertigo (BPPV)

Symptoms:

• Brief episodes of vertigo triggered by head position changes; nystagmus

Superior Canal Dehiscence (SCD)

A thinning or opening (dehiscence) in the bone overlying the superior semicircular canal

Superior Canal Dehiscence (SCD)

Causes:

• Congenital weakness, trauma, pressure changes, progressive bone thinning

Superior Canal Dehiscence (SCD)

Symptoms:

• Sound/pressure-induced vertigo (Tullio phenomenon), autophony, conductive hearing loss, oscillopsia

Vestibulotoxicity

Damage to the vestibular hair cells or nerve due to ototoxic medications

Vestibulotoxicity

Causes:

• Aminoglycosides (gentamicin, tobramycin), chemotherapy drugs (cisplatin), high-dose loop diuretics

Vestibulotoxicity

Symptoms:

• Oscillopsia, imbalance, difficulty walking in the dark, bilateral vestibular hypofunction

Vestibular Neuritis / Labyrinthitis

Inflammation of the vestibular nerve

Vestibular Neuritis / Labyrinthitis

Causes:

• Viral infections, post-viral inflammation