NeuroAnatomy Lecture 12 Objectives - Vestibular System

Question 1

What is the main function of the vestibular system?

Answer 1

Maintains equilibrium/postural control

Question 2

What structures are a part of the peripheral vestibular system?

Answer 2

semicircular canals, otolithic organs (utricle/saccule), CN8

Question 3

What structures are a part of the central vestibular system?

Answer 3

vestibular nuclei in the brainstem

Question 4

What is the primary input to the vestibular nuclei?

Answer 4

peripheral vestibular system, visual pathways, and proproceptive/mechanosensory pathways

Question 5

Where is the inner ear located?

Answer 5

Within the temporal bone

Question 6

What two types of information does the inner ear process?

Answer 6

Vestibular and Auditory

Question 7

What is the function of the semicircular canals?

Answer 7

Senses angular/rotational movement and acceleration/deceleration

Question 8

What is the function of the Otolithic organ : Utricle?

Answer 8

senses horizontal acceleration

Question 9

What is the function of the Otolithic organ : Saccule?

Answer 9

senses verticle movemet

Question 10

What / Where is the Ampulla?

Answer 10

it is an enlarged area with receptors located in each semicircular canal

Question 11

What are the receptors in the Ampulla called?

Answer 11

hair cells

Question 12

Where do the hair cells emerge from?

Answer 12

the Crista Ampullaris

Question 13

What are the hair cells embedded in?

Answer 13

the hair cells are embedded in a gelatinous mass known as the cupula

Question 14

What are the hair cells connected to?

Answer 14

they are connected to CN 8

Question 15

what is the fluid inside the semicircular canals?

Answer 15

Endolymph fluid

Question 16

How is directional movement detected in the semicircular canals?

Answer 16

the endolymph within the semicircular canals moves and “bends” the cupula and hair cells, which stimulates an action potential in the vestibular nerve

Question 17

which Otolithic organ do the ampullas connect to?

Answer 17

utricle

Question 18

what are the functions of the otolithic organs?

Answer 18

detecting linear movement and acceleration/deceleration as well as head position in a static position

Question 19

Where are the receptors of the utricle and saccule?

Answer 19

within the macula

Question 20

what is the structure of the macula?

Answer 20

hair cells are embelled in a gel-like substance with “otoliths” on top of the gel layer

Question 21

what are the otoconia?

Answer 21

they are calcium carbonite crystals, they have some weight to them

Question 22

Which otolithic organ is slightly superior?

Answer 22

the utricle is slightly superior, the saccule is slightly inferior

Question 23

what type of linear movement does the saccule detect?

Answer 23

vertical motion

Question 24

What is BBPV?

Answer 24

Benign Paroxysmal Positional Vertigo // most common vestibular disorder and cause of vertigo in adults

Question 25

What are the characteristics of BBPV?

Answer 25

acute/sudden onset of vertigo and nystagmus, symptoms last seconds up to 2 minutes

Question 26

What clinically happens during an episode of BPPV?

Answer 26

the otoliths/otoconia dislodge from the macula of the otolithic organs and travel to the semicircular canals. they can either get stuck in a canal or the cupula.

Question 27

What is Canalithiasis?

Answer 27

when otoliths accumulate in the endolymph fluid in the semicircular canal, usually near the cupula and/or free flow in the canal

Question 28

What is Cupulolithiasis?

Answer 28

when otoliths accumulate or get stuck in the cupula

Question 29

what is the most common cause of BPPV?

Answer 29

when otoliths accumulate in the posterior semicircular canal

Question 30

What are the characteristics of Canalithiasis?

Answer 30

free flowing otoliths in canal, delay of onset of symptoms, symptoms last less than 60 seconds

Question 31

What are teh characteristics of Cupulolithiasis?

Answer 31

otoliths adhered to the cupula, no delay in symptom onset, symptoms last more than 60 seconds

Question 32

What is the Dix-Hallpike Test?

Answer 32

To assess for *posterior* canal BPPV

Question 33

How is the Dix-Hallpike Test performed?

Answer 33

patient seated w/ head rotated to 45°, quickly brought to supine with head extended to 30°, observe for nystagmus or dizziness. // *testing ear that is down*

Question 34

What maneuver / treatment do you administer for a positive Dix-Hallpike test?

Answer 34

Particle Repositioning Maneuvers (PRM) (most common is Epley Maneuver) // repositioning of patient in attempt of redirecting fluid flow in posterior canal for otoliths to go back to macula.

Question 35

What are symptoms of Meniere's Disease?

Answer 35

sensation of fullness in ears / hearing loss // tinnitus // vertigo // N/V

Question 36

What are the clinical characteristics of Meniere's Disease?

Answer 36

slow, chronic onset // lasts for 2-3 days with gradual improvement over 2 weeks // associated with abnormal endolymph fluid pressures

Question 37

How is Meniere's Disease diagnosed?

Answer 37

two or more definitive episodes of spontaneous rotational vertigo lasting at least 20 minutes, low-frequency hearing loss, tinnitus or aural fullness in affected ear, exclusion of other causes for above symptoms

Question 38

What is the second most common cause of vertigo?

Answer 38

Vestibular Neuritis

Question 39

What is vestibular neuritis?

Answer 39

an acute unilateral vestibulopathy, usually due to viral infection affecting vestibular nerve unlitaterally

Question 40

What are the clinical characteristics of Vestibular Neuritis?

Answer 40

general vestibular symptoms (dizziness, n/v), onset of symptoms occur about 2 weeks post infection and gradually resolve over 6 weeks - 3 months

Question 41

What are symptoms of Vestibular Neuritis?

Answer 41

complaints of imbalance, motion intolerance, headache, dizziness more easily provoked

Question 42

What is Labyrinthitis?

Answer 42

inflammation of the membranous labyrinth often due to either bacterial or viral infection -- causes inflammation to *both* CN8 branches

Question 43

What are common symptoms of Labyrinthitis?

Answer 43

changes in hearing, dizziness, imbalance, vertigo resolving within days - weeks

Question 44

What is Perilymphatic Fistula?

Answer 44

an abnormal communication of inner and middle ear spaces leading to vertigo

Question 45

What are some symptoms of a Perilymphatic Fistula?

Answer 45

vestibular symptoms (dizziness, N/V, etc) or hearing loss