Vestibular System

Question 1

What 2 places does information from the vestibular nuclei go to?

Answer 1

1. Ocular Muscles (VOR)

2. Spinal cord (VSR)

Question 2

What 3 sections is the vestibular section divided into?

Answer 2

1. Peripheral (sensory input, ss canals and otoliths)
2. Central Processor (vest. nuclei and vest cerebellum)
3. Mechanism for Motor Output (VSR, VOR)

Question 3

True or False. The Bony Labyrinth is filled with PERILYMPH and the Membranous Labyrinth is filled with ENDOLYMPH.

Answer 3

True

Question 4

What direction does the urtricle lay/hang? What direction does the saccule lay/hang? Motions that each detect?

Answer 4

utricle: horizonally - horizontal plane motions (front-to-back, left-to-right)
saccule: vertically - saggital plane motions (front-to-back, up-and-down).

Question 5

What two types of cilia does the hair cells contain?

Answer 5

1. Stereocilia (50-70)

2. Kinocilium (1)

Question 6

True or False. Movement TOWARD the kinocilium DECREASES the rate of nerve firing.

Answer 6

False. movement toward it increases the rate and movement away decreases the rate.

Question 7

What is the crista ampullaris. What is the maculae?

Answer 7

crista ampullaris - sensory area of the ampullae composed of a tuft of blood vessels and nerve fibers.
Maculae - the sensory areas containing the saccule and utricle.

Question 8

Define:

1. cupula

2. otoconia

Answer 8

1. gelatinous membrane that covers hair cells to completely seal the semicircular canals
2. calcium carbonate crystals that cover the gelatinous materal covering the hair cells in the otolith organs. Lags behind when movement, causing hair cells to bend.

Question 9

What are the 2 advantages of the spatial arrangement of the semicircular canals?

Answer 9

1. Sensory redundancy (in case one side is lost)

2. Allows brain to ignore changes that occur to both sides at once (changes in body temp or chemistry).

Question 10

Damage to the vestibular cortex can result in what 2 conditions?

Answer 10

1. loss of awareness of “upright” position

2. unilateral pusher syndrome

Question 11

Explain where the following pathways from the vestibular nuclei lead to and what they do:

1. Medial longitudinal fasciculus
2. Vestibulospinal tracts
3. Vestibulocollic pathways
4. Vestibulothalamocortical
5. Vestibuloautonomic
6. Vestibulocerebellar

Answer 11

1. extraocular nuclei & superior colliculus - eye movements (VOR)
2. LMN’s - posture influence
3. XI nuclei - influences head position
4. cortex - conscious awareness of head position/movement
5. reticular formation - vomiting/nausea
6. vestibulocerebellum - eye movements and postural muscle activity via VOR and VSR respectively.

Question 12

What symptoms does BPPV produce and what does it not produce?

Answer 12

BPPV produces short-lived (30s-2min) vertigo with rapid changes in head position (ext with head turned). It does not produce loss of hearing, “fullness” in the ear, or tinnitus.

Question 13

1. Is BPPV more common in men or women?
2. Is it usually unilateral or bilateral?
3. How long does it usually last?
4. What is the name of the test used to dx it and positive sign of it?

Answer 13

1. women
2. unilateral
3. 6-12 mo with certain cases on/off for years
4. Dix-Hallpike positioning test. + is vertigo and nystagmus.

Question 14

Explain the 2 pathophysiological theories behind BPPV.

Answer 14

1. Cupulolithiasis - deposition of otoconial material onto the cupula
2. Canalithiasis - debris of higher density than endolymph is free-floating in the canal.

Question 15

What are the 4 signs/symptoms of vestibular neuritis?

Answer 15

1. Acute onset of prolonged, severe rotational vertigo
2. Imbalance
3. Nausea
4. Nystagmus toward the good ear (not while fixating).

Question 16

1. Is hearing loss associated with vestibular neuritis?
2. How can you test for vestibular neuritis?
3. What are the 2 ways that recovery happens?
4. What is the term used for complete deafferentation or destruction of a labyrinth?

Answer 16

1. no
2. Caloric testing (warm or cold water in ear).
3. Central compensation of vestibular tone balance and peripheral restoration of labyrinthine function.
4. Unilateral Vestibular Deafferentation Syndrome.

Question 17

Describe the attack process of Meniere’s Disease

Answer 17

1. Initially fullness in ear, tinnitus and hearing loss
2. After a few minutes, 30 min to 24 hrs of severe rotational vertigo, postural imbalance, and N & V.
3. After 24 hrs worst symptoms abate and person ambulatory in 2-3 days. Instability can persist for days/weeks but normal WILL return. Hearing loss and tinnitis may persist or go away.

Question 18

1. Is Meniere’s Disease usually unilateral or bilateral?
2. Attacks ________ in frequency over the 1st year, then _________.
3. What is the pathophysiology of Meniere’s?
4. How can PT’s treat Meniere’s?

Answer 18

1. unilateral
2. increase, decrease
3. etiology unknown, result is increase in endolymphatic fluid pressure within inner ear.
4. We can’t. Tx is medical in nature and PT’s can only work with pts whom imbalance problems persist in remission with habituation and balance activities.

Question 19

1. What are some causes of bilateral vestibular disorders?

2. How are bilateral vestibular disorders treated?

Answer 19

1. Meningitis, labyrinthine infections, paget’s, bilat. tumors (acoustic neuromas, meds (vancomyosine), autoimmine disorders.
2. Accomodation not possible b/c bilat. Tx medical (vestibular suppressants and coricosteroids for vertigo and autoimmune problems respectively).