Vastibular and Auditory pathway Flashcards
1
Q
Where is the vestibule?
A
- central portion of inner ear
the system is found within the TEMPORAL bone
2
Q
What is the vestibular system responsible for?
A
- balance, posture and equilibrium
- coordinates head and eye movement
3
Q
What makes up the Vestibular system?
A
- 3 Semicircular canals —-that lie on diff. planes
(X,Y,Z)
—-filled with endolymph
4
Q
What do the ampulla of the semicircular canals contain?
A
- – hair cells that BEND with rotation
- —-these hair cells RELEASE NT > AP prodn
- —-signals produced is based on MOTION
5
Q
Which organs of the vestibule contain otolith?
A
-UTRICLE and SACCULE
otolith= ear stones= Calcium carbonate crystals
6
Q
What is the otolith responsible for?
A
- —sits on TOP of hair cells
- drags hair cells in response to LINEAR MOTION (up, down, forward and backward)
- —-generating VESTIBULAR neural activity
7
Q
Where does the Vestibular nerve send signals to ?
A
- the BRAINSTEM (vestibular nuclei)
- the CEREBELLUM
8
Q
Where is the vestibular nuclei found?
A
- beneath the FLOOR of the 4th ventricle (in PONS/ MEDULLA)
9
Q
3 typical symptoms a.w dysfxn of the Vestibular system?
A
- VERTIGO: spinning room (when head is still)
- nystagmus
- N.V
10
Q
Describe how nystagmus presents as?
A
- rhythmic beating of the eyes
- –slow drift of eye to one direction
- —correction to the other directions
11
Q
What form of nystagmus does a pt have, if their RIght eye quickly corrects to the left side?
A
- Left-ward nystagmus
- –named for direction of the fast correction
12
Q
Name the diff. types of nystagmus, which indicate a PERIPHERAL vestibular dysfxn.
A
- left, right and torsional
- –issues with the vestibular apparatus in the INNER ear
13
Q
Name the types of nystagmus a.w CENTRAL vestibular dysfxn.
A
UPBEAT and DOWNBEAT
—in brainstem lesions (strokes/ tumors)
14
Q
Which form of nystagmus is bad, central or peripheral?
A
CENTRAL
- –indicative of potential:
- brainstem/cerebellar lesion
- TIA/ vertebrobasilar stroke
- tumor (posterior fossa)
- cerebellar infarction and hemorrhage
15
Q
Name benign causes of nystagmus.
A
- peripheral lesions/ conditions > Inner Ear problem > BPV (benign positional vertigo) > vestibular neuritis > Meniere's disease
16
Q
What are the signs of Central vertigo?
A
- pure VERTICAL nystagmus
- —nystagmus changes direction with gaze (look r; upbeat/ L= downbeat)
- DIPLOPIA
- DYSMETRIA (nose-finger test)
- —skew deviation (vertical misalignment of the eyes)
- POSITIONAL testing= IMMEDIATE nysatgmus
—-other CNS symptoms
17
Q
What is seen with peripheral nystagmus?
A
- mixed horizontal and torsional nystagmus
- —DELAYED nystagmus (on positional testing)
- —nystagmus FATIGUES over time
- —-stable ROMBERG
18
Q
How to perform postional testing?
A
- DIX-HALLPIKE MANEUVER
- –done to reproduce vertigo and cause NYSTAGMUS
- –seated pt, turn head to side; rapidly lie pt on table; heading hanging over end
19
Q
What helps DX BPV?
A
- Dix Hallpike Maneuver
20
Q
What is seen in a typical DHM?
A
- BPV
- —no symptoms for 5-10s
- —-room spins (vertigo) and TORSIONAL nystagmus occurs
- —resolved with SITTING up
- FEWER symptoms with repeated maneuvers
21
Q
Why does BPV develop?
A
- Nystagmus that develops due to HEAD turning and positioning
- due to calcium debris in the semicircular canals; weighs down on hair cells (CANALITHIASIS) —-
22
Q
What helps BPV to go away?
A
- Epley Maneuver (repositions otoconia)
23
Q
What causes vestibular neuronitis?
A
- VIRAL or POST-inflammatory neuropathy of the VESTIBULAR portion of CN VIII
- –benign/ self limited
24
Q
What occurs in Meniere’s disease?
A
- endolymph fluid accumulation
(HYDROPS)
—swelling of the labyrinthine system
25
What are the signs and symptoms of Meniere's disease?
1. TINNITUS
2. Sensorineural hearing loss (WEBER is LOUDER in NORMAL ear) ---Rinne: AC> BC
3. Vertigo
26
How to treat meniere's disease?
- avoid high salt (REDUCES swelling)
- avoid caffeine, nicotine (vasoconstrictors, reduce flow from inner ear)
- diuretics
27
What are the 3 bones of the inner ear? What do these bone do?
Malleus, INcus and Stapes
| - amplify the tympanic membrane motion
28
What does the stapes do?
- PUSHES the fluid-filled cochlea
| - ----> tiny hair cells get stimulated; depending on freq. of sound ===> electrical signal is generated
29
Once sound is picked up by the cochlear nerve, where to next?
- cerebellopontine angle
- ---LATERAL pons
-----at this angle most brainstem lesions with hearing loss is here
30
What is conductive hearing loss? Why may it come about?
- Sound waves CAN'T convert to NERVE signals
| - ---d.t obstruction (WAX), INFECTION (otitis media) or otosclerosis (bony OVERGROWTH of stapes)
31
What causes sensorineural hearing loss?
- issue with the nerve
- d.t Cochlea disease/ cochlear nerve failure (acoustic neuroma)
or CN damage
32
What is presbycusis?
- age-related hearing loss
| - --degen. of ORGAN of CORTI > sensorineural hearing loss (slow developm)
33
What is a NORMAL Weber's Test?
- should be heard EQUALLY in both ears; when tuning fork is placed on the forehead
34
Does the Weber test indicate what type of hearing loss the pt has?
NO
| ---just makes you aware of A POTENTIAL hearing defect
35
In Weber test, if the pt has conducitve hearing loss in the right ear. What is the expected results in this test?
- LOUDER in the BAD ear in CONDUCTIVE hearing loss
- ---no background noise
- --louder in R ear
36
IF the pt has sensorineural hearing loss in the L ear, what is expected in the Weber test?
- LOUDER in the GOOD ear
- ---no nerve to sense condxn
- --LOUDER in R ear
37
What is a normal Rinne Test?
- AC >BC
| should be easy for sound waves to move through AIR and not bone
38
What is expected in conductive hearing loss in Rinne Test ?
---pt CANNOT hear NEXT to the ear
| AC
39
What is expected in Sensorineural hearing loss in Rinne test?
- AC >BC
- ---but BOTH are reduced
- --in bad ear just 5s of AC and BC (as opposed to 10s in good ear)
40
What are the results for RINNE and WEBER in CONDUCTIVE HEARING LOSS?
WEBER: LOUDER in BAD ear
RINNE: AC
41
What results for sensorineural hearing loss?
WEBER: louder in GOOD wear
RINNE: reduced AC>BC (like normal)
42
How to truly diagnose hearing loss?
with AUDIOMETRY
43
When may one experience SUDDEN hearing loss?
- after LOUD noise
| - ---d/t TYMPANIC membrane rupture
44
What occurs with LONG -term exposure to noise?
- damage tociliated cells of Organ of Corti
| - ----high freq. is LOST
45
Where do fibres carrying info with LOW freq. sound end?
- in the ANTEROLATERAL part of the auditory cortex
------posteromedial part for HIGH freq. sound)
46
What happens with damage to Broca's area?
- diff. to PRODUCE language
- -aka MOTOR aphasia
- no problem comprehending
47
What occurs with damage to Wernicke's Area?
- can't comprehend language
| - ----puts words out of order and make up meaning less word
48
What does the vestibular nuclei relay info to ?
- thalamus
- Cerebellum
- Nuclei of CNs III, IV, VI
- Cerebellum
- Spinal cord
49
Where does the LOWER visual field projected to ?
- to the gyrus SUPERIOR to the calcarine sulcus
---upper is projected to gyrus inferior to the calcarine sulcus
50
Where does the macula project to?
- to the POSTERIOR pole of VISUAL cortex
| - ---occupies GREATER proportion of the cortex
51
How does the upper visual field end up projecting to the gyrus INFERIOR to the calcarine sulcus?
----upper visual field fibres from the geniculocalcarine tract will first LOOP anteriorly AROUND the TEMPORAL part of lateral ventricle in Meyer's loop
