Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PHTY2230 > Vestibular > Flashcards

Vestibular Flashcards

1
Q

Roles of vestibular system

A
  • Orientate to vertical
  • Control center of mass
  • Stabilise head
  • Sense and perceive self motion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Bony Labyrinth Anatomy

A

Sits within the temporal bone

Forms the structure and chambers of the peripheral vestibular system

Has 3 semicircular canals, vestibule (central chamber) and the cochlear

Filled with perilympatic fluid - high Na:K ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Membranous Labyrinth Anatomy

A

Sits suspended within the bony labyrinth and perilympahtic fluid (5% of space within bony)

Contains the 5 sensory organs (3 semicircular canals and 2 otolith organs)

Filled with endolymphatic fluid high K:Na ratio meaning it has a higher viscosity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Layers of the vestibular organ

A

Bony labyrinth → perilymph → membranous labyrinth → endolymph

Endolymph has higher viscosity due to high K:Na ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

SCC structures and functions

Ampulla, Cupula and Hair cells

A
  • Ampulla
    • Bulb like expansion at the base of each of the canals
    • Contains the cupula as well as the crista ampullaris (tuft of blood vessels, nerve fibers and supporting structures)
  • Cupula
    • Bridges the width of the ampulla which seals off the canal so endolymph cannot go from one side to the other
  • Hair cells
    • Housed within cupula
    • 50-70 small stereocilia and one long kinocilium (these are arranged from smallest to longest)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Stimulation of hair cells within the SCC

A
  • Each afferent neuron has a basal firing rate (base activity level), approx. 1.1.5 Hz
  • Deflection of air cells with either excite of inhibit this firing rate based on the direction, this defection is caused by movement of endolymph fluid
    • Excitation - stereocilia deflected towards kinocilium
    • Inhibition - stereocilia deflected away from kinocilium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Structure of the otolith organs and the two types

A

Sensory maculae are hair cells covered in a gelatinous membrane

Otoconia refers to the calcium carbonate crystal imbedded into this membrane which provide increases mass making the membrane heavy.

This mass causes them to be sensitive to gravity and accelerations

Utricles - sensitive to horizontal motion

Saccule - sensitive to vertical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Vestibular nerve pathway and portions

A
  • Primarily afferent fibers wit only 5-8% efferent
  • Travels through the internal auditory canal to enter the brainstem at the pontomedullary junction
  • Has 2 portions (pathologies may only effect one portion)
    • Superior - supplies the anterior canal, lateral canal and utricle
    • Inferior - supplies the posterior canal and saccule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Blood supply to the vestibular system

A

Supplied by the labyrinthine artery which originates from the anterior inferior cerebella artery (AICA) and basilar artery

There is no collateral blood supply meaning ischemic event or stroke will cause immediate damage

Also supplies cochlear meaning occlusion causes hearing loss with vestibular symptoms

The PICA supplies cerebellum so an occlusion hear will cause vestibular dysfunction within interruption to hearing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

4 major vestibular nuclei in the brainstem

A
  • Superior and medial - mostly input from SCC

- Lateral and inferior - mostly input from otolith organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

SCC function

A
  • Provide information about velocity and direction, particularly CHANGES in these
  • Enable VOR reflex, generates eye movement that match head velocity
  • They are in a perpendicular arrangement, meaning each canal is perpendicular to the other two which allows for sensing of movement in all planes (yaw, pitch and roll)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Co-planar pairing of SCC

A
  • 6 SCC form 3 pairs
  • Laterals/horizontal pair
  • LARP (left ant and right post)
  • RALP (right ant and left post)

These are aligned with the optimal pull of the ocular muscle causing quick and effective VOR

It creates a push-pull rhythm meaning the endolymph within the pair is displaced in the opposite directions causing increased neural firing rate in one and decreased in the other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Advantages of co planar pairing of SCC

A
  • Creates a sensory redundancy when there is a unilateral loss meaning the brain will still receive information from the opposite side
  • The brain can ignore changes in the neural firing rate that occur on both sides simultaneous. Such as when there is increased body or environment temp causing the endolymph to swell and increase viscosity
  • Assists in compensation of sensory overload
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which direction does excitation occur

A

A canal is excited by head motion towards that canal in the appropriate plane e.g. L horizontal excited by L turns. Will cause excitation in one canal and inhibition in its pair.

However, the neural firing rate cannot go below 0 causing the sensory redundancy feature of the pair to not be accurate at high speeds (>180 deg/s) as the excitatory side is still increasing while the inhibitory side can no longer decrease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Ampullopetal and Ampullofugal flow

A

Ampullopetal flow = toward the ampulla

Ampullofugal flow = away from ampulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ewald’s Laws

A

These laws are only appropriate for peripheral disorders!

1st

  • Eye and head movement always occur in the same plane as the canal being stimulated
  • Axis of nystagmus should match axis of SCC that generated it

2nd

  • In horizontal SCCs ampullopetal flow cause greater stimulation than ampullofugal

3rd

  • In vertical SCC ampullofugal flow causes greater stimulation than ampullopetal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Functions of the otolith organs

A

Sense linear acceleration of the head in all 3 planes in an upright position and the orientation of the head with respect to gravity

Utricle = horizontal

Saccule = vertical

They are very curved and the hair cells are fanned out meaning that can detect effects of gravity in all 3 planes (bean shaped)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the 3 main vestibular reflexes

A

Vestivulo ocular reflex
Vestibulospinal Reflex
VestibuloCollic Reflex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

VOR - Vestivulo ocular reflex main function

A
  • Maintains stable and clear vision during quick or non constant head movements. Maintains the image on the fovea f the retina during movements
  • Head must be moving at variable velocity, visual target can be stationary or in motion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

VOR Gain

A

Output (eye movement) : input (head movement)

  • Gain of 1 - output = input
  • Gain of 2 output is twice that of input
  • Gain of 0.5 output is half that of input

Vestibular loss causes the gain to reduce → difficulty keeping eyes on target during fast head movements (retinal slip which will cause corrective saccade)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

VSR - Vestibulospinal Reflex function and pathways

A
  • Stabilises the head on the body and maintains upright posture
  • Uses more input from otolith than SCC
  • 3 major connections:
    • Lateral vestibulospinal tract - anti grav postural motor activity
    • Medial vestibulospinal tract - Ongoing postural changes and head position in response to SCC
    • Reticulospinal tract - most balance reflexes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

VCR - VestibuloCollic Reflex

A
  • Acts on neck muscles to stabilise the head

- Reflex movement counters movement sensed by vestibular sensory organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Outline of Vestibular Neuritis

A
  • 2nd most common cause of vertigo
  • Caused by acute inflammation of the Vestibular nerve CN 8
  • Normally preceded (sometimes) by viral infection such as herpes, GI or upper resp infection
  • Can be partial or full depending of which portions of the nerve are affected
    • Superior VN= ant SCC, horizontal SCC and utricle (more common)
    • Inferior VN = Posterior SCC and Saccule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Symptoms of Vestibular Neuritis

A

Symptoms:

  • Acute onset of prolonged vertigo (1-4 days) this is referred to as Acute Vestibular Syndrome
  • Nausea/vomiting
  • Imbalance - sudden loss of one nerve will change basal firing rate
  • NO hearing loss or other hearing symptoms as cochlea nerve remains intact

Sub acute symptoms:

  • Movement induced giddiness
  • Imbalance
  • Nausea
  • Fatigue
  • Blurred or jumpy vision with head movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Labyrinthitis outline and symptoms

A

Inflammation of the labyrinth within inner ear

Presents identical to neuritis (1-4 day, nausea, imbalance ect) but will also have hearing loss (normally unilateral)

Needs to differentiated from more central vestibular disorders such as AICA stroke (AICA also supplied cochlear)

Therefore, medical emergency with patients with unilateral hearing loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Meniere’s Disease outline and symptoms

A

Accumulation of endolymph in the cochlear and vestibular organs either from increased production or decreased absorption, episodic due to fluid flucutation

  • Two or more spontaneous episodes of vertigo each last 20 mins to 12 hrs
  • Low to medium frequency hearing loss in one ear + low frequency tinnitus
    • Lower frequencies are detected in the middle of the cochlear and due to pressure accumulation the center of the spiral or more susceptible
  • Fluctuating aural symptoms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Phases of Meniere’s Disease

A

Acute:

  • Acute onset vertigo, 20 mins -12 hrs (<1day)
  • Unilateral auditory symptoms on effected side
  • Imbalance +/- directional propulsion (feel like being pushed)
  • Nausea/vomiting
  • Horizontal nystagmus TOWARDS affected ear (if its cute go towards)

Sub Acute:

  • Giddiness worsens with movement
  • Symtpoms may fully resolve
  • Pressure damage to the hair cells may cause residual HL/tinnitus
  • Vertigo lessens with disease progression, dead ear stage no hearing no vertigo
  • Horizontal nystagmus away from affected ear (causes damage to hair cells and function over time)
28
Q

Acoustic Neuroma cause and symptoms

A

Non malignant tumor of the vestibular portion of CN 8

Vestibular schwannoma is the abnormal growth of Schwann cells

Third most common intercranial tumor in adults

Symptoms:

  • Unilateral HL +/- tinnitus (first sign)
  • Imbalance and directional propulsion (feel like being pushed)
  • Headaches
  • Giddiness/rocking sensation
  • Facial weakness and numbness as tumor grows and invades facial nerve
  • Rarely causes vertigo, due to slow growth of the tumor the body has time to adapt
29
Q

Third Window 2 common causes

A

2 most common third window syndromes are Peri lymphatic Fistula and Superior Canal Dehiscence

  • Perilymphatic Fistula
    • Occurs at oval or round window
    • Often due to head trauma, surgery or straining
  • Superior Canal Dehiscence
    • Occurs at superior semicircular canal
    • Thinning and loss of bone at roof of SCC due to age or postnatal development
30
Q

Third window symptoms

A
  • Brief episodes of dizziness that are often aggravated by pressure or sound
  • Associated imbalance
  • Nausea
  • Auditory symptoms of hearing loss and autophony (heading body movements such as pulse or eyes moving)
31
Q

Vestibular Migraine Diagnosis

A

Varied presentation meaning it can mimic other vestibular conditions particularly MD, diagnosis of exclusion.

Typical onset between 30-60 yrs and more common in women around menopause

Diagnosis:

  • Current or past Hx of migrain +/- aura (sparkles in vision)
  • 5 episodes that have mod-sever vestibular symptoms (5 mins to 72 hrs) or 50% of dizzy episodes are associated with headache/visual aura/ photophobia
32
Q

5 D’s

A
  • Dizziness
  • Diplopia (double vision or visual field loss)
  • Dysarthria/dysphasia (difficulty with speech or finding words)
  • Dysphagia (difficulty swallowing of horse voice)
  • Drop Attacks (sudden collapse without loss of consciousness)
33
Q

3 N’s

A
  • Nystagmus
  • Nausea/vomiting
  • Numbness or paraesthesia
34
Q

Acute management of Neuritis and Labyrinthitis

A
  • Vestibular suppressants for symptom relief
  • Labyrinthitis refer to ENT
  • Corticosteroids often used to assist inflammation particularly for labyrinthitis
  • Gentle head movements and mobility encouraged
35
Q

Sub Acute management of Neuritis and Labyrinthitis

A
  • Vestibular and balance rehab
  • Wean off vestibular suppressants
  • Possible hyperbaric oxygen therapy for hearing loss
36
Q

3 Main consideration of history of presenting condition

A

Symptoms experienced - vestibular, auditory, neuro, N/V, vision
Temporal
Circumstance of onset

37
Q

What is the TiTraTe diagnostic approach

A

Classifies vestibular condition into 4 dizziness syndrome based on Timing (acute vs episodic) Triggers and Targeted exam

Acute and Episodic have both spontaneous and triggered sub categories (4)

38
Q

AVS from TiTraTe

A
  • Timing = Sudden vertigo lasting from seconds >24 hrs. Also associated N/V, imbalance, nystagmus and head motion intolerance
  • Spontaneous = No obvious or specific trigger
    • Neuritis, labyrinthitis, stroke, MD or VM
  • Triggered - trauma or toxin
    • TBI, concussion, third window, intoxication
39
Q

EVS from TiTraTe

A
  • Timing - Recurrent episodes of vertigo 30 mins <24hrs. Also associated N/V, imbalance, nystagmus and head motion intolerance
  • Spontaneous - No obvious or specific trigger
    • Meniere’s Disease, Vestibular migraine, Vasovagal, Panic
  • Triggered - Specific head motion or body positions
    • BBPV, central positional vertigo, orthostatic hypotension
40
Q

4 components of objective assessment

A

Oculomotor
VOR testing
Positional testing
Balance and functional

41
Q

Components of the oculomotor exam (7)

A
  • Cervical ROM and VBI
  • Spontaneous nystagmus
  • Gaze evoked Nystagmus
  • Ocular ROM
  • Smooth pursuit
  • Saccades
  • Test of Scew
42
Q

3 VOR tests

A
  • Head impulse test
  • Dynamic Visual acuity
  • Head shake nystagmus
43
Q

What is a Nystagmus

A

Involuntary rhythmic oscillation of the eyes defined by a slow drift phase (pathological) and fast phase correction (central). Brain detects slow drift and corrects

Named in the direction of the fast phase

44
Q

What is Ewald’s law for peripheral nystagmus

A

Axis of nystagmus matches axis of the semicircular canal that generated it

  • Horizontal canal = horizontal nystagmus
  • Ant/post canal = vertical and torsional nystagmus
45
Q

What are alexanders law’s for peripheral nystagmus

A
  • Nystagmus will increase with gaze in direction of nystagmus and decrease with gaze away
  • Nystagmus does not change direction
  • 1st degree = same side, second = same and mid, third = same, mid and opposite
  • Peripheral nystagmus will decrease with fixation present and increase when it is removed (google and IR camera) =, takes away cerebella inhibition. If no change then the nystagmus is central in origin.
46
Q

What is the HINTS exam (and HINTS+)

A

HINTS = rules out vertebra-basilar stoke in AVS (acute vestibular syndrome)

Used within first 48 hrs (must be in acute stage with symptoms)

Head Impulse (right and left) Nystagmus type (spontaneous or gaze evoked) Test of Skew

Same as above + sudden unilateral hearing loss, same side as the positive HIT indicates vascular lesion

47
Q

How is the HINTS exam interpreted

A

Impulse Normal, Fast-phase Alternating (direction change with gaze not EOR), Refixation on Cover Test

This is used to interpret the HINTS exam

Impulse test should not be normal, if they have acute vestibular symptoms then either right or left will be altered

48
Q

Key components of occulomotor exam indicating central condition

A

Changing direction of nystagmus
Abnormalities with smooth pursuit

Saccades testing, dysmetric is bad accuracy:
Hypometric (small is normal in elderly) is midbrain or pons
Hyper is always abnormal and indicates cerebellar issue
Refixation on cover test

49
Q

Head impulse test

A

Turn patients head within 30 degree quickly and see if they can keep eyes on your nose

Refixation is sign of hypofunction

50
Q

Dynamic Visual aquity

A

Tests VOR function
Make sure distance from letters is same between tests

Twist head to one side at 60 bpm or 120 bpm across both

Abnormal is 3 lines gap and indicates VOR deficit

51
Q

Head shake Nystagmus

A

Best done without fixation

Shake at 2 hz, 20 cycle per second for 20 cycles and observe nystagmus

Indicates vestibular hypofunction

Nystagmus towards side with more neural input i.e. right nystagmus is left hypofunction

If nystagmus is not horizontal then it is a central finding

52
Q

Designing the right treatment program with deficits in mind

A
  • Do they have BPPV = repositioning maneuvers
  • VOR deficit or poor DVA = adaption exercises (gaze stability)
  • Motion sensitivity = Habituation exercises (desensitising)
  • Reduce static or dynamic balance = balance and mobility retraining
  • Substitute for poor vestibular input (not responding) = Substitution exercises and education on falls prevention
53
Q

3 BPPV assessment test and what canals do they relate to

A

HPD and side lying HPD do ant and post (canal vs cupulo dependant on symptoms duration ect)

Head roll for horizontal

54
Q

Head roll interpretation

A

Up is CUP is LEAST

Ageotropic means cupulo - worse to unaffected
Geotrophic means canal - worse to effected

55
Q

Causes of BPPV

A

Most are idiopathic but head trauma, vestibular neuritis or osteoporosis can all contribute

56
Q

Diagnostic criteria for BPPV

A
  • Recurrent attacks of positional verite or position dizziness provoked by lying down or turning over in supine position
  • <1 mins duration
  • Not attributed to another disease
  • The nystagmus direction is specific to each canal
    • Post - torsional verticle
    • Horizontal - horinzontal
57
Q

How to perform HPD + diagnosis

A

Turn patient head towards testing side (45)
Move back quickly extending to 30 and holding for at least 1 min or double duration of symptoms
Maintain rotation and return patient to sitting, make sure to observe as symptoms may reverse.

PCS = ipsilateral rot with upbeat 
ACS = ipsilateral rot with downbeat

Canal vs cupulo dependent on symptoms

58
Q

How to perform sideling HPD

A

Patient towards head away from testing side (45)

Move patient down so they looking at ceiling

59
Q

How to perform a head roll test + interpretation

A

Patient on pillow (20 yaw for plane optimisation)
Turn head quickly to one side (90)
Observe nystagmus and ask for patient intensity rating
Go back to neutral and wait for symptoms to subside
Repeat on the other side

Latency and duration are still the same for canal vs cupolu
But remember UP is CUP is LEAST

60
Q

How to perform modified Epley repositioning manoeuvre

A

Sit upright in long sitting, rotate head towards affected side (45)
Lie back supine with 30 neck extension
Turn head 90 to unaffected side
Roll onto unaffected side maintaining head angle
Bring legs to the floor and sit up (nose to armpit)

61
Q

How to perform a BBQ roll

A

Supine with head in pillow
Turn head to affected (hold 2x symptoms)
Rotate to centre (hold 2x symptoms)
Turn to unaffected side (2x symptoms)
Roll body and turn head to face the plinth (2x symptoms)
Continue

62
Q

What canal is the sermont liberating manoeuvre for and how to perform it

A

PSC

Patient sits on the edge of the bed turning head 45 toward unaffected side
Patient quickly onto affected side maintaining head position, hold for 2 mins
Move rapidly onto unaffected side

63
Q

What canal is the modified sermont liberating manoeuvre for and how to perform it

A

ASC

Patient sits on the edge of the bed turning head 45 toward affected side
Patient quickly onto affected side maintaining head position, hold for 2 mins
Move rapidly onto unaffected side

64
Q

What canal is the Gufoni for Ageo for and how to perform it

A

Horizontal
AAA = ageo, affected side down, turn head away from ground

Patient sits on edge of bed
Lie onto affected side (onto pillow)
Hold for 2 mins 
Look away from ground and hold for 2 mins 
Slowly sit up
65
Q

Differences between canal and cup

A
  • Canalithiasis - otoconia floating in canal (Crescendo effect - latency, quick build up and eases 30-60 secs)
  • Cupulolithisis- otoconia attached to Capula (stimulate as long as head in position - doesn’t relay on endo movement, otoconia will pull on cupula based on position). Will start immediately

PHTY2230 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions