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Neuro Dev/Control II > Intro to Vestibular Exam > Flashcards

Intro to Vestibular Exam Flashcards

1
Q

What does TiTrATE stand for

A
  • Triage
  • Timing
  • Triggers
  • Targeted Exam
  • Test
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2
Q

Describe Triage

A
  • Screen for serious pathology
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3
Q

Safe to go features for triggered episodic vestibular syndrome (t-EVS)

A
  • No pain, auditory, neurologic Sx, or syncope
  • Sx not limited to arising & occur when tipping head fwd/bwd or rolling in bed
  • Asymptomatic w/head stationary, Sx reproduced by specific positional tests
  • Characteristic, canal specific, peripheral type nystagmus on positional tests
  • Therapeutic response to canal specific repositioning maneuvers
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4
Q

Safe to go features for spontaneous episodic vestibular syndrome (s-EVS)

A
  • No cardiorespiratory symptoms or transient loss of consciousness
  • No diplopia or other ‘Dangerous D’ symptoms (dysarthria, dysphagia, dysphonia, dysmetria)
  • No papilledema, Horner’s syndrome, cranial nerve signs (e.g., facial palsy) [esp. if headache present]
  • No Sudden, Severe, or Sustained pain (especially located in the posterior neck)
  • Strong/long past history of dizziness episodes (at least 5 spells over >2 years)
  • Clear precipitants (e.g., stress, food, visual motion) for multiple episodes or ABCD2 risk score ≤3
  • Migraine: history of migraine headache; classic visual aura or photophobia with most attacks
  • Menière’s: history of unilateral fluctuating hearing loss or tinnitus with most attacks
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5
Q

Safe to go features for spontaneous acute vestibular syndrome (s-AVS)

A
  • Max 1 prodromal spell <48hrs before onset
  • No excessive vomiting or gait disorder
  • No pain, auditory, neurologic symptoms
  • No papilledema, Horner’s syndrome, cranial nerve signs (e.g., facial palsy) [esp. if headache present]
  • Stands and walks unassisted (even if unsteady or wide-based)
  • HINTS plus Hearing/Ear Exam –
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6
Q

What does “S.E.N.D. H.I.M. O.N. H.O.M.E.”

A
  • S.E.N.D. – Straight Eyes (no vertical ocular misalignment a.k.a. ‘skew’), No Deafness
  • H.I.M. – Head Impulse Misses (unilateral abnormal impulse opposite nystagmus direction)
  • O.N. – One-way Nystagmus (unidirectional nystagmus worse in gaze towards fast phase)
  • H.O.M.E. – Healthy Otic and Mastoid Exam (pearly tympanic membrane with no pimples, pus, or perforation; no pain on palpation of the mastoid)
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7
Q

What are the window into the vestibular system

A
  • the eyes
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8
Q

What does the oculomotor exam consist of

A
  • Ocular alignment -> primary gaze position: skew deviation (vertical deviations are more concerning for central pathology)
  • Ocular motility -> H-Test: ROM, conjugate eye movement, quality of movement
  • Nystagmus -> spontaneous, gaze evoked, rebound: pure vertical, pure torsional, or direction changing nystagmus are central signs while spontaneous nystagmus seen in acute peripheral vestibular lesions is direction fixed & follows Alexander’s Law
  • Saccades: impaired saccades are a central sign
  • Smooth pursuit: saccadic/cogwheel pursuit is a central sign & dysconjugate gaze is a central sign
  • VOR cancellation: inability to suppress VOR is a central sign
  • VOR
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9
Q

What are the eye movements systems

A
  • Saccades
  • Smooth pursuit
  • Vergence
  • Fixation
  • Vestibule-Ocular Reflex (VOR)
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10
Q

What is the goal of eye movements systems and describe its role

A
  • Goal: to position & maintain similar images on corresponding areas of the retinae in order to sustain fusion during eye, head, & body movements, or change in position of the visual stimulus
  • Coordinated eye movements are under supra nuclear control
  • Any type of cooperation b/w the two eyes, whether sensory or motor, necessitates cortical control
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11
Q

Clinical findings & suspected area of damage

A
  • Isolated vertical saccadic paresis: Midbrain
  • Isolated horizontal saccadic paresis/isolated unilateral horizontal saccadic paresis: Pons lesion ipsilateral to PPRF
  • Hypemetric saccades: Cerebellum
  • Isolated vertical gaze evoked nystagmus that is upwards & downwards: Midbrain
  • Isolated gaze paretic nystagmus, right & left: Ponto-medullary/cerebellar
  • Internuclear ophthalmoplegia: Ipsilateral MLF, lesion on side of impaired eye adduction
  • Downbeat nystagmus: mostly cerebellum with bilateral flocculus impairment
  • Upbeat nystagmus: Medulla oblongata or midbrain
  • Convergence-retraction nystagmus: Midbrain
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12
Q

Vestibular nerve or vestibular nuclei lesion effects on eye movements

A
  • Nystagmus at rest
  • Normal ability to voluntarily direct eyes past midline
  • No double vision
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13
Q

Frontal eye fields lesion effects on eye movements

A
  • Both eyes deviated ipsilaterally at rest
  • Unable to direct eyes past midline contralaterally
  • No double vision
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14
Q

Pontine paramedian reticular formation lesion effects on eye movements

A
  • Both eyes deviated contralaterally at rest
  • Unable to direct eyes past midline ipsilaterally
  • No double vision
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15
Q

Abducens nucleus lesion effects on eye movements

A
  • Normal position at rest
  • Unable to direct either eye past midline ipsilaterally
  • No double vision
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16
Q

Abducens nerve lesion effects on eye movements

A
  • Ipsilateral eye deviated medially at rest
  • Inability to abduct the ipsilateral eye
  • Double vision
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17
Q

Medial Longitudinal Fasciculus (MLF) lesion effects on eye movements

A
  • Normal position at rest
  • If the lesion is b/w the abducens & oculomotor nuclei, unable to adduct the ipsilateral eye past midline
  • Double vision
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18
Q

Define tropia

A
  • Ocular malalignment that is always present
  • Deviation of eyes during targeted viewing
  • Present in ALL circumstances
  • Cannot “correct” the misalignment when focusing on a target
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19
Q

Define phoria

A
  • Ocular malalignment only evident when binocular viewing/fusion is blocked
  • Deviation of the eyes that presents itself with monocular viewing
  • Not always apparent, may only be evident when binocular viewing/fusion is blocked
  • Becomes more apparent with fatigue
  • Best elicited with Cross-Cover Test
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20
Q

Describe a MLF lesion via the internuclear ophthalmoplegia

A
  • Normally when moving the eyes horizontally an area in the frontal lobe sends signals via an area in the pons to the abducens nucleus
  • In turn the abducens nucleus sends signals to ipsilateral lateral rectus & contralateral oculomotor nucleus
  • The oculomotor nucleus sends signals to the medial rectus via oculomotor nerve
  • Therefore when the connection b/w the abducens nucleus & oculomotor nucleus is interrupted the eye contralateral to the lesion moves normally but the eye ipsilateral to lesion cannot adduct past the midline when the contralateral eye moves laterally
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21
Q

Define internuclear ophthalmoplegia (INO)

A
  • Characterized by paresis of ipsilateral eye adduction in horizontal gas but not in convergence
  • Can be unilateral or bilateral
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22
Q

What structures does the MLF connect

A
  • 6th cranial nerve nucleus (lateral rectus muscle)
  • Adjacent horizontal gaze center
  • Contralateral 3rd cranial nerve nucleus
  • Connects the vestibular nuclei with the 3rd & 4th cranial nerve nuclei
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23
Q

Cause of INO in young people and older people

A
  • Young: multiple sclerosis (MS) & often bilateral
  • Old: stroke & is unilateral
24
Q

Define gaze stability and what systems it depends on

A
  • Gaze stability is the ability to hold the eyes stationary on a target
  • Systems: Smooth pursuit, Saccades, VOR, and Cervical Ocular Reflex
25
Q

Describe smooth pursuit and its purpose

A
  • Used to stabilize a moving target on the fovea of the retina during low velocities & frequencies of head motion or target motion
  • Generated from multiple cortical regions in addition to the brainstem & cerebellum
  • Ineffective at maintaining fixation of a moving target when the velocity or frequency of the target exceeds 60 deg/sec or 1 Hz
  • Can assist gaze stability at target velocities from 75-90 deg/sec
26
Q

Describe saccades and it purpose

A
  • Saccades are rapid, conjugate eye rotations that quickly move the eyes to place the fovea on the target of interest
  • Generated from neurons within the brainstem, basal ganglia, frontal eye fields, & cerebellum
  • Require healthy cranial nerve & extra ocular muscle function
27
Q

When do horizontal versus vertical/torsional saccades occur

A
  • Horizontal: occur from excitatory burst neurons within the parapontine reticular formation of the pons
  • Vertical/Torsional: occur from excitatory burst neurons within the rostral interstitial nucleus of the medial longitudinal fasciculus of the midbrain
28
Q

At what frequency does each eye system function best

A
  • Pursuit: <1 Hz and a Max velocity of 60 deg/sec
  • Saccadic: Doesn’t function well with unpredictable movement
  • Cervico-ocular reflex: studies have failed to identify a cervico-ocular reflex in which the eye movements are in the compensatory direction
  • VOR: functions across frequencies of 8 Hz or more for activities (walking/running) & gaze stabilization during unpredictable & predictable head movements
29
Q

Which side does nystagmus beat toward

A
  • The side of increased neural activity
  • Direction of nystagmus is named for the fast phase
  • Fast phase is under central control
  • Slow phase is vestibular reset of eye position
30
Q

Define Alexander’s Law

A
  • The amplitude of the nystagmus increases when the eye moves in the direction of the fast phase
  • Manifested during spontaneous nystagmus in a patient with an acute vestibular lesion
  • Nystagmus increase when visual fixation is blocked
31
Q

Define J.R. Ewald’s Laws

A
  • Law #1: a stimulation of the semicircular canal causes a movement of the eyes in the plane of the stimulated canal
  • Law #2: In horizontal semicircular canals an ampullopetal (displacement toward the ampulla) endolymph movement causes a greater stimulation than an ampullofugal (displacement away from the ampulla) one
  • Law #3: In the vertical semicircular canals the reverse is true
32
Q

To maintain normal vision how good does the VOR have to be

A
  • Retinal image motion must be <2 degrees per sec
  • The gain of the VOR must be 98% accurate
  • The velocity of the eyes should be exactly opposite to head movement, when this happens the ratio of eye movement to head movement velocity (gain) equals -1.0
33
Q

Describe the purpose of the head impulse test

A
  • Clinical test for VOR function
  • Normal function: patient will keep gaze on target
  • Hypofunction: eyes will move with the head (gaze error) which leads to a corrective saccade at the end of head movement
  • Must rotate head at a minimum of 200 deg/sec
34
Q

Describe the cerebellums role in VOR

A
  • Slides 57-58
35
Q

What direction is the nystagmus when there is a left sided lesion

A
  • Right sided nystagmus
  • Left positive head impulse test
36
Q

Effects of vestibular lesion on balance

A
  • The vestibular systems operates through a wider frequency & velocity range than do vision & somatosensation
  • Consider implications for an individual with vestibular dysfunction & peripheral neuropathy trying to walk in the dark
37
Q

What are the optimal frequency ranges for each sensory loop related to balance

A
  • Vision: low frequency
  • Vestibular: high frequency
  • Somatosensory: Mid range frequency
38
Q

Describe the vestibulospinal reflex (VSR)

A
  • Head tilted to one side -> both canals & otoliths are stimulated
  • Vestibular nerve & nucleus are activated
  • Impulses transmitted via lateral & medial vestibular tracts to the spinal cord
  • Extensor activity is induced on the side to which the head is inclined, flexor activity is induced on the opposite side
39
Q

What are the 2 perceptions of moving visual stimuli

A
  • Object motion
  • Self-motion
40
Q

Visually perceived motion can have destabilizing effect on balance when

A
  • It does not match vestibular or somatosensory cues
  • Vestibular cues are absent or altered
41
Q

Describe visual control of balance related to sway

A
  • AP and lateral sway increase with decreased visual acuity
  • Sway increases as a function of the distance b/w the eyes & the visual reference point
  • Central visual field dominates over the peripheral visual field in the control of postural sway
42
Q

Define acute vestibular syndrome (AVS)

A
  • Well-defined clinical syndrome
  • Vertigo or dizziness with nausea or vomiting
  • Head motion intolerance
  • Gait unsteadiness
  • Nystagmus lasting days to weeks
  • Caused by peripheral or central lesions
  • 25% of cases are due to stroke
43
Q

Peripheral pattern HINTS

A
  • Unilaterally abnormal head impulse test
  • Direction fixed horizontal or horizontal > torsional nystagmus obeying Alexander’s Law
  • Absent skew deviation (Alternate Cover Test)
44
Q

Central pattern HINTS

A
  • Normal head impulse test bilaterally
  • Spontaneous or Gaze evoked nystagmus that is either direction changing or predominately vertical or torsional
  • Skew deviation present (Alternate Cover Test)
  • If any of the above are present, stroke work-up recommended
  • Acute change/loss in hearing (HINTS Plus)
45
Q

Describe the stroke screening ABCD2 risk assessment

A
  • Age ≥60 = 1 point
  • Blood pressure: systolic ≥140 or diastolic ≥90 = 1 point
  • Clinical features: unilateral weakness = 2 points; speech disturbance w/o weakness = 1 point; any other symptom = 0 points
  • Duration of symptoms: <10 min = 0 points; 10-59 min = 1 point; ≥60 min = 2 points
  • Diabetes: present = 1 point
46
Q

What bedside exam outperforms MRI for diagnostic accuracy of stroke within 1st 48 hours post-onset

A
  • H.I.N.T.S
  • Head Impulse (normal) Nystagmus (direction changing) Test of Skew deviation (vertical ocular misalignment)
47
Q

What is the single best bedside predictor of stroke in acute vestibular syndrome

A
  • A normal HIT (head impulse test)
48
Q

What is HINTS Plus

A
  • The same tests as HINTS plus a hearing test
  • Bedside hearing test by finger rub
  • Generally unilateral & on the side of the abnormal head impulse test
49
Q

What does INFARCT stand for and used for

A
  • Used for stroke screening
  • I.N. -> impulse normal (HIT negative bilaterally)
  • F.A. -> fast phase alternating (direction changing nystagmus)
  • R.C.T. -> refutation on cover test (skew deviation)
50
Q

Peripheral findings of HINTS Plus

A
  • Must have ALL of the following
  • Unidirectional nystagmus -> direction fixed
  • No skew deviation
  • Abnormal head impulse test -> unilateral, away from fast phase of nystagmus
  • No new hearing loss
51
Q

Central findings of HINTS Plus

A
  • Stroke is suspected if ANY of the following exist
  • Normal head impulse test
  • Direction changing nystagmus in eccentric gaze (gaze evoked nystagmus)
  • Skew deviation (vertical ocular misalignment)
  • New hearing loss
52
Q

Pitfalls of HINTS Plus

A
  • Assuming that the HINTS Plus signs apply to any patient with vertigo.
  • HINTS cannot be relied on in patients with episodic vestibular syndromes which can last from seconds to hours and may be due to such etiologies as vestibular migraine, Meniere disease or transient ischemic attacks (spontaneous onset), or benign paroxysmal positional vertigo (triggered).
  • Findings have not been validated in younger patients <18 years old
  • HINTS exam should NOT be solely relied on outside the 72 hour time window
53
Q

Pearls of HINTS Plus

A
  • The HINTS Plus signs are of significant value in patients with acute, spontaneous, continuous vertigo, particularly when they have nystagmus. If they do not have nystagmus, patients may need to have at least postural instability to increase the specificity of HINTS.
54
Q

What does SEND HIM ON HOME SAFE stand for and used for

A
  • Findings that suggest acute peripheral vestibulopathy
  • Straight Eyes -> no skew deviation
  • No Deafness -> no new hearing loss, either side
  • Head Impulse Misses -> unilaterally abnormal HIT opposite the fast phase of nystagmus
  • One-way Nystagmus -> predominantly horizontal, direction fixed in all gaze positions
  • Healthy Otic & Mastoid Exam -> pearly tympanic membranes, no pimples, pus, perforation, or pain on palpation of the mastoid
  • Stands Alone -> no balance difficulty in unsupported standing
  • Face Even -> no facial palsy or weakness
55
Q

What does STANDING stand for and used for

A
  • Used as a Ddx for patients presenting to the ED with complaints of isolated vertigo
  • SponTAneous Nystagmus -> present of absent?
  • Direction -> if spontaneous nystagmus is present, what direction?
  • head Impulse test -> normal or not?
  • standiNG -> ataxic or unable?

Neuro Dev/Control II (19 decks)

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