assessment of vestibular system

How to conduct basic subjective Ax for patient w/ dizziness ? 

Symptoms experienced	Temporal characteristics	Circumstance of onset
Vestibular  Auditory  Associated  Neurological	Spells → how long: seconds/ mins/ hrs  Acute: < 3 days  Persistent/ chronic ( > 3 days )	Spontaneous/ triggered  Aggravating/ easing factors  Constant/ intermittent

Vestibular symptoms 1

Symptoms	Meaning	Descriptors
Vertigo	Sensation of self motion when no self motion is occurring	Spinning/ swaying/ bobbing/ bouncing/ sliding
Dizziness	Sensation of disturbed/ impaired spatial orientation	Giddy/ lightheaded/ woozy/ unsteady

Vestibular symptoms 2

Vestibulo-visual	External vertigo: false sense that visual surrounding is moving  Oscillopsia: false sense that visual surrounding is oscillating Visual lag: visual surrounding delayed after head movement/ oriented off true vertical	Oscillopsia: visual surrounding is moving regularly back + forth
Postural	Unsteadiness  Directional pulsion Falls + near misses

Auditory + visual symptoms

Auditory	Visual
Hearing loss  → unilateral/ bilateral  → sudden/ gradual	Blurred vision
Aural fullness:  → uni/ bilateral  → constant/ intermittent	Double vision
Tinnitus → pitch: high/ low  → constant/ intermittent/ pulsatile  → uni/bilateral/ asymmetrical	Visual lag/ tilt

Neuro + headache + other symptoms

Neuro	Headache	Other
Pins + needles / tingling	Headaches	Sweating
Weakness	Photophobia/ phonophobia	Anxiety/ stress
Coordination	Visual aura	Heart palpitations
Speech/ swallowing	Neck pain
Bladder/ bowel

History

Subjective
Past history	First vestibular episode?  Initial onset + frequency of episodes  How have their symptoms changed over time
Past medical history	Cardiac Stroke  Cancer Diabetes  HTN  Migraines  Infections Neck pain
Past family history	Migraines  Strokes  Vertigo  Ataxias

Other items on subjective exam

Medications	Vestibular supressants Anti-histamines  Diazepam
Investigations	CT MRI brain  Audiogram  Blood test
Social history	Social supports  Home set up  Work
Functional status	Previous/ current incl limiting factors
Falls history	No of falls  Context + injuries

Diagnostic basis for acute vs episodic

	Timing	Spontaneous	Triggered
Acute	Sudden vertigo  seconds - > 24 hrs	X obvious triggers  → neuritis/ labyrinthitis/ stroke/ 1st episode meniere’s disease/ vestibular migraine	Trauma ( head injury, barotrauma ), toxin  → traumatic brain injury, concussion, third window, intoxication, carbon monoxide poisoning, medications
Episodic	Recurrent eps of  vertigo  30 mins - < 24 hrs	X obvious triggers  → meniere’s disease, vestibular migraine, vasovagal, panic	Specific head motion/ body positions  → BPPV, central positional vertigo, orthostatic hypotension

components of oculomotor exam

Cervical ROM + VBI

Spontaneous nystagmus

Gaze evoked nystagmus

Ocular ROM incl convergence

Smooth puruit

Saccades

Test of Skew

What to look for for cervical ROM + VBI

5Ds:

1. Dizziness + unsteadiness 

2. Diplopia: double vision/ visual field loss 

3. Dysarthria/ dysphasia: difficulty w/ speech/ finding words 

4. Dysphagia: difficulty swallowing/ unexplained hoarse voice

5. Drop attacks 

3Ns:

1. Nystagmus 

2. Nausea/ vomiting 

3. Numbness/ paraesthesia

Considerations for cervical ROM + VBI / spontaneous nystagmus

If nystagmus occurs:  In acute situations:   What direction( in pt’s perspective + direction of fast phase )   → Right beat nystagmus: slow drifting phase to the left + quick fast phase to the right  Does it align w/ Alexander’s Law for peripheral AVS:  Intensity of nystagmus increases w/ gaze in direction of nystagmus + decreases w/ gaze in opposite direction   X change in direction of nystagmus Peripheral nystagmus intensity decreases w/ fixation ( no object to fixate on )

Considerations for cervical ROM + VBI/ spontaneous nystagmus

3.  Degrees of nystagmus: 

→ 1st degree: present on right gaze 

→ 2nd degree: present on right + central gaze 

→ 3rd degree: present in right + left + central 

4. Effect of fixation: 

→ peripheral: intensity increases w/ fixation removed 

→ central disorders: X change in intensity w/ fixation removed 

5. Ewald’s Law: 

Axis of nystagmus matching w/ axis of SCC generating it 

→ Horizontal N: horizontal canal 

→ Vertical + torsional N: anterior/ posterior canal

Interpretations of results in cervical ROM + VBI/ spontaneous nystagmus

1. Whether it is a peripheral/ central vestibular syndrome 

2. If peripheral: which side of peripheral vestibular system is damaged

Considerations for gaze evoked nystagmus + interpretation of results

Gaze evoked nystagmus

Direction of nystagmus

Direction changes: central  Direction fixed: likely peripheral

Considerations for gaze evoked nystagmus + interpretation of results

Document:  Range: Full/ reduced in certain directions  Conjugate eye movement: if both eyes move together  Smooth/ jerky/ saccadic

Difficulty w/ conjugate eye movement → possible gaze palsies ( central nervous system )

Considerations for saccades + interpretation of results

Document:  Speed: normal/ slow  Accuracy: undershoot/ overshoot  Latency  Cheating: blinking to initiate saccades

Slow saccades: mid-brain/ pons  Great hypometria( undershoot): mid brain/ pons  Hypermetria: cerebellar issue Large latency: central indicator

Considerations for smooth pursuit + interpretation of results

Document:  Smooth + conjugate eye movement Slight saccadic pursuit within 2-3 beats through midline for older adults

Abnormalities: central pathology e.g. parieto-occipital frontal cortex, pons, cerebellar vermis, flocculus

Interpretation of results for test of skew

Abnormal: 

1. One eye deviates up when covered 

2. Other eye deviates down when covered 

→ central pathology( multiple sclerosis, brainstem lesions) / otolith dysfunction 

→ imbalance bwt 2 vestibular integrating systems

Considerations for head impulse test

Tests	Considerations
Head impulse test	Keep eyes on target consistently ? Corrective saccade when fixation of target is lost → which side ?  → side of corrective re-fixation: side of hypofunction

Considerations for dynamic visual acuity

Dynamic visual acuity

Functional testing  Using eye chart + read from top to bottom w/ head static  Stop at first line of error  Repeat w/ head shakes at 120 bpm→ stop when neck stiffens/ first line of error  Abnormal: > 3 lines of error  → functional deficit

Considerations for head shake nystagmus test

Head shake nystagmus test

Performed w/ fixation removed Tilt head 20’ → tuck chin in  Shake head at 2 Hz ( 2 cycles/ sec) for 20 cycles  Result: Nystagmus > 3 beats: abnormal  → N to side w/ more neural input