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ENT
Vestibular Testing
Built from Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
What’s inside
10 sections · 123 slides
Overview
- Scope of laboratory vestibular assessment
- Reflex pathway tested by each modality
- Structure of this account
Electronystagmography
- Principle of electronystagmography
- Physiologic and spontaneous nystagmus in the vestibulo-ocular reflex
- Methods available for recording eye movement
- The corneoretinal potential
- Torsional nystagmus and the limits of electrooculography
- Electrooculography and videonystagmography recording
- Videonystagmography
- Disadvantages of videonystagmography
- Magnetic scleral search coil technique
- Infrared oculography
Routine components of the ENG battery
- Three groups of the ENG test battery
- What each group is designed to detect
- The saccade control system
- Saccade test sequence and derived measures
- Abnormally slow saccades
- Saccadic accuracy and latency abnormalities
- The smooth pursuit system
- The pursuit tracking test
- Tracking test target, tracing and gain plot
- Causes of impaired smooth pursuit
- The optokinetic test
Abnormal eye movements
- The gaze test
- End-gaze nystagmus in normal subjects
- Spontaneous vestibular nystagmus
- Features suggesting a central lesion on gaze testing
- Gaze-evoked nystagmus: associated causes
- The positional test
- Prolonged observation for periodic alternating nystagmus
- Positional versus positioning nystagmus
- The Dix-Hallpike manoeuvre
- Nystagmus of posterior canal BPPV
- Apparent paradox on electrooculographic tracings
- Change in nystagmus direction with gaze in BPPV
- Limitations of the Dix-Hallpike and the Bojrab-Calvert alternative
- Positioning testing and posterior canal mechanics
- Testing for lateral semicircular canal BPPV
- Nystagmus of lateral canal BPPV
Bithermal caloric testing
- Why the caloric test is laterality specific
- Principle and patient position for caloric testing
- Patient position for caloric irrigation
- Expected direction of caloric nystagmus
- Parameters calculated from the caloric response
- Jongkees formula for unilateral weakness
- Ice water irrigation for absent responses
- Insensitivity of caloric testing to bilateral loss
- Advantages of electronystagmographic testing
- Structural limitations of ENG
- Fluctuating results in BPPV and Meniere's disease
- Vestibular suppressants before testing
- Non-vestibular causes of dizziness
- Place of ENG in the evaluation of dizziness
The video head impulse test
- Principle of the video head impulse test
- Abnormal findings on vHIT
- Clinical position of vHIT
Rotational testing
- Passive and active rotational tests
- The rotary chair test
- Slow harmonic acceleration paradigm
- Stimulus strength compared with caloric testing
- Signal processing in rotary chair testing
- Rotary chair recording from a normal individual
- Gain in rotational testing
- Phase in rotational testing
- Symmetry in rotational testing
- Frequency dependence of phase and gain
- Normal phase, gain and asymmetry across oscillation frequency
- Four categories of rotary chair abnormality
- Vestibular habituation and asymmetry: acute unilateral lesion
- Rotational findings in an acute right peripheral vestibular lesion
- Origin of high-frequency asymmetry
- Vestibular habituation: chronic unilateral loss
- Caloric weakness and phase lead in the same series
- Rotational findings in a chronic left peripheral lesion
- Vestibular deficit: bilateral hypofunction
- Gentamicin-associated bilateral loss
- Absent rotational responses at all oscillation frequencies
- Preserved high-frequency gain despite absent caloric responses
- Vestibular asymmetry at high frequencies
- Clinical indications for rotational chair testing
- Vestibular autorotational testing
- Frequency ranges sampled by the vestibular battery
Computerized dynamic posturography
- The posturography platform
- Measurement of body sway
- Sensory integration in normal balance
- The six conditions of the sensory organization test
- The equilibrium score
- The vestibular ratio
- Normal posturography results compared with instability
- Clinical uses of posturography
Vestibular evoked myogenic potentials
- What VEMP testing adds to the battery
- cVEMP pathway and recording
- cVEMP interpretation parameters
- Performing the cVEMP
- Normal cVEMP waveform and latencies
- Interaural asymmetry ratio
- Cervical VEMP pathway and sternocleidomastoid response
- Decreased and increased cVEMP amplitude
- VEMP in superior semicircular canal dehiscence
- Latency of P1 and central vestibular dysfunction
- The ocular VEMP
- Ocular VEMP pathway and inferior oblique response
- cVEMP and oVEMP compared
Putting the battery together
- What each test localises
- Test selection in common clinical situations
- Interpreting apparently conflicting results
- Conclusions
- References
- References (continued)
- References (continued)
- References (continued)
- Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
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