Training in vHIT

VEMP and vHIT in Vestibular Neuritis Patients

Introductory

10 mins

Reading

09 February 2022

Description

What results would I expect to see in VEMP and vHIT in a patient with acute superior vestibular neuritis and acute inferior vestibular neuritis patient?

Vestibular neuritis is a condition where dizziness is caused due to an infection (mainly viral) of the vestibular nerve. The vestibular nerve has two branches which innervate the inner ear vestibular structures: The superior branch and the inferior branch. It is important not to forget that the neuritis can affect either branch individually or both branches at the same time. In order to understand the pattern of test results found in acute patients which have either superior vestibular neuritis or inferior vestibular neuritis it is important to know which organs each nerve synapses to.

Have a look at the image below. The Superior vestibular (Grey) nerve connects to lateral semi-circular canal, anterior semi-circular canal and the utricle. Whereas the inferior vestibular (Black) nerve has connections to the saccule and the posterior semi-circular canal.

Now that we know the inner ear anatomy with relation to each vestibular nerve, we now need to know which piece anatomy each diagnostic test measures. The video head impulse test can measure the function of each of the semi-circular canal independently and their corresponding vestibular nerves, the cVEMP measures the function of the saccule and the inferior vestibular nerve and the oVEMP measures the function of mainly the utricle and the superior vestibular nerve. Therefore if a patient presents with a neuritis on the left superior nerve then you should expect the following results:

The Video head impulse test will show reduced VOR gain and catch up saccades in the lateral and anterior canals. Whereas the posterior vHIT should reveal normal test findings. The cVEMP will be normal as it only tests the inferior nerve but the oVEMP will be abnormal as the superior nerve needs to be intact to record a response from the utricle.

Related course: Balance testing for beginners

To assist you with differentiating between inferior vestibular neuritis and superior vestibular neuritis, see the tables below which show expected tests results in acute patients.

Expected test results in acute inferior vestibular neuritis

Pure tone audiometry	Normal or not changed
Spontaneous nystagmus	Nystagmus present Direction fixed with fast phases toward the good ear Reduces or is completely suppressed with fixation
Gaze testing	Gaze-evoked nystagmus followng Alexander's law Direction fixed Reduces or is completely suppressed with fixation Linear slow phases
Saccades	Latency: within normal limits Accuracy: within normal limits Velocity: within normal limits Evidence of spontaneous nystagmus may be present on tracings
Smooth pursuit	Gain: within normal limits Symmetry: within normal limits Evidence of spontaneous nystagmus may be present on tracings
Optokinetic	Gain: enhanced when the stmulus moves in the same direction of the spontaneous fast phases
Dix-Hallpike	Negative
Head roll	Negative
Caloric test	Total response: within normal limits Unilateral weakness: less than 25% Directional preponderance: less than 30% Fixation index: less than 50%
cVEMP	Ratio: larger than 36% Amplitude: reduced on affected ear or absent cVEMP Latency: within normal limits
oVEMP	Ratio: less than 33% Amplitude: within normal limits Latency: within normal limits
vHIT lateral	Gain: larger than 0.7 Asymmetry: less than 7% Catch-up saccades: not present or less than 50%
vHIT vertical	Gain: less than 0.7 on affected side Asymmetry: larger than 7% toward affected side Catch-up saccades: generated
Sinusoidal harmonic acceleration	Gain: typically reduced outside of the normative range Phase: increased phase lead above normal range Symmetry: asymmetry toward affected ear
Velocity step test	Time constant: less than 10 seconds Gain: typically reduced outside of the normative range Symmetry: asymmetry toward affected ear

Expected test results in acute superior vestibular neuritis

Pure tone audiometry	Normal or not changed
Spontaneous nystagmus	Nystagmus present Direction fixed with fast phases toward the good ear Reduces or is completely suppressed with fixation
Gaze testing	Gaze-evoked nystagmus followng Alexander's law Direction fixed Reduces or is completely suppressed with fixation Linear slow phases
Saccades	Latency: within normal limits Accuracy: within normal limits Velocity: within normal limits Evidence of spontaneous nystagmus may be present on tracings
Smooth pursuit	Gain: within normal limits Symmetry: within normal limits Evidence of spontaneous nystagmus may be present on tracings
Optokinetic	Gain: enhanced when the stmulus moves in the same direction of the spontaneous fast phases
Dix-Hallpike	Negative
Head roll	Negative
Caloric test	Total response: within normal limits Unilateral weakness: larger than 25% toward affected side Directional preponderance: larger than 30% toward unaffected side Fixation index: less than 50%
cVEMP	Ratio: less than 36% Amplitude: within normal limits Latency: within normal limits
oVEMP	Ratio: larger than 33% Amplitude: reduced on affected ear or absent oVEMP Latency: within normal limits
vHIT lateral	Gain: less than 0.7 on affected side Asymmetry: larger than 7% toward affected side Catch-up saccades: generated
vHIT vertical	Gain: less than 0.7 on affected side Asymmetry: larger than 7% toward affected side Catch-up saccades: generated
Sinusoidal harmonic acceleration	Gain: typically reduced outside of the normative range Phase: increased phase lead above normal range Symmetry: asymmetry toward affected ear
Velocity step test	Time constant: less than 10 seconds Gain: typically reduced outside of the normative range Symmetry: asymmetry toward affected ear

Disclaimer

This resource is a tool based on the needs of medical professionals and students that allows quick access to the typical assessment findings in a range of common vestibular disorders. The resource was developed to provide fast, easy-to-use, and always available information which can aid in reaching the correct diagnosis. The information contained within is provided as an information resource only, and should not be used as a substitute for professional diagnosis and management.

Presenter

Michael Maslin

After working for several years as an audiologist in the UK, Michael completed his Ph.D. in 2010 at The University of Manchester. The topic was plasticity of the human binaural auditory system. He then completed a 3-year post-doctoral research program that built directly on the underpinning work carried out during his Ph.D. In 2015, Michael joined the Interacoustics Academy, offering training and education in audiological and vestibular diagnostics worldwide. Michael now works for the University of Canterbury in Christchurch, New Zealand, exploring his research interests which include electrophysiological measurement of the central auditory system, and the development of clinical protocols and clinical techniques applied in areas such as paediatric audiology and vestibular assessment and management.