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The Video Head Impulse Test (vHIT) of Semicircular Canal Function - Age-Dependent Normative Values of VOR Gain in Healthy Subjects.

McGarvie LA, MacDougall HG, Halmagyi GM, Burgess AM, Weber KP, Curthoys IS - Front Neurol (2015)

Bottom Line: The VOR gain was measured for all canals across a range of head velocities for at least 10 healthy subjects in decade age bands: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89.The results are considered in relation to recent evidence about the effect of age on VOR performance.These normative values allow the results of any particular patient to be compared to the values of healthy people in their age range and so allow, for example, detection of whether a patient has a bilateral vestibular loss.

View Article: PubMed Central - PubMed

Affiliation: Neurology Department, Institute of Clinical Neurosciences, Royal Prince Alfred Hospital , Camperdown, NSW , Australia.

ABSTRACT

Background/hypothesis: The video Head Impulse Test (vHIT) is now widely used to test the function of each of the six semicircular canals individually by measuring the eye rotation response to an abrupt head rotation in the plane of the canal. The main measure of canal adequacy is the ratio of the eye movement response to the head movement stimulus, i.e., the gain of the vestibulo-ocular reflex (VOR). However, there is a need for normative data about how VOR gain is affected by age and also by head velocity, to allow the response of any particular patient to be compared to the responses of healthy subjects in their age range. In this study, we determined for all six semicircular canals, normative values of VOR gain, for each canal across a range of head velocities, for healthy subjects in each decade of life.

Study design: The VOR gain was measured for all canals across a range of head velocities for at least 10 healthy subjects in decade age bands: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89.

Methods: The compensatory eye movement response to a small, unpredictable, abrupt head rotation (head impulse) was measured by the ICS impulse prototype system. The same operator delivered every impulse to every subject.

Results: Vestibulo-ocular reflex gain decreased at high head velocities, but was largely unaffected by age into the 80- to 89-year age group. There were some small but systematic differences between the two directions of head rotation, which appear to be largely due to the fact that in this study only the right eye was measured. The results are considered in relation to recent evidence about the effect of age on VOR performance.

Conclusion: These normative values allow the results of any particular patient to be compared to the values of healthy people in their age range and so allow, for example, detection of whether a patient has a bilateral vestibular loss. VOR gain, as measured directly by the eye movement response to head rotation, seems largely unaffected by aging.

No MeSH data available.


The average VOR gain for left and right horizontal canal stimulation across velocities ± 2 SDs around the mean, for each decade age band.
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Figure 3: The average VOR gain for left and right horizontal canal stimulation across velocities ± 2 SDs around the mean, for each decade age band.

Mentions: Figures 3–5 show the means ± 2 SDs for VOR gain for horizontal, anterior, and posterior canals, respectively at each age band from 10–19 to 80–89, averaged across all velocities. Figure 3 shows that for the youngest subjects, horizontal VOR gain is tightly clustered around a gain of 1.0 at low velocities, with a small decrease in VOR gain as velocity increases. A similar pattern occurred for each decade band and for all canals (Figures 4 and 5). Variability of VOR gain was much greater in the vertical planes, with a more rapid drop-off in VOR gain as head velocity increased. For each decade age group, the results were similar, with the average VOR gain across velocities showing only a small decline with age.


The Video Head Impulse Test (vHIT) of Semicircular Canal Function - Age-Dependent Normative Values of VOR Gain in Healthy Subjects.

McGarvie LA, MacDougall HG, Halmagyi GM, Burgess AM, Weber KP, Curthoys IS - Front Neurol (2015)

The average VOR gain for left and right horizontal canal stimulation across velocities ± 2 SDs around the mean, for each decade age band.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4495346&req=5

Figure 3: The average VOR gain for left and right horizontal canal stimulation across velocities ± 2 SDs around the mean, for each decade age band.
Mentions: Figures 3–5 show the means ± 2 SDs for VOR gain for horizontal, anterior, and posterior canals, respectively at each age band from 10–19 to 80–89, averaged across all velocities. Figure 3 shows that for the youngest subjects, horizontal VOR gain is tightly clustered around a gain of 1.0 at low velocities, with a small decrease in VOR gain as velocity increases. A similar pattern occurred for each decade band and for all canals (Figures 4 and 5). Variability of VOR gain was much greater in the vertical planes, with a more rapid drop-off in VOR gain as head velocity increased. For each decade age group, the results were similar, with the average VOR gain across velocities showing only a small decline with age.

Bottom Line: The VOR gain was measured for all canals across a range of head velocities for at least 10 healthy subjects in decade age bands: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89.The results are considered in relation to recent evidence about the effect of age on VOR performance.These normative values allow the results of any particular patient to be compared to the values of healthy people in their age range and so allow, for example, detection of whether a patient has a bilateral vestibular loss.

View Article: PubMed Central - PubMed

Affiliation: Neurology Department, Institute of Clinical Neurosciences, Royal Prince Alfred Hospital , Camperdown, NSW , Australia.

ABSTRACT

Background/hypothesis: The video Head Impulse Test (vHIT) is now widely used to test the function of each of the six semicircular canals individually by measuring the eye rotation response to an abrupt head rotation in the plane of the canal. The main measure of canal adequacy is the ratio of the eye movement response to the head movement stimulus, i.e., the gain of the vestibulo-ocular reflex (VOR). However, there is a need for normative data about how VOR gain is affected by age and also by head velocity, to allow the response of any particular patient to be compared to the responses of healthy subjects in their age range. In this study, we determined for all six semicircular canals, normative values of VOR gain, for each canal across a range of head velocities, for healthy subjects in each decade of life.

Study design: The VOR gain was measured for all canals across a range of head velocities for at least 10 healthy subjects in decade age bands: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89.

Methods: The compensatory eye movement response to a small, unpredictable, abrupt head rotation (head impulse) was measured by the ICS impulse prototype system. The same operator delivered every impulse to every subject.

Results: Vestibulo-ocular reflex gain decreased at high head velocities, but was largely unaffected by age into the 80- to 89-year age group. There were some small but systematic differences between the two directions of head rotation, which appear to be largely due to the fact that in this study only the right eye was measured. The results are considered in relation to recent evidence about the effect of age on VOR performance.

Conclusion: These normative values allow the results of any particular patient to be compared to the values of healthy people in their age range and so allow, for example, detection of whether a patient has a bilateral vestibular loss. VOR gain, as measured directly by the eye movement response to head rotation, seems largely unaffected by aging.

No MeSH data available.