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Age dependent normal horizontal VOR gain of head impulse test as measured with video-oculography.

Mossman B, Mossman S, Purdie G, Schneider E - J Otolaryngol Head Neck Surg (2015)

Bottom Line: Although normative data is available for VOR gain with video-oculography, most normal studies in general include small numbers of subjects and do not include analysis of variation of VOR gain with age.A non-physiologically high horizontal HVOR velocity gain was found to occur in tests where passive HITs were predictable in direction and time and where target distance was below 0.70 m.Normative data with respect to HVOR velocity gain decreases slightly with age, but with careful attention to methodology the 2 SD lower limit of normal is relatively robust across a wide age range and into the eighth decade, without requirement for adjustment with age.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Wellington Hospital, Riddiford Street, Private Bag 7902, Wellington South, Wellington, New Zealand. mossman.benjamin@gmail.com.

ABSTRACT

Background: The head impulse test (HIT) is a recognised clinical sign of the high frequency vestibulo-ocular reflex (VOR), which can be quantified with video-oculography. This measures the VOR gain as the ratio of angular eye velocity to angular head velocity. Although normative data is available for VOR gain with video-oculography, most normal studies in general include small numbers of subjects and do not include analysis of variation of VOR gain with age. The purpose of our study was to establish normative data across 60 control subjects aged 20 to 80 years to represent a population distribution.

Methods: Sixty control subjects without any current or previous form of brain disorder or vertigo participated in this study and form the basis for future comparison to patients with vestibular lesions. The relationship between the horizontal vestibulo-ocular reflex (HVOR) velocity gain and age was analysed using a mixed regression model with a random effect for subjects. Differences in testing technique were assessed to ensure reliability in results.

Results: The mean HVOR velocity gain of 60 normal subjects was 0.97 (SD = 0.09) at 80 ms and 0.94 (SD = 0.10) at 60 ms. The 2 SD lower limit of normal HVOR velocity gain was 0.79 at 80 ms and 0.75 at 60 ms. No HVOR velocity gain fell below 0.76 and 0.65 at 80 ms and 60 ms respectively. The HVOR velocity gain declined by 0.012 and 0.017 per decade as age increased at 80 ms and 60 ms respectively. A non-physiologically high horizontal HVOR velocity gain was found to occur in tests where passive HITs were predictable in direction and time and where target distance was below 0.70 m.

Conclusions: Normative data with respect to HVOR velocity gain decreases slightly with age, but with careful attention to methodology the 2 SD lower limit of normal is relatively robust across a wide age range and into the eighth decade, without requirement for adjustment with age.

No MeSH data available.


Related in: MedlinePlus

Method of testing, where the subject’s head is firmly held by the mandible, with three fingers clasped below and a thumb and forefinger above the jaw line
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Fig1: Method of testing, where the subject’s head is firmly held by the mandible, with three fingers clasped below and a thumb and forefinger above the jaw line

Mentions: Eye and head rotations were measured during the HIT while the examiner manually applied rapid unpredictable (in direction and time) angular head rotations (peak head velocity 150 °/s to 300 °/s) [7]. Instantaneous HVOR velocity gains were calculated by the EyeSeeCam VOG software at 80 ms and 60 ms [8]. Head accelerations were manually controlled so that peak head velocity would occur at 80 ± 15 ms into each rotation [9]. This was achieved with angular head displacements of small amplitude (6° – 12°) and rapid rotation. Rotation of the subject’s head was performed with the examiner standing behind the seated subject. Six to ten unpredictable head rotations in both directions were performed from a central head position. This sequence was repeated twice to ensure adequate data collection and a check for data consistency, but more frequently if a subject needed additional training or if results were affected by artefact. Head rotations were achieved by the examiner firmly holding the mandible with three fingers clasped below and a thumb and forefinger above the jaw line (Fig. 1). This reduced skin movement and thus goggle slippage, decreasing the amount of artefact. Care was taken to avoid touching the goggles strap during head rotation. A single examinerBM performed all tests throughout the study.Fig. 1


Age dependent normal horizontal VOR gain of head impulse test as measured with video-oculography.

Mossman B, Mossman S, Purdie G, Schneider E - J Otolaryngol Head Neck Surg (2015)

Method of testing, where the subject’s head is firmly held by the mandible, with three fingers clasped below and a thumb and forefinger above the jaw line
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4506627&req=5

Fig1: Method of testing, where the subject’s head is firmly held by the mandible, with three fingers clasped below and a thumb and forefinger above the jaw line
Mentions: Eye and head rotations were measured during the HIT while the examiner manually applied rapid unpredictable (in direction and time) angular head rotations (peak head velocity 150 °/s to 300 °/s) [7]. Instantaneous HVOR velocity gains were calculated by the EyeSeeCam VOG software at 80 ms and 60 ms [8]. Head accelerations were manually controlled so that peak head velocity would occur at 80 ± 15 ms into each rotation [9]. This was achieved with angular head displacements of small amplitude (6° – 12°) and rapid rotation. Rotation of the subject’s head was performed with the examiner standing behind the seated subject. Six to ten unpredictable head rotations in both directions were performed from a central head position. This sequence was repeated twice to ensure adequate data collection and a check for data consistency, but more frequently if a subject needed additional training or if results were affected by artefact. Head rotations were achieved by the examiner firmly holding the mandible with three fingers clasped below and a thumb and forefinger above the jaw line (Fig. 1). This reduced skin movement and thus goggle slippage, decreasing the amount of artefact. Care was taken to avoid touching the goggles strap during head rotation. A single examinerBM performed all tests throughout the study.Fig. 1

Bottom Line: Although normative data is available for VOR gain with video-oculography, most normal studies in general include small numbers of subjects and do not include analysis of variation of VOR gain with age.A non-physiologically high horizontal HVOR velocity gain was found to occur in tests where passive HITs were predictable in direction and time and where target distance was below 0.70 m.Normative data with respect to HVOR velocity gain decreases slightly with age, but with careful attention to methodology the 2 SD lower limit of normal is relatively robust across a wide age range and into the eighth decade, without requirement for adjustment with age.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Wellington Hospital, Riddiford Street, Private Bag 7902, Wellington South, Wellington, New Zealand. mossman.benjamin@gmail.com.

ABSTRACT

Background: The head impulse test (HIT) is a recognised clinical sign of the high frequency vestibulo-ocular reflex (VOR), which can be quantified with video-oculography. This measures the VOR gain as the ratio of angular eye velocity to angular head velocity. Although normative data is available for VOR gain with video-oculography, most normal studies in general include small numbers of subjects and do not include analysis of variation of VOR gain with age. The purpose of our study was to establish normative data across 60 control subjects aged 20 to 80 years to represent a population distribution.

Methods: Sixty control subjects without any current or previous form of brain disorder or vertigo participated in this study and form the basis for future comparison to patients with vestibular lesions. The relationship between the horizontal vestibulo-ocular reflex (HVOR) velocity gain and age was analysed using a mixed regression model with a random effect for subjects. Differences in testing technique were assessed to ensure reliability in results.

Results: The mean HVOR velocity gain of 60 normal subjects was 0.97 (SD = 0.09) at 80 ms and 0.94 (SD = 0.10) at 60 ms. The 2 SD lower limit of normal HVOR velocity gain was 0.79 at 80 ms and 0.75 at 60 ms. No HVOR velocity gain fell below 0.76 and 0.65 at 80 ms and 60 ms respectively. The HVOR velocity gain declined by 0.012 and 0.017 per decade as age increased at 80 ms and 60 ms respectively. A non-physiologically high horizontal HVOR velocity gain was found to occur in tests where passive HITs were predictable in direction and time and where target distance was below 0.70 m.

Conclusions: Normative data with respect to HVOR velocity gain decreases slightly with age, but with careful attention to methodology the 2 SD lower limit of normal is relatively robust across a wide age range and into the eighth decade, without requirement for adjustment with age.

No MeSH data available.


Related in: MedlinePlus