Semicircular Canal Structure during Postnatal Development in Cat and Guinea Pig

1982 ◽  
Vol 91 (2) ◽  
pp. 185-192 ◽  
Author(s):  
I. S. Curthoys ◽  
R. H. I. Blanks ◽  
C. H. Markham
Keyword(s):  
Postnatal Development ◽  
Semicircular Canal ◽  
Receptor Cell ◽  
Semicircular Canals ◽  
Postnatal Growth ◽  
Related Function ◽  
Ocular Reflex ◽  
Skull Growth ◽  
Vestibulo Ocular Reflex ◽  
The Stability

The gain of the vestibulo-ocular reflex in the cat continues to increase for some time after birth. The reason for this increase is not presently known and one possibility is that it occurs because the cat semicircular canals increase in size. The present study examined this possibility by measuring the radii of curvature (R) of individual semicircular canals and the angular relationships of the semicircular canal planes within a labyrinth in cats and guinea pigs during postnatal growth. It was found that the labyrinths do move apart substantially during postnatal development in both species, but neither the planar relations nor the radii of curvature change significantly during postnatal development. The stability of semicircular canal structure during postnatal skull growth indicates that postnatal developmental changes in canal-related function, such as increased gain in the vestibulo-ocular reflex, in these species are probably due to receptor cell or neural maturational factors.

scholarly journals Optimizing the Sensitivity of the Head Thrust Test for Identifying Vestibular Hypofunction

2004 ◽  
Vol 84 (2) ◽  
pp. 151-158 ◽  
Author(s):  
Michael C Schubert ◽  
Ronald J Tusa ◽  
Lawrence E Grine ◽  
Susan J Herdman
Keyword(s):  
Health Information ◽  
Sensitivity And Specificity ◽  
Semicircular Canal ◽  
Medical Records ◽  
Semicircular Canals ◽  
Test Results ◽  
Lateral Semicircular Canal ◽  
Ocular Reflex ◽  
Vestibular Hypofunction ◽  
Vestibulo Ocular Reflex

Abstract Background and Purpose. The head thrust test (HTT) is used to assess the vestibulo-ocular reflex. Sensitivity and specificity for diagnosing unilateral vestibular hypofunction (UVH) in patients following vestibular ablation is excellent (100%), although sensitivity is lower (35%–39%) for patients with nonsurgically induced UVH. The variability of the test results may be from moving the subject's head outside the plane of the lateral semicircular canals as well as using a head thrust of predictable timing and direction. The purpose of this study was to examine sensitivity and specificity of the horizontal HTT in identifying patients with UVH and bilateral vestibular hypofunction (BVH) when the head was flexed 30 degrees in attempt to induce acceleration primarily in the lateral semicircular canal and the head was moved unpredictably. Subjects. The medical records of 176 people with and without vestibular dysfunction (n=79 with UVH, n=32 with BVH, and n=65 with nonvestibular dizziness) were studied. Methods. Data were retrospectively tabulated from a de-identified database (ie, with health information stripped of all identifiers). Results. Sensitivity of the HTT for identifying vestibular hypofunction was 71% for UVH and 84% for BVH. Specificity was 82%. Discussion and Conclusion. Ensuring the head is pitched 30 degrees down and thrust with an unpredictable timing and direction appears to improve sensitivity of the HTT.

scholarly journals Does vestibulo-ocular reflex gain measured by video head impulse test decrease with age?

2021 ◽  
Vol 7 (5) ◽  
pp. 712
Author(s):  
Yijin Jereme Gan ◽  
Yih Meei Heng ◽  
Shailesh Khode ◽  
Aruni Seneviratna ◽  
Annabelle Leong
Keyword(s):  
Semicircular Canal ◽  
Semicircular Canals ◽  
Community Dwelling ◽  
Head Impulse Test ◽  
Video Head Impulse Test ◽  
Head Impulse ◽  
Ocular Reflex ◽  
Age Dependent ◽  
Vestibulo Ocular Reflex ◽  
The Mean

<p class="abstract"><strong>Backgrounds:</strong> The Video Head Impulse Test (vHIT) is used to test the function of each of the six semicircular canals. Each semicircular canal is tested by measuring eye rotation in response to head movements in the plane of the canal and is calculated as the Vestibulo-ocular reflex (VOR) gain. The aims of the study were firstly, to determine age-dependent normative values of VOR gain for the vHIT of semicircular canal function in healthy Asian subjects in each decade year of life. Secondly, to investigate if vHIT measured VOR gain decreases with age.</p><p class="abstract"><strong>Methods: </strong>A prospective cohort study of 60 healthy voluntary community-dwelling subjects, between 21 to 80 years of age. Subjects with prior history of vertigo were excluded. vHIT was conducted on each subject and analysed with the Interacoustics (EyeSeeCam) video goggles by the senior audiologist. The VOR gain for all six semicircular canals were calculated for each subject.</p><p class="abstract"><strong>Results: </strong>The mean (SD) vHIT (VOR) gain of all the 6 semicircular canals for the entire population were 1.18 (0.19). The mean of the VOR gain for each of the six semicircular canals were analysed to develop a normative guide. The mean VOR gain per decade year did not vary significantly with age (p=0.417). The correlation between age and mean VOR values was negligible (pearson’s r=0.121).</p><p class="abstract"><strong>Conclusions: </strong>We propose that our normative age-dependent data guide be used to improve the differentiation between normal and abnormal values of VOR gain in an Asian population. Our study shows that VOR gain is not associated with aging.</p>

Torsional vestibulo-ocular reflex during whole-body oscillation in the upright and the supine position: II. Responses in patients after vestibular neuritis

2004 ◽  
Vol 14 (4) ◽  
pp. 353-359
Author(s):  
A. Schmid-Priscoveanu ◽  
A.A. Kori ◽  
D. Straumann
Keyword(s):  
Supine Position ◽  
Semicircular Canal ◽  
Low Frequency ◽  
Phase Changes ◽  
Vestibular Neuritis ◽  
Whole Body ◽  
Healthy Human ◽  
Phase Lead ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

In a recent study we demonstrated that otolith input modifies the torsional angular vestibulo-ocular reflex (torVOR) of healthy human subjects: Compared to turntable oscillations in supine position, oscillations in upright position increased the gain of torVOR by 0.1 and cancelled the phase lead originating from low-frequency semicircular canal signals. We asked whether these otolith-related changes of torVOR are still present in patients after vestibular neuritis (VN). Eight patients were sinusoidally oscillated about their naso-occipital axis in supine (canal-only stimulation) and upright (canal-and-otolith stimulation) position. Three-dimensional eye movements were recorded with dual search coils. The patients showed similar otolith-related gain and phase changes of the torVOR as healthy subjects: the gain increased by about 0.1 (p < 0.05) and the low-frequency phase lead from semicircular canal signals was abolished. These results indicate that otolith function after VN is still sufficient to interact with semicircular canal signals to optimize torsional gaze stabilization when the head is upright.

The click-evoked vestibulo-ocular reflex in superior semicircular canal dehiscence

Neurology ◽  
2003 ◽  
Vol 60 (7) ◽  
pp. 1172-1175 ◽  
Author(s):  
G.M. Halmagyi ◽  
L. A. McGarvie ◽  
S. T. Aw ◽  
R. A. Yavor ◽  
M. J. Todd
Keyword(s):  
Semicircular Canal ◽  
Superior Semicircular Canal Dehiscence ◽  
Superior Semicircular Canal ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Canal Dehiscence

scholarly journals Importance of Vestibulo-ocular Reflex Gain and Refixation Saccade Analysis in Individuals with Auditory Neuropathy Spectrum Disorder

2019 ◽  
Vol 24 (02) ◽  
pp. e140-e148
Author(s):  
Sujeet Kumar Sinha ◽  
Anuj Kumar Neupane ◽  
Krithika Gururaj
Keyword(s):  
Otoacoustic Emissions ◽  
Pure Tone ◽  
Semicircular Canals ◽  
Normal Hearing ◽  
Auditory Neuropathy ◽  
Spectrum Disorder ◽  
Auditory Neuropathy Spectrum Disorder ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Reflex Gain

Abstract Introduction Auditory neuropathy spectrum disorder (ANSD) features the presence of otoacoustic emissions, poor speech identification score and absent auditory brainstem response. Objective The present study was designed to evaluate the functioning of all six semicircular canals in individuals with ANSD and to compare it with those of normal-hearing individuals. Methods A total of 50 individuals participated in the present study, in which Group I comprised 25 normal-hearing individuals, and Group II comprised 25 individuals with ANSD. All of the participants underwent case history, pure tone audiometry, immittance, otoacoustic emissions, auditory evoked response and video head impulse test (vHIT). Results The independent sample t-test revealed significantly lower vestibulo-ocular reflex gain values in individuals with ANSD. A presence of 100% corrective refixation saccades was observed in the same group. The Pearson correlation test revealed no significant correlation between vestibulo-ocular reflex (VOR) gain with duration of hearing loss and pure tone thresholds for any of the three orthogonal planes. The chi-squared test revealed no association between the VOR gain values and the presence or absence of saccades in any of the semicircular canals (p > 0.05). Conclusion Huge percentages of individuals with ANSD have been found to have associated vestibular dysfunction as well. Therefore, the vHIT can be used as one of the important tests of the vestibular test battery to evaluate all six semicircular canals in individuals with ANSD.

Click-evoked vestibulo-ocular reflex

Neurology ◽  
2006 ◽  
Vol 66 (7) ◽  
pp. 1079-1087 ◽  
Author(s):  
S. T. Aw ◽  
M. J. Todd ◽  
G. E. Aw ◽  
J. S. Magnussen ◽  
I. S. Curthoys ◽  
...  
Keyword(s):  
Semicircular Canal ◽  
Rotation Axis ◽  
Head Orientation ◽  
Superior Canal Dehiscence ◽  
Ocular Reflex ◽  
Eye Rotation ◽  
Vestibulo Ocular Reflex ◽  
Low Threshold ◽  
Canal Dehiscence ◽  
Click Polarity

Background: An enlarged, low-threshold click-evoked vestibulo-ocular reflex (VOR) can be averaged from the vertical electro-oculogram in a superior canal dehiscence (SCD), a temporal bone defect between the superior semicircular canal and middle cranial fossa.Objective: To determine the origin and quantitative stimulus–response properties of the click-evoked VOR.Methods: Three-dimensional, binocular eye movements evoked by air-conducted 100-microsecond clicks (110 dB normal hearing level, 145 dB sound pressure level, 2 Hz) were measured with dual-search coils in 11 healthy subjects and 19 patients with SCD confirmed by CT imaging. Thresholds were established by decrementing loudness from 110 dB to 70 dB in 10-dB steps. Eye rotation axis of click-evoked VOR computed by vector analysis was referenced to known semicircular canal planes. Response characteristics were investigated with regard to enhancement using trains of three to seven clicks with 1-millisecond interclick intervals, visual fixation, head orientation, click polarity, and stimulation frequency (2 to 15 Hz).Results: In subjects and SCD patients, click-evoked VOR comprised upward, contraversive-torsional eye rotations with onset latency of approximately 9 milliseconds. Its eye rotation axis aligned with the superior canal axis, suggesting activation of superior canal receptors. In subjects, the amplitude was less than 0.01°, and the magnitude was less than 3°/second; in SCD, the amplitude was up to 60 times larger at 0.66°, and its magnitude was between 5 and 92°/second, with a threshold 10 to 40 dB below normal (110 dB). The click-evoked VOR magnitude was enhanced approximately 2.5 times with trains of five clicks but was unaffected by head orientation, visual fixation, click polarity, and stimulation frequency up to 10 Hz; it was also present on the surface electro-oculogram.Conclusion: In superior canal dehiscence, clicks evoked a high-magnitude, low-threshold, 9-millisecond-latency vestibulo-ocular reflex that aligns with the superior canal, suggesting superior canal receptor hypersensitivity to sound.

scholarly journals Vestibulo-ocular reflex gain and compensatory saccades in three semicircular canals by video head impulse test

2019 ◽  
Author(s):  
Homa Zarrinkoob ◽  
Hadi Behzad ◽  
Seyed Mehdi Tabatabaee
Keyword(s):  
High Velocity ◽  
Semicircular Canals ◽  
Head Impulse Test ◽  
Video Head Impulse Test ◽  
Low Velocity ◽  
Head Impulse ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Reflex Gain ◽  
The Right

Background and Aim: One of the tools for ass­essing the vestibulo-ocular reflex (VOR) is using video head impulse test (vHIT). In this test by placing the head at different angles and shaking the head, three semicircular canals of the vestibular system in each ear can be exami­ned separately. The purpose of this study was to investigate the relationship between the low and high velocities of the vHIT test with VOR and its compensatory saccades. Methods: The vHIT test was performed by an examiner in 49 normal individuals aged 23–39 at low and high velocities. All participants had normal hearing, visual, and vestibular systems. Results: Mean gains in the horizontal, anterior and posterior semicircular canals in the right ear respectively were 0.92, 1 and 0.90 and in the left ear 0.93, 0.99 and 0.95 for low velocity and 0.78, 0.92 and 0.79 in the right ear and 0.80, 0.85 and 0.86 in the left ear for high velocity. Also, the number of compensatory saccade at high velocity was higher than those at the low velocity and the latency of compensatory sacc­ade was lower at the higher velocity. Conclusion: In the vHIT test, VOR gain decreases at high velocity that is statistically significant. Also, compensatory saccades are more likely to occur at high velocity with sma­ller delay. Therefore, high-velocity vHIT test is not recommended for the purpose of examining the VOR gain and compensatory saccade.

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