Are gain values significantly altered by manual data selection when performing the video Head Impulse Test (v-HIT) on all six semicircular canals with two different v-HIT systems

Vestibular dysfunction in lateral semicircular canal dysplasia

Introduction

Lateral semicircular canal (LSCC) dysplasia is the most common inner ear malformation. The severity of dysplasia can appear in various spectrums, from a short and broad LSCC with normal or small-sized central bony island (CBI) to a single fluid-filled cavity confluent with the vestibule without CBI. However, reports on the association between LSCC dysplasia and the loss of vestibular function are still lacking. In this study, the results of vestibular function tests [caloric test and video-head impulse test (vHIT)] in patients with LSCC dysplasia were analyzed and compared between groups with and without CBI.

Methods

This study retrospectively enrolled 17 patients (23 ears) who had LSCC dysplasia following computed tomography or magnetic resonance imaging and underwent vestibular function tests.

Results

LSCC dysplasia was observed unilaterally in 11 patients and bilaterally in six patients. Nine of 23 ears had CBIs, and 14 ears had no CBI. Three of 17 patients experienced dizziness. Abnormal caloric tests were detected in 11 of the 16 patients who underwent the caloric tests (69%); in contrast, 11 of 12 patients who underwent the vHIT (92%) had normal LSCC vestibulo-ocular reflex (VOR) gain on vHIT. A significant correlation was found between the maximum slow-phase velocity of the caloric test and LSCC VOR gain of the vHIT (correlation coefficient 0.792, p = 0.004). The CBI-absent group showed significantly lower SPV and LSCC VOR gains than the CBI-present group (p = 0.001 and 0.004, respectively).

Discussion

LSCC dysplasia impairs VOR function, especially in the absence of CBI.

[Gain characteristics of three pairs of semicircular canals in video head impulse paradigm test and suppression head impulse paradigm test in healthy young Chinese population]

Objective:To summarize gain characteristics of three pairs of semicircular canals in head impulse paradigm （HIMP） and suppression head impulse paradigm （SHIMP） in healthy young Chinese population. Methods:HIMP and SHIMP tests were performed on 40 healthy young volunteers enrolled as study group, by using EyeseeCam examiantion system （Interacoustics，Denmark）. The elicitation rates and gain values of the two saccades were recorded, and the gain values were compared and analyzed. Results:The results of 40 healthy young people were as follows: in HIMP, the instantaneous gain at 60 ms of the horizontal semicircular canals were 1.11±0.07 on the left side and 1.08±0.07 on the right side; the regression gain of the horizontal semicircular canals were 1.09±0.06 on the left side and 1.10±0.06 on the right side; the regression gain of the vertical semicircular canals were 1.08±0.12 on the right anterior, 1.07±0.11 on the left posterior, 1.41±0.16 on the right posterior and 1.42±0.16 on the left anterior. So in HIMP, no significant difference could be found between left and right side in both horizontal and vertical semicircular canal conjugate plane regarding regression gain （P>0.05）, except that 60 ms instantaneous gain on the left horizontal semicircular canals was slightly higher than that on the right side （P<0.05）.The instantaneous gain values of the horizontal semicircular canal at 60 ms in SHIMP were 1.08±0.08 on the left side and 1.06±0.07 on the right side; the regression gain in horizontal semicircular canals were 1.06±0.07 on the left side and 1.07±0.06 on the right side, respectively; the regression gains of vertical semicircular canal were 1.06±0.13, 1.08±0.16, 1.49±0.16, 1.39±0.15, on the right anterior, left posterior, right posterior, and left anterior side. So in SHIMP, no significant difference could be found in 60 ms instantaneous gain in horizontal conjugate plane, regression gain in horizontal conjugate plane and regression gain in right anterior left posterior conjugate plane （P>0.05）, while the regression gain of the left anterior right posterior conjugate plane in the right was found slightly higher than that of the left （P<0.05）.Both 60 ms instantaneous gain and regression gain in horizontal conjugate plane in HIMP were slightly higher than that of SHIMP （P<0.05）, while no significant difference could be found in vertical conjugate planes （P>0.05）. In both HIMP and SHIMP tests, gains of the left anterior right posterior conjugate plane was slightly higher than that of both horizontal plane and the right anterior left posterior conjugate plane （P<0.05）, while no significant difference could be found in gains between horizontal and the right anterior left posterior conjugate plane （P>0.05）. Conclusion:Gain values of HIMP and SHIMP were slightly different among different semicircular canals conjugate planes.It is suggested that each examination center should establish normal values for their own and make correction regularly.

Comparison between caloric and video-head impulse tests in Ménière's disease and vestibular neuritis

OBJECTIVE

To compare the diagnostic accuracies of air caloric testing with electronystagmography and the vHIT (video-head impulse test).

DESIGN

Prospective, controlled study.

STUDY SAMPLE

MD (Ménière's disease), 26; vestibular neuritis, 27; control, 56.

RESULTS

In MD, CP (canal paresis) was pathological in 88.5%, the GA (gain asymmetry) on vHIT was pathological in 65.3%, and the gain was abnormal in only one patient. The GA and CP, were significantly higher in the MD group than in the control group, indicating hypofunction of the horizontal canals in MD, whereas a hyperfunction may also occur. No correlation was observed between the results of the two tests for evaluating MD, suggesting that pathological outcomes of one test do not guarantee abnormalities on the other test. For vestibular neuritis, significantly higher CP (96.3%), GA (81.5%), and gain (51.9%) values were detected. A correlation was identified between the two tests for vestibular neuritis, indicating a similar diagnostic efficiency. The higher percentage of pathological GA versus pathological gain values indicates that the asymmetry may be more informative.

CONCLUSIONS

The vHIT showed a higher specificity, whereas the caloric test a higher sensitivity. No correlation between the two methods was observed; therefore, the tests appear to provide complementary information.