Association Analysis of HIMP and SHIMP Quantitative Parameters in Patients With Vestibular Neuritis and Healthy Participants

Changes in vestibular-related responses to combined noisy galvanic vestibular stimulation and cerebellar transcranial direct current stimulation

Vestibular nuclei and cerebellar function comprise vestibular neural networks that control vestibular-related responses. However, the vestibular-related responses to simultaneous stimulation of these regions are unclear. This study aimed to examine whether the combination of noisy galvanic vestibular stimulation (nGVS) and cerebellar transcranial direct current stimulation (ctDCS) using a complex transcranial electrical stimulation device alters vestibular-dominant standing stability and vestibulo-ocular reflex (VOR) function. The center of foot pressure (COP) sway and VOR of participants (28 healthy, young adults) were assessed under four conditions of transcranial electrical stimulation using nGVS and ctDCS. The COP was calculated with the participant standing on a soft-foam surface with eyes closed using a force plate to evaluate body sway. VOR measurements were collected via passive head movements and fixation on a target projected onto the front wall using a video head impulse test (vHIT). VOR gain was calculated in six directions using a semicircular canal structure based on the ratio of eye movement to head movement. The nGVS + ctDCS and nGVS + sham ctDCS conditions decreased COP sway compared to the sham nGVS + ctDCS and sham nGVS + sham ctDCS conditions. No significant differences were observed in the main effect of stimulation or the interaction of stimulation and direction on the vHIT parameters. The results of this study suggest that postural stability may be independently affected by nGVS. Our findings contribute to the basic neurological foundation for the clinical application of neurorehabilitation using transcranial electrical stimulation of the vestibular system.

Video Suppression Head Impulses and Head Impulses Paradigms in Patients with Vestibular Neuritis: A Comparative Study

Background: This study aims to explore the clinical relevance of the Suppression Head Impulse Paradigm (SHIMP) to better understand if it represents an additional clinical value compared to the Head Impulse Paradigm (HIMP) in patients with vestibular neuritis (VN) in different stages of the disease. Methods: From January 2020 to June 2022, patients with unilateral VN were found in a database of an ENT vestibular clinic. Clinical presentation, vestibular test outcomes, therapy, and recovery were examined in medical records. Results: A total of 42 patients (16 Females, mean age 51.06 ± 12.96; 26 Male, mean age 62.50 ± 9.82) met the inclusion criteria and were enrolled in the study. The means of the VOR gain for both paradigms were respectively 0.38 ± 0.12 (SHIMP) and 0.46 ± 0.13 (HIMP) at T0 and 0.55 ± 0.20 (SHIMP) and 0.64 ± 0.19 (HIMP) at T1 for the lesional side. For the HIMP, the gain value <0.76 identified the affected side of VN with 100% sensitivity (92−100) and 100% specificity (91−100). For the SHIMP, the gain value <0.66 identified the affected side of VN with 100% sensitivity (92−100) and 100% specificity (91−100) and an AUC of 1.0 (0.96−1.0, p < 0.0001). Conclusion: The SHIMP paradigm has a diagnostic accuracy equal to the classic HIMP paradigm in patients with VN. The assessment of VOR slow phase velocity and vestibulo-saccadic interaction in patients with VN could be easier with the use of the SHIMPs paradigm. SHIMPs paradigm provides helpful information about the evaluation of VOR slow phase velocity and vestibulo-saccadic interaction as new recovery strategies in patients with VN.

[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.