Differentiation of peripheral and non-peripheral etiologies in children with vertigo/dizziness: The video-head impulse test and suppression head impulse paradigm

OBJECTIVES

To identify the etiology of vertigo/dizziness and determine the effectiveness of the video-head impulse test (vHIT) and the suppression head impulse paradigm (SHIMP) tests in distinguishing between peripheral and non-peripheral etiologies in children who presented to the otolaryngology department with complaints of vertigo/dizziness.

METHODS

The vHIT and SHIMP tests were applied to the children. The vestibulo-ocular reflex (VOR) gain and saccade parameters were compared.

RESULTS

In 27 children presenting with vertigo/dizziness, the most common etiological factor was inner ear malformation (IEM) (n = 6/27, 22.2%), followed by cochlear implant surgery (11.1%) and migraine (11.1%). Vestibular hypofunction was indicated by the vHIT results at a rate of 60% (9/15 children) and SHIMP results at 73.3% (11/15 children) among the children with a peripheral etiology, while these rates were 8.3% (1/12 children) and 25% (3/12 children), respectively, in the non-peripheral etiology group. SHIMP-VOR and vHIT-VOR gain values had a moderate positive correlation (p = 0.01, r = 0.349). While there were overt/covert saccades in the vHIT, anti-compensatory saccade (ACSs) were not observed in the SHIMP test (p = 0.041). The rates of abnormal vHIT-VOR gain (p = 0.001), over/covert saccades (p = 0.019), abnormal vHIT response (p = 0.014), ACSs (p = 0.001), and abnormal SHIMP response (p = 0.035) were significantly higher in the peripheral etiology group.

CONCLUSIONS

IEM was the most common etiological cause, and the rate of vestibular hypofunction was higher in these children with peripheral vertigo. vHIT and SHIMP are effective and useful vestibular tests for distinguishing peripheral etiology from non-peripheral etiology in the pediatric population with vertigo/dizziness. These tests can be used together or alone, but the first choice should be the SHIMP test, considering its short application time (approximately 4-5 min) and simplicity.

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.

Suppression Head Impulse Test (SHIMP) versus Head Impulse Test (HIMP) When Diagnosing Bilateral Vestibulopathy

The Suppression Head Impulse (SHIMP) test was introduced as an alternative to the Head Impulse Paradigm (HIMP) to overcome challenges in VOR gain calculation due to the interference of covert saccades. The objectives of this study were (1) to determine if SHIMP, compared to HIMP, reduces covert saccades in BV patients and (2) to define the agreement on diagnosing BV between SHIMP and HIMP. First, the number of covert saccades was compared between SHIMP and HIMP. Secondly, VOR gain was compared between SHIMP and HIMP. Lastly, the agreement between SHIMP and HIMP on identifying BV (horizontal VOR gain <0.6) was evaluated. A total of 98 BV patients were included. To our knowledge, this is the largest study population on SHIMP testing in BV patients. Covert saccades were significantly reduced, and a lower VOR gain was found during SHIMP compared to HIMP (p < 0.001). However, the clinical relevance of these statistically significant differences is small. In 93% of the patients, an agreement was found between the two paradigms regarding the diagnosis of BV, and both paradigms detect BV in the vast majority of patients.

The feasibility of SHIMP for judging subjective vertigo and recovery in patients with vestibular neuritis

PURPOSE

We aimed to study the results of the head impulse paradigm (HIMP) and the suppression head impulse paradigm (SHIMP) in patients with acute vestibular neuritis (AVN) to compare dizziness handicap inventory (DHI) scores before and after treatment. We also wanted to investigate the correlation between the HIMP, SHIMP and DHI score and to analyze the factors that affect the recovery with AVN in the short term.

METHODS

The HIMP, SHIMP, and DHI score were assessed in 20 patients with AVN before (T₀) and after treatment (T₁). We collected the following indicators: T₀, T₁-HIMP VOR gain; T₀, T₁-SHIMP VOR gain; the percentage of the anti-compensatory saccades of T₀-SHIMP and T₁-SHIMP on the affected side; T₀-DHI score, T₁-DHI score; and efficacy index (EI). The correlation between HIMP and SHIMP parameters with the DHI score and EI was analyzed, and the factors that affect the recovery of patients with AVN were assessed.

RESULTS

T₀-SHIMP anti-compensatory saccades (%),T₁-SHIMP VOR gain, and T₁-SHIMP anti-compensatory saccades (%) were significantly correlated with the corresponding DHI score and EI (P < 0.05). T₀, T₁-HIMP VOR gain and T₀-SHIMP VOR gain had no correlation with the corresponding DHI score and EI (P > 0.05). T₀-SHIMP anti-compensatory saccades (%) significantly affect EI (P < 0.05).

CONCLUSION

Both HIMP and SHIMP can assess the current vestibular function and recovery of AVN patients, but SHIMP can more accurately reflect the degree of subjective vertigo. At the same time, T₀-SHIMP anti-compensatory saccades (%) can be used as a good index to evaluate the short-term recovery of AVN patients.

Influence of predictability on saccade timing in a head impulse VOR suppression task

Gaze stabilization performance has been shown to be influenced differently when the head is either passively or actively moved in normal healthy participants. However, for a visual fixation suppression task, it remains unknown if the pattern of coordinated head and eye movement is influenced differently by passive or active head movements. We used a suppression head impulse paradigm (SHIMP), where the subject's goal was to maintain gaze stabilized on a visual target that moved with the head during rapid impulsive head movements, to evaluate gaze fixation performance in three conditions: (1) passive-unpredictable where the examiner applied impulsive head yaw rotations with random timing and direction, (2) passive-predictable where the direction of head rotation was announced and then the examiner repeatedly applied impulses in the same direction, and (3) active where the test subject self-generated their head movements. Thirteen young healthy adults performed all three conditions to assess the percentage of early saccades that initiated the gaze shift toward the final visual target position and the latency of first saccades. Early saccades were defined as those occurring within the duration of the head impulse. Results showed that active head impulses generated the greatest percentage of early saccades, followed by predictable and unpredictable. Among the two passive conditions, predictability shortened the first saccade onset latencies. Active condition onset latencies were shorter than in either of the passive conditions, showing a consistent head-leads-eye pattern defining a specific behavioral pattern that could vary across patient groups leading to insights into central neural mechanisms that control eye-head coordination.

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

Background: The Head Impulse Paradigm (HIMP) and Suppression Head Impulse Paradigm (SHIMP) are objective, quantitative methods that directly test the vestibulo-ocular reflex (VOR) and are increasingly becoming a standard in evaluating patients with vestibular disorders. Objective: The main objective was to assess the correlations between HIMP and SHIMP parameters in patients with superior vestibular neuritis (VN) and healthy participants. Additionally, the correlations between the parameters of each method were analyzed. Methods: A retrospective cohort, non-randomized study was designed. HIMP and SHIMP were performed on 40 patients with VN and 20 healthy participants (40 ears). HIMP and SHIMP parameters were measured and calculated. Pearson's or Spearson's correlations were used to establish the associations among them. Results: A strong positive correlation was found between HIMP and SHIMP gain (Pearson's r = 0.957, p = 0.000), while strong negative correlations were detected between HIMP and SHIMP saccade amplitudes (r = -0.637, p = 0.000) and percentages of overt saccades (r = -0.631, p = 0.000). In HIMP, strong and moderate positive correlations were identified between gain and saccade amplitude (R ² = 0.726, p = 0.000) and gain and saccade percentage (R ² = 0.558, p = 0.000), respectively. By contrast, an extremely weak positive correlation was observed between gain and latency (R ² = 0.053, p = 0.040). In SHIMP, strong and moderate positive correlations were found between gain and saccade percentage (R ² = 0.723, p = 0.000) and gain and saccade amplitude (R ² = 0.525, p = 0.000), respectively, but no correlation was detected between gain and latency (R ² = 0.006, p = 0.490). Conclusions: HIMP and SHIMP-related parameters were highly correlated (inter-method). Within each method (intra-method), moderate to strong correlations in VOR assessment were observed. These results further contribute to our understanding of the relationship between HIMP and SHIMP as well as to the diagnosis.

Effect of different head impulse procedures on vestibulo-ocular reflex gain

OBJECTIVE

to study the effects on vestibulo-ocular reflex (VOR) gain using both video head impulse test (vHIT) and Suppression Head impulse test (SHIMP) either using the outward or the inwards head impulse.

METHODS

Twenty healthy subjects were enrolled in the study. They were examined using otometric vHIT and SHIMP test lateral plane using the lateral outwards head impulse ten impulses for each side and the inwards head impulse ten impulses for each side. The VOR gain resulting from the outwards versus inwards head impulse during the vHIT and SHIMP were statistically compared.

RESULTS

Twenty healthy subjects, 10 Males and 10 females with a mean age 35±11.7. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (1.1±.12) using outwards versus (1.03 ± .22) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (1.1 ± .22) using outwards head impulse (1.1 ± .3) for inwards head impulse in vHIT. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (0.96 ± 0.2)using outwards versus (1.04 ± 0.2) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (0.98 ± 0.25) using outwards head impulse (1.1 ± 0.28) for inwards head impulse in SHIMP test. No statistical significant difference was found between the VOR gain resulting from the right versus the left semicircular canal.

CONCLUSION

The starting head position does not affect the VOR gain using both vHIT and SHIMP tests.

Suppression head impulse test paradigm (SHIMP) characteristics in people with Parkinson's disease compared to healthy controls

The suppression head impulse test paradigm (SHIMP) is a newly described indicator of vestibular function which yields two measures: vestibulo-ocular reflex (VOR) gain and a saccadic response. It is an alternative and complementary test to the head impulse test paradigm (HIMP). Parkinson's disease (PD) has known saccadic and central vestibular pathway dysfunction. This paper is the first description of SHIMP VOR gain and saccade characteristic in this population. This prospective observational study measured the SHIMP VOR gain and saccade characteristics in 39 participants with idiopathic PD and compared this to 40 healthy controls (HC). The effect of group, demographic variables and SHIMP characteristics were evaluated. SHIMP VOR gains were not significantly different between groups (p = 0.10). Compared to HC, the PD group mean SHIMP peak saccade velocity was significantly reduced by an average of 77.07°/sec (p < 0.001), and SHIMP saccade response latency was longer, with an average delay of 23.5 ms (p = 0.003). SHIMP saccade peak velocity was also associated with both head impulse velocity (p = 0.002) and SHIMP VOR gain (p = 0.004) variables, but there was no significant influence of these variables when SHIMP saccade peak velocity was considered as a predictor of PD (p = 0.52-0.91). VOR gains were unaffected by PD. PD-specific saccadic dysfunction, namely reduced peak saccade velocities and prolonged response latencies, were observed in the SHIMP-induced saccade responses. VOR gain using slow phase eye velocity is preferred as the indicator of vestibular function in the SHIMPs paradigm as non-vestibular factors affected saccade peak velocity.

Prognosis after acute unilateral vestibulopathy: Usefulness of the suppression head impulse paradigm (SHIMP)

OBJECTIVES

This cross-sectional study aims to describe the features of the suppression head impulse paradigm (SHIMP) in acute unilateral vestibulopathy (AUV) and to define its role in predicting the recovery of patients.

METHODS

Thirty patients diagnosed with AUV were retrospectively analyzed. The dizziness handicap inventory score and video head impulse test parameters performed 4-8 weeks from the AUV onset constituted the main outcome measures. Patients with a worse recovery (Group 1) and patients who recovered spontaneously (Group 2) were compared.

RESULTS

The SHIMP vestibulo-ocular reflex (VOR) gain was statistically significantly lower than the conventional head impulse paradigm (HIMP) VOR gain (P <  0.001). The SHIMP VOR gain was negatively correlated with the DHI (P <  0.001) and was positively correlated with the HIMP VOR gain (P <  0.001) and the SHIMP overt saccades (%) (P <  0.001). Patients with a worse recovery exhibited the following: higher DHI (P <  0.001), lower SHIMP and HIMP VOR gain (P <  0.001 and P = 0.007, respectively), and lower SHIMP and greater HIMP overt saccade prevalence values (P = 0.007 and P = 0.032, respectively).

CONCLUSIONS

The SHIMP and HIMP help in improving our approach to AUV. SHIMP appears to better identify the extent of the vestibular damage in patient suffering from AUV than HIMP and could provide interesting information about the course of the disease. Particularly, the analysis of SHIMP VOR gain and overt saccade prevalence would provide useful information about the recovery of patients.

Angular vestibulo ocular reflex loss with preserved saccular function in Machado-Joseph disease

OBJECTIVE

To provide a comprehensive evaluation of the vestibular function in Machado-Joseph Disease (MJD).

METHODS

21 MJD patients and 19 healthy Controls underwent a detailed clinical neuro-otological evaluation including VOR gain of all six semicircular canals by video Head Impulse Test (vHIT), remaining horizontal VOR function by Suppression Head Impulse test (SHIMP), and saccular function by cervical Vestibular Evoked Myogenic Potentials (cVEMP).

RESULTS

All MJD had significantly lower VOR gain in all six semicircular canals (p < 0.001) with a mean ± SEM of horizontal gain of 0.52 ± 0.04 and vertical gain of 0.57 ± 0.03 versus Controls' gain of 0.95 ± 0.01 and 0.81 ± 0.02, respectively (p < 0.001). MJD showed also a significantly lower VOR gain on the SHIMP test with left gain of 0.51 ± 0.04 and right gain of 0.46 ± 0.03 versus Controls' gain of 0.79 ± 0.01 and 0.83 ± 0.03, respectively (p < 0.001). In contrast, MJD had normal saccular function reflected by the presence of cVEMP response in 18/20 patients and in 12/17 of Controls, with a non-significant difference between MJD and Controls of P13 and N23 peaks latency and normalized peak-to-peak amplitude. ROC analysis of horizontal VOR gain resulted in an area under the curve of 0.993 making the average lateral canals' VOR gain an excellent classifier of MJD vs Controls.

CONCLUSIONS

Horizontal and vertical VOR impairment with preserved sacculo-collic function seems to be a distinctive feature of MJD and could be explained by selective, mostly medial and superior vestibular nuclei degeneration. This study further supports the idea that horizontal VOR gain measured by vHIT could be a potential neurophysiological biomarker of MJD.

Suppression head impulse testing is recommended for vestibular testing of patients with untreated unilateral vestibular schwannoma

PURPOSE

Suppression head impulse testing (SHIMP) is a new vestibular method capable of quantifying vestibular function. The aim of this study was to evaluate the feasibility of this test in patients with existing or newly diagnosed vestibular schwannoma (VS) patients by comparing the results with the traditionally used video head impulse test (vHIT or HIMP).

METHODS

Fifty-five patients with unilateral VS underwent a wide battery of audiological and vestibular tests. HIMP results were evaluated using newly introduced objective guidelines based on the trace evaluation of pathological saccades. The sensitivity and specificity of HIMP and SHIMP were evaluated and compared. A new SHIMP parameter is presented; the anticompensatory saccade amplitude ratio (ASAR).

RESULTS

We found a marked increase in specificity in HIMP testing using the objective guidelines. SHIMP testing revealed a gain threshold of 0.7 to be optimal in terms of achieving high specificity and sensitivity in relation to HIMP testing. Significant correlations were found between a low ASAR and a high degree of vestibular pathology.

CONCLUSION

The SHIMP test is a viable addition to the standard HIMP test in patients with VS, especially with the addition of the ASAR, which could prove useful in monitoring the residual vestibular function.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

N/A.

Suppression Head Impulse Paradigm (SHIMP) in evaluating the vestibulo-saccadic interaction in patients with vestibular neuritis

PURPOSE

Evaluate the potential clinical application of the Suppression Head Impulse Paradigm (SHIMP) in evaluating the vestibulo-saccadic interaction in patients with vestibular neuritis (VN).

METHODS

A retrospective study was performed. Fifteen patients diagnosed with unilateral VN were identified from a database of ENT vestibular clinic from January 2011 to February 2020. Medical records were reviewed to determine clinical presentation, vestibular testing results, treatment, and recovery.

RESULTS

Fifteen patients (7 left ear, 8 right ear, mean age 58.73 ± 10.73, six female) met the inclusion criteria and were enrolled in the study. Significant differences were found in the within-subjects analysis at T1 in DHI score (p = 0.001), VOR gain (p < 0.005), and in the percentages of impulses containing a SHIMPs saccade when the head is passively turned toward the affected side (p = 0.001).

CONCLUSIONS

SHIMPs paradigm provides useful information about the value of vestibulo-saccadic interaction as new recovery strategies in patients with VN.

Vestibulo-ocular reflex gain values in the suppression head impulse test of healthy subjects

OBJECTIVE

To assess whether there are differences in vestibulo-ocular reflex (VOR) gain for suppression head impulse (SHIMP) and head impulse (HIMP) video head impulse test paradigms, and if so, what are their causes.

METHODS

Prospective multicenter observational double-blind nonrandomized clinical study was performed by collecting 80 healthy subjects from four reference hospitals. SHIMP data was postprocessed to eliminate impulses in which early SHIMP saccades were detected. Differences between HIMP and SHIMP VOR gain values were statistically evaluated. Head impulse maximum velocity, gender, age, direction of impulse, and hospital center were considered as possible influential factors.

RESULTS

A small significant statistical difference between HIMP and SHIMP VOR gain values was found on repeated measures analysis of variance (-0.05 ± 0.006, P < 0.001). Optimized linear model showed a significant influence of age variable on the observed differences for HIMP and SHIMP gain values and did not find influence between gain values differences and maximum head impulse velocity. Both HIMP and SHIMP VOR gain values were significant lower (-0.09, P < 0.001) when the impulses were performed to the left side.

CONCLUSION

We had observed a difference in SHIMP and HIMP gain values not adequately explained by known gain modification factors. The persistence of this slight but significant difference indicates that there are more factors causing lower SHIMP VOR gain values. This difference must to be considered in further studies as well as in the clinical SHIMP testing protocols. We hypothesized that VOR phasic response inhibition could be the underlying cause of this difference.

LEVEL OF EVIDENCE

2b. Laryngoscope, 128:2383-2389, 2018.

The Video Head Impulse Test

In 1988, we introduced impulsive testing of semicircular canal (SCC) function measured with scleral search coils and showed that it could accurately and reliably detect impaired function even of a single lateral canal. Later we showed that it was also possible to test individual vertical canal function in peripheral and also in central vestibular disorders and proposed a physiological mechanism for why this might be so. For the next 20 years, between 1988 and 2008, impulsive testing of individual SCC function could only be accurately done by a few aficionados with the time and money to support scleral search-coil systems—an expensive, complicated and cumbersome, semi-invasive technique that never made the transition from the research lab to the dizzy clinic. Then, in 2009 and 2013, we introduced a video method of testing function of each of the six canals individually. Since 2009, the method has been taken up by most dizzy clinics around the world, with now close to 100 refereed articles in PubMed. In many dizzy clinics around the world, video Head Impulse Testing has supplanted caloric testing as the initial and in some cases the final test of choice in patients with suspected vestibular disorders. Here, we consider seven current, interesting, and controversial aspects of video Head Impulse Testing: (1) introduction to the test; (2) the progress from the head impulse protocol (HIMPs) to the new variant—suppression head impulse protocol (SHIMPs); (3) the physiological basis for head impulse testing; (4) practical aspects and potential pitfalls of video head impulse testing; (5) problems of vestibulo-ocular reflex gain calculations; (6) head impulse testing in central vestibular disorders; and (7) to stay right up-to-date—new clinical disease patterns emerging from video head impulse testing. With thanks and appreciation we dedicate this article to our friend, colleague, and mentor, Dr Bernard Cohen of Mount Sinai Medical School, New York, who since his first article 55 years ago on compensatory eye movements induced by vertical SCC stimulation has become one of the giants of the vestibular world.