Impulsivity Paradigm Research Articles

Is galvanic VEMP a prediction of the nerve origin and damage in patients of vestibular schwannoma

Background Recent studies proved that certain proportions of vestibular schwannoma (VS) originated other than vestibular nerve of the eighth cranial nerve. Aims/objectives Unlike air-conducted sounds (ACS) and bone-conducted vibration (BCV), galvanic vestibular stimulation (GVS) evokes vestibular evoked myogenic potentials (VEMPs) from the vestibular nerve. Materials and methods Case-control study was conducted in unilateral VS patients pre-operatively. Healthy ears were controls. Patients examined ACS, BCV and GVS ocular VEMP (oVEMP) and cervical VEMP (cVEMP), caloric test, video head impulse test (vHIT), suppression head impulse paradigm (SHIMP) and pure tone audiometry (PTA). Results Seven (26.9%) tumors affected left ear and 19 (73.1%) on the right(p < .05). Response rates in VS group were statistically lower than control except for ACS-cVEMP (p < .05). Response rates of VEMPs in VS patients decreased with the tumor size grows. But not all BCV and GVS VEMPs disappeared in the largest tumor group. Abnormal rates of caloric test, vHIT gains and SHIMP were found. Conclusions and significance Response rates of GVS VEMPs decreased with the residual functional nerve fibers. GVS VEMPs help to differentiating labyrinthine and retro-labyrinthine lesions. GVS combined with BCV VEMPs probably reflex the tumor origin from the eighth cranial nerve and/or the remaining vestibular function.

Correlation between parameters of suppression head impulse paradigm and changesin DHI score in acute vestibular neuritis

Objective:To explore the correlation between the parameters of suppression head impulse paradigm（SHIMP） and changes in dizziness handicap inventory（DHI） scores. Additionally, to evaluate the degree of vertigo and prognosis of patients with acute vestibular neuritis through SHIMP parameters. Methods:Thirty-three patients with acute vestibular neuritis were enrolled for DHI evaluation, vHIT and SHIMP. A secondary DHI score were evaluated after after two weeks, once patients no longer exhibited spontaneous nystagmus. The decrease in the second DHI score was used as the efficacy index（EI）. All patients were divided into significantly effective group, effective group and ineffective group based on EI. Differences of the VOR gain values of SHIMP and the anti-compensatory saccade were compared among the three groups. Results:There were 13 cases in the significant effective group, 11 cases in the effective group, and 9 cases in the ineffective group. ①The mean gain of the horizontal semicircular canal in the significant effective group, the effective group, and the ineffective group was（0.50±0.11）, （0.44±0.12）, and（0.34±0.08）, respectively. The difference between the significant effective group and the ineffective group was statistically significant（P<0.01）. The gain of horizontal semicircular canal was positively correlated with EI（r=0.538 5, P<0.01） 。②The occurrence rate of the anti-compensatory saccade in the significant effective group, the effective group, and the ineffective group was（51.23±19.59）, （33.64±17.68）, and（13.78±11.81）, respectively. Pairwise comparisons between each group showed statistical significance（P<0.05）. The occurrence rate of anti-compensatory saccade was positively correlated with EI（r=0.658 2, P<0.01）. Conclusion:The horizontal semicircular canal gain and the occurrence rate of the anti-compensatory saccade in SHIMP for patients with acute vestibular neuritis were closely correlated with decrease in DHI score.

Video head impulse test in subacute and chronic stroke survivors: new perspectives for implementation of assessment in rehabilitation.

The Video Head Impulse Test (vHIT) is a safe and reliable assessment of peripheral vestibular function. Many studies tested its accuracy in clinical settings for differential diagnosis and quantification of the vestibulo-oculomotor reflex (VOR) in various disorders. However, the results of its application after lesions of the CNS are discordant and have never been studied in rehabilitation. This study aims to assess the VOR performance in a sample of stroke survivors. This is a cross-sectional study on 36 subacute and chronic stroke survivors; only persons with first-ever stroke and able to walk independently, even with supervision, were included. We performed VOR assessments for each semicircular canal by vHIT and balance assessments by the Berg Balance Scale and the MiniBESTest scale. Two hundred and sixteen semicircular canals were assessed using the Head Impulse paradigm (in both the vertical and horizontal planes), while 72 semicircular canals were assessed using the Suppressed Head Impulse paradigm (horizontal plane). There was a high prevalence of participants with dysfunctional canals, particularly for the left anterior and right posterior canals, which were each prevalent in more than one-third of our sample. Furthermore, 16 persons showed an isolated canal dysfunction. The mean VOR gain for the vertical canals had confidence intervals out of the normal values (0.74-0.91 right anterior; 0.74-0.82 right posterior; 0.73-0.87 left anterior). Our findings suggest that peripheral vestibular function may be impaired in people with stroke; asystematic assessment in a rehabilitation setting could allow a more personalized and patient-centred approach.

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

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

Suppression head impulse test in children-experiences in a tertiary paediatric vestibular centre.

The suppression head impulse paradigm (SHIMP) involves suppression of the vestibulo-ocular reflex (VOR) and anticompensatory saccades generated thereof. SHIMP is gaining importance to understand vestibular compensation with its different parameters (VOR gain/peak saccadic velocity PSV/latency of saccades). SHIMP studies are emerging in adults, but pediatric studies have hardly been performed. This study is a retrospective case note audit over a period of 2 months in a tertiary pediatric vestibular center in the United Kingdom to investigate whether SHIMP is safe/robust to be used in children conforming to existing standards/norms in normal children and whether it yields any meaningful inferences in pediatric vestibular hypofunction. This is the largest pediatric SHIMP study to date. A total of 44 referred children (6-18 years, female children>male children) with a range of complaints from dizziness, imbalance, motor incoordination, postural instability, and hearing loss were included, and their SHIMP parameters were measured. All children underwent comprehensive functional/objective audiovestibular assessments. Two groups were defined-Group A with normal vestibular function and Group B with abnormal vestibular function. The normal population showed an average SHIMP VOR gain of 0.98+/-0.08 and latency of overt saccades at 215.68+/-46.16 milliseconds agreeing with published evidence. The PSV of overt saccades was 315.39+/-56.30/s, and there was a gain asymmetry of 7.42+/-4.68 between the sides. Statistically significant differences with moderate/large effect sizes were observed between the groups in terms of VOR gain and PSV but not in saccade latencies. Covert saccades were rare in SHIMP, while overt saccades were observed in 100% of children. VOR gain difference between the head impulse paradigm (HIMP) and the SHIMP was significant as well. We observed statistically significant differences in side asymmetry of VOR gain between the groups. Furthermore, we identified a group of children with cerebellar lesions where overt saccades in SHIMP were rather low in number. Further research is recommended to investigate pediatric PSV, asymmetry, and inability to generate overt saccades that may suggest useful means to assess compensation and central function. We conclude that SHIMP yields valuable information and is a safe, easy to perform, and a reliable test that should be used in children to supplement HIMP.

Kanıtlanmış Vestibüler ve İşitme Kaybı olan Meniere Hastalarında Supresyon Baş Savurma Paradigması (SHIMP) ve Video Baş Savurma Testinin (vHIT) Değerlendirilmesi

This study aimed to examine the results of the video head impulse test (vHIT), and suppression head impulse paradigm (SHIMP) in adult diagnosed with definite Meniere’s disease (MD). This study was conducted with 20 patients aged 18-45 years with canal paresis and sensorineural type hearing loss in symptomatic ears, who were diagnosed with unilateral definite MD. The subjects were assessed with conventional audiometry (0.125–8 kHz), the bithermal binaural air caloric test, vHIT, and SHIMP. The mean SHIMP vestibulo-ocular reflex (S-VOR) gain of the MD side was 0.69, and that of the healthy side was 0.77. The S-VOR gain values were statistically lower than the mean vHIT VOR gain (V-VOR) values on both sides (p&amp;lt;0.001). There was no significant difference between the MD and healthy sides in terms of the anti-compensatory saccades (ACSs) latency and amplitude and S-VOR gain (p&amp;gt;0.05). In the MD group, the vHIT results were abnormal in 35% (7/20 ears) of the ears, and the SHIMP results were abnormal in 50% (10/20 ears). On the healthy side, the vHIT results were abnormal in 10% (2/20 ears) of the ears, and the SHIMP results were abnormal in 35% (7/20 ears). In this study, the V-VOR and S-VOR gains, vHIT saccades, SHIMP saccade latency, and SHIMP saccade amplitude were not found to be beneficial parameters in differentiating affected and healthy ears in the patients with MD. In other words, contrary to expectations, vHIT and SHIMP tests were not sufficient to detect pathological involvement in Meniere's disease.

Transcranial Direct Current Stimulation Decreases P3 Amplitude and Inherent Delta Activity during a Waiting Impulsivity Paradigm: Crossover Study.

The inability to wait for a target before initiating an action (i.e., waiting impulsivity) is one of the main features of addictive behaviors. Current interventions for addiction, such as transcranial Direct Current Stimulation (tDCS), have been suggested to improve this inability. Nonetheless, the effects of tDCS on waiting impulsivity and underlying electrophysiological (EEG) markers are still not clear. Therefore, this study aimed to evaluate the effects of neuromodulation over the right inferior frontal gyrus (rIFG) on the behavior and EEG markers of reward anticipation (i.e., cue and target-P3 and underlying delta/theta power) during a premature responding task. For that, forty healthy subjects participated in two experimental sessions, where they received active and sham tDCS over the rIFG combined with EEG recording during the task. To evaluate transfer effects, participants also performed two control tasks to assess delay discounting and motor inhibition. The active tDCS decreased the cue-P3 and target-P3 amplitudes, as well as delta power during target-P3. While no tDCS effects were found for motor inhibition, active tDCS increased the discounting of future rewards when compared to sham. These findings suggest a tDCS-induced modulation of the P3 component and underlying oscillatory activity during waiting impulsivity and the discounting of future rewards.

Relation Between Horizontal Saccade Test and Anti-Compensatory Saccade in the Suppression Head Impulse Test Paradigm

Background and Objectives There is limited study reported on the relationship between horizontal saccades and anti-compensatory saccades (ACS) in the suppression head impulse paradigm (SHIMP). We investigated the relationship between horizontal saccades and ACS in SHIMP in individuals with normal vestibular function and determined the correlation between the associated factors.Subjects and Method Medical records of 79 patients with normal vestibular function and brain magnetic resonance images were retrospectively reviewed.Results ACS and horizontal saccades results were strongly correlated with velocity (R= 0.345, &lt;i&gt;p&lt;/i&gt;&lt;0.001) and latency (R=0.547, &lt;i&gt;p&lt;/i&gt;&lt;0.001). The latency of ACS was significantly shorter (&lt;i&gt;p&lt;/i&gt;&lt;0.001) than that of horizontal saccades. The velocity of ACS was negatively correlated with the latencies of ACS (R=-0.318, &lt;i&gt;p&lt;/i&gt;&lt;0.001) and horizontal saccades (R=-0.322, &lt;i&gt;p&lt;/i&gt;&lt;0.001). Bilateral ACS latency (R=0.384 and 0.471 in right and left, &lt;i&gt;p&lt;/i&gt;&lt;0.001 in both side) and left side ACS velocity (R=-0.263, &lt;i&gt;p&lt;/i&gt;=0.019) were significantly affected by age.Conclusion ACS in the SHIMP was strongly correlated with horizontal saccades. However, the latency of ACS was shorter than that of horizontal saccades. Therefore, patient age and results of the horizontal saccades tests should be considered while interpreting the ACS velocity, which reflects vestibulo-ocular reflex function in patients with vestibulopathy.

Test-retest reliability of suppression head impulse paradigm (SHIMP) in healthy individuals

Objective The Video Head Impulse Test (vHIT) is an efficient tool to assess VOR. vHIT has been widely used to detect the presence of peripheral vestibular impairment. vHIT uses two paradigms: HIMP (Head Impulse Paradigm) and SHIMP (Suppression Head Impulse Paradigm). The current study aimed to determine the test-retest reliability of the Suppression Head Impulse Paradigm (SHIMP) in normal individuals. Method Twenty-eight healthy young individuals aged 18–30 years with normal hearing sensitivity and normal middle ear function participated in the study. The participants also had no signs and symptoms or history of vestibular problems. The SHIMP paradigm was performed twice (sessions I and II) with an inter-session interval of twodays. Results Paired sample t-test showed no significant difference in VOR gain and asymmetry values between sessions I and II. Cronbach’s alpha also showed a good test-retest reliability for VOR gain and asymmetry values. Kappa Coefficient showed good reliability for the presence of anticompensatory saccades. Conclusion VOR Gain functions and the presence of anti-compensatory saccades are highly reliable parameters when tested with SHIMP. Thus, any deviance in the gain parameters indicates a vestibular impairment rather than variability in the SHIMP test paradigm.

Serotonergic modulation of normal and abnormal brain dynamics: The genetic influence of the TPH2 G-703T genotype and DNA methylation on wavelet variance in children and adolescents with and without ADHD.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that often persists into adulthood. Core symptoms of ADHD, such as impulsivity, are caused by an interaction of genetic and environmental factors. Epigenetic modifications of DNA, such as DNA methylation, are thought to mediate the interplay of these factors. Tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in brain serotonin synthesis. The TPH2 gene has frequently been investigated in relation to ADHD, e.g., showing that TPH2 G-703T (rs4570625) polymorphism influences response control and prefrontal signaling in ADHD patients. In this (epi)genetic imaging study we examined 144 children and adolescents (74 patients, 14 females) using fMRI at rest and during performing a waiting impulsivity (WI) paradigm. Both, TPH2 G-703T (rs4570625) genotype and DNA methylation in the 5' untranslated region (5'UTR) of TPH2 were associated with wavelet variance in fronto-parietal regions and behavioral performance, taking TPH2 genotype into account. In detail, comparisons between genotypes of patients and controls revealed highest wavelet variance and longest reaction times in patients carrying the T allele [indicative for a gene-dosage effect, i.e., the WI phenotype is a direct result of the cumulative effect of ADHD and TPH2 variation]. Regressions revealed a significant effect on one specific DNA methylation site in ADHD patients but not controls, in terms of a significant prediction of wavelet variance in fronto-parietal regions as well as premature responses. By the example of the TPH2 G-703T (rs4570625) polymorphism, we provide insight into how interactive genetic and DNA methylation affect the ADHD and/or impulsive endophenotype.

The Conventional Head Impulse Test Versus the Suppression Head Impulse Test: A Clinical Comparative Study.

The suppression head impulse test is a new paradigm of the head impulse test, recently introduced for clinical use. The aim of this study was to assess the importance of the suppression head impulse paradigm in evaluating vestibular function. This comparative study was conducted from June 2020 to June 2022. The ears of the participants were divided into 2 groups: (i) ears with vestibular weakness and (ii) healthy controls. All participants underwent video head impulse tests at the time of presentation with both conventional head impulse paradigm and suppression head impulse paradigm, performed by the same examiner. The results of the 2 tests were compared, and the correlation between the corresponding parameters obtained (vestibulo-ocular reflex gain and saccades) was examined. Ninety-five participants were included in the study (190 ears) with a mean age of 42.2 ± 12.6 years. Forty-six ears had vestibular weakness, and 144 were healthy controls. The suppression head impulse paradigm test showed a significantly lower vestibulo-ocular reflex gain than the head impulse paradigm in both groups. A positive correlation emerged between the vestibulo-ocular reflex gain measured with both paradigms. Regarding the saccades, a negative correlation was observed between the overt saccades latency and amplitude measured with both paradigms. The new suppression head impulse paradigm complements the head impulse paradigm for a better evaluation of the vestibular function. The inconsistency of covert saccades in suppression head impulse paradigm makes it superior to head impulse paradigm in measuring vestibulo-ocular reflex gain, especially in patients with vestibular loss.

Test-Retest Reliability, Effects of Age and Comparison of Horizontal 2 Semicircular Canals Gain Values between Head Impulse and Suppression Head Impulse Paradigms.

This study investigates the test-retest reliability, aging effects, and differences in horizontal semicircular canals gain values between the head impulse paradigm and suppression head impulse paradigm. Sixty healthy adult subjects aged 22-76-year-old (mean ± standard deviation=47.27 ± 18.29) participated in the head impulse paradigm and suppression head impulse paradigm using the video head impulse test. The Head impulse paradigm was used to assess all 6 semicircular canals, while suppression head impulse paradigm measured only the horizontal canals. Twenty subjects aged 22-40-year-old (25.25 ± 4.9) underwent a second session for the test-retest reliability. There were good test-retest reliability for both measures (right horizontal head impulse paradigm, intraclass correlation coefficient=0.80; left horizontal head impulse paradigm, intraclass correlation coefficient=0.77; right anterior head impulse paradigm, intraclass correlation coefficient=0.86; left anterior head impulse paradigm, intraclass correlation coefficient=0.78; right posterior head impulse paradigm, intraclass correlation coefficient=0.78; left posterior head impulse paradigm, intraclass correlation coefficient=0.75; right horizontal suppression head impulse paradigm, intraclass correlation coefficient=0.76; left horizontal suppression head impulse paradigm, intraclass correlation coefficient=0.79). The test-retest reliability for suppression head impulse paradigmanti-compensatory saccade latency and amplitude were moderate (right latency, intraclass correlation coefficient=0.61; left latency, intraclass correlation coefficient=0.69; right amplitude, intraclass correlation coefficient=0.69; left amplitude, intraclass correlation coefficient=0.58). There were no significant effects of age on head impulse paradigm and suppression head impulse paradigm vestibulo-ocular reflex gain values and suppression head impulse paradigmsaccade latency. However, the saccade amplitude became smaller with increasing age, P < .001. The horizontal suppression head impulse paradigm vestibuloocular reflex gain values were significantly lower than the head impulse paradigm for both sides (right, P = .004; left, P = .004). There was good test-retest reliability for both measures, and the gain values stabilized with age. However, suppression head impulse paradigm anti-compensatory saccade latency and amplitude had lower test-retest reliability than the gain. The suppression head impulse paradigm vestibulo-ocular reflex gain was lower than the head impulse paradigm and its anti-compensatory saccade amplitude reduced with increasing age.

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.

The Clinical Use of the Suppression Head Impulse Paradigm in Patients with Vestibulopathy: A Systematic Review.

Background: This review aims to explore the potential clinical application of the suppression head impulse paradigm (SHIMP) in patients with unilateral and bilateral vestibulopathy. Methods: An electronic search was conducted by two independent reviewers in the following databases: Embase, MEDLINE (PubMed), and Scopus. The screening of titles, abstracts, and full texts and data extraction were undertaken independently by pairs of reviewers. The included studies were quality appraised using a modified version of the Newcastle–Ottawa Scale. Results: The results were reported following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Our search yielded 935 unique records, of which 16 remained after screening titles and abstracts. A total of 11 studies were included, covering a total of 418 participants (230 patients and 188 healthy participants). Conclusion: SHIMP could be a useful tool to diagnose a VOR alteration in patients with vestibulopathy in both the acute and chronic phases of vestibulopathy.

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.

Abnormal Responses in Cognitive Impulsivity Circuits Are Associated with Glycosylated Hemoglobin Trajectories in Type 1 Diabetes Mellitus and Impaired Metabolic Control.

Risky health decisions and impulse control profiles may impact on metabolic control in type 1 diabetes mellitus (T1DM). We hypothesize that the neural correlates of cognitive impulsivity and decision-making in T1DM relate to metabolic control trajectories. We combined functional magnetic resonance imaging (fMRI), measures of metabolic trajectories (glycosylated hemoglobin [HbA1c] over multiple time points) and behavioral assessment using a cognitive impulsivity paradigm, the Balloon Analogue Risk Task (BART), in 50 participants (25 T1DM and 25 controls). Behavioral results showed that T1DM participants followed a rigid conservative risk strategy along the iterative game. Imaging group comparisons showed that patients showed larger activation of reward related, limbic regions (nucleus accumbens, amygdala) and insula (interoceptive saliency network) in initial game stages. Upon game completion differences emerged in relation to error monitoring (anterior cingulate cortex [ACC]) and inhibitory control (inferior frontal gyrus). Importantly, activity in the saliency network (ACC and insula), which monitors interoceptive states, was related with metabolic trajectories, which was also found for limbic/reward networks. Parietal and posterior cingulate regions activated both in controls and patients with adaptive decision-making, and positively associated with metabolic trajectories. We found triple converging evidence when comparing metabolic trajectories, patients versus controls or risk averse (non-learners) versus patients who learned by trial and error. Dopaminergic reward and saliency (interoceptive and error monitoring) circuits show a tight link with impaired metabolic trajectories and cognitive impulsivity in T1DM. Activity in parietal and posterior cingulate are associated with adaptive trajectories. This link between reward-saliency-inhibition circuits suggests novel strategies for patient management.

Correlation between subjective and objective measures in bilateral vestibulopathy

Background Bilateral vestibulopathy (BVP) is a chronic and potentially very disabling condition. The impact of the vestibular loss on quality of life (QoL) is variable and still up for discussion. However, previous studies have reported that BVP has a negative impact of QoL. Aims/Objectives The aim of the study was to evaluate the association between vestibulo-ocular reflex (VOR) gain and saccade pattern and patient reported QoL. Materials and methods Ten patients fulfilling the Bárány criteria of BVP were included in the study. All patients underwent vestibular evaluation using Head Impulse Paradigm (HIMP) and Suppression Head Impulse Paradigm (SHIMP) and responded to Dizziness Handicap Inventory (DHI). DHI was used as a measurement for QoL. Results Linear regression revealed a tendency to a correlation between lateral VOR-gain measured by HIMP or SHIMP and total DHI score. Covert saccades were related to low total DHI scores. No association was found between type of SHIMP saccade and QoL. No significant correlations were found. Conclusion and significance A tendency was found towards a relationship between lateral VOR-gain by HIMP or SHIMP and total DHI score. The study also indicates that covert saccades are related to low impact on QoL.

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.

Center of pressure displacement due to graded controlled perturbations to the trunk in standing subjects: the force-impulse paradigm.

Many studies have investigated postural reactions (PR) to body-delivered perturbations. However, attention has been focused on the descriptive variables of the PR rather than on the characterization of the perturbation. This study aimed to test the hypothesis that the impulse rather than the force magnitude of the perturbation mostly affects the PR in terms of displacement of the center of foot pressure (ΔCoP). Fourteen healthy young adults (7 males and 7 females) received 2 series of 20 perturbations, delivered to the back in the anterior direction, at mid-scapular level, while standing on a force platform. In one series, the perturbations had the same force magnitude (40N) but different impulse (range: 2-10 Ns). In the other series, the perturbations had the same impulse (5 Ns) but different force magnitude (20-100N). A simple model of postural control restricted to the sagittal plane was also developed. The results showed that ΔCoP and impulse were highly correlated (on average: r = 0.96), while the correlation ΔCoP-force magnitude was poor (r = 0.48) and not statistically significant in most subjects. The normalized response, ΔCoPn = ΔCoP/I, was independent of the perturbation magnitude in a wide range of force amplitude and impulse and exhibited good repeatability across different sets of stimuli (on average: ICC = 0.88). These results were confirmed by simulations. The present findings support the concept that the magnitude of the applied force alone is a poor descriptor of trunk-delivered perturbations and suggest that the impulse should be considered instead.