Effects of passenger body movements in a visual task during and after vehicle rotation on post-rotatory illusion and motion sickness.

We explored how body movements influence illusory body motion intensity and their association with motion sickness. Twelve individuals who were seated in the back of a passenger car, performed a visual task and were subjected to continuous rotations followed by driving in a straight line. The body movements during and immediately after rotation were categorized as follows: (A) upright posture; (B) leaning the body in the yaw direction towards the rotation center, returning the yaw angle to zero upon transitioning to straight line travel, and tilting in the roll condition and gradually returning to upright; and (C) tilting in roll conditions towards the centripetal direction during rotation and becoming upright upon transitioning to straight line travel. In experiment-1, after spanning half a lap, participants reported the intensity of the illusory motion experienced during straight line travel immediately after rotation. In experiment-2, after travelling up to eight laps, the participants reported the symptom level of motion sickness experienced during two straight sections per lap using the MIsery SCale (MISC). Experiment-1 revealed that condition (C) had significantly larger illusions than Conditions (A) and (B). Experiment-2 revealed that motion sickness progressed significantly more in Condition (C) than in Condition (A). A significant positive correlation was found between the observed MISC and the illusion strength. Our findings suggest that body movements during and immediately after continuous rotation have a significant impact on the illusion strength. Additionally, illusory motion could serve as an indicator of impending motion sickness.

Course of Duration and Trigger Factors of Vertigo Attacks in Patients with Benign Recurrent Vertigo, Menière's Disease, or Vestibular Migraine.

INTRODUCTION: Benign recurrent vertigo (BRV), Menière's disease (MD), and vestibular migraine (VM) show many similarities with regard to the course of vertigo attacks and clinical features. In this paper, we elaborate on the decreasing frequency of vertigo attacks observed in a previous study from our group by exploring changes in the duration and trigger factors of vertigo attacks in patients with BRV, MD, or VM. METHODS: For this 3-year prospective cohort study in our tertiary referral center we recruited patients with a confirmed diagnosis of BRV, MD, or VM by a neurologist and otorhinolaryngologist in our center in 2015-2016. A study-specific questionnaire was used to assess the usual duration of vertigo attacks and their potential triggers every 6 months. Main outcome measures were changes in duration and trigger factors of vertigo attacks in the subgroups of patients with persisting attacks, which were analyzed using repeated measures logistic regression models. RESULTS: 121 patients were included (BRV: n = 44; MD: n = 43; VM: n = 34) of whom 117 completed the 3-year follow-up period and 57 (48.7%) kept reporting vertigo attacks at one more follow-up measurements. None of the diagnosis groups showed statistically significant shortening of attack duration at the subsequent annual follow-up measurements compared to baseline. At baseline, stress and fatigue being reported as triggers for attacks differed significantly between the three groups (stress: BRV 40.9%, MD 62.8%, VM 76.5%, p = 0.005; fatigue: BRV 31.0%, MD 48.8%, VM 68.8%, p = 0.003). In the VM group, a consistent reduction of stress and fatigue as triggers was observed up until the 24- and the 30-month follow-up measurements, respectively, with odds ratios (ORs) ranging from 0.15 to 0.33 (all p < 0.05). In the MD group, a consistent reduction of head movements as trigger was observed from the 24-month measurement onward (ORs ranging from 0.07 to 0.11, all p < 0.05). CONCLUSION: Our study showed no reduction in vertigo attack duration over time in patients with BRV, MD, and VM who remain to have vertigo attacks. In VM and MD patients with persisting vertigo attacks stress, fatigue and head movements became less predominant triggers for vertigo attacks.

Strategies for enhancing automatic fixation detection in head-mounted eye tracking.

Moving through a dynamic world, humans need to intermittently stabilize gaze targets on their retina to process visual information. Overt attention being thus split into discrete intervals, the automatic detection of such fixation events is paramount to downstream analysis in many eye-tracking studies. Standard algorithms tackle this challenge in the limiting case of little to no head motion. In this static scenario, which is approximately realized for most remote eye-tracking systems, it amounts to detecting periods of relative eye stillness. In contrast, head-mounted eye trackers allow for experiments with subjects moving naturally in everyday environments. Detecting fixations in these dynamic scenarios is more challenging, since gaze-stabilizing eye movements need to be reliably distinguished from non-fixational gaze shifts. Here, we propose several strategies for enhancing existing algorithms developed for fixation detection in the static case to allow for robust fixation detection in dynamic real-world scenarios recorded with head-mounted eye trackers. Specifically, we consider (i) an optic-flow-based compensation stage explicitly accounting for stabilizing eye movements during head motion, (ii) an adaptive adjustment of algorithm sensitivity according to head-motion intensity, and (iii) a coherent tuning of all algorithm parameters. Introducing a new hand-labeled dataset, recorded with the Pupil Invisible glasses by Pupil Labs, we investigate their individual contributions. The dataset comprises both static and dynamic scenarios and is made publicly available. We show that a combination of all proposed strategies improves standard thresholding algorithms and outperforms previous approaches to fixation detection in head-mounted eye tracking.

A tutorial: Analyzing eye and head movements in virtual reality.

This tutorial provides instruction on how to use the eye tracking technology built into virtual reality (VR) headsets, emphasizing the analysis of head and eye movement data when an observer is situated in the center of an omnidirectional environment. We begin with a brief description of how VR eye movement research differs from previous forms of eye movement research, as well as identifying some outstanding gaps in the current literature. We then introduce the basic methodology used to collect VR eye movement data both in general and with regard to the specific data that we collected to illustrate different analytical approaches. We continue with an introduction of the foundational ideas regarding data analysis in VR, including frames of reference, how to map eye and head position, and event detection. In the next part, we introduce core head and eye data analyses focusing on determining where the head and eyes are directed. We then expand on what has been presented, introducing several novel spatial, spatio-temporal, and temporal head-eye data analysis techniques. We conclude with a reflection on what has been presented, and how the techniques introduced in this tutorial provide the scaffolding for extensions to more complex and dynamic VR environments.

Comparison of vestibular input statistics during natural activities and while piloting an aircraft.

The present study investigates the statistics and spectral content of natural vestibular stimuli experienced by healthy human subjects during three unconstrained activities. More specifically, we assessed how the characteristics of vestibular inputs are altered during the operation of a complex human-machine interface (a flight in a helicopter simulator) compared with more ecological tasks, namely a walk in an office space and a seated visual exploration task. As previously reported, we found that the power spectra of vestibular stimuli experienced during self-navigation could be modeled by two power laws but noted a potential effect of task intensity on the transition frequency between the two fits. In contrast, both tasks that required a seated position had power spectra that were better described by an inverted U shape in all planes of motion. Taken together, our results suggest that 1) walking elicits stereotyped vestibular inputs whose power spectra can be modeled by two power laws that intersect at a task intensity-dependent frequency; 2) body posture induces changes in the frequency content of vestibular information; 3) pilots tend to operate their aircraft in a way that does not generate highly nonecological vestibular stimuli; and 4) nevertheless, human-machine interfaces used as a means of manual navigation still impose some unnatural, contextual constraints on their operators.NEW & NOTEWORTHY Building upon previously published research, this study assesses and compares the vestibular stimuli experienced by healthy subjects in natural tasks and during the interaction with a complex machine: a helicopter simulator. Our results suggest the existence of an anatomical filter, meaning that body posture shapes vestibular spectral content. Our findings further indicate that operators control their machine within a constrained operating range such that they experience vestibular stimulations that are as ecological as possible.

Complexity analysis of head movements in autistic toddlers.

BACKGROUND: Early differences in sensorimotor functioning have been documented in young autistic children and infants who are later diagnosed with autism. Previous research has demonstrated that autistic toddlers exhibit more frequent head movement when viewing dynamic audiovisual stimuli, compared to neurotypical toddlers. To further explore this behavioral characteristic, in this study, computer vision (CV) analysis was used to measure several aspects of head movement dynamics of autistic and neurotypical toddlers while they watched a set of brief movies with social and nonsocial content presented on a tablet. METHODS: Data were collected from 457 toddlers, 17-36 months old, during their well-child visit to four pediatric primary care clinics. Forty-one toddlers were subsequently diagnosed with autism. An application (app) displayed several brief movies on a tablet, and the toddlers watched these movies while sitting on their caregiver's lap. The front-facing camera in the tablet recorded the toddlers' behavioral responses. CV was used to measure the participants' head movement rate, movement acceleration, and complexity using multiscale entropy. RESULTS: Autistic toddlers exhibited significantly higher rate, acceleration, and complexity in their head movements while watching the movies compared to neurotypical toddlers, regardless of the type of movie content (social vs. nonsocial). The combined features of head movement acceleration and complexity reliably distinguished the autistic and neurotypical toddlers. CONCLUSIONS: Autistic toddlers exhibit differences in their head movement dynamics when viewing audiovisual stimuli. Higher complexity of their head movements suggests that their movements were less predictable and less stable compared to neurotypical toddlers. CV offers a scalable means of detecting subtle differences in head movement dynamics, which may be helpful in identifying early behaviors associated with autism and providing insight into the nature of sensorimotor differences associated with autism.

Training spatial hearing in unilateral cochlear implant users through reaching to sounds in virtual reality.

BACKGROUND AND PURPOSE: Use of unilateral cochlear implant (UCI) is associated with limited spatial hearing skills. Evidence that training these abilities in UCI user is possible remains limited. In this study, we assessed whether a Spatial training based on hand-reaching to sounds performed in virtual reality improves spatial hearing abilities in UCI users METHODS: Using a crossover randomized clinical trial, we compared the effects of a Spatial training protocol with those of a Non-Spatial control training. We tested 17 UCI users in a head-pointing to sound task and in an audio-visual attention orienting task, before and after each training.
Study is recorded in clinicaltrials.gov (NCT04183348). RESULTS: During the Spatial VR training, sound localization errors in azimuth decreased. Moreover, when comparing head-pointing to sounds before vs. after training, localization errors decreased after the Spatial more than the control training. No training effects emerged in the audio-visual attention orienting task. CONCLUSIONS: Our results showed that sound localization in UCI users improves during a Spatial training, with benefits that extend also to a non-trained sound localization task (generalization). These findings have potentials for novel rehabilitation procedures in clinical contexts.

Effect of masticatory movements on head and trunk sways, and sitting and foot pressure distributions during sitting position.

BACKGROUND: The head plays an important role in the postural control. Chewing co-activates jaw and neck muscles leading to coordinated jaw and head-neck movements. Therefore, to examine effect of masticatory movements on head and trunk sways, and sitting and foot pressure distributions during mastication is helpful in the attempt to understand the interrelationship between stomatognathic function and posture control system in the sitting position. OBJECTIVES: The purpose of this study was to test the hypothesis in healthy subjects that masticatory movements affect head and trunk sways and sitting and foot pressure distributions during sitting position. METHODS: A total of 30 healthy male subjects with an average age of 25.3 years (range, 22-32 years) were evaluated. The CONFORMat™ and MatScan™ system were used to analyse changes in sitting pressure distribution center of sitting pressure (COSP) and changes in foot pressure distribution center of foot pressure (COFP), respectively, and the three-dimensional motion analysis system was used to analyse changes in head and trunk postures while subjects remained sitting position with rest position, centric occlusion and chewing. The total trajectory length of COSP/COFP, COSP/COFP area, and head and trunk sway values were compared between the three conditions to evaluate whether masticatory movement affected the stability of head and trunk sways and sitting and foot pressure distributions. RESULTS: Total trajectory length of COSP and COSP area during chewing were significantly shorter and smaller respectively than it was in rest position and centric occlusion (p ⟨ .016). Head sway value during chewing was significantly larger than it was in rest position and centric occlusion (p ⟨ .016). CONCLUSION: Masticatory movements affect sitting pressure distribution and head movements during sitting position.

Benefits of active listening during 3D sound localization.

In everyday life, sound localization entails more than just the extraction and processing of auditory cues. When determining sound position in three dimensions, the brain also considers the available visual information (e.g., visual cues to sound position) and resolves perceptual ambiguities through active listening behavior (e.g., spontaneous head movements while listening). Here, we examined to what extent spontaneous head movements improve sound localization in 3D-azimuth, elevation, and depth-by comparing static vs. active listening postures. To this aim, we developed a novel approach to sound localization based on sounds delivered in the environment, brought into alignment thanks to a VR system. Our system proved effective for the delivery of sounds at predetermined and repeatable positions in 3D space, without imposing a physically constrained posture, and with minimal training. In addition, it allowed measuring participant behavior (hand, head and eye position) in real time. We report that active listening improved 3D sound localization, primarily by ameliorating accuracy and variability of responses in azimuth and elevation. The more participants made spontaneous head movements, the better was their 3D sound localization performance. Thus, we provide proof of concept of a novel approach to the study of spatial hearing, with potentials for clinical and industrial applications.

Head kinematics in patients with neck pain compared to asymptomatic controls: a systematic review.

BACKGROUND: Neck pain is one of the most common musculoskeletal disorders encountered by healthcare providers. A precise assessment of functional deficits, including sensorimotor control impairment, is regarded necessary for tailored exercise programmes. Sensorimotor control can be measured by kinematic characteristics, such as velocity, acceleration, smoothness, and temporal measures, or by assessing movement accuracy. This systematic review aims to identify movement tasks and distinct outcome variables used to measure kinematics and movement accuracy in patients with neck pain and present their results in comparison to asymptomatic controls. METHODS: Electronic searches were conducted in MEDLINE, PEDro, Cochrane Library and CINAHL databases from inception to August 2020. Risk of bias of included studies was assessed. Movement tasks and specific outcome parameters used were collated. The level of evidence for potential group differences in each outcome variable between patients with neck pain and controls was evaluated. RESULTS: Twenty-seven studies examining head kinematics and movement accuracy during head-aiming, functional and unconstrained movement tasks of the head were included. Average Risk of Bias of included studies was moderate. In total, 23 different outcome variables were assessed. A strong level of evidence for an increased movement time and for an increased number of errors during head aiming tasks was found. Moderate evidence was found in traumatic neck pain for a decreased mean velocity, peak acceleration, and reaction time, and for point deviation and time on target during head aiming tasks. Moderate evidence was found for decreased acceleration during unconstrained movements, too. Results on the remaining movement task and outcome variables showed only limited, very limited or even conflicting level of evidence for patients with neck pain to differ from controls. CONCLUSIONS: Sensorimotor control in NP in the way of kinematic and movement accuracy characteristics of head motion was examined in head aiming, functional or unconstrained movement tasks. The results from this review indicate that for some characteristics that describe sensorimotor control, patients with NP differ from healthy controls. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number: CRD42020139083.

Head movement kinematics are altered during balance stability exercises in individuals with vestibular schwannoma.

BACKGROUND: Balance stabilization exercises are often prescribed to facilitate compensation in individuals with vestibular schwannoma (VS). However, both the assessment and prescription of these exercises are reliant on clinical observations and expert opinion rather than on quantitative evidence. The aim of this study was to quantify head motion kinematics in individuals with vestibular loss while they performed commonly prescribed balance stability exercises. METHODS: Using inertial measurement units, head movements of individuals with vestibular schwannoma were measured before and after surgical deafferentation and compared with age-matched controls. RESULTS: We found that individuals with vestibular schwannoma experienced more variable head motion compared to healthy controls both pre- and postoperatively, particularly in absence of visual input, but that there was little difference between preoperative and postoperative kinematic measurements for our vestibular schwannoma group. We further found correlations between head motion kinematic measures during balance exercises, performed in the absence of visual input, and multiple clinical measurements for preoperative VS subjects. Subjects with higher head motion variability also had worse DVA scores, moved more slowly during the Timed up and Go and gait speed tests, and had lower scores on the functional gait assessment. In contrast, we did not find strong correlations between clinical measures and postoperative head kinematics for the same VS subjects. CONCLUSIONS: Our data suggest that further development of such metrics based on the quantification of head motion has merit for the assessment and prescription of balance exercises, as demonstrated by the calculation of a "kinematic score" for identifying the most informative balance exercise (i.e., "Standing on foam eyes closed").

Small head movements increase and colour noise in data from five video-based P-CR eye trackers.

We empirically investigate the role of small, almost imperceptible balance and breathing movements of the head on the level and colour of noise in data from five commercial video-based P-CR eye trackers. By comparing noise from recordings with completely static artificial eyes to noise from recordings where the artificial eyes are worn by humans, we show that very small head movements increase levels and colouring of the noise in data recorded from all five eye trackers in this study. This increase of noise levels is seen not only in the gaze signal, but also in the P and CR signals of the eye trackers that provide these camera image features. The P and CR signals of the SMI eye trackers correlate strongly during small head movements, but less so or not at all when the head is completely still, indicating that head movements are registered by the P and CR images in the eye camera. By recording with artificial eyes, we can also show that the pupil size artefact has no major role in increasing and colouring noise. Our findings add to and replicate the observation by Niehorster et al., (2021) that lowpass filters in video-based P-CR eye trackers colour the data. Irrespective of source, filters or head movements, coloured noise can be confused for oculomotor drift. We also find that usage of the default head restriction in the EyeLink 1000+, the EyeLink II and the HiSpeed240 result in noisier data compared to less head restriction. Researchers investigating data quality in eye trackers should consider not using the Gen 2 artificial eye from SR Research / EyeLink. Data recorded with this artificial eye are much noisier than data recorded with other artificial eyes, on average 2.2-14.5 times worse for the five eye trackers.

Sensorimotor serial dependencies in head movements.

On average, we redirect our gaze with a frequency at about 3 Hz. In real life, gaze shifts consist of eye and head movements. Much research has focused on how the accuracy of eye movements is monitored and calibrated. By contrast, little is known about how head movements remain accurate. I wondered whether serial dependencies between artificially induced errors in head movement targeting and the immediately following head movement might recalibrate movement accuracy. I also asked whether head movement targeting errors would influence visual localization. To this end, participants wore a head-mounted display and performed head movements to targets, which were displaced as soon as the start of the head movement was detected. I found that target displacements influenced head movement amplitudes in the same trial, indicating that participants could adjust their movement online to reach the new target location. However, I also found serial dependencies between the target displacement in trial n-1 and head movements amplitudes in the following trial n. I did not find serial dependencies between target displacements and visuomotor localization. The results reveal that serial dependencies recalibrate head-movement accuracy. NEW & NOTEWORTHY Head movements are recalibrated by serial dependencies by errors between consecutive trials. Head movements are subject to a regression of the average target location.

Corrective Saccades in Unilateral and Bilateral Vestibular Hypofunction During Slow Rotation Expressed by Visually Enhanced VOR and VOR Suppression: Role of the Cerebellum.

In clinical practice, the head impulse test paradigm (HIMP) and the suppression head impulse paradigm (SHIMP) stimulate high-frequency head movements so that the visual system is temporarily suppressed. The two tests could also be useful tools for vestibular assessment at low frequencies: VVOR (visually enhanced vestibulo-ocular reflex) and VORS (vestibulo-ocular reflex suppression). The aim of this study is to analyze the eye movements typically found during VVOR and VORS testing in patients with unilateral and bilateral vestibular hypofunction. Twenty patients with unilateral vestibular hypofunction, three patients with bilateral vestibular hypofunction, and ten patients with normal vestibular function (control group) were analyzed through VVOR and VORS testing with an Otometrics ICS Impulse system. During the VVOR test, patients with unilateral vestibular hypofunction exhibited corrective saccades to the same direction of the nystagmus fast phase toward the healthy side when the head rotates toward the affected side, while patients with bilateral vestibular hypofunction exhibited corrective saccades to the opposite side of head movements to each side. During the VORS test, patients with unilateral vestibular hypofunction seem to exhibit larger corrective saccades to the healthy side when the head was moved to this side, while patients with bilateral vestibular hypofunction did not exhibit corrective saccades during head movements to either side. Our data suggest that the VVOR and VORS tests yield the same diagnostic information as the HIMP and SHIMP tests in unilateral and bilateral vestibular hypofunction, and can contribute to the diagnosis of a peripheral vestibular loss as well as the affected side.

Impaired neck motor control in chronic whiplash and tension-type headache.

OBJECTIVES: The purpose of this study is twofold, first to present a new method based on head laser tracking designed to measure head or hand movements and second to further investigate if patients suffering from chronic whiplash or tension-type headache have impaired motor control of neck muscles. MATERIAL AND METHODS: A new laser tracking instrument was designed to measure the ability of a test person to track a reference point moving on the wall by a laser fixed to the forehead or held in the hand. The reference point to be tracked moves in runs of a circle or a square at three different speeds 10, 20, or 30 cm/s. We used a 1 × 1 ×1 m setup geometry to provide head movements well below pain release. Groups of 22 patients diagnosed with chronic whiplash-associated disorder grade 2, 19 patients diagnosed with chronic tension-type headache, and 37 control persons were compared. RESULTS: A small but highly significant dyscoordination of head movements was observed in both patient groups and in whiplash also of the hand. CONCLUSIONS: Our study presents a new method based on laser tracking for precision quantitative measurements of head or hand movements during standardized conditions. The results confirm that motor control of head movements is impaired in both chronic whiplash and tension-type headache, and in whiplash also of the hand. This suggests involvement of the central nervous system in the pathology of these diseases.

Head-neck movement may predispose to the development of arytenoid dislocation in the intubated patient: a 5-year retrospective single-center study.

BACKGROUND: Arytenoid dislocation is a rare laryngeal injury that may follow endotracheal intubation. We aimed to determine the incidence and risk factors for arytenoid dislocation after surgery under general anaesthesia. METHODS: We reviewed the medical records of patients who underwent operation under general anaesthesia with endotracheal intubation from January 2014 to December 2018. Patients were divided into the non-dislocation and dislocation groups depending on the presence or absence of arytenoid dislocation. Patient, anaesthetic, and surgical factors associated with arytenoid dislocation were determined using Poisson regression analysis. RESULTS: Among the 25,538 patients enrolled, 33 (0.13%) had arytenoid dislocation, with higher incidence after anterior neck and brain surgery. Patients in the dislocation group were younger (52.6 ± 14.4 vs 58.2 ± 14.2 yrs, P = 0.025), more likely to be female (78.8 vs 56.5%, P = 0.014), and more likely to be intubated by a first-year anaesthesia resident (33.3 vs 18.5%, P = 0.048) compared to those in the non-dislocation group. Patient positions during surgery were significantly different between the groups (P = 0.000). Multivariable Poisson regression identified head-neck positioning (incidence rate ratio [IRR], 3.10; 95% confidence interval [CI], 1.50-6.25, P = 0.002), endotracheal intubation by a first-year anaesthesia resident (IRR, 2.30; 95% CI, 1.07-4.64, P = 0.024), and female (IRR, 3.05; 95% CI, 1.38-7.73, P = 0.010) as risk factors for arytenoid dislocation. CONCLUSION: This study showed that the incidence of arytenoid dislocation was 0.13%, and that head-neck positioning during surgery, less anaesthetist experience, and female were significantly associated with arytenoid dislocation in patients who underwent surgeries under general anaesthesia with endotracheal intubation.

A Person- and Time-Varying Vector Autoregressive Model to Capture Interactive Infant-Mother Head Movement Dynamics.

Head movement is an important but often overlooked component of emotion and social interaction. Examination of regularity and differences in head movements of infant-mother dyads over time and across dyads can shed light on whether and how mothers and infants alter their dynamics over the course of an interaction to adapt to each others. One way to study these emergent differences in dynamics is to allow parameters that govern the patterns of interactions to change over time, and according to person- and dyad-specific characteristics. Using two estimation approaches to implement variations of a vector-autoregressive model with time-varying coefficients, we investigated the dynamics of automatically-tracked head movements in mothers and infants during the Face-Face/Still-Face Procedure (SFP) with 24 infant-mother dyads. The first approach requires specification of a confirmatory model for the time-varying parameters as part of a state-space model, whereas the second approach handles the time-varying parameters in a semi-parametric ("mostly" model-free) fashion within a generalized additive modeling framework. Results suggested that infant-mother head movement dynamics varied in time both within and across episodes of the SFP, and varied based on infants' subsequently-assessed attachment security. Code for implementing the time-varying vector-autoregressive model using two R packages, dynr and mgcv, is provided.

Design and Implementation of a Position, Speed and Orientation Fuzzy Controller Using a Motion Capture System to Operate a Wheelchair Prototype.

The design and implementation of an electronic system that involves head movements to operate a prototype that can simulate future movements of a wheelchair was developed here. The controller design collects head-movements data through a MEMS sensor-based motion capture system. The research was divided into four stages: First, the instrumentation of the system using hardware and software; second, the mathematical modeling using the theory of dynamic systems; third, the automatic control of position, speed, and orientation with constant and variable speed; finally, system verification using both an electronic controller test protocol and user experience. The system involved a graphical interface for the user to interact with it by executing all the controllers in real time. Through the System Usability Scale (SUS), a score of 78 out of 100 points was obtained from the qualification of 10 users who validated the system, giving a connotation of "very good". Users accepted the system with the recommendation to improve safety by using laser sensors instead of ultrasonic range modules to enhance obstacle detection.

Changes in Vertebral Arterial Blood Flow During Premanipulative Tests in Participants With Upper Cervical Spine Motion Restriction.

OBJECTIVE: The purpose of the present study was to measure changes in blood flow velocity and volume flow rate (VFR) in the contralateral vertebral artery (VA) during end-range rotation and pre-manipulative hold at C1-C2 and to compare these measurements between participants with and without C1-C2 range of motion (ROM) restriction. METHODS: This research was approached as an exploratory study and designed as a parallel noninterventional controlled trial with intentionally equal allocation, for studying diagnostic tests. Fifteen women and 13 men (mean age 44) were recruited (volunteer sample) in physiotherapy clinics. No participant had any current neurologic or vertebrobasilar insufficiency symptoms. The measurements of 13 participants with a limited ROM C1-C2 and 15 with no limitation were compared. Blood flow velocity and VFR in the contralateral VA were measured using color duplex Doppler imaging in 3 neck positions: neutral, maximal rotation, and pre-manipulative hold of C1-C2. RESULTS: Pre-manipulative hold significantly (P < .01) decreased all blood flow velocity parameters and VFR, mainly in the left VA. End-range rotation showed a significant (P < .05) decrease in the peak systolic velocity in the left VA. No significant differences were found between participants grouped by the presence or absence of a C1-C2 ROM restriction. CONCLUSION: A C1-C2 rotational ROM restriction does not appear associated with change in a significantly reduced VA blood flow due to the neck position.

Does Pain Neuroscience Education and Cognition-Targeted Motor Control Training Improve Cervical Motor Output? Secondary Analysis of a Randomized Clinical Trial.

BACKGROUND: In the context of interventions aimed at reducing pain, disability, and maladaptive pain cognitions in chronic neck pain, it is hypothesized that patients who have greater symptom reduction possibly also demonstrate greater improvement in cervical motor output. Therefore, the aim of this study was to examine the effect of pain neuroscience education plus cognition-targeted motor control training on cervical motor output. METHODS: Impairments in cervical motor output were measured in 64 subjects with chronic neck pain using standardized tests. Cervical muscle strength, cervical mobility, balance, and cervical neuromuscular control were derived. To assess the differences between groups in response to treatment, a random-intercept linear mixed-models analysis, applying a diagonal covariance matrix, was used. RESULTS: A significant treatment × time interaction effect was found for neuromuscular control of the deep cervical flexors, favoring the experimental treatment at 3 months' follow-up (mean group difference: 1.982; 95% confidence interval 0.779, 3.185; large effect size d = 0.82). Significant main effects of time were found for the neuromuscular capacity of scapulothoracic muscles and for cervical mobility. No significant effects were found for balance, cervical muscle strength, or endurance of cervical flexors. CONCLUSION: Pain neuroscience education combined with cognition-targeted motor control training is not more effective than biomedically focused education and exercise therapy for improving cervical motor output in people with chronic neck pain. Our findings question the relative importance of factors such as pain, disability, and maladaptive pain cognitions on cervical motor output and the need to address it in treatment.