Body Movements Research Articles

Tip, torque and rotation of maxillary molars during distalization using Invisalign: a CBCT study

BackgroundDesirable molar distalization by bodily movement is challenging and can be difficult to achieve. This study investigated changes in molar angulation (mesiodistal tipping), molar inclination (buccolingual torque) and rotation during distalization using clear aligner therapy (CAT).Materials and methodsThis retrospective study included 38 cone beam computed tomographic images (CBCTs) taken for patients treated with molar distalization using CAT. The study evaluated pre- (T0) and post-treatment (T1) CBCTs of 19 adult patients (36.68 ± 13.50 years) who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization. Changes in maxillary molar tip, torque and rotation were measured for 61 molars (183 roots). Paired t-test was used to evaluate the differences between pre- and post-treatment readings. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by the intraclass correlation coefficient (ICC).ResultsMolar angulation did not show significant change after distalization (p = 0.158) however, there was significant increase in buccal molar inclination (p = 0.034) and mesiobuccal molar rotation (p < 0.001).ConclusionMolar distalization of 2 mm did not cause significant molar tipping. Maxillary molars showed significant buccal inclination (increased torque) and mesiobuccal rotation after distalization.

Nonlinear modelling of arrays of submerged wave energy converters

Studies of arrays of wave energy converters (WECs) with respect to power absorption and array interactions are often performed using linear models. However, nonlinear effects can be important and may change power estimates and optimal array designs. In this study, we have compared linear predictions of the behaviour of a shallowly submerged, buoyant point absorber with predictions from the nonlinear model SWASH with a WEC incorporated (WEC-SWASH). The latter was first comprehensively validated against 1:20 Froude scaled measured data from physical experiments. WEC-SWASH predictions of body motions and mean power absorption were generally in good agreement with measurements (absolute bias within 25%), although some discrepancies were observed in the body motions, especially when the device exhibited motion instabilities. The validated WEC-SWASH model was then compared with a linear frequency-domain model, as the latter is well-known and widely used because of its computational efficiency. Model comparisons were carried out for both an isolated WEC and small arrays (up to 5 devices). The mean power estimates from the linear model and WEC-SWASH for two representative wave farms showed good agreement for mild waves, with a difference of less than 5%. However, for larger waves, the disagreement increased to about 75 to 85% between the models (for the two wave farms tested). We found that array interactions for these arrays depend on wave amplitude and not just wave frequency. Furthermore, we discovered that the power take-off coefficients optimized using the linear model were not the optimum coefficients for the nonlinear model (WEC-SWASH).

Skin-inspired ultra-tough, self-healing anisotropic wood-based electronic skin for multidimensional sensing

Skin is a flexible and stretchable sensor composed of anisotropic dermis (DM) and repairable epidermis (EM). It repairs itself when damaged and has a multi-dimensional sensing system that can assist the body in performing some complex multi-dimensional movements. Inspired by skin, we utilized natural wood as the skeleton and for the first time designed a low-cost, double-layer structure wood-based electronic skin (wood-eskin). Simple chemical treatments were employed to directionally regulate the ray structure of natural wood and to enhance its porosity. Subsequently, physical freeze-thawing was employed to facilitate the formation of an entangled network structure between the PVA solution and the wood nanofibers. Wood-eskin with multi-dimensional sensing was obtained by further introducing ions by immersing in salt solution. In comparison to the majority of contemporary bionic e-skins, wood-eskin exhibits superior mechanical properties. Additionally, it is capable of performing complex deformations, such as bending and knotting. After fracture, wood-eskin can also repair itself and recover ∼94 % of its mechanical properties. The oriented arrangement of cellulose nanofiber channels gives wood-eskin a multidimensional sensing capability that can be used to monitor more complex body movements. The low-cost, biodegradable wood-eskin exhibits similar functionality to human skin, and its potential for biomedical and bionic robotics applications is considerable.

Dynamic Analysis of Rigid–Flexible Structures with Piezoelectric Actuation and Control

In this paper, the dynamic equation of a rigid body coupled with two flexible beams was established, considering the rotational motion of the rigid body and the elastic deflection of the flexible beams. The coupling effect between the rigid body rotation and flexible beam vibration was studied in detail. The dynamic response of the flexible beam with piezoelectric effect was established based on Hamilton’s principle. Under the premise of ignoring the nonlinear vibration coupling term of flexible beams, only the first two modes of transverse displacement and one directional rotation motion were studied in case studies. It was found that the coupling term caused by rigid body rotation can slightly alter the natural frequency and amplitude of flexible beams, mainly reflected in the first-order mode. With increasing the external excitation on the rigid body, the induced transverse displacement at the tip of the flexible beam increased significantly. Meanwhile, when the flexible beam was under external excitation, the vibration could also induce rigid body rotation. With the inverse piezoelectric effect, one may actively actuate the flexible beam vibration and rigid body rotation or control the undesired motion of the system. The control effect can be adjusted by varying the applied voltage excitation on the piezoelectric patches as well as patch positions. The conclusions drawn from this study can be applied to active precise control of space facilities such as satellites. Based on the dynamic modeling of rigid–flexible multi-body systems, this paper completed the study of the coupling effects of rigid body rotation and flexible body vibration, and proposed an application idea for completing small-angle maneuvers of rigid–flexible multi-body systems through piezoelectric control.

Acceleration of a wave-structure interaction solver by the Parareal method

Potential flow theory-based solvers are commonly used in ocean engineering to investigate the interactions between ocean waves and floating bodies. Depending on assumptions, several methods have been proposed. Among them, the Weak-Scatterer method is an interesting trade-off in the sense that this approach is not limited in theory by the small wave amplitudes and small body motions assumptions of linear methods. Moreover, this approach is in practice more stable than the fully non-linear methods. An implementation of the Weak-Scatterer method is the WS-CN code (Letournel, 2015; Chauvigné, 2016; Wuillaume, 2019).The computational time of the WS-CN code which is considered in the present study is relatively long for engineering purposes. In order to reduce it, the present paper presents an implementation of the Parareal method in the WS-CN code. The Parareal method is an algorithm for parallelizing a simulation in time that can accelerate the complete simulation (Lions, 2001) . This is a key difference in comparison to other acceleration techniques which have been studied in the literature (e.g. the Fast Multipole Method (FMM), the precorrected Fast Fourier Transform (pFFT) method, … ). To the authors’ knowledge, the present study is the first to couple the Parareal method to a potential flow theory-based wave-structure interaction solver. It is shown that the method can significantly reduce the computational time for small wave steepness, but that the performance decreases rapidly with increasing steepness.

A software-based observational coding approach for evaluating paediatric dental pain, anxiety, and fear.

Dental practitioners desire non-pharmacological methods to alleviate anxiety, fear, and pain in children receiving dental care; high-quality evidence, however, is required to evaluate methods' efficacy. This study aimed to develop and validate an observation-based coding approach (paediatric dental pain, anxiety, and fear coding approach [PAFCA]) to evaluate non-pharmacological behavior management techniques for anxiety, fear, and pain. Objective (video-based) and subjective (self-reported) anxiety, fear, and pain data were collected from a pilot clinical trial evaluating animal-assisted therapy (AAT) in paediatric dentistry, in which 37 children aged 7-14 were assigned to AAT or control before dental treatment (restorations or extractions). A coding approach utilizing a codebook, a gold standard calibration video, and a user training guide was developed. Trained examiners coded the gold standard video for inter-rater agreement, and masked, calibrated examiners analyzed videos using the Noldus Observer XT software. A novel, software-based coding approach was developed, with moderately high inter-rater agreement. Using PAFCA, we found children reporting higher levels of pain, fear, and anxiety exhibited treatment-interfering behaviors, including crying/moaning, attempts to dislodge instruments, and more upper and lower body movements. PAFCA shows promise as a reliable tool for assessing anxiety, pain, and fear in behavioral research for paediatric dentistry.

Awareness of embodiment enhances enjoyment and engages sensorimotor cortices.

Whether in performing arts, sporting, or everyday contexts, when we watch others move, we tend to enjoy bodies moving in synchrony. Our enjoyment of body movements is further enhanced by our own prior experience with performing those movements, or our 'embodied experience'. The relationships between movement synchrony and enjoyment, as well as embodied experience and movement enjoyment, are well known. The interaction between enjoyment of movements, synchrony, and embodiment is less well understood, and may be central for developing new approaches for enriching social interaction. To examine the interplay between movement enjoyment, synchrony, and embodiment, we asked participants to copy another person's movements as accurately as possible, thereby gaining embodied experience of movement sequences. Participants then viewed other dyads performing the same or different sequences synchronously, and we assessed participants' recognition of having performed these sequences, as well as their enjoyment of each movement sequence. We used functional near-infrared spectroscopy to measure cortical activation over frontotemporal sensorimotor regions while participants performed and viewed movements. We found that enjoyment was greatest when participants had mirrored the sequence and recognised it, suggesting that awareness of embodiment may be central to enjoyment of synchronous movements. Exploratory analyses of relationships between cortical activation and enjoyment and recognition implicated the sensorimotor cortices, which subserve action observation and aesthetic processing. These findings hold implications for clinical research and therapies seeking to foster successful social interaction.

Computational biomechanics for a standing human body: Modal analysis and simulation.

We develop computational mechanical modeling and methods for the analysis and simulation of the motions of a human body. This type of work is crucial in many aspects of human life, ranging from comfort in riding, the motion of aged persons, sports performance and injuries, and many ergonomic issues. A prevailing approach for human motion studies is through lumped parameter models containing discrete masses for the parts of the human body with empirically determined spring, mass, damping coefficients. Such models have been effective to some extent; however, a much more faithful modeling method is to model the human body as it is, namely, as a continuum. We present this approach, and for comparison, we choose two digital CAD models of mannequins for a standing human body, one from the versatile software package LS-DYNA and another from open resources with some of our own adaptations. Our basic view in this paper is to regard human motion as a perturbation and vibration from an equilibrium position which is upright standing. A linear elastodynamic model is chosen for modal analysis, but a full nonlinear viscoelastoplastic extension is possible for full-body simulation. The motion and vibration of these two mannequin models is analyzed by modal analysis, where the normal vibration modes are determined. LS-DYNA is used as the supercomputing and simulation platform. Four sets of low-frequency modes are tabulated, discussed, visualized, and compared. Higher frequency modes are also selectively displayed. We have found that these modes of motion and vibration form intrinsic basic modes of biomechanical motion of the human body. This view is supported by our finding of the upright walking motion as a low-frequency mode in modal analysis. Such a "walking mode" shows the in-phase and out-of-phase movements between the legs and arms on the left and right sides of a human body, implying that this walking motion is spontaneous, likely not requiring any directives from the brain. Dynamic motions of CAD mannequins are also simulated by drop tests for comparisons and the validity of the models is discussed through Fourier frequency analysis. All computed modes of motion are collected in several sets of video animations for ease of visualization. Samples of LS-DYNA computer codes are also included for possible use by other researchers.

From lab to life: assessing the impact of real-world interactions on the operation of rapid serial visual presentation-based brain-computer interfaces

Objective. Brain-computer interfaces (BCI) have been extensively researched in controlled lab settings where the P300 event-related potential (ERP), elicited in the rapid serial visual presentation (RSVP) paradigm, has shown promising potential. However, deploying BCIs outside of laboratory settings is challenging due to the presence of contaminating artifacts that often occur as a result of activities such as talking, head movements, and body movements. These artifacts can severely contaminate the measured EEG signals and consequently impede detection of the P300 ERP. Our goal is to assess the impact of these real-world noise factors on the performance of a RSVP-BCI, specifically focusing on single-trial P300 detection. Approach. In this study, we examine the impact of movement activity on the performance of a P300-based RSVP-BCI application designed to allow users to search images at high speed. Using machine learning, we assessed P300 detection performance using both EEG data captured in optimal recording conditions (e.g. where participants were instructed to refrain from moving) and a variety of conditions where the participant intentionally produced movements to contaminate the EEG recording. Main results. The results, presented as area under the receiver operating characteristic curve (ROC-AUC) scores, provide insight into the significant impact of noise on single-trial P300 detection. Notably, there is a reduction in classifier detection accuracy when intentionally contaminated RSVP trials are used for training and testing, when compared to using non-intentionally contaminated RSVP trials. Significance. Our findings underscore the necessity of addressing and mitigating noise in EEG recordings to facilitate the use of BCIs in real-world settings, thus extending the reach of EEG technology beyond the confines of the laboratory.

Learning from risk: an ethnography of a risky play

This text discusses the relationship between risk and learning in the practice of the rolling cart, based on an ethnography carried out in the metropolitan region of Belo Horizonte between 2019 and 2022. The community involved in the activity is characterized by disputes and interests about this practice. Although it is considered risky, different narratives about the risks of this practice emerge in an urban and contemporary context. The analysis presented argues that risk is a social construction, in line with Jean Lave's theories of situated learning and Tim Ingold's ecological approach. According to these theories, the skills necessary to practice rolling cart are developed through a process of education of attention, and not through mental representations that are converted into body movements. Thus, men, women, adults and children participate, constitute and are constituted by the practice, which is polysemic and situated. The theories of Giddens and Douglas are also relevant to the discussion, as they suggest the social construction of risk and the importance of the cultural and social context in which this practice is carried out. In short, the analysis emphasizes the complexity of the relationship between risk and learning in rolling cart practice and the importance of considering the ecological approach to understand the dynamics of this community of practice.

Effects of ciprofol infusion on hemodynamics during induction and maintenance of anesthesia and on postoperative recovery in patients undergoing thoracoscopic lobectomy: Study protocol for a randomized, controlled trial.

Ciprofol, a new candidate drug, is effective and safe for the maintenance of anesthesia in non-cardiothoracic and non-neurological elective surgery. However, few studies have been conducted on general anesthesia using ciprofol in patients undergoing thoracoscopic lobectomy. Therefore, this study aims to observe the effects of ciprofol on hemodynamics and on postoperative recovery in patients undergoing thoracoscopic lobectomy. This randomized controlled trial will include 136 patients aged 18-65 years undergoing elective thoracoscopic lobectomy between April 2023 and December 2024. The participants will be randomly assigned to the propofol or ciprofol group. The primary outcome to be assessed is the hemodynamic fluctuation during the induction and maintenance of anesthesia. The secondary outcomes involve quality of anesthesia induction and quality of recovery from anesthesia. The former includes TLOC (time to loss of consciousness), the use of vasoactive agents, the incidence of injection pain, body movement, muscle twitching and coughing during induction of anesthesia. The latter includes TROC (time to recovery of consciousness), post anesthesia care unit (PACU) time, incidence of postoperative nausea and vomiting (PONV), postoperative agitation, intraoperative awareness and quality of recovery (QoR) score. A number of clinical trials have confirmed that ciprofol, as a new sedative-hypnotic agent, has advantages of better tolerance, higher sedation satisfaction score, and lower incidence of adverse reactions, especially in reducing the incidence of injection pain. But considering that ciprofol was recently developed, limited data are available regarding its use for general anesthesia. This study aims to investigate the effects of ciprofol on hemodynamics and on postoperative recovery of patients undergoing thoracoscopic lobectomy. The results of this study may provide evidence for the safe application of ciprofol, a new choice of general anesthetic for thoracic surgery. ClinicalTrials.gov (NCT05664386).

Multimodal Technologies for Remote Assessment of Neurological and Mental Health.

Automated remote assessment and monitoring of patients' neurological and mental health is increasingly becoming an essential component of the digital clinic and telehealth ecosystem, especially after the COVID-19 pandemic. This review article reviews various modalities of health information that are useful for developing such remote clinical assessments in the real world at scale. We first present an overview of the various modalities of health information-speech acoustics, natural language, conversational dynamics, orofacial or full body movement, eye gaze, respiration, cardiopulmonary, and neural-which can each be extracted from various signal sources-audio, video, text, or sensors. We further motivate their clinical utility with examples of how information from each modality can help us characterize how different disorders affect different aspects of patients' spoken communication. We then elucidate the advantages of combining one or more of these modalities toward a more holistic, informative, and robust assessment. We find that combining multiple modalities of health information allows for improved scientific interpretability, improved performance on downstream health applications such as early detection and progress monitoring, improved technological robustness, and improved user experience. We illustrate how these principles can be leveraged for remote clinical assessment at scale using a real-world case study of the Modality assessment platform. This review article motivates the combination of human-centric information from multiple modalities to measure various aspects of patients' health, arguing that remote clinical assessment that integrates this complementary information can be more effective and lead to better clinical outcomes than using any one data stream in isolation.

Fluid–Structure Interaction Analysis of Manta-Bots with Self-Induced Vertical Undulations during Fin-Based Locomotion

Driven by the demands of ocean exploration, an increasing number of manta ray-inspired robots have been designed and manufactured, primarily utilizing flexible skeletons combined with motor-driven mechanisms. However, the mechanical analysis of these designs remains underdeveloped, often relying on simplistic imitation of biological prototypes and typically neglecting the vertical motion induced by pectoral fin flapping. This paper presents a fluid–structure interaction analysis framework that couples rigid body motion with elastic deformation using flexible multibody dynamics and the vortex particle method. An implicit iterative algorithm with Aitken relaxation is employed to address added-mass instability, and the framework has been validated against experimental data. An analysis of a representative manta-bot model shows that self-induced vertical undulations reduce the thrust coefficient by approximately 40% compared to fixed vertical degrees of freedom, while slightly improving overall propulsive efficiency. The study also highlights the critical role of mass distribution in manta-bots, noting that excessive focus on complex pectoral fin movements and large fin mass can significantly reduce thrust by increasing vertical displacement, ultimately proving counterproductive.

Embedding textile capacitive sensing into smart wearables as a versatile solution for human motion capturing

This work presents a novel and versatile approach to employ textile capacitive sensing as an effective solution for capturing human body movement through fashionable and everyday-life garments. Conductive textile patches are utilized for sensing the movement, working without the need for strain or direct body contact, wherefore the patches can sense only from their deformation within the garment. This principle allows the sensing area to be decoupled from the wearer’s body for improved wearing comfort and more pleasant integration. We demonstrate our technology based on multiple prototypes which have been developed by an interdisciplinary team of electrical engineers, computer scientists, digital artists, and smart fashion designers through several iterations to seamlessly incorporate the technology of capacitive sensing with corresponding design considerations into textile materials. The resulting accumulation of textile capacitive sensing wearables showcases the versatile application possibilities of our technology from single-joint angle measurements towards multi-joint body part tracking.

Piezoelectricity in chalcogenide perovskites

Piezoelectric materials show potential to harvest the ubiquitous, abundant, and renewable energy associated with mechanical vibrations. However, the best performing piezoelectric materials typically contain lead which is a carcinogen. Such lead-containing materials are hazardous and are being increasingly curtailed by environmental regulations. In this study, we report that the lead-free chalcogenide perovskite family of materials exhibits piezoelectricity. First-principles calculations indicate that even though these materials are centrosymmetric, they are readily polarizable when deformed. The reason for this is shown to be a loosely packed unit cell, containing a significant volume of vacant space. This allows for an extended displacement of the ions, enabling symmetry reduction, and resulting in an enhanced displacement-mediated dipole moment. Piezoresponse force microscopy performed on BaZrS3 confirmed that the material is piezoelectric. Composites of BaZrS3 particles dispersed in polycaprolactone were developed to harvest energy from human body motion for the purposes of powering electrochemical and electronic devices.

Positive Play

This book results from an initiative by the European university consortium EUGLOH - European University Alliance for Global Health - between the University of Porto, Portugal (U.P.), and the University of the Arctic, Norway (UiT). To support the activity consisting of a three-day masterclass and workshop at UiT, designated as “Tromsø Idea Camp 2024 - Developing ideas through co-creation using human-centred design,” which had as its motto: . “Identify the needs and expectations of Vardesenteret’s patients before, during, and after treatment, considering their and volunteers’ points of view and creating projectual answers that foster empathy and communication”, a handbook was created, which later formed the basis of this book. It has three sections dedicated to Person-Centred Design in the Context of Health and Well-being. The first section— ”Reported Experience”, — Relates to the doctoral project “Ludic Activities in Health Context: An Anorexia Nervosa Case in the Hospital Environment,” which systematizes Ludic methods and tools created in and for a clinical context to support the treatment and monitoring of Anorexia Nervosa. Part of the project stems from collaborative work with São João Central Hospital, Portugal, in a group dedicated to treating eating disorders. The second section - “Documented Experience” — Explores the concept of Positive Play, coined by Giesteira, B., Cardoso, P., and Peçaibes, V. in various papers and book chapters from 2021 onwards. It presents a group of methods and tools created by the authors in recent years, such as the SEED Toolkit - “SomaEsthetics for Enabling Designers” (Giesteira, B. 2023) and the ANgame Collab (Cardoso, P., Peçaibes, V., Giesteira, B. 2022). The first tool aims to work on the concept of Somaesthetics, promoting empathy and contributing to identifying feelings and sensations interdependent on body activities and movements. The second tool aims to mediate playful sessions of Participatory Design, especially in the ‘user research’ phase. Other tools and methods were selected because, based on the aforementioned authors’ experience, they are most suitable for applied research in Health Technology Design. The third section - “Lived Experience” — Records the three days of the workshop dedicated to the themes: “Emotional Design and Somaesthetics”; “Human-Centered and Participatory Design”; “Ideation, Lateral Thinking, and Prototype.” In addition to the aforementioned themes, the different phases of development of the participants' projects from the various universities of the EUGLOH university consortium are recorded, which, in a Participatory Design approach, involved the collaboration of volunteers and oncology patients from Vardesenteret. This section shares the tools used to support each phase of product or service design and the final results of the low-fidelity prototypes.

Development of full-body rhythmic synchronization in middle childhood

Rhythmic entrainment is a fundamental aspect of musical behavior, but the skills required to accurately synchronize movement to the beat seem to develop over many years. Motion capture studies of corporeal synchronization have shown immature abilities to lock in to the beat in children before age 5, and reliable synchronization ability in adults without musical training; yet there is a lack of data on full-body synchronization skills between early childhood and adulthood. To document typical rhythmic synchronization during middle childhood, we used a wireless motion capture device to measure period- and phase-locking of full body movement to rhythm and metronome stimuli in 6 to 11 year-old children in comparison with adult data. Results show a gradual improvement with age; however children’s performance did not reach adult levels by age 12, suggesting that these skills continue to develop during adolescence. Our results suggest that in the absence of specific music training, full-body rhythmic entrainment skills improve gradually during middle childhood, and provide metrics for examining the continued maturation of these skills during adolescence.

Data-driven sensor fault diagnosis for vibration-based structural health monitoring under ambient excitation

In vibration-based structural health monitoring (SHM), the early detection of sensor faults is key to preventing false alarms and misleading conclusions on the condition of monitored structures. Since sensor networks are exposed to hostile environments, they are prone to unexpected errors that might influence the quality of measured data. This paper proposes a novel method for detecting and isolating faulty sensors from vibration response data by establishing an overdetermined system between the measured signals and the actual motion. The method assumes a rigid body motion of the monitored system, describable by a limited number of degrees of freedom (DOFs), to define the overdetermined relation between the sensor outputs and the system’s DOFs. The concept is later extended to systems not governed by rigid body motions by considering their vibration mode shapes. The robustness of the proposed methodology is demonstrated using vibration response data from an experimental monitoring campaign.

Impact of Dental Midline Shift on the Perception of Facial Attractiveness in Young Adults.

Background/Objectives: The aim of this study was to quantify the threshold of a dental midline shift that would compromise facial attractiveness and indicate a need for treatment from the points of view of laypeople and dental professionals. Methods: Whole-face natural photographs of a male and a female model were digitally manipulated to create various degrees of upper and lower dental midline shifts through bodily movement of the upper or lower midlines as well as alteration of the axial inclination of the upper teeth. The samples were then assessed by two groups of observers (laypeople (LP) and dental professionals (DP)). Results: The lower midline shift did not negatively affect the DP and LP's perceptions of smile attractiveness. The first significant loss of attractiveness was registered by the DP with an upper midline shift of 1 mm in the female model. However, the LP registered this at 2 mm. The DP registered the necessity of treatment at a threshold of 2 mm in the female model and 3 mm in the male model. LP identified the need for treatment at 3 mm for both males and females. The female model was judged more critically than her male counterpart by both female and male observers. Conclusions: DP assess the midline deviation more critically than LP. Both DP and LP were more sensitive to midline deviations in the female model regardless of their own gender. Both groups registered the need for treatment at a higher threshold than the reduction in smile attractiveness.

Brainstem auditory evoked responses in horses with hearing loss and during general anesthesia

The brainstem auditory evoked response (BAER) is a diagnostic approach to examine the hearing system of horses objectively. The aim of this BAER examination was the diagnosis of conductive or sensorineural hearing loss or deafness in horses with external otitis, head trauma, headshaking, tinnitus or skittish horses with eye disease. Brainstem dysfunction is induced by intracranial hypotension. BAER was used in horses with colic surgery which had a low arterial blood pressure during general anesthesia. The endoscopic finding of the guttural pouch was the ipsilateral mild to severe hypertrophy of the tympanostylohyoideum in horses with external otitis or head trauma. The otoscopic examination of standing sedated horses was done before BAER. The cartilagineous and osseous part of the external ear canal in horses with external otitis were obstructed with exsudate and tympanic membranes were not visible. Horses with right sided external otitis: right moderate to severe conductive hearing loss (significantly prolonged latencies of I, III, V and interpeak latencies I-III, I-V, III-V; thresholds of hearing levels 60 to 80 dB right); horses with left sided external otitis: left severe conductive hearing loss (no correct identification of BAER peaks, latencies not measurable, 80 dB); horse with left sided head trauma: severe left sided conductive hearing loss (blood in the left external ear canal, no visible tympanic membrane, no correct identification of BAER peaks, latencies not measurable, 80 dB); horses with head shaking: mild sensorineural hearing loss on both sides (on both sides osseous parts II/III with keratin scales of the junction, visible tympanic membranes, significantly prolonged V, I-III, I-V, 40 dB); moderate to severe skittish horses with chronic eye disease (mostly left sided equine recurrent uveitis): moderate sensorineural hearing loss on both sides (normal otoscopical findings, significantly prolonged latencies and interpeak latencies left; I-V, III-V right, 60 dB, pathological involvement in the auditory pathway of the brainstem between the cochlear nucleus and colliculus caudalis); horse with a tinnitus on both sides: mild sensorineural hearing loss on both sides (normal otoscopical findings, prolonged V, I-III, I-V, III-V, 40 dB, pathology of auditory nerve, cochlear nucleus and above the level of this nucleus); American paint horses: sensorineurale deafness on both sides (normal otoscopical findings, absent BAER peaks, isoelectric lines and 80 dB on both sides). The prolonged latencies of I, III and V including interpeak latencies I-III only left and I-V and III-V on both sides in horses with laparotomy during general anesthesia were associated with low arterial blood pressure (62 mmHg, median). These findings could demonstrate a hypotension in the brainstem too. The BAER could be a technical tool during general anesthesia for normalizing the arterial blood pressure and brainstem function to prevent imbalance of body movements after general anesthesia.