The Vestibular Implant: Quo Vadis?

Objective: To assess the progress of the development of the vestibular implant (VI) and its feasibility short-term. Data sources: A search was performed in Pubmed, Medline, and Embase. Key words used were “vestibular prosth*” and “VI.” The only search limit was language: English or Dutch. Additional sources were medical books, conference lectures and our personal experience with per-operative vestibular stimulation in patients selected for cochlear implantation. Study selection: All studies about the VI and related topics were included and evaluated by two reviewers. No study was excluded since every study investigated different aspects of the VI. Data extraction and synthesis: Data was extracted by the first author from selected reports, supplemented by additional information, medical books conference lectures. Since each study had its own point of interest with its own outcomes, it was not possible to compare data of different studies. Conclusion: To use a basic VI in humans seems feasible in the very near future. Investigations show that electric stimulation of the canal nerves induces a nystagmus which corresponds to the plane of the canal which is innervated by the stimulated nerve branch. The brain is able to adapt to a higher baseline stimulation, while still reacting on a dynamic component. The best response will be achieved by a combination of the optimal stimulus (stimulus profile, stimulus location, precompensation), complemented by central vestibular adaptation. The degree of response will probably vary between individuals, depending on pathology and their ability to adapt

Alignment of angular velocity sensors for a vestibular prosthesis

Vestibular prosthetics transmit angular velocities to the nervous system via electrical stimulation. Head-fixed gyroscopes measure angular motion, but the gyroscope coordinate system will not be coincident with the sensory organs the prosthetic replaces. Here we show a simple calibration method to align gyroscope measurements with the anatomical coordinate system. We benchmarked the method with simulated movements and obtain proof-of-concept with one healthy subject. The method was robust to misalignment, required little data, and minimal processing

A cane-based low cost sensor to implement attention mechanisms in telecare robots

Telepresence robots have been recently used for Comprehensive Geriatric Assessment (CGA). Since the robot can not track a person continuously, there are several strategies to decide when to check them, from cyclic checks to simple requests from users and/or caregivers. In order to adapt to the user needs and condition, it is preferable to perform CGA as soon as regularities appear. However, this requires detection of potential issues in users to offer immediate service. In this work we propose a new low cost force sensor system to detect user’s condition and attract attention of CGA robots, so they can perform a full examination on a need basis. The main advantages of this system are: i) it can be attached to any standard commercial cane; ii) its power consumption is very reduced; and iii) it provides continuous information as long as the user walks. It has been tested with several elderly volunteers in care facilities. Results have proven that the sensor readings are indeed correlated with the users’ condition.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

The Speed, Precision and Accuracy of Human Multisensory Perception following Changes to the Visual Sense

Human adults can combine information from multiple senses to improve their perceptual judgments. Visual and multisensory experience plays an important role in the development of multisensory integration, however it is unclear to what extent changes in vision impact multisensory processing later in life. In particular, it is not known whether adults account for changes to the relative reliability of their senses, following sensory loss, treatment or training. Using psychophysical methods, this thesis studied the multisensory processing of individuals experiencing changes to the visual sense. Chapters 2 and 3 assessed whether patients implanted with a retinal prosthesis (having been blinded by a retinal degenerative disease) could use this new visual signal with non-visual information to improve their speed or precision on multisensory tasks. Due to large differences between the reliabilities of the visual and non-visual cues, patients were not always able to benefit from the new visual signal. Chapter 4 assessed whether patients with degenerative visual loss adjust the weight given to visual and non-visual cues during audio-visual localization as their relative reliabilities change. Although some patients adjusted their reliance on vision across the visual field in line with predictions based on cue relative reliability, others - patients with visual loss limited to their central visual field only - did not. Chapter 5 assessed whether training with either more reliable or less reliable visual feedback could enable normally sighted adults to overcome an auditory localization bias. Findings suggest that visual information, irrespective of reliability, can be used to overcome at least some non-visual biases. In summary, this thesis documents multisensory changes following changes to the visual sense. The results improve our understanding of adult multisensory plasticity and have implications for successful treatments and rehabilitation following sensory loss

Development of a limits of stability protocol for use in transtibial prosthesis users: learning effects and reliability of outcome variables

The aims of this study were to empirically quantify reliability and learning effects of a Limits of Stability protocol for transtibial prosthesis users. Outcome variables from center of pressure and center of mass were tested on: 1) multiple test repetitions within a single test occasion; and 2) between multiple test occasions. Trantibial prosthesis users (n=7) and matched controls (n=7) executed five trials of the Limits of Stability protocol on two occasions per day, on two consecutive days. Inter-trial learning effects and reliability of outcomes extracted via center of mass and center of pressure were evaluated utilizing standard biomechanics laboratory equipment. Reliability was good to excellent except the reaction time variable which was poor (Pooled 95%CI of ICC=0.248-0.484). An inter-trial learning effect was present in directional control for prosthesis users when the first trial was included in analysis (center of mass: 95%CI of r=0.065-0.239; center of pressure: 95%CI of r=0.076-0.249). The use of standard biomechanics lab equipment can produce reliable results for the Limits of Stability protocol. Researchers should be aware of low reliability of reaction time variable in the protocol assessed and should execute at least one practice trial prior to that which is used in subsequent analysis

Embodiment, ownership and disownership

There are two main pathways to investigate the sense of body ownership, (i) through the study of the conditions of embodiment for an object to be experienced as one's own and (ii) through the analysis of the deficits in patients who experience a body part as alien. Here, I propose that E is embodied if some properties of E are processed in the same way as the properties of one's body. However, one must distinguish among different types of embodiment, and only self-specific embodiment can lead to feelings of ownership. I address issues such as the functional role and the dynamics of embodiment, degrees and measures of ownership, and shared body representations between self and others. I then analyse the interaction between ownership and disownership. On the one hand, I show that there is no evidence that in the Rubber Hand Illusion, the rubber hand replaces the biological hand. On the other hand, I argue that the sense of disownership experienced by patients towards their body part cannot be reduced to the mere lack of ownership

Auditory brainstem implant technology and use: Auditory implants

Cochlear implant (CI) technology is used in the treatment of deep sensorineural hearing loss (SNHL). However, an intact cochlea and an intact cochlear nerve are needed for CI applications. CI does not help in pathologies that may occur in these regions, and it is necessary to ensure the continuity of auditory conduction by direct stimulation of the cochlear nuclei. The method developed to ensure this auditory continuity is auditory brainstem implant (ABI) applications. In short, the ABI functions without the cochlea and the cochlear nerve. It does not need these structures. According to CI practices, postoperative gains are unfortunately not at the desired level. Auditory information can be helpful in lip-reading, although its benefits on speech perception are generally limited. In addition, ABI applications enable environmental sounds to be heard even if they are not fully perceived, and it is known to be beneficial on quality of life

Finding a balance: A systematic review of the biomechanical effects of vestibular prostheses on stability in humans

This is the final version. Available on open access from MDPI via the DOI in this recordThe vestibular system is located in the inner ear and is responsible for maintaining balance in humans. Bilateral vestibular dysfunction (BVD) is a disorder that adversely affects vestibular function. This results in symptoms such as postural imbalance and vertigo, increasing the incidence of falls and worsening quality of life. Current therapeutic options are often ineffective, with a focus on symptom management. Artificial stimulation of the vestibular system, via a vestibular prosthesis, is a technique being explored to restore vestibular function. This review systematically searched for literature that reported the effect of artificial vestibular stimulation on human behaviours related to balance, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) technique. A total of 21 papers matched the inclusion criteria of the literature search conducted using the PubMed and Web of Science databases (February 2019). The populations for these studies included both healthy adults and patients with BVD. In every paper, artificial vestibular stimulation caused an improvement in certain behaviours related to balance, although the extent of the effect varied greatly. Various behaviours were measured such as the vestibulo-ocular reflex, postural sway and certain gait characteristics. Two classes of prosthesis were evaluated and both showed a significant improvement in at least one aspect of balance-related behaviour in every paper included. No adverse effects were reported for prostheses using noisy galvanic vestibular stimulation, however, prosthetic implantation sometimes caused hearing or vestibular loss. Significant heterogeneity in methodology, study population and disease aetiology were observed. The present study confirms the feasibility of vestibular implants in humans for restoring balance in controlled conditions, but more research needs to be conducted to determine their effects on balance in non-clinical settings

Impacted Central Incisors in the Upper Jaw in an Adolescent Patient: Orthodontic-Surgical Treatment—A Case Report

The inclusion of both maxillary permanent central incisors is uncommon. This condition compromises face aesthetics, phonation andmasticatory function. Therefore, early diagnosis is essential to avoid complications and failures. There are various reasons for inclusion, but supernumerary teeth are the leading cause. Early causes of removal and rapid expansion of the palate determine a high probability of success with the spontaneous eruption of the impacted elements. However, it is often necessary to proceed with a surgical–orthodontic treatment. The inclination of teeth in relation to the midline and the root maturation degree determine prognosis and therapeutic timing. In this case report, the orthopantomogram (OPG) X-ray of a 9-year-old boy revealed two impacted supernumerary teeth in the anterior maxillary region, preventing the eruption of the permanent upper central incisors. The impacted supernumerary teeth were surgically removed at different times. A straight wire multibrackets technique associated with a fixed palatal appliance was used. The palatal appliance featured an osteomucous resin support at the level of the retroincisal papilla. Subsequently, surgical exposure was carried out using the closed eruption technique and elastictraction, bringing 11 and 21 back into the arch