Wavelets in somatosensory evoked potential processing.

Os potenciais evocados somato-sensitivos são úteis para detectar e localizar lesões nas vias sensoriais. Sua obtenção exige a média síncrona de mais de mil respostas individuais. A redução do número de estímulos elétricos para obter o potencial evocado resulta na diminuição do tempo do exame e do desconforto do paciente. O objetivo desta dissertação foi o de estudar o potencial de contribuição de duas técnicas de tempo-freqüência (ondaletas e filtros associados a trechos temporais específicos) à estimação de potenciais evocados somato-sensitivos, quando se utilizam apenas 100 respostas individuais. Quanto aos filtros, sugere-se o uso de dois passa-baixas. O primeiro, com freqüência de corte em 900Hz, deve ser utilizado no trecho inicial de 3ms a 35ms e o segundo, com freqüência de corte em 200Hz, no trecho final de 25ms a 60ms. Em relação aos parâmetros da técnica baseada em ondaletas, recomenda-se a utilização da ondaleta-mãe biortogonal 5.5, pois ela fornece erros menores e apresenta curvas visualmente boas. Além disso, ela apresenta a vantagem de ter fase linear, que é mais adequada ao processamento de potenciais evocados. Os 20% maiores coeficientes das escalas D3, D4 e D5 e os 50% maiores coeficientes da escala D6 que se encontram em trechos temporais específicos, além de todos os coeficientes de aproximação da escala 6, reconstroem adequadamente o potencial evocado. A análise estatística dos erros quadráticos normalizados indicou que a estimação por ondaletas é a melhor dentre as técnicas testadas. Também se verificou que ambas as técnicas resultaram na redução do erro quadrático normalizado, quando comparadas à média síncrona de 100 respostas individuais. Conclui-se que tanto as ondaletas quanto os filtros contribuem de forma positiva à obtenção de melhores estimativas do potencial evocado, mesmo quando um número reduzido de respostas individuais é utilizado.Somatosensory evoked potentials are useful to detect and locate lesions in sensory pathways. In order to obtain somatosensory evoked potentials, more than one thousand single sweeps must be synchronously averaged. The smaller the number of electrical stimuli used for evoked potentials, the lower is the examination length and the patient discomfort. The objective of this thesis is to study the contribution potential of two time-frequency techniques (wavelets and filters associated to specific time intervals) to the estimation of somatosensory evoked potentials, when only one hundred individual responses are used. For the filtering technique, it is suggested that two low-pass filters be used. The first filter has a 900Hz cutoff frequency and must be used in the 3ms-35ms time interval. The second one has a 200Hz cutoff frequency and should be applied to the 25ms-60ms section. Regarding wavelet parameters, it is recommended that a biorthogonal 5.5 mother wavelet be used, because it provides smaller errors and the results are visually good. Besides it, this mother wavelet has linear phase, which is useful to the evoked potential processing. The 20% greatest coefficients in D3, D4, D5 scales, and the 50% greatest D6 coefficients are candidates to the reconstruction. Those that fall in specific time intervals are used together with all the A6 coefficients. They reconstruct evoked potentials in a satisfactory manner. The statistical analysis of the normalized squared errors indicates that the wavelet estimation is the best technique among the tested ones. This work also shows that both techniques resulted in the reduction of the normalized squared errors, when compared to the synchronous averaging of 100 individual responses. As a conclusion, both wavelets and filters contribute in a positive manner to improve evoked potential estimation, even when a reduced number of individual responses is used

Factors that influence the adoption of rehabilitation technologies: a multi-disciplinary qualitative exploration

Abstract Background Technological innovation is recognised as having the potential to enhance rehabilitation for people with disability. Yet, resistance to, and abandonment of, rehabilitation technology is prevalent and the successful translation of technology into rehabilitation settings remains limited. Therefore, the aim of this work was to develop an in-depth, multi-stakeholder perspective on what influences the adoption of rehabilitation technologies. Methods Semi-structured focus groups were conducted as part of a larger research project aiming to facilitate the co-design of a novel neurorestorative technology. Focus group data were analysed using a five-phase hybrid deductive-inductive approach to qualitative data analysis. Results Focus groups were attended by 43 stakeholders with expertise in one or more of the following fields: people with disability, allied health, human movement science, computer science, design, engineering, ethics, funding, marketing, business, product development, and research development. Six main themes influencing the adoption of technology in rehabilitation were identified: cost beyond the purchase price, benefits to all stakeholders, trust to be earned in technology, ease of technology operation, ability to access technology, and the ‘co’ in co-design. All six themes were found to be interrelated; in particular, the importance of direct stakeholder engagement in the development of rehabilitation technologies (the ‘co’ in co-design) was prevalent in all themes. Conclusions A range of complex and interrelated factors influence the adoption of rehabilitation technologies. Importantly, many of the issues that have the potential to negatively impact rehabilitation technology adoption may be addressed during development by utilising the experience and expertise of stakeholders who influence its supply and demand. Our findings state that a wider cohort of stakeholders needs to be actively engaged in the development of rehabilitation technologies to better address the factors that contribute to technology underutilisation and abandonment and facilitate better outcomes for people with disability

Estimating Movement Smoothness From Inertial Measurement Units

Inertial measurement units (IMUs) are increasingly used to estimate movement quality and quantity to the infer the nature of motor behavior. The current literature contains several attempts to estimate movement smoothness using data from IMUs, many of which assume that the translational and rotational kinematics measured by IMUs can be directly used with the smoothness measures spectral arc length (SPARC) and log dimensionless jerk (LDLJ-V). However, there has been no investigation of the validity of these approaches. In this paper, we systematically evaluate the use of these measures on the kinematics measured by IMUs. We show that: (a) SPARC and LDLJ-V are valid measures of smoothness only when used with velocity; (b) SPARC and LDLJ-V applied on translational velocity reconstructed from IMU is highly error prone due to drift caused by integration of reconstruction errors; (c) SPARC can be applied directly on rotational velocities measured by a gyroscope, but LDLJ-V can be error prone. For discrete translational movements, we propose a modified version of the LDLJ-V measure, which can be applied to acceleration data (LDLJ-A). We evaluate the performance of these measures using simulated and experimental data. We demonstrate that the accuracy of LDLJ-A depends on the time profile of IMU orientation reconstruction error. Finally, we provide recommendations for how to appropriately apply these measures in practice under different scenarios, and highlight various factors to be aware of when performing smoothness analysis using IMU data.ISSN:2296-418

Biomechanics of Ankle Ligament Reconstruction: A Cadaveric Study to Compare Stability of Reconstruction Techniques Using 1 or 2 Fibular Tunnels

Background Anatomic lateral ankle ligament reconstruction has been proposed for patients with chronic ankle instability. A reliable approach is a reconstruction technique using an allograft and 2 fibular tunnels. A recently introduced approach that entails 1-fibular tunnel reconstruction might reduce the risk of intraoperative complications and ultimately improve patient outcome. Hypothesis We hypothesized that both reconstruction techniques show similar ankle stability (joint laxity and stiffness) and are similar to the intact joint condition. Study Design Controlled laboratory study. Methods A total of 10 Thiel-conserved cadaveric ankles were divided into 2 groups and tested in 3 stages-intact, transected, and reconstructed lateral ankle ligaments-using either the 1- or the 2-fibular tunnel technique. To quantify stability in each stage, anterior drawer and talar tilt tests were performed in 0°, 10°, and 20° of plantarflexion (anterior drawer test) or dorsiflexion (talar tilt test). Bone displacements were measured using motion capture, from which laxity and stiffness were calculated together with applied forces. Finally, reconstructed ligaments were tested to failure in neutral position with a maximal applicable torque in inversion. A mixed linear model was used to describe and compare the outcomes. Results When ankle stability of intact and reconstructed ligaments was compared, no significant difference was found between reconstruction techniques for any flexion angle. Also, no significant difference was found when the maximal applicable torque of the 1-tunnel technique (9.1 ± 4.4 N·m) was compared with the 2-tunnel technique (8.9 ± 4.8 N·m). Conclusion Lateral ankle ligament reconstruction with an allograft using 1 fibular tunnel demonstrated similar biomechanical stability to the 2-tunnel approach. Clinical Relevance Demonstrating similar stability in a cadaveric study and given the potential to reduce intraoperative complications, the 1-fibular tunnel approach should be considered a viable option for the surgical therapy of chronic ankle instability. Clinical randomized prospective trials are needed to determine the clinical outcome of the 1-tunnel approach

Technology-aided assessments of sensorimotor function: current use, barriers and future directions in the view of different stakeholders

Background: There is growing interest in the use of technology in neurorehabilitation, from robotic to sensor-based devices. These technologies are believed to be excellent tools for quantitative assessment of sensorimotor ability, addressing the shortcomings of traditional clinical assessments. However, clinical adoption of technology-based assessments is very limited. To understand this apparent contradiction, we sought to gather the points-of-view of different stakeholders in the development and use of technology-aided sensorimotor assessments. Methods: A questionnaire regarding motivators, barriers, and the future of technology-aided assessments was prepared and disseminated online. To promote discussion, we present an initial analysis of the dataset; raw responses are provided to the community as Supplementary Material. Average responses within stakeholder groups were compared across groups. Additional questions about respondent's demographics and professional practice were used to obtain a view of the current landscape of sensorimotor assessments and interactions between different stakeholders. Results: One hundred forty respondents from 23 countries completed the survey. Respondents were a mix of Clinicians (27%), Research Engineers (34%), Basic Scientists (15%), Medical Industry professionals (16%), Patients (2%) and Others (6%). Most respondents were experienced in rehabilitation within their professions (67% with > 5 years of experience), and had exposure to technology-aided assessments (97% of respondents). In general, stakeholders agreed on reasons for performing assessments, level of details required, current bottlenecks, and future directions. However, there were disagreements between and within stakeholders in aspects such as frequency of assessments, and important factors hindering adoption of technology-aided assessments, e.g., Clinicians' top factor was cost, while Research Engineers indicated device-dependent factors and lack of standardization. Overall, lack of time, cost, lack of standardization and poor understanding/lack of interpretability were the major factors hindering the adoption of technology-aided assessments in clinical practice. Reimbursement and standardization of technology-aided assessments were rated as the top two activities to pursue in the coming years to promote the field of technology-aided sensorimotor assessments. Conclusions: There is an urgent need for standardization in technology-aided assessments. These efforts should be accompanied by quality cross-disciplinary activities, education and alignment of scientific language, to more effectively promote the clinical use of assessment technologies. Trial registration: NA; see Declarations section

Additional file 1: of Transfemoral amputee recovery strategies following trips to their sound and prosthesis sides throughout swing phase

Representative examples of recovery strategies in response to trips on able-bodied, prosthesis and sound side limbs. Graphical representation of able-bodied and amputee subjects recovering from trips. The video is separated by recovery strategies; sample trials from each limb group that presented a specific recovery strategy are presented in sequence. Each trial begins with foot-strike of the perturbed stride and continue for one or two additional strides for typical able-bodied and amputee-specific strategies, respectively. The tripped leg is highlighted in red. The pelvis and lower limbs are represented by bony segments (intact limbs) or cylindrical segments (prosthesis side). Video speed is reduced 2.5 times. (MP4 18472 kb

A framework for closing the loop between human experts and computational algorithms for the assessment of movement disorders

Clinical assessment of abnormal neuromechanics is typically performed by manipulation of the affected limbs; a process with low inter- and intra-rater reliability. This paper aims at formalizing a framework that closes the loop between a clinician's expertise and computational algorithms, to enhance the clinician's diagnostic capabilities during physical manipulation. The framework's premise is that the dynamics that can be measured by manipulation of a limb are distinct between movement disorders. An a priori database contains measurements encoded in a space called the information map. Based on this map, a computational algorithm identifies which probing motions are more likely to yield distinguishing information about a patient's movement disorder. The clinician executes this movement and the resulting dynamics, combined with clinician input, is used by the algorithm to estimate which of the movement disorders in the database are most probable. This is recursively repeated until a diagnosis can be confidently made. The main contributions of this paper are the formalization of the framework and the addition of the information map to select informative movements. The establishment of the framework provides a foundation for a standardized assessment of movement disorders and future work will aim at testing the framework's efficacy