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Coupaud S.,University of Glasgow | Coupaud S.,Scottish Center for Innovation in Spinal Cord Injury | McLean A.N.,Scottish Center for Innovation in Spinal Cord Injury | Purcell M.,Scottish Center for Innovation in Spinal Cord Injury | And 2 more authors.
Bone | Year: 2015

Background: Disuse osteoporosis occurs in response to long-term immobilization. Spinal cord injury (SCI) leads to a form of disuse osteoporosis that only affects the paralyzed limbs. High rates of bone resorption after injury are evident from decreases in bone mineral content (BMC), which in the past have been attributed in the main to loss of trabecular bone in the epiphyses and cortical thinning in the shaft through endocortical resorption. Methods: Patients with motor-complete SCI recruited from the Queen Elizabeth National Spinal Injuries Unit (Glasgow, UK) were scanned within 5. weeks of injury (baseline) using peripheral Quantitative Computed Tomography (pQCT). Unilateral scans of the tibia, femur and radius provided separate estimates of trabecular and cortical bone parameters in the epiphyses and diaphyses, respectively. Using repeat pQCT scans at 4, 8 and 12. months post-injury, changes in BMC, bone mineral density (BMD) and cross-sectional area (CSA) of the bone were quantified. Results: Twenty-six subjects (5 female, 21 male) with SCI (12 paraplegic, 14 tetraplegic), ranging from 16 to 76. years old, were enrolled onto the study. Repeated-measures analyses showed a significant effect of time since injury on key bone parameters at the epiphyses of the tibia and femur (BMC, total BMD, trabecular BMD) and their diaphyses (BMC, cortical BMD, cortical CSA). There was no significant effect of gender or age on key outcome measures, but there was a tendency for the female subjects to experience greater decreases in cortical BMD. The decreases in cortical BMD in the tibia and femur were found to be statistically significant in both men and women. Conclusions: By carrying out repeat pQCT scans at four-monthly intervals, this study provides a uniquely detailed description of the cortical bone changes that occur alongside trabecular bone changes in the first year of complete SCI. Significant decreases in BMD were recorded in both the cortical and trabecular bone compartments of the tibia and femur throughout the first year of injury. This study provides evidence for the need for targeted early intervention to preserve bone mass within this patient group. © 2015 Elsevier Inc. Source

Gollee H.,University of Glasgow | Gollee H.,Scottish Center for Innovation in Spinal Cord Injury | Volosyak I.,University of Bremen | McLachlan A.J.,University of Glasgow | And 4 more authors.
IEEE Transactions on Biomedical Engineering | Year: 2010

A braincomputer interface (BCI) based on steady-state visual-evoked potentials (SSVEPs) is combined with a functional electrical stimulation (FES) system to allow the user to control stimulation settings and parameters. The system requires four flickering lights of distinct frequencies that are used to form a menu-based interface, enabling the user to interact with the FES system. The approach was evaluated in 12 neurologically intact subjects to change the parameters and operating mode of an abdominal stimulation system for respiratory assistance. No major influence of the FES on the raw EEG signal could be observed. In tests with a self-paced task, a mean accuracy of more than 90% was achieved, with detection times of approximately 7.7 s and an average information transfer rate of 12.5 bits/min. There was no significant dependency of the accuracy or time of detection on the FES stimulation intensity. The results indicate that the system could be used to control FES-based neuroprostheses with a high degree of accuracy and robustness. © 2010 IEEE. Source

McCaughey E.J.,Macquarie University | McCaughey E.J.,University of Glasgow | McLean A.N.,Scottish Center for Innovation in Spinal Cord Injury | Allan D.B.,Scottish Center for Innovation in Spinal Cord Injury | Gollee H.,University of Glasgow
Journal of Spinal Cord Medicine | Year: 2015

Context: Respiratory complications, attributed to the build-up of secretions in the airway, are a leading cause of rehospitalisation for the tetraplegic population. Previously, we observed that the application of Abdominal Functional Electrical Stimulation (AFES) improved cough function and increased demand for secretion removal, suggesting AFES may aid secretion clearance. Clinically, secretion clearance is commonly achieved by using Mechanical insufflation-exsufflation (MI-E) to simulate a cough. In this study the feasibility of combining AFES with MI-E is evaluated. Findings: AFES was successfully combined with MI-E at eight fortnightly assessment sessions conducted with one sub-acute participant with tetraplegia. By using the signal from a pressure sensor, integrated with the MI-E device, AFES was correctly applied in synchrony with MI-E with an accuracy of 96.7%. Acute increases in exhaled volume and peak flow were observed during AFES assisted MI-E, compared to MI-E alone, at six of eight assessment sessions. Conclusion: The successful integration of AFES with MI-E at eight assessment sessions demonstrates the feasibility of this technique. The acute increases in respiratory function observed at the majority of assessment sessions generate the hypothesis that AFES assisted MI-E may be more effective for secretion clearance than MI-E alone. © 2016 The Author(s). Published by Taylor & Francis. Source

Pennycott A.,University of Glasgow | Pennycott A.,Scottish Center for Innovation in Spinal Cord Injury | Hunt K.J.,University of Glasgow | Hunt K.J.,Scottish Center for Innovation in Spinal Cord Injury | And 5 more authors.
IEEE Transactions on Control Systems Technology | Year: 2010

Body-weight-supported robot-assisted devices can be used to promote gait rehabilitation and as exercise tools for neurologically impaired persons such as stroke and spinal-cord-injured patients. Here, we propose a novel feedback-control structure for real-time control of oxygen uptake during robot-assisted gait, in which we use the following methods. 1) A feedback-control structure is proposed, consisting of a dynamic controller operating on target and actual levels of oxygen uptake in order to set a target work rate. Target work rate is achieved by an inner volitional feedback loop which relies on the subject's exercise input. 2) The dynamic oxygen-uptake controller is based on an empirically derived model of the oxygen-uptake dynamics and is synthesized by pole placement. 3) The resulting control system is tested during the robot-assisted treadmill ambulation of five able-bodied subjects. A single linear controller was designed based on identification data from tests with one subject and used for closed-loop control tests with all five subjects. In all cases, the actual oxygen-uptake response closely followed the ideal response as specified by the feedback design parameters. The control of oxygen uptake during body-weight-supported robot-assisted ambulation is feasible in the able-bodied population; the robustness of the system is demonstrated within the class of subjects tested. Further testing is required to validate the approach with neurologically impaired subjects. © 2009 IEEE. Source

Dunne A.C.,University of Glasgow | Dunne A.C.,Scottish Center for Innovation in Spinal Cord Injury | Allan D.B.,Queen Elizabeth National Spinal Injuries Unit | Allan D.B.,Scottish Center for Innovation in Spinal Cord Injury | And 2 more authors.
Biomedical Signal Processing and Control | Year: 2010

Background: Robotics-assisted treadmill exercise (RATE) is a new mode of exercise available to people with an incomplete spinal cord injury (SCI) that allows them to utilise their lower limb muscles during stepping. Pilot data suggest that RATE elicits a non-linear oxygen uptake (over(V, ̇) O2) response corresponding to a linear increase in work rate. However, a linear over(V, ̇) O2 response during an incremental exercise test (IET) may be important to enable accurate estimation of key cardiopulmonary performance parameters. Aim: This study aims to characterise the linearity of the over(V, ̇) O2 response elicited by a linearly increasing work rate during robotics-assisted treadmill exercise in subjects with incomplete SCI. Methods: Utilising the Lokomat system, 10 subjects each performed two IETs on a robotics-assisted treadmill to the limit of their tolerance. By employing work rate estimation algorithms, subjects were asked to use cognitive feedback and volitional control of their contribution to the exercise to follow a linearly increasing target work rate that was displayed on screen. Pulmonary gas exchange and ventilatory measurements (including over(V, ̇) O2) were continuously measured throughout the exercise using a breath-by-breath respiratory monitoring system. Linear and 3rd-order non-linear approximations with comparable R2 values were computed for each subject's over(V, ̇) O2 response to the linear increasing work rate. Results: R2 values for the non-linear approximations were 9% higher on average (p = 0.015) than the corresponding R2 values for the linear approximations. Conclusion: The over(V, ̇) O2 response elicited by a linearly increasing work rate during robotics-assisted treadmill exercise in those with incomplete SCI is non-linear. To ensure the intensity of exercise increases linearly, a more appropriate IET may be implemented by employing feedback control of over(V, ̇) O2 to track a linear target. © 2009 Elsevier Ltd. All rights reserved. Source

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