GENERAL SESSION 2
Rehabilitation Technology

H-Reflex Modulation during Robotic Body-Weight Supported Treadmill Training
Fides Pacheco, M.D.2; Ross Querry, P.T., Ph.D.1; Thiru Annaswamy, M.D.; Lance Goetz, M.D. 2; Patricia K. Winchester, P.T., Ph.D. 1; Keith Tansey, M.D., Ph.D. 1
1Spinal Cord Injury Laboratory, The University of Texas Southwestern Medical Center; Dallas, Texas
2VA North Texas Health Care System, Dallas VA Medical Center

Objective: To determine changes in the H-reflex during robotic body-weight supported treadmill training (BWSTT).

Design: Repeated measures design

Participants/Methods: One subject with complete spinal cord injury (SCI), one with incomplete SCI undergoing BWSTT and a control were recruited for this pilot study. Subjects were instrumented for acquisition of the soleus H-reflex. The stimulus intensity was defined by the M-wave producing the largest H-reflex amplitude with subjects in prone position. Subjects were placed in the Lokomat® system and ambulated with 40% body-weight support at 1.8 and 2.5 km/hr. Computer-controlled stimulation was synchronized to midstance of the gait cycle. The M-wave and H-reflex characteristics were monitored in real-time and recorded. Post-hoc signal averaging was completed on all events that met M-wave criteria.

Results: The M-wave amplitude was consistent during prone, standing and walking in all subjects. In the control subject and subject with incomplete SCI completing BWSTT, the H/M ratio decreased with increased treadmill speed from 1.8 to 2.5 km/hr (3.25 to 2.81; 2.09 to 1.64, respectively). In the subject with complete SCI, the H-reflex, which was present in prone and standing, was obliterated during walking.

Conclusions: These results identify potential differences in subjects with complete and incomplete SCI. Possible causes for these differences may include completeness of injury and BWSTT. Furthermore, H/M ratios may be affected by gait speed. More studies will be necessary to determine effect of BWSTT in SCI and to further analyze changes in the H-reflex during BWSTT.

Objective: To determine if a “motor learning approach”, based on movement error compensation, can be used to modify the control of specific muscle groups during locomotion.

Design: Descriptive study.

Participants/Methods: Three force fields (FF; 20% of MVC; generated by Theraband™ elastic tubing) were tested on 3 different groups of 5 healthy subjects. FF#1 was applied between the foot and the frame of the treadmill, producing a whole leg perturbation that increased swing velocity. FF#2 and FF#3 perturbed only the ankle by means of a modified ankle orthosis. FF#2 increased dorsiflexion, and FF#3 increased plantarflexion. EMG and kinematics were obtained during treadmill walking before, during and after a 5-10 min. exposure to the FF. Instruction to the subjects was to compensate for the presence of the force field.

Results: For all FFs, the initial effect was a perturbation of the leg kinematics in the direction imposed by the FF. Then, gradually, subjects actively compensated and leg kinematics returned to normal. This compensation occurred by progressive modifications in the muscle activation pattern normally present during walking. These modifications were specific to each FF, with an increase in activity of knee flexors for FF#1, decrease in activity of ankle dorsiflexor (TA) for FF#2, and an increase in TA activity for FF#3. For all FFs, the majority of these modifications persisted after FF removal, gradually fading away over > 20 step cycles.

Conclusion: Together, these results suggest that FF can be used to modify the muscle activation pattern normally present during walking. Furthermore, specific muscle groups can be targeted and up or down regulated by adequately selecting the site of application of this force field. This method may provide a new approach to improve walking in persons with partial spinal cord injury.

Support: This project was funded by a CIHR operating grant.

Objective: To assess the effects of frequent cycle training by functional electrical stimulation (FES) on bone parameters of subjects with chronic spinal cord injury (SCI).

Desing: longitudinal intervention study

Participants/methods: Twelve SCI subjects (all ASIA A) with paralysis duration of at least 3 years were included in this multi-centre study. During the first three months they performed muscle conditioning consisting of three times weekly, one hour isometric bilateral FES of the Mm. gluteus, quadriceps, and hamstrings. Thereafter, the subjects started FES-induced cycling consisting of initially three (first three months) and then five training sessions of 1h, for the next three months with increases in resistance. Bone parameters of the femur and tibia shafts and epiphyses (except femur proximal epiphysis) were measured by peripheral quantitative computed tomography at baseline and after finishing six months of FES-cycle training.

Results: In the femoral distal epiphysis, bone parameters showed increases of 4.3 ±9.6 % (mean ± SD) in bone mass, 4.9 ±9.3 % in total bone mineral density (BMD) and 10.0 ±19.1% in trabecular BMD. In contrast, the tibial epiphysis and the femoral and tibial diaphyses showed on average, only minor bone changes in all measured parameters (range from -2.4 ±5.3 % to 0.1 ±0.7%).

Conclusion: These data suggest that high volume FES leg-cycling has a positive impact on bone formation in the distal femur of individuals with chronic SCI and may therefore contribute to a reduced fracture risk at this site. In contrast, high volume FES-cycling seems to have only a minor effect on bone formation in the tibial epiphysis and diaphysis and the femoral diaphysis.

Support: This project was funded by the Swiss Paraplegic Foundation (Nottwil), and the UK Engineering and Physical Sciences Research Council (Glasgow, London).

Objective: To investigate the feasibility of Functional Electrical Stimulation (FES) assisted rowing as a high intensity cardiovascular exercise for Spinal Cord Injury (SCI).

Design: Development study with a small cohort (n=6).

Participants/methods: Various prototypes of the FES-rowing machine were developed and tested by six individuals with paraplegia (thoracic lesions, ASIA A). Oxygen consumption, heart rate, blood lactate and distance rowed were monitored during sub-max FES-rowing testing. Steady state physiological values were compared with published data from other types of FES exercise for SCI.

Results: A standard Concept 2 rowing ergometer has been equipped with a back rest, leg stabilisers and FES technology. FES-rowing at sub-maximal intensity results in oxygen consumption levels between 1.8 and 2.8 l/min, these can be sustained for 15-30 minutes per session, in which participants row 2000-5000 meters. Blood lactate during FES-rowing quickly rises to >10 mmol/l.

Conclusion: The results of this pilot study imply that FES-rowing is a high intensity exercise that gives very high oxygen consumption values, higher than other types of FES exercise for SCI. Therefore, due to the high intensity, FES-rowing could give optimal reductions in risk factors for coronary heart diseases, type 2 diabetes and obesity, without giving the repetitive stress on the shoulder and upper extremities as seen in wheelchair propulsion. At the same time FES-rowing has enabled paraplegic rowers to compete in mainstream able-bodied indoor rowing competitions.

Support: This project was funded by The Henry Smith Charity, The Trusthouse Charitable Foundation, Inspire and Concept 2. For full list of collaborating centres and supporters see www.fesrowing.org.

Objective: Due to the repetitive motion involved in wheelchair propulsion and transfers, individuals with spinal cord injury who use manual wheelchairs are at risk for carpal tunnel syndrome. This study examines the relationship between patient age, gender, handedness, level of injury and length of time since injury, and median motor and sensory amplitudes of the non-dominant hand.

Design: Multi-center cross-sectional study.

Participants/Methods: 83 subjects, 19 women and 64 men, aged 23 to 69 years (41.4 ± 13.4 years), with spinal cord injury levels T2 to L2, and length of time since injury from 1.2 to 30.3 years (13.4 ± 12.1 years). Subjects underwent median nerve conduction studies. The relationship between subject demographic information and median motor and sensory amplitude was analyzed using multivariate linear regression model.

Results: In the regression model, injury level was inversely related to median motor amplitude (p < 0.05). The length of time since injury was inversely related to median sensory amplitude (p < 0.01). Females had significantly lower motor amplitudes than males (p < 0.04), however males had significantly lower sensory amplitudes than females (p < 0.001). Right-handed subjects had significantly higher sensory amplitudes in their non-dominant hands when compared to those who were left-handed (p < 0.0006).

Conclusion: This is the largest study to date examining patient demographics and their relation to median nerve health in spinal cord injury. The findings provide further insight into risk factors and the natural course of carpal tunnel syndrome.

Support: This project was funded as a NIDRR Multicenter Collaborative Trial # H133A011107 and VA grant #B3057R

Objective: To compare intensity and duration of electromyographic (EMG) activity of 4 shoulder muscles recorded during standard manual wheelchair propulsion (Standard) with that recorded during power-assisted (PAPAW), and lever propulsion (Lever).

Design: Repeated measures, case series.

Participants/methods: Three individuals with complete spinal cord injury (SCI) participated. Subjects represented 3 functional levels of SCI: paraplegia, C7 tetraplegia, and C6 tetraplegia. Fine wire electrodes were inserted into 4 shoulder muscles active during the push phase of wheelchair propulsion: anterior deltoid (ADELT), pectoralis major (PMAJ), supraspinatus (SUPRA), and infraspinatus (INFRA). Subjects were tested using a wheelchair mounted to a stationary ergometer. Propulsion speed was controlled in each test condition.

Results: During PAPAW propulsion, decreased EMG activity of ADELT and PMAJ was recorded in each subject compared with Standard propulsion. In contrast, Lever propulsion resulted in increased ADELT and decreased PMAJ intensity in each subject. Rotator cuff EMG during PAPAW and Lever propulsion varied by level of SCI. SUPRA and INFRA decreased for the subject with paraplegia whereas increased intensity was recorded in both muscles for the subject with C7 tetraplegia. For the subject with C6 tetraplegia, INFRA intensity decreased and SUPRA intensity increased. Duration of ADELT and PMAJ activity was decreased or similar during the PAPAW condition compared with the Standard wheelchair for all subjects. In contrast, during Lever propulsion, these muscles had similar or increased duration for all subjects. Rotator cuff EMG duration was inconsistent across subjects and conditions.

Conclusion: Although PAPAW propulsion reduced the demand of the larger propulsion muscles for all subjects, increased muscle intensity was noted for the rotator cuff musculature in subjects with tetraplegia. Lever propulsion shifted the power demands of propulsion to the ADELT which may increase glenohumeral joint shear forces. Further study of these products is essential to understand their impact on reducing shoulder pathology.

Support: Funded by the National Institute of Disability and Rehabilitation Research grant# H133E020732. Supported by Sunrise Medical and Super Quad Inc.

Objective: Kinetic bed therapy (RotoRest) is currently used to combat the complications associated with immobilization, but the effect on the unstable spine has not been quantified. The objective of this study was to determine how much intervertebral motion is incurred during use of the RotoRest and from the traditional log-roll maneuver.

Design: In vitro biomechanics study.

Participants/methods: Both a lumbar and cervical instability were created in 3 fresh unembalmed cadavers. The amount of 3D angulation resulting from RotoRest and log roll was measured using a Fastrak electromagnetic motion analysis device. The RotoRest was rotated to 40 degrees in each direction.

Results: In the lumbar spine, log-roll produced significantly more axial rotation (4.5o vs 21.2o) and flexion (8.1o vs 10.8o). In the cervical spine, the log-roll resulted in significantly more flexion (2.4o vs 7.3o). There was no significant difference between techniques in the other planes of motion.

Conclusion: The results of the present study demonstrated that there is a substantial increase in lumbar and cervical spine motion when performing the log-roll compared to turning on the RotoRest. This analysis strongly suggests that the kinetic therapy table causes less angular motion than the log roll even when the log roll is performed carefully. This may be explained by the type of motion, consistency of motion, and by the patient’s weight distribution on the RotoRest. Even though the global instability will require surgical stabilization, consideration should be given to initial immobilization on a RotoRest to decrease the likelihood of secondary injury.

Support: This project was funded by a grant from the Southwest Medical Foundati

Objectives: To evaluate baseline cardiovascular parameters, the incidence of orthostatic hypotension (OH), involvement of medical personnel in its management, and the use of midodrine during the first month following acute spinal cord injury (SCI).

Design: Retrospective data analysis.

Participants/Methods: Eighty-nine individuals with acute traumatic SCI categorized into cervical (n=55 or 62%), upper thoracic (n=12 or 13%), and lower thoracic/lumbar injuries (n=22 or25%). Each group was further divided into motor complete (ASIA impairment scale A or B) or motor incomplete (ASIA impairment scale C or D) injuries.

Results: During the first month, baseline systolic blood pressure was lower in individuals with cervical motor complete (ASIA A or B) SCI (p<0.01). OH was more common in cervical and upper thoracic motor complete SCI (p<0.01). OH persisted during the first month following SCI in 74% of cervical and 20% of upper thoracic motor complete SCI individuals. Individuals with cervical SCI had a significantly higher number of orthostatic challenge tests (18+2.07) than those with upper (10+1.95; p<0.01) or lower thoracic (6+1.11; p<0.01) SCI. Midodrine was prescribed only in individuals with cervical SCI (n=13 or 23%). Seventy-seven % (n=10) of those to whom midodrine was prescribed showed improvement of OH within one week (p<.05).

Conclusion: Individuals with cervical motor complete SCI are more likely to develop cardiovascular instability in the acute rehabilitation period, than patients with lower injuries. Individuals with persistent OH require more intensive medical personnel involvement during acute rehabilitation period. Midodrine significantly improved OH in patients with cervical SCI.

Support: This study was sponsored by the Rick Hansen Man in Motion Foundation Research Fund

Objective: Investigate the feasibility of using passive conductors to stimulate the sacral roots and pudendal nerves to restore lower urinary tract function after spinal cord injury.

Design: Implantation of passive conductors to deliver electrical pulses from surface electrodes to spinal roots and pudendal nerves. Bladder pressure and volume monitored with an intravesical catheter and intraurethral pressure monitored with an intraurethral catheter.

Participants/Methods: Acute experiments in n=6 cats surgically anesthetized with isoflurane. The pudendal nerve, its distal branches, and sacral roots were exposed bilaterally and monopolar nerve cuff electrodes or hook electrodes were positioned on them. The insulated lead wires were connected to pickup electrodes consisting of thin metal disks or helically wound coils positioned under the skin. An adhesive surface cathodal electrode was placed directly over the subcutaneous pickup electrode and an indifferent surface electrode was placed some distance away. The surface electrodes were connected to a constant voltage stimulator. Upon stimulation, the pickup electrode routed sufficient current to the target nerve to activate it.

Results: Low-frequency (10-40 Hz) stimulation of the pudendal nerves elicited contractions of the external sphincter sufficient to maintain continence at elevated bladder pressures. High-frequency (600-4000 Hz) stimulation of the pudendal nerve blocked contraction of the external sphincter caused by low-frequency stimulation of the sacral roots or proximal pudendal nerve. Large, maintained bladder contractions were elicited by sacral root stimulation.

Conclusion: These data suggest that existing stimulation paradigms could be combined with stimulus routing techniques to form the basis of a simple neuroprosthesis for lower urinary tract control after spinal cord injury.

Support: National Institutes of Health N01-NS-2-2342 and the Alberta Heritage Foundation for Medical Research.

Design: Cross-sectional investigation.

Participants/Methods: Male (n = 32) and female (n = 30) adults with complete and incomplete spinal cord lesions below C6 volunteered to participate in this study. The average length of time since the onset of disability was 9 years (range = 1.5 – 40 years). Using an interview-formatted survey (Quality of Well-Being Scale), a measure of quality of life was obtained for each participant. Physical activity levels were determined using the Physical Activity Scale for Individuals with Physical Disabilities Scale.

Results: A strong positive association (r = .75; p < .05) was observed between level of physical activity and quality of life. Multiple regression analysis also revealed that when level of physical activity, anatomical location of the injury, completeness of injury, and time since injury were used as explanatory variables, level of physical activity was the only significant predictor of quality of life, accounting for 57% of the total variation in quality of life.

Conclusions: Results from this study demonstrate that a significant and moderately strong positive relationship exists between level of physical activity and quality of life in adults with spinal cord injury. From a clinical perspective, these findings suggest that interventions aimed at promoting physical activity may be effective in improving quality of life in adults with spinal cord injury.

Objective: Develop evidence based maps of rehabilitation for different lesion categories

Design: Retrospective data analysis

Participants/methods: All newly-injured patients aged eighteen or over who were first admitted to MCSI across a five-year period from January 2000 to January 2005. Data sources and measures: Needs Assessment Checklist (a measure of functional independence), data from the audit of the goal planning system, the electronic patient record system and paper notes.

Results: Data from 422 patients was divided into lesion categories. Standard milestones that patients in a given category would be expected to reach in rehabilitation, by domain, were identified using goals set at goal planning meetings and in consultation with the multidisciplinary team. We calculated when patients reached these milestones by week. For example, we looked at the lesion category of complete T8 to T12 (n=21). Average time from starting rehabilitation to discharge is 9.25 weeks. In the domain of bowel management we can say that a key milestone is learning to self care. At least 25% of patients for whom this was recorded as a goal had started learning to self care by Week 3 of rehabilitation. At least 75% had achieved this by Week 8.

Conclusion: Pathways of care can be used in a number of ways: to identify need for service change; to audit service change; to provide evidence-based expectations to staff, patients and external parties; to look at variances affecting care; to make our service transparent; to provide figures for comparison with other philosophies of care; and to ensure consistency across the service.

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