Motor Complete Spinal Cord Injury Research Articles

Transspinal stimulation increases motoneuron output of multiple segments in human spinal cord injury.

Targeted neuromodulation strategies that strengthen neuronal activity are in great need for restoring sensorimotor function after chronic spinal cord injury (SCI). In this study, we established changes in the motoneuron output of individuals with and without SCI after repeated noninvasive transspinal stimulation at rest over the thoracolumbar enlargement, the spinal location of leg motor circuits. Cases of motor incomplete and complete SCI were included to delineate potential differences when corticospinal motor drive is minimal. All 10 SCI and 10 healthy control subjects received daily monophasic transspinal stimuli of 1-ms duration at 0.2 Hz at right soleus transspinal evoked potential (TEP) subthreshold and suprathreshold intensities at rest. Before and two days after cessation of transspinal stimulation, we determined changes in TEP recruitment input-output curves, TEP amplitude at stimulation frequencies of 0.1, 0.125, 0.2, 0.33 and 1.0 Hz, and TEP postactivation depression upon transspinal paired stimuli at interstimulus intervals of 60, 100, 300, and 500 ms. TEPs were recorded at rest from bilateral ankle and knee flexor/extensor muscles. Repeated transspinal stimulation increased the motoneuron output over multiple segments. In control and complete SCI subjects, motoneuron output increased for knee muscles, while in motor incomplete SCI subjects motoneuron output increased for both ankle and knee muscles. In control subjects, TEPs homosynaptic and postactivation depression were present at baseline, and were potentiated for the distal ankle or knee flexor muscles. TEPs homosynaptic and postactivation depression at baseline depended on the completeness of the SCI, with minimal changes observed after transspinal stimulation. These results indicate that repeated transspinal stimulation increases spinal motoneuron responsiveness of ankle and knee muscles in the injured human spinal cord, and thus can promote motor recovery. This noninvasive neuromodulation method is a promising modality for promoting functional neuroplasticity after SCI.

Acquisition of a precision walking skill and the impact of proprioceptive deficits in people with motor-incomplete spinal cord injury.

Many people with motor-incomplete spinal cord injury (m-iSCI) experience difficulty navigating obstacles, such as curbs and stairs. The ability to relearn walking skills may be limited by proprioceptive deficits. The purpose of this study was to determine the capacity of participants to acquire a precision walking skill, and to evaluate the influence of proprioceptive deficits on the skill acquisition in individuals with m-iSCI. Sixteen individuals with m-iSCI and eight controls performed a precision walking task that required matching their foot height to a target during the swing phase. Proprioceptive deficits were quantified at the hip and knee for joint position and movement detection sense. Participants completed 600 steps of training with visual feedback. Pretraining and posttraining tests were conducted without visual feedback, along with a transfer test with an ankle weight. Posttraining and transfer tests were repeated 1 day later. Participants returned to the laboratory 1 wk later to repeat the training. Performance was calculated as the vertical distance between the target and actual foot height for each step. The posttraining and transfer performances were similar between groups. However, participants with m-iSCI had a slower rate of acquisition to achieve a similar performance level compared with controls. Acquisition rate and posttraining performance of the precision walking task were related to lower limb joint position sense among SCI participants. Although they can achieve a similar level of performance in a precision walking task, proprioceptive deficits impair the rate of learning among individuals with m-iSCI compared with able-bodied controls. NEW & NOTEWORTHY People with motor-incomplete spinal cord injuries are able to achieve the same level of performance accuracy on a precision walking task as able-bodied controls; however, the rate of learning is slower, indicating that more practice is required to stabilize performance. Our findings also show a relationship between impaired sensory function and reduced accuracy when performing a precision walking task after spinal cord injury.

Aquatic, deep water peak VO2 testing for individuals with spinal cord injury

Objective: To determine the reliability of peak VO2 testing for individuals with spinal cord injury (SCI) in deep water and on land; and to examine the relationship between these two testing conditions.Design: Reliability study.Setting: Comprehensive rehabilitation center in Baltimore, MD, USA.Participants: 17 participants (13 men, 4 women) with motor complete and incomplete SCI. Participants were randomized into either aquatic or arm cycle ergometer first measurements.Intervention: Pilot study to assess peak VO2.Outcome measures: Peak VO2 measured with metabolic cart in supported deep water with the addition of Aquatrainer® connection, and on land with arm cycle ergometer. Two trials were conducted for each condition with 48 h separating each test.Results: Peak oxygen consumption reliability was statistically significant for both conditions, aquatic (r = 0.93, P < 0.001) and arm cycle ergometry (r = 0.96, P < 0.001). Additionally, aquatic and arm cycle peak VO2 correlation existed (r = 0.72, P < 0.001). For these 17 participants, lower extremity motor score influenced supported, deep water peak VO2, B = 0.57, P < 0.02, whereas age, sex, and weight did not impact deep water or ergometer values.Conclusion: Determining peak VO2 for individuals with SCI is highly reproducible for arm cycle ergometry and in deep water assessment. Additionally, aquatic, deep water peak VO2 testing is valid when compared to arm cycle ergometry. Although the peak VO2 relationship between deep water and arm cycle ergometry is high, variance in the two conditions does exist. Therefore, it is important to assess peak VO2 via the same exercise modality utilized in the treatment intervention.

Stimulation of paralysed quadriceps muscles with sequentially and spatially distributed electrodes during dynamic knee extension

BackgroundDuring functional electrical stimulation (FES) tasks with able-bodied (AB) participants, spatially distributed sequential stimulation (SDSS) has demonstrated substantial improvements in power output and fatigue properties compared to conventional single electrode stimulation (SES). The aim of this study was to compare the properties of SDSS and SES in participants with spinal cord injury (SCI) in a dynamic isokinetic knee extension task simulating knee movement during recumbent cycling.MethodUsing a case-series design, m. vastus lateralis and medialis of four participants with motor and sensory complete SCI (AIS A) were stimulated for 6 min on both legs with both electrode setups. With SES, target muscles were stimulated by a pair of electrodes. In SDSS, the distal electrodes were replaced by four small electrodes giving the same overall stimulation frequency and having the same total surface area. Torque was measured during knee extension by a dynamometer at an angular velocity of 110 deg/s. Mean power of the left and right sides (PmeanL,R) was calculated from all stimulated extensions for initial, final and all extensions. Fatigue is presented as an index value with respect to initial power from 1 to 0, whereby 1 means no fatigue.ResultsSDSS showed higher PmeanL,R values for all four participants for all extensions (increases of 132% in participant P1, 100% in P2, 36% in P3 and 18% in P4 compared to SES) and for the initial phase (increases of 84%, 59%, 66%, and 16%, respectively). Fatigue resistance was better with SDSS for P1, P2 and P4 but worse for P3 (0.47 vs 0.35, 0.63 vs 0.49, 0.90 vs 0.82 and 0.59 vs 0.77, respectively).ConclusionConsistently higher PmeanL,R was observed for all four participants for initial and overall contractions using SDSS. This supports findings from previous studies with AB participants. Fatigue properties were better in three of the four participants. The lower fatigue resistance with SDSS in one participant may be explained by a very low muscle activation level in this case. Further investigation in a larger cohort is warranted.

The effects and potential mechanisms of locomotor training on improvements of functional recovery after spinal cord injury.

Body-weight-supported locomotor training is an activity-based therapy used frequently to train individuals with spinal cord injury (SCI) for restoring walking ability. Locomotor training after SCI is developed on the basic scientific findings of activity-dependent neuroplasticity. Based on the research from animal SCI models, there exists a spinal neural networks for locomotion which can be reactivated by intense repetitive locomotor training. Notably, the effectiveness of locomotor training depends largely on the severity of injury and time after injury. Locomotor training, using body-weight-supported walking overground or on a treadmill, with assistance manually or robotically, with a variety of training intensity and training programs, has been shown to elicit improvements in locomotor function for incomplete SCI individuals. For chronic and motor complete SCI, other interventions with proven effectiveness such as epidural stimulation might be applied in addition to locomotor training to improve the chance of locomotor recovery. In this chapter, we review the factors that influence the functional outcomes of locomotor training. We also summarize the circuitry, cellular and molecular levels of mechanisms underlying the positive role of locomotor training in inducing neuroplasticity and functional recovery following SCI.

Effects of exercise interventions on cardiovascular health in individuals with chronic, motor complete spinal cord injury: protocol for a randomised controlled trial [Cardiovascular Health/Outcomes: Improvements Created by Exercise and education in SCI (CHOICES) Study

IntroductionRecent studies demonstrate that cardiovascular diseases and associated complications are the leading cause of morbidity and mortality in individuals with spinal cord injury (SCI). Abnormal arterial stiffness, defined by a...

Epidural Spinal Cord Stimulation Acutely Modulates Lower Urinary Tract and Bowel Function Following Spinal Cord Injury: A Case Report.

Regaining control of autonomic functions such as those of the cardiovascular system, lower urinary tract and bowel, rank among the most important health priorities for individuals living with spinal cord injury (SCI). Recently our research provided evidence that epidural spinal cord stimulation (ESCS) could acutely modulate autonomic circuits responsible for cardiovascular function after SCI. This finding raised the question of whether ESCS can be used to modulate autonomic circuits involved in lower urinary tract and bowel control after SCI. We present the case of a 32-year-old man with a chronic motor-complete SCI (American Spinal injury Association Impairment Scale B) at the 5th cervical spinal segment. He sustained his injury during a diving accident in 2012. He was suffering from neurogenic lower urinary tract and bowel dysfunction. Epidural stimulation of the lumbosacral spinal cord immediately modulated both functions without negatively affecting the cardiovascular system. Specifically, the individual’s bowel function was assessed using different pre-set configurations and stimulation parameters in a randomized order. Compared to the individual’s conventional bowel management approach, ESCS significantly reduced the time needed for bowel management (p = 0.039). Furthermore, depending on electrode configuration and stimulation parameters (i.e., amplitude, frequency, and pulse width), ESCS modulated detrusor pressure and external anal sphincter/pelvic floor muscle tone to various degrees during urodynamic investigation. Although, ESCS is currently being explored primarily for restoring ambulation, our data suggest that application of this neuroprosthetic intervention may provide benefit to lower urinary tract and bowel function in individuals with SCI. To fully capitalize on the potential of improving lower urinary tract and bowel function, further research is needed to better understand the neuronal pathways and identify optimal stimulation configurations and parameters.

Short- and long-term reproducibility of diffusion-weighted magnetic resonance imaging of lower extremity musculature in asymptomatic individuals and a comparison to individuals with spinal cord injury

BackgroundDiffusion-weighted magnetic resonance imaging (DW-MRI) of skeletal muscle has the potential to be a sensitive diagnostic and/or prognostic tool in complex, enigmatic neuromusculoskeletal conditions such as spinal cord injury and whiplash associated disorder. However, the reliability and reproducibility of clinically accessible DW-MRI parameters in skeletal muscle remains incompletely characterized – even in individuals without neuromusculoskeletal injury – and these parameters have yet to be characterized for many clinical populations. Here, we provide normative measures of the apparent diffusion coefficient (ADC) in healthy muscles of the lower limb; assess the rater-based reliability and short- and long-term reproducibility of the ADC in the same muscles; and quantify ADC of these muscles in individuals with motor incomplete spinal cord injury.MethodsTwenty individuals without neuromusculoskeletal injury and 14 individuals with motor incomplete spinal cord injury (SCI) participated in this investigation. We acquired bilateral diffusion-weighted MRI of the lower limb musculature in all participants at 3 T using a multi-shot echo-planar imaging sequence with b-values of 0, 100, 300 and 500 s/mm2 and diffusion-probing gradients applied in 3 orthogonal directions. Outcome measures included: (1) average ADC in the lateral and medial gastrocnemius, tibialis anterior, and soleus of individuals without neurological or musculoskeletal injury; (2) intra- and inter-rater reliability, as well as short and long-term reproducibility of the ADC; and (3) estimation of average muscle ADC in individuals with SCI.ResultsIntra- and inter-rater reliability of the ADC averaged 0.89 and 0.79, respectively, across muscles. Least significant change, a measure of temporal reproducibility, was 4.50 and 11.98% for short (same day) and long (9-month) inter-scan intervals, respectively. Average ADC was significantly elevated across muscles in individuals with SCI compared to individuals without neurological or musculoskeletal injury (1.655 vs. 1.615 mm2/s, respectively).ConclusionsThese findings provide a foundation for future studies that track longitudinal changes in skeletal muscle ADC of the lower extremity and/or investigate the mechanisms underlying ADC changes in cases of known or suspected pathology.

Overground walking with a robotic exoskeleton elicits trunk muscle activity in people with high-thoracic motor-complete spinal cord injury

BackgroundThe trunk muscles are critical for postural control. Recent neurophysiological studies have revealed sparing of trunk muscle function in individuals with spinal cord injury (SCI) classified with thoracic or cervical motor-complete injuries. These findings raise the possibility for recruiting and retraining this spared trunk function through rehabilitation. Robotic gait training devices may provide a means to promote trunk muscle activation. Thus, the objective of this study was to characterize and compare the activation of the trunk muscles during walking with two robotic gait training devices (Ekso and Lokomat) in people with high thoracic motor-complete SCI.MethodsParticipants with chronic motor-complete paraplegia performed 3 speed-matched walking conditions: Lokomat-assisted walking, Ekso-assisted walking overground, and Ekso-assisted walking on a treadmill. Surface electromyography (EMG) signals were recorded bilaterally from the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) muscles.ResultsGreater recruitment of trunk muscle EMG was elicited with Ekso-assisted walking compared to the Lokomat. Similar levels of trunk EMG activation were observed between Ekso overground and Ekso on the treadmill, indicating that differences between Ekso and Lokomat could not be attributed to the use of a hand-held gait aid. The level of trunk EMG activation during Lokomat walking was not different than that recorded during quiescent supine lying.ConclusionsEkso-assisted walking elicits greater activation of trunk muscles compared to Lokomat-assisted walking, even after controlling for the use of hand-held assistive devices. The requirement of the Ekso for lateral weight-shifting in order to activate each step could lead to better postural muscle activation.

Submaximal Marker for Investigating Peak Muscle Torque Using Neuromuscular Electrical Stimulation after Paralysis.

Spinal cord injury (SCI) results in deleterious skeletal muscle adaptations, such as relevant atrophy and loss of force. In particular, the relevant loss of lower-limb force-generating capacity may limit functional mobility even if neuronal control was sufficient. Currently, methods of assessing maximal force-generating capacity using neuromuscular electrical stimulation (NMES) are limited in individuals who cannot tolerate higher stimulation amplitudes, such as those with residual sensation and those at risk of fracture. In this study, we examined the relationship between NMES amplitude and muscle torque exerted (recruitment curve) in order to determine whether maximal torque output can be characterized by a submaximal marker. Recruitment curves for knee extensors, knee flexors, and ankle plantarflexors were recorded from 30 individuals with motor complete SCI. NMES was delivered starting with an amplitude of 5 mA, and increasing by 5 mA for every subsequent stimulation until either the participant requested to stop the stimulation or the maximum stimulation amplitude (140 mA) was reached. Significant correlations between peak slope of the recruitment curve and peak torque for all muscle groups were found (knee extensors, r = 0.75; p < 0.0001; knee flexors, r = 0.68; p < 0.0001; ankle plantarflexors, r = 0.91; p < 0.0001), indicating that muscles that show greater peak slope of the recruitment curve tend to generate a greater peak torque. This suggests that peak slope, which was achieved at an average stimulation intensity (55.0 mA) that was 43% smaller than that corresponding to peak torque (97.4 mA), may be used as a submaximal marker for characterizing maximal torque output in individuals with SCI.

Serum testosterone levels may influence body composition and cardiometabolic health in men with spinal cord injury.

Study Design:Cross-sectional studyObjectiveTo establish the association between serum testosterone (T) levels, biomarkers of cardiometabolic health and regional body composition variables after spinal cord injury (SCI).Setting:Medical research centerMethodsMetabolic and body composition measurements were collected from thirty-six men with chronic motor complete SCI. Serum T, carbohydrate and lipid profiles were measured after an overnight fast. Body composition was measured using anthropometrics, dual energy x-ray absorptiometry and magnetic resonance imaging. Participants were evenly classified into tertiles based on their serum T levels into low, mid-normal and normal ranges.ResultsLow, mid-normal and normal range serum T were 288.8 ± 84.9ng/dL, 461.0 ± 52.5ng/dL and 648.0 ± 53.5ng/dL, respectively. Low range serum T group had greater total (9.6%, P= 0.04) percentage fat mass and visceral adipose tissue (VAT) area (72%, P= 0.01) compared to normal range serum T group. Serum T was related to the absolute whole thigh muscle area (r= 0.40, P< 0.05) after controlling for body mass index. Serum T was negatively related to fasting plasma glucose (r= −0.46, P= 0.006) and insulin (r= −0.42, P= 0.01), HbA1c (r= −0.39, P= 0.02) and triglycerides (r= −0.36, P= 0.03).ConclusionMen with low serum T have more unfavorable body composition and cardiometabolic health outcomes after SCI. Testosterone replacement therapy may serve as a potential strategy in preventing cardiometabolic disorders after SCI.

Estimates of the precision of total and regional soft tissue body composition by dual-energy X-ray absorptiometry in persons with chronic spinal cord injury

Introduction In both the clinical and research setting, the total body dual energy X-ray absorptiometry (DXA) scan is widely employed to measure longitudinal changes in fat tissue mass and lean tissue mass of the total body and regional areas in persons with spinal cord injury (SCI). Knowledge of the precision error is essential due to less than optimal limb positioning (i.e., joint contracture and spasticity) that could confound the reliability of body composition measurements. Objective The objective of this prospective observational study was to determine the short- and long-term reliability of total and regional soft tissue body composition assessments from a DXA total body scan in persons with motor-complete SCI. Methods Twenty-four individuals with SCI completed within day precision testing by repositioning study participants between scans (short-term precision error). An additional and separate cohort of 22 individuals with motor-complete SCI were scanned twice on a GE-Lunar Prodigy scanner separated by a 4-week interval (long-term precision error). To quantify precision error, the root mean square coefficient of variation percent (RMS-CV%) values and the inter-class correlation coefficient (ICC) values for the total body and regional areas (arms, legs, trunk, android, and gynoid regions) for all body composition variables [% fat mass, fat mass (kg), lean mass (kg), and total mass (kg)] were calculated and are presented. Results For all soft tissue body composition variables, the short-term precision assessment revealed the highest RMS-CV% from the body composition variables did not exceed 5.6%, 2.7%, 3.8%, 3.5%, 5.8% and 2.3% for arms, legs, trunk, android, gynoid, and total body, respectively. In the long-term precision assessment, revealed the highest RMS-CV% from the body composition variables did not exceed 6%, 3%, 4.4%, 6.7%, 3.4% and 1.96% for arms, legs, trunk, android, gynoid, and total body, respectively. To support the long-term precision error assessment, the interclass-correlation coefficient in the long-term precision group demonstrated excellent linear agreement between repeat scans for all regions (r ≥ 0.95). Conclusion Precision error of the total body and regional soft tissue body composition variables were similar to that reported in the non-disabled population. These findings support the use of DXA as a reliable method to assess longitudinal changes in the total body and regional areas from various pharmacological and therapeutic interventions in persons with SCI.

Femoral Artery Blood Flow and Microcirculatory Perfusion During Acute, Low-Level Functional Electrical Stimulation in Spinal Cord Injury.

Functional electrical stimulation (FES) may help to reduce the risk of developing macrovascular and microvascular complications in people with spinal cord injury. Low-intensity FES has significant clinical potential because this can be applied continuously throughout the day. This study examines the acute effects of low-intensity FES using wearable clothing garment on vascular blood flow and oxygen consumption in people with spinal cord injury. This was a cross-sectional observation study. Eight participants with a motor complete spinal cord injury received four 3-min unilateral FES to the gluteal and hamstring muscles. Skin and deep femoral artery blood flow and oxygen consumption were measured at baseline and during each bout of stimulation. Femoral artery blood flow increased by 18.1% with the application of FES (P = 0.02). Moreover, femoral artery blood flow increased further during each subsequent block of FES (P = 0.004). Skin perfusion did not change during an individual block of stimulation (P = 0.66). Skin perfusion progressively increased with each subsequent bout (P < 0.001). There was no change in femoral or skin perfusion across time in the nonstimulated leg (all P > 0.05). Low-intensity FES acutely increased blood flow during stimulation, with a progressive increase across subsequent FES bouts. These observations suggest that continuous, low-intensity FES may represent a practical and effective strategy to improve perfusion and reduce the risk of vascular complications.

Recovery of Over-Ground Walking after Chronic Motor Complete Spinal Cord Injury

SummaryPersons with motor complete spinal cord injury, signifying no voluntary movement or sphincter function below the level of injury but including retention of some sensation, do not recover independent walking. We tested intense locomotor treadmill training with weight support and simultaneous spinal cord epidural stimulation in four patients 2.5 to 3.3 years after traumatic spinal injury and after failure to improve with locomotor training alone. Two patients, one with damage to the mid-cervical region and one with damage to the high-thoracic region, achieved over-ground walking (not on a treadmill) after 278 sessions of epidural stimulation and gait training over a period of 85 weeks and 81 sessions over a period of 15 weeks, respectively, and all four achieved independent standing and trunk stability. One patient had a hip fracture during training. (Funded by the Leona M. and Harry B. Helmsley Charitable Trust and others; ClinicalTrials.gov number, NCT02339233.)

Use of nonsteroidal anti-inflammatory drugs to prevent heterotopic ossification after spinal cord injury: a retrospective chart review.

Retrospective chart review. The objective of this study is to evaluate the efficacy of nonsteroidal anti-inflammatory drug (NSAID) prophylaxis for heterotopic ossification (HO) in the acute phase after spinal cord injury (SCI). Acute rehabilitation hospital in California, USA. This retrospective chart review (October 2013-March 2017) included individuals with motor complete SCI followed by the SCI service within 60 days of injury. Group demographics and HO diagnosis were compared in those who received and those who did not receive NSAID prophylaxis. A backward stepwise multiple regression was employed to assess the predictive association between injury characteristics and HO prophylaxis on HO diagnosis. A total of 108 AIS A and B cases were included, and 27 received ≥ 15 days of therapy (overall range 6-44 days). Logistic regression analysis revealed those who received ≥ 15 days of NSAID prophylaxis had an odds ratio of 0.1 of being diagnosed with HO compared with those who did not (95% CI, 0.02 to 0.52). Significant predictors of HO diagnosis were tracheostomy (OR 2.8, 95% CI, 1.05 to 7.5), urinary tract infection (OR 4.3, 95% CI, 1.5 to 12.2), and pressure injury (OR 3.3, 95% CI, 1.1 to 9.5). Adverse effects of NSAID use were minimal. NSAID prophylaxis appears to help prevent HO development during the acute phase after SCI. Prospective study with prolonged follow up is necessary to confirm the long-term efficacy of HO prevention and to further evaluate safety following spinal fusion. None.

EEG-controlled functional electrical stimulation for hand opening and closing in chronic complete cervical spinal cord injury

Background. There are over 33 000 people in the US living with complete tetraplegia due to spinal cord injury (SCI). People with complete tetraplegia rank restoration of hand and arm function as their highest priority, as it would offer greater independence and improved quality of life. In this study, we show that subjects with chronic (>1-year post-injury) C5 or C6 level, motor-complete SCI are able to control a brain computer interface-functional electrical stimulation (BCI-FES) system to enable hand opening and closing. Methods: 8 subjects with C5 or C6 motor-level SCI and 6 uninjured, control subjects participated in 6 sessions of BCI-FES sessions. Electroencephalographic (EEG) signals were acquired using a wireless EEG system and subjects were asked to ‘imagine moving their right hand’ for motor imagery. Average power was extracted in 5 Hz bins (6–35 Hz) from C3, C1, Cz, C2, and C4 electrodes and input as features to a support vector machine classification algorithm. When ‘movement intention’ was classified correctly from the motor imagery period, a custom-designed stimulation sequence was delivered to the forearm muscles via surface electrodes to enable opening and closing of the hand. Results: Average online decoding accuracy during the closed-loop BCI-FES sessions was similar for the SCI (74.8% ± 17.76) and the control (75.5% ± 11.94) group. Online decoding accuracies were validated using Monte Carlo simulations that used 30%, 50%, and 70% training data to validate the decoded online accuracy and Wilcoxon rank sum test found no significant differences between the SCI and Control subjects. Conclusions: This study demonstrates that subjects with motor complete, cervical SCI were able to control a BCI-FES system with decoding accuracies similar to healthy controls after minimal BCI-training. Non-invasive BCI-FES systems may have the potential to restore hand function in people with motor-complete SCI to improve their quality of life.

Longitudinal Examination of Bone Loss in Male Rats After Moderate-Severe Contusion Spinal Cord Injury.

To elucidate mechanisms of bone loss after spinal cord injury (SCI), we evaluated the time-course of cancellous and cortical bone microarchitectural deterioration via microcomputed tomography, measured histomorphometric and circulating bone turnover indices, and characterized the development of whole bone mechanical deficits in a clinically relevant experimental SCI model. 16-weeks-old male Sprague-Dawley rats received T9 laminectomy (SHAM, n = 50) or moderate-severe contusion SCI (n = 52). Outcomes were assessed at 2-weeks, 1-month, 2-months, and 3-months post-surgery. SCI produced immediate sublesional paralysis and persistent hindlimb locomotor impairment. Higher circulating tartrate-resistant acid phosphatase 5b (bone resorption marker) and lower osteoblast bone surface and histomorphometric cancellous bone formation indices were present in SCI animals at 2-weeks post-surgery, suggesting uncoupled cancellous bone turnover. Distal femoral and proximal tibial cancellous bone volume, trabecular thickness, and trabecular number were markedly lower after SCI, with the residual cancellous network exhibiting less trabecular connectivity. Periosteal bone formation indices were lower at 2-weeks and 1-month post-SCI, preceding femoral cortical bone loss and the development of bone mechanical deficits at the distal femur and femoral diaphysis. SCI animals also exhibited lower serum testosterone than SHAM, until 2-months post-surgery, and lower serum leptin throughout. Our moderate-severe contusion SCI model displayed rapid cancellous bone deterioration and more gradual cortical bone loss and development of whole bone mechanical deficits, which likely resulted from a temporal uncoupling of bone turnover, similar to the sequalae observed in the motor-complete SCI population. Low testosterone and/or leptin may contribute to the molecular mechanisms underlying bone deterioration after SCI.

Functional independence of persons with long-standing motor complete spinal cord injury in the Netherlands

Context/Objective: Since life expectancy of persons with spinal cord injury (SCI) has improved, it is relevant to know whether this group is able to maintain functional abilities many years after onset of SCI. Objectives of this study were (1) to examine associations between time since injury (TSI) and functional independence in persons with long-standing SCI and (2) to explore associations between functional independence and level of injury, comorbidities, mental health, waist circumference and secondary health conditions (SHCs).Design: TSI-stratified cross-sectional study. Strata were 10–19, 20–29 and 30+ years.Setting: Community.Participants: 226 persons with long-standing SCI. Inclusion criteria: motor complete SCI; age at injury 18–35 years; TSI ≥ 10 years; current age 28–65 years; wheelchair dependency.Interventions: Not applicable.Outcome measures: The Spinal Cord Independence Measure III (SCIM) was administered by a trained research assistant. Level of injury, comorbidities, mental health, waist circumference and SHCs were assessed by a rehabilitation physician.Results: Mean TSI was 23.6 (SD 9.1) years. No significant differences in SCIM scores were found between TSI strata. SCIM scores were lower for persons with tetraplegia, autonomic dysreflexia, hypotension, more than four SHCs and a high waist circumference. In linear regression analyses, TSI nor age was associated with the SCIM total score. Only level of injury (β = –0.7; P < .001) and waist circumference (β = –0.1; P = .042) were independent determinants (explained variance 55%).Conclusion: We found no association between TSI and functional independence in persons with long-standing motor complete SCI. This study confirms the possible effect of overweight on functional independence.

Variable Geometry Stair Ascent and Descent Controller for a Powered Lower Limb Exoskeleton

This paper describes a control approach for a lower limb exoskeleton intended to enable stair ascent and descent of variable geometry staircases for individuals with paraplegia resulting from spinal cord injury (SCI). To assess the efficacy of ascent and descent functionality provided by the control approach, the controller was implemented in a lower limb exoskeleton and tested in experimental trials on three subjects with motor-complete SCI on three staircases of varying geometry. Results from the assessments indicate that subjects were able to capably ascend and descend step heights varying from 7.6 to 16.5 cm without changing control settings; the controller provided for step time consistency highly representative of healthy subjects (9.2% variation in exoskeleton step time, relative to 7.7% variation in healthy subjects); and the exoskeleton provided peak joint torques on average 110% and 74% of the healthy-subject peak joint torques during stair ascent and descent, respectively. Subject perceived exertion during the stair ascent and descent activities was rated between “light” and “very light.”

Obesity cutoff values in Korean men with motor complete spinal cord injury: body mass index and waist circumference.

Cross-sectional. To determine the obesity cutoff values for body mass index (BMI) and waist circumference (WC) in Korean men with motor complete spinal cord injury (SCI). Tertiary level hospital in Seoul, Korea. BMI (kg/m2) was calculated and WC (cm) was measured in each participant in the supine position. Percentage of total body fat (%) was determined using whole-body dual-energy X-ray absorptiometry. Receiver operating characteristic curves were generated to determine the obesity cutoff values for BMI and WC. The optimal cutoff values were determined using the Youden index. Identified cutoff values were compared with those of 195 age- and BMI-matched men in the general population (GP), obtained from the Korea National Health and Nutrition Examination Survey. This study included 52 Korean men with motor complete SCI. A BMI of 20.2 kg/m2 and WC of 81.3 cm were identified as obesity cutoff values in Korean men with motor complete SCI. The area under the curve (AUC) was 0.928, specificity was 100%, and sensitivity was 84.8% according to the ROC curve of BMI for participants. AUC was 0.964, specificity was 100%, and sensitivity was 84.8% in the ROC curve of WC for participants. A BMI of 22.5 kg/m2 and WC of 85.5 cm were identified as obesity cutoff values in age- and BMI-matched men in the GP. The obesity cutoff values in Korean men with motor complete SCI that were determined in this study were lower than those of the Korean GP and western people with SCI.