Low-frequency fatigue in individuals with spinal cord injury

BACKGROUND/OBJECTIVE: This study examined magnitude and recovery of low-frequency fatigue (LFF) in the quadriceps after electrically stimulated contractions in spinal cord-injured (SCI) and able-bodied subjects. SUBJECTS: Nine SCI (ASIA A-C, levels C5-T9, injured 13.6 +/- 12.2 years) and 9 sedentary able-bodied subjects completed this study. METHODS: Fatigue was evoked in 1 thigh, and the nonfatigued leg served as a control. The fatigue test for able-bodied subjects lasted 15 minutes. For SCI, stimulation was adjusted so that the relative drop in force was matched to the able-bodied group. Force was assessed at 20 (P20) and 100 Hz (P100), and the ratio of P20/P100 was used to evaluate LFF in thighs immediately after, at 10, 20, and 60 minutes, and at 2, 4, 6, and 24 hours after a fatigue test. RESULTS: The magnitude of LFF (up to 1 hour after fatigue) was not different between able-bodied and patients with SCI. However, recovery of LFF over 24 hours was greater in able-bodied compared with patients with SCI in both the experimental (P < 0.001) and control legs (P < 0.001). The able-bodied group showed a gradual recovery of LFF over time in the experimental leg, whereas the SCI group did not. CONCLUSIONS: These results show that individuals with SCI are more susceptible to LFF than able-bodied subjects. In SCI, simply assessing LFF produced considerable LFF and accounted for a substantial portion of the response. We propose that muscle injury is causing the dramatic LFF in SCI, and future studies are needed to test whether "fatigue" in SCI is actually confounded by the effects of muscle injury.     

Platform Presentations 1–36

Abstract

Objective

Stiffness and viscosity represent passive resistances to joint motion related with the structural properties of the joint tissue and of the musculotendinous complex. Both parameters can be affected in patients with spinal cord injury (SCI). The purpose of this study was to measure passive knee stiffness and viscosity in patients with SCI with paraplegia and healthy subjects using Wartenberg pendulum test.

Design

Non-experimental, cross-sectional, case–control design.

Setting

An outpatient physical therapy clinic, University of social welfare and Rehabilitation Science, Iran.

Patients

A sample of convenience sample of 30 subjects participated in the study. Subjects were categorized into two groups: individuals with paraplegic SCI (n = 15, age: 34.60 ± 9.18 years) and 15 able-bodied individuals as control group (n = 15, age: 30.66 ± 11.13 years).

Interventions

Not applicable.

Main measures

Passive pendulum test of Wartenberg was used to measure passive viscous-elastic parameters of the knee (stiffness, viscosity) in all subjects.

Results

Statistical analysis (independent t-test) revealed significant difference in the joint stiffness between healthy subjects and those with paraplegic SCI (P = 0.01). However, no significant difference was found in the viscosity between two groups (P = 0.17). Except for first peak flexion angle, all other displacement kinematic parameters exhibited no statistically significant difference between normal subjects and subjects with SCI.

Conclusions

Patients with SCI have significantly greater joint stiffness compared to able-bodied subjects.     

Incidence And Clinical Correlates Of Increased Serum Creatine Kinase Levels In Persons With Spinal Cord Injury

Abstract

Background: Elevated plasma levels of creatine kinase (CPK) are found in various neuromuscular conditions as a result of muscle damage and necrosis. Elevated CPK has also been described in elite wheelchair athletes and in able-bodied individuals after strenuous exercise.

Methods: The incidence of elevated CPK in individuals with spinal cord injury (SCI) has not been well established. We reviewed laboratory data from 581 individuals with chronic SCI.

Results: Most individuals with SCI (73.3%) had CPK values within 95% confidence intervals for able-bodied individuals. The highest levels were seen in African Americans (21% had CPK values > 95 confidence intervals for able-bodied individuals). Significant associations between CPK and the following independent variables were identified: impairment group, gender, duration of injury, body mass index, and ethnic group. Multiple regression analysis revealed significant correlations between CPK and oxygen consumption (beta .37, P < .01) in 32 individuals who performed the exercise test.

Conclusions: These findings are important for clinicians evaluating symptoms of fatigue and myopathy in individuals with SCI.     

Pulse Wave Velocity for Assessment of Arterial Stiffness Among People With Spinal Cord Injury: A Pilot Study

Background/Objective: The most significant complication and leading cause of death for people with spinal cord injury (SCI) is coronary artery disease (CAD). It has been confirmed that aortic pulse wave velocity (PVW) is an emerging CAD predictor among able-bodied individuals. No prior study has described PWV values among people with SCI. The objective of this study was to compare aortic (the common carotid to femoral artery) PWV, arm (the brachial to radial artery) PVW, and leg (the femoral to posterior tibial artery) PVW in people with SCI (SCI group) to able-bodied controls (non-SCI group).

Methods: Participants included 12 men with SCI and 9 non-SCI controls matched for age, sex, height, and weight. Participants with a history of CAD or current metabolic syndrome were excluded. Aortic, arm, and leg PVW was measured using the echo Doppler method.

Results: Aortic PVW (mean ± SD) in the SCI group (1,274 ± 369 cm/s) was significantly higher (P < 0.05) than in the non-SCI group (948 ± 110 cm/s). There were no significant between-group differences in mean arm PVW (SCI: 1,152 ± 193 cm/s, non-SCI: 1,237 ± 193 cm/s) or mean leg PVW (SCI: 1,096 ± 1 73 cm/s, non-SCI: 994 ±178 cm/s) values.

Conclusions: Aortic PVW was higher among the SCI group compared with the non-SCI group. The higher mean aortic PVW values among the SCI group compared with the non-SCI group indicated a higher risk of CAD among people with SCI in the absence of metabolic syndrome.     

Resting energy expenditure in male athletes with a spinal cord injury

Objective: To investigate whether there are differences in the resting energy expenditure (REE) and body composition of athletes with a spinal cord injury (SCI) compared to active able-bodied controls.

Design: In this cross sectional study, male athletes with a SCI were compared to active able-bodied controls matched for age, stretch stature and body mass. In addition, the accuracy of standard REE prediction equations in estimating REE was assessed.

Participants: Seven male wheelchair athletes with a SCI and six matched active able-bodied controls volunteered to participate.

Outcome measures: REE was measured using indirect calorimetry and estimated using population-specific prediction equations. Body composition (lean tissue mass, fat mass and bone mineral content) was measured by dual energy X-ray absorptiometry (DXA).

Results: While absolute and adjusted REE in the athletes with SCI was lower than controls, this difference was not significant (P?=?0.259). When adjusted for lean tissue mass (LTM), REE was significantly higher (P?=?0.038) in the athletes with SCI compared to the controls (146 ± 29kJ/kg LTM vs. 125 ± 8kJ/kg LTM). LTM was significantly lower in the athletes with SCI (44.35 ± 6.98?kg) compared to the able-bodied controls (56.02 ± 4.93?kg; P < 0.01). The differences between predicted and measured REE in the athletes with SCI were not statistically significant (except for the Owen equation), however there was no significant correlation between the measures.

Conclusion: This suggests that existing prediction equations used to estimate energy requirements may require modification for athletes with SCI.     

Measuring Tissue Perfusion During Pressure Relief Maneuvers: Insights Into Preventing Pressure Ulcers

Abstract

Background/Objective: To study the effect on tissue perfusion of relieving interface pressure using standard wheelchair pushups compared with a mechanical automated dynamic pressure relief system.

Design: Repeated measures in 2 protocols on 3 groups of subjects.

Participants: Twenty individuals with motor-complete paraplegia below T4, 20 with motor-complete tetraplegia, and 20 able-bodied subjects.

Methods: Two 1-hour sitting protocols: dynamic protocol, sitting configuration alternated every 10 minutes between a normal sitting configuration and an off-loading configuration; wheelchair pushup protocol, normal sitting configuration with standard wheelchair pushup once every 20 minutes.

Main Outcome Measures: Transcutaneous partial pressures of oxygen and carbon dioxide measured from buttock overlying the ischial tuberosity and interface pressure measured at the seat back and buttocks. Perfusion deterioration and recovery times were calculated during changes in interface pressures.

Results: In the off-loading configuration, concentrated interface pressure during the normal sitting configuration was significantly diminished, and tissue perfusion was significantly improved. Wheelchair pushups showed complete relief of interface pressure but incomplete recovery of tissue perfusion.

Conclusions: Interface pressure analysis does not provide complete information about the effectiveness of pressure relief maneuvers. Measures of tissue perfusion may help establish more effective strategies. Relief achieved by standard wheelchair pushups may not be sufficient to recover tissue perfusion compromised during sitting; alternate maneuvers may be necessary. The dynamic seating system provided effective pressure relief with sustained reduction in interface pressure adequate for complete recovery of tissue perfusion. Differences in perfusion recovery times between subjects with spinal cord injury (SCI) and controls raise questions about the importance of changes in vascular responses to pressure after SCI.     

Fibrinogen Metabolism in Patients With Spinal Cord Injury

Abstract

Background/Objective: Deep venous thrombosis and pulmonary thromboembolism are common within weeks of spinal cord injury (SCI) but clinically uncommon in the chronically paralyzed. Fibrinogen half-life (FHL) and fibrin uptake of the legs (FUT), as indicators of an active thrombotic process, have been used to test this clinical impression.

Methods: Data from the use of autologous preparations of radioiodinated fibrinogen to determine FHL and FUT in 17 men paralyzed at cervical (6), thoracic (10), and lumbar levels (1), at ASIA grades A (15) and C (2) in 1974 to 1976 were reviewed. Group A consisted of 12 subjects 29 ± 8 years of age and paralyzed 1week to 5 months (median, 1 month). Group B consisted of 5 subjects 46 ± 17 years of age and paralyzed 24 to 96 months (median, 36 months). Group B subjects were older and paralyzed longer than Group A. Group C consisted of 4 able-bodied control subjects enrolled at the same time for FHL studies, and these subjects were 34 to 38 years of age.

Results: FHL was 61 ± 14 hours for all SCI subjects and 95 ± 23 hours for Group C (P = 0.001). Group A FHL was 59 ± 16 hours, and FUT was positive in 8 of 12 subjects. Group B FHL was 66 ±7 hours, and FUT was positive in 3 of 4 subjects (1 FUT not done; P= 0.30 and 1.0, respectively).

Conclusions: Fibrinogen metabolism was abnormal in patients with acute SCI at high risk for pulmonary thromboembolism (PE) but continued to be abnormal beyond the high risk period for PE, possibly because of the greater age of the patients in the long-term paralysis group.     

Acute Effects Of Locomotor Training on Overground Walking Speed and H-Reflex Modulation in Individuals with Incomplete Spinal Cord Injury

Abstract

Objective: The purpose of this study was to assess the effect of a single bout of a locomotor-training paradigm on overground walking speed and H-reflex modulation of individuals with incomplete spinal cord injury (SCI).

Methods: Self-selected and maximum walking speeds and soleus H-reflexes (H/M ratios) during standing and stance and swing phases of walking (self-selected velocity) were obtained from 4 individuals with American Spinal Injury Association impairment classification D. Data were collected immediately before and after a single bout of locomotor training with body weight support on a treadmill. The pretraining H/M ratios of the SCI subjects were also compared with values from 4 able-bodied subjects who did not receive the intervention. Maximum H/M ratios while standing and during midstance and midswing phases of overground walking were considerably greater in the SCI subjects than in the control subjects.

Results: After the single bout of training, self-selected and maximum overground walking speeds of the subjects with SCI increased by 26% and 25%, respectively. Furthermore, H-reflexes were significantly more depressed in the SCI subjects during overground walking (28% less during stance, 34% less during swing).

Conclusions: Although preliminary, these findings indicate that a single bout of locomotor training produced immediate increases in walking velocity and acute neurophysiologic changes in individuals with incomplete SCI.     

Dietary intake and adherence to the 2010 Dietary Guidelines for Americans among individuals with chronic spinal cord injury: A pilot study

Abstract

Objective

To investigate dietary intake and adherence to the 2010 Dietary Guidelines for Americans in individuals with chronic spinal cord injury (SCI) and able-bodied individuals.

Design

A pilot study of dietary intake among a sample of individuals with SCI >1 year ago from a single site compared with able-bodied individuals.

Participants/methods

One hundred black or white adults aged 38–55 years old with SCI >1 year and 100 age-, sex-, and race-matched adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Dietary intake was assessed by the CARDIA dietary history. Linear regression analysis was used to compare dietary intake between the subjects with SCI and those enrolled in the CARDIA study. Further, adherence to the 2010 Dietary Guidelines for dairy, fruits, and vegetables, and whole-grain foods was assessed.

Results

Compared with CARDIA participants, participants with SCI consumed fewer daily servings of dairy (2.10 vs. 5.0, P < 0.001), fruit (2.01 vs. 3.64, P = 0.002), and whole grain foods (1.20 vs. 2.44 P = 0.007). For each food group, fewer participants with SCI met the recommended servings compared with the CARDIA participants. Specifically, the participants with SCI and in CARDIA who met the guidelines were, respectively: dairy, 22% vs. 54% (P < 0.001), fruits and vegetables 39% vs. 70% (P = 0.001), and whole-grain foods 8% vs. 69.6% (P = 0.001).

Conclusions

Compared with able-bodied individuals, SCI participants consumed fewer daily servings of fruit, dairy, and whole grain foods than proposed by the 2010 Dietary Guideline recommendations. Nutrition education for this population may be warranted.     

Apolipoprotein E s4 Allele and Outcomes of Traumatic Spinal Cord Injury

Abstract

Background/Objective: To test the hypothesis that apolipoprotein E (APOE) polymorphisms are associated with outcomes after spinal cord injury (SCI).

Methods: Retrospective cohort study, from rehabilitation admission to discharge.

Participants: Convenience sample of 89 persons with cervical SCI (C3-C8) treated from 1995 through 2003. Median age was 30 years (range 14-70); 67 were male (75%) and 83 were white (93%).

Main Outcome Measures: American Spinal Injury Association (ASIA) motor and sensory scores, ASIA Impairment Scale (AIS), time from injury to rehabilitation admission, and length of stay (LOS) in rehabilitation.

Results: Subjects with an APOE s4 allele (n = 15; 17%) had significantly less motor recovery during rehabilitation than did individuals without an s4 allele (median 3.0 vs 5.5; P < 0.05) and a longer rehabilitation LOS (median 106 vs 89 days; P = 0.04), but better sensory-pinprick recovery (median 5.0 vs 2.0; P = 0.03). There were no significant differences by APOE s4 allele status in sensory-light touch recovery, likelihood of improving AIS Grade, or time from injury to rehabilitation admission.

Conclusions: APOE ε4 allele was associated with differences in neurological recovery and longer rehabilitation LOS. Genetic factors may be among the determinants of outcome after SCI and warrant further study.     

Effects of Intermittent Pneumatic Compression on Leg Vascular Function in People with Spinal Cord Injury: A Pilot Study

Objective: The purpose of this pilot study was to determine whether 60 mins of intermittent pneumatic compression therapy (IPC) could acutely increase leg blood flow-induced shear stress and enhance vascular endothelial function in persons with spinal cord injury (SCI).

Design: Pretest with multiple posttests, within subject randomized control design.

Setting: University of Southern Mississippi, Spinal Cord Injury Research Program within the School of Kinesiology, recruiting from the local community in Hattiesburg, Jackson, and Gulfport, MS.

Participants: Eight adults with SCI (injury level: T3 and below; ASIA class A-C; age: 41±17 yrs).

Interventions: A 60-min IPC session was performed in one leg (experimental leg; EXP), with the other leg serving as a control (CON).

Outcomes Measures: Posterior-tibial artery shear rate (Doppler-ultrasound) was examined at rest, and at 15 and 45 mins during IPC. Endothelial function was assessed using the flow-mediated dilation (FMD) technique, before and after IPC.

Results: Resting FMD (mm) was similar between legs at rest. A two-way repeated measures ANOVA (leg x time) revealed that during IPC, peak shear rate increased in the EXP leg (215±137 to 285±164 s^?1 at 15 mins; +39±29%, P?=?0.03), with no change occurring in the CON. In addition, FMD significantly increased in the EXP leg (Pre IPC: 0.36±0.14 vs. Post IPC: 0.47±0.17 mm; P?=?0.011, d?=?0.66), with no change occurring in the CON leg.

Conclusion: These preliminary findings suggests that IPC therapy may acutely increase leg shear stress within 15 mins, with a resultant moderate-large improvement in vascular endothelial function after 60 mins in people with SCI.     

The combined effect of granulocyte-colony stimulating factor (G-CSF) treatment and exercise in rats with spinal cord injury

Objective: To identify that the combined G-CSF and treadmill exercise is more effective in functional recovery after spinal cord injury (SCI).

Design: Rats were divided into 4 groups: a SCI group treated with G-CSF (G-CSF group, n?=?6), a SCI group treated with treadmill exercise plus G-CSF (G-CSF/exercise group, n?=?6), a SCI group with treadmill exercise (exercise group, n?=?6), and a SCI group without treatments (control group, n?=?6). We performed laminectomy at the T8–10 spinal levels with compression injury of the spinal cord in all rats. G-CSF (20?μg/ml) was administered intraperitoneally for 5 consecutive days after SCI in G-CSF and G-CSF/exercise groups. From one week after surgery, animals in G-CSF/exercise and exercise groups received 30?min of exercise 5 days per week for 4 weeks. Functional recoveries were assessed using the Basso, Beattie, and Bresnahan (BBB) scale and the inclined plane test. Five weeks after SCI, hematoxylin and eosin staining for cavity size and immunohistochemistry for glial scar formation and neuro-regeneration factor expression were conducted.

Setting: Inha University School of medicine, Incheon, Korea

Results: Rats in G-CSF/exercise group showed the most effective functional recovery in the BBB scale and the inclined plane test, and spinal cord cavity size by injury were the smallest, and immunohistochemistry revealed expression of higher BDNF (brain-derived neurotrophic factor) and VEGF (vascular endothelial growth factor) and lower GFAP (glial fibrillary acidic protein) than others.

Conclusion: Combined treatment provided more effective neuroplasty and functional recovery than individual treatments.     

Sexual abuse in people with spinal cord damage

Objectives: There are few studies of sexual abuse in people with spinal cord damage (SCD). Objective of this study was to determine the prevalence and impact of sexual abuse in SCD.

Design: Survey (web and paper-based).

Setting: Australia (August 2013–June 2014).

Participants: People with SCD (n?=?136); able-bodied controls (n?=?220).

Interventions: None.

Outcome measures: Spinal Cord Injury Secondary Conditions Scale, International SCI Quality of Life Basic Dataset, and the Physical Disability Sexual and Body Esteem scale. Questions regarding demographic and clinical characteristics, sex, sexual orientation, relationship status, disability, sexual interest and satisfaction, and sexual abuse.

Results: Most SCD participants were male (n?=?92, 67%), the average age was 46 years (SD?=?14) and they were median of 11 years (IQR 4–21) after SCD. Of these, 19% (n?=?26) reported sexual abuse. Females were much more likely to report being abused (odds ratio 3.3, 95%CI 1.5–7.4; χ ²=10.9, P?=?0.001). Participants reporting sexual abuse were younger (P?=?0.01) and more likely to have been abused before their SCD (69%). There was no significant difference between those with SCD who reported sexual abuse and those who did not regarding their quality of life as a whole (P?>?0.1). There was no difference regarding the reporting of sexual abuse between able-bodied and those with SCD (P?=?0.1).

Conclusion: Sexual abuse was relatively common and was not associated with an adverse relationship with the covariates assessed. Further research is needed to better determine the prevalence of sexual abuse in people with SCD and its impact.     

The relationship between the postprandial lipemic response and lipid composition in persons with spinal cord injury

Abstract

Objective

To determine the influence of lipid concentration, lipid particle size, and total abdominal fat (TAF) on postprandial lipemic response (PPLr) in persons with spinal cord injury (SCI).

Methods

Thirty-five persons with SCI (17 paraplegia, 18 tetraplegia) and 18 able-bodied (AB) individuals participated. Following a 10-hour fast, blood was drawn for lipids, apolipoprotein (apo) A1 and B concentrations, and low-density (LSP) and high-density (HSP) lipoprotein particle sizes. A high-fat milkshake was consumed (～1.3 g fat/kg). Blood was drawn at 2, 4, and 6 hours to determine PPLr, (triglyceride (TG) area under the curve). TAF and visceral (VF) fat were measured by ultrasonography; total body fat (TBF) by dual-energy X-ray absorptiometry. Differences between the groups were determined by independent sample t-tests. Pearson correlation coefficients determined the relationship among PPLr and lipids, and TAF.

Results

There were no significant differences in fasting TG, low-density lipoprotein (LDL), apoB, TAF, or PPLr values between the groups. In SCI, PPLr significantly correlated with: apoB (r = 0.63, P < 0.01, LSP (r = 0.57, P < 0.01), and TAF (r = 0.36, P < 0.01). After controlling for age and duration of injury, PPLr significantly correlated with apoB (r = 0.66, P = 0.001), TBF (r = 0.45, P = 0.03), VF (r = 0.66, P = 0.02), and TAF (r = 0.56, P = 0.007).

Conclusions

Although concentrations of LDL cholesterol and apoB were not different between SCI and AB groups, LSP, apoB, and TAF correlated with PPLr in persons with SCI. ApoB was associated with a greater PPLr in those with motor complete SCI, after controlling for age and duration of injury.     

The effects of whole body vibration on pulse wave velocity in men with chronic spinal cord injury

Objective: A pilot study to evaluate the therapeutic potential of 40 weeks of passive standing with whole body vibration (PS-WBV) on central and peripheral arterial stiffness among men with chronic spinal cord injury (SCI).

Methods: Consenting participants were pre-screened to ensure safe participation. Fifteen individuals with chronic SCI were enrolled to participate in PS-WBV sessions three times per week for 40 weeks on a modified WAVE platform custom-fitted with an EASYStand 5000. Knee angle was set at 160°, and vibration parameters were 45Hz frequency and 0.7mm displacement. Each 45-minute session of PS-WBV training was intermittent (60 seconds on and 120 seconds off). Aortic and leg pulse wave velocity (PWV) was measured at baseline, mid-point (20 weeks) and exit (40 weeks).

Results: Nine males (age 41±11 years, American Spinal Injury Association Impairment Scale A-D, neurological level of injury T4-T10, years post-injury 12±8 years) completed the intervention. Aortic PWV was collected on n=7 at exit, and leg PWV was collected on n=6 at exit. No changes over time were found for either aortic PWV (P?=?0.46) or leg PWV (P?=?0.54). One possible study-related serious adverse event occurred during study intervention: the development of a grade III pressure sore on the right proximal anterior shin (n=1).

Conclusion: Forty weeks of PS-WBV in adults with SCI did not result in an observable change in arterial stiffness.     

Invited Review Carbohydrate And Lipid Metabolism In Chronic Spinal Cord Injury

Abstract

Background: Abnormalities of carbohydrate and lipid metabolism are more common in the spinal cord injury (SCI) population than in the able-bodied population. This is an important consideration in the long-term care of individuals with SCI.

Design: Literature review.

Findings: When compared with the able-bodied population, people with SCI are more likely to have oral carbohydrate intolerance, insulin resistance, elevated low-density lipoprotein cholesterol, and reduced high-density lipoprotein cholesterol, associated with increased prevalences of diabetes mellitus and cardiovascular disease.

Conclusions: Because of increased risk factors for diabetes mellitus and heart disease in individuals with SCI, modifiable risk factors should be addressed, eg, obesity, inactivity, dietary factors, and smoking. To reduce mortality and morbidity associated with these risk factors, periodic screening for carbohydrate and lipid abnormalities is recommended, with appropriate therapeutic interventions.     

Comparison of Lung Volume Measurements In Individuals With Spinal Cord Injury By Two Different Methods

Abstract

Background/Objective: Few detailed studies have been performed among subjects with spinal cord injury (SCI) using whole body plethysmography for measurement of static lung volumes. Because abdominal gas volumes and respiratory patterns among subjects with varying Ieveis of SCI may differ significantly from able-bodied individuals, methodological concerns related to this technique could conceivably Iead to inaccuracies in lung volume measurements. The purpose of this study was to compare lung volume parameters obtained by whole body plethysmography with those determined by the commonly used nitrogen washaut technique among individuals with SCI.

Participants: Twenty-nine clinically stable men, 14 with chronic tetraplegia (injury C4-C7) and 15 with paraplegia (injury below T5) participated in the study.

Methods: Lung volumes were obtained using whole body plethysmography and the open-circuit nitrogen washout technique. Within both study groups, data were evaluated by the paired Student’st test and by determination of correlation coefficients.

Results: No statistically significant differences for any lung volume parameter were found within either group. ln subjects with tetraplegia on paraplegia, respectively, strong correlation coefficients were found for measurements of totallung capacity (.8 6 and .97), functional residual capacity (.87 and .96), and residual volume (.77 and .85).

Conclusion: These findings indicate that body plethysmography is a valid technique for determining lung volumes among subjects with SCI. Because airway resistance measurements can also be obtained du ring same study sessions for assessment of airway caliber and bronchial responsiveness, body plethysmography is a useful tool for examining multiple aspects of pulmonary physiology in this population.     

Effect of acute intermittent hypoxia on motor function in individuals with chronic spinal cord injury following ibuprofen pretreatment: A pilot study

Introduction: Acute intermittent hypoxia (AIH) enhances lower extremity motor function in humans with chronic incomplete spinal cord injury (SCI). AIH-induced spinal plasticity is inhibited by systemic inflammation in animal models. Since SCI is frequently associated with systemic inflammation in humans, we tested the hypothesis that pretreatment with the anti-inflammatory agent ibuprofen enhances the effects of AIH.

Methods: A randomized, double-blinded, placebo-controlled crossover design was used. Nine adults (mean age 51.1?±?13.1 years) with chronic motor-incomplete SCI (7.7?±?6.3 years post-injury) received a single dose of ibuprofen (800?mg) or placebo, 90 minutes prior to AIH. For AIH, 9% O₂ for 90 seconds was interspersed with 21% O₂ for 60 seconds. Maximal voluntary ankle plantar flexion isometric torque was assessed prior to, and at 0, 30, and 60 minutes post-AIH. Surface electromyography (EMG) of plantar flexor muscles was also recorded.

Results: Torque increased significantly after AIH at 30 (P?=?0.007; by ～20%) and 60 (P?2?=?0.17, P?2?=?0.17, P?Conclusions: AIH systematically increased lower extremity torque in individuals with chronic incomplete SCI, but there was no significant effect of ibuprofen pretreatment. Our study re-confirms the ability of AIH to enhance leg strength in persons with chronic incomplete SCI.     

Transmission of low-intensity vibration through the axial skeleton of persons with spinal cord injury as a potential intervention for preservation of bone quantity and quality

Abstract

Background/objective: Persons with spinal cord injury (SCI) develop marked bone loss from paralysis and immobilization. Low-intensity vibration (LIV) has shown to be associated with improvement in bone mineral density in post-menopausal women and children with cerebral palsy. We investigated the transmissibility of LIV through the axial skeleton of persons with SCI as an initial approach to determine whether LIV may be used as a clinical modality to preserve skeletal integrity.

Methods: Transmission of a plantar-based LIV signal (0.27 ± 0.11 g; 34 Hz) from the feet through the axial skeleton was evaluated as a function of tilt-table angle (15, 30, and 45°) in seven non-ambulatory subjects with SCI and ten able-bodied controls. Three SCI and five control subjects were also tested at 0.44 ± 0.18 g and 34 Hz. Transmission was measured using accelerometers affixed to a bite-bar to determine the percentage of LIV signal transmitted through the body.

Results: The SCI group transmitted 25, 34, and 43% of the LIV signal, and the control group transmitted 28, 45, and 57% to the cranium at tilt angles of 15, 30, and 45°, respectively. No significant differences were noted between groups at any of the three angles of tilt.

Conclusion: SCI and control groups demonstrated equivalent transmission of LIV, with greater signal transmission observed at steeper angles of tilt. This work supports the possibility of the utility of LIV as a means to deliver mechanical signals in a form of therapeutic intervention to prevent/reverse skeletal fragility in the SCI population.     

Altered resting hemodynamics in lower-extremity arteries of individuals with spinal cord injury

Abstract

Objective

To investigate lower-extremity arterial hemodynamics in individuals with spinal cord injury (SCI). We hypothesized that oscillatory shear index would be altered and resting mean shear would be higher in the lower-extremity arteries of SCI.

Research

Cross-sectional study of men and women with SCIs compared to able-bodied controls.

Subjects

Subjects included 105 ages 18–72 years with American Spinal Injury Association (ASIA) Impairment Scale grades A, B, or C and injury duration at least 5 years. Subjects were matched for age and cardiovascular disease risk factors with 156 able-bodied controls.

Methods

Diameter and blood velocity were determined with subject at rest via ultrasound in superficial femoral, popliteal, brachial, and carotid arteries. Mean shear, antegrade shear, retrograde shear, and oscillatory shear index were calculated.

Results

Oscillatory shear index was lower in SCI compared to controls for superficial femoral (0.16 ± 0.10 vs. 0.26 ± 0.06, P < 0.01) and popliteal arteries (0.20 ± 0.11 vs. 0.26 ± 0.05, P < 0.01). Mean shear rate was higher in SCI compared to controls for superficial femoral (43.54 ± 28.0 vs. 20.48 ± 13.1/second, P < 0.01) and popliteal arteries (30.43 ± 28.1 vs. 11.68 ± 9.5/second, P < 0.01).

Conclusions

The altered resting hemodynamics in SCI are consistent with an atheroprotective hemodynamic environment.