Low-level Spinal Cord Injury Research Articles

Spinal Cord Injury Enhances Lung Inflammation and Exacerbates Immune Response After Acute Lung Injury.

The severity of spinal cord injury (SCI) is closely tied to pulmonary function, especially in cases of higher SCI levels. Despite this connection, the underlying pathological mechanisms in the lungs post-SCI are not well understood. Previous research has established a connection between disrupted sympathetic regulation and splenocyte apoptosis in high thoracic SCI, leading to pulmonary dysfunction. The aim of this study was to investigate whether mice with low-level SCI exhibit increased susceptibility to acute lung injury by eliciting systemic inflammatory responses that operate independently of the sympathetic nervous system. Here, we employed T9 contusion SCI and exposed mice to aerosolized lipopolysaccharide (LPS) to simulate lung inflammation associated with acute respiratory distress syndrome (ARDS). Twenty-four hours post-LPS exposure, lung tissues and bronchoalveolar lavage (BAL) fluid were analyzed. LPS markedly induced proinflammatory gene expression (SAA3, IRG1, NLRP3, IL-1beta, MCP-1) and cytokine release (IL-1beta, IL-6, MCP-1) in SCI mice compared to controls, indicating an exaggerated inflammatory response. Infiltration of Ly6G/C positive neutrophils and macrophages was significantly higher in SCI mice lungs post-LPS exposure. Interestingly, spleen size and weight did not differ between control and SCI mice, suggesting that T9 SCI alone does not cause spleen atrophy. Notably, bone-marrow-derived macrophages (BMDMs) from SCI mice exhibited hyper-responsiveness to LPS. This study demonstrated an increase in lung inflammation and immune responses subsequent to low-level T9 SCI, underscoring the widespread influence of systemic inflammation post-SCI, especially pronounced in specific organs like the lungs.

Decomposing the complexity of heart-rate variability by the multifractal–multiscale approach to detrended fluctuation analysis: an application to low-level spinal cord injury

Objective: While several studies have assessed autonomic cardiovascular control after a spinal cord lesion using heart-rate variability (HRV) indices in the frequency and time domains, complexity measures have rarely been used, even if detrended fluctuation analysis (DFA) appeared promising. Recent developments in DFA decompose the multifractal contributions using temporal scales. Our aim is to evaluate the potential of these new DFA tools, considering as an example application the decomposition of HRV complexity in individuals with spinal cord injury (SCI) at a low lesion level, for whom alterations in traditional indices are not expected. Approach: We enrolled 14 subjects with SCI with a lesion below the eleventh thoracic vertebra and 34 able-bodied (AB) controls. We recorded the R–R intervals (RRI) for 10 min in supine and sitting postures. We applied the multifractal–multiscale (MFMS) DFA to derive scale coefficients, α(q,τ), with function of the multifractal order q and scale τ, and evaluated a scale-coefficient dispersion index, αSD(τ), as the standard deviation of α(q,τ) over q. We calculated the RRI increments, their magnitude and sign, estimating the MFMS DFA coefficients for the series of magnitude αm(q,τ) and sign αs(q,τ). Main results: While sitting, differences between SCI and AB groups depended on q for coefficients 16 < τ < 32 s, so that αSD(τ) was lower in individuals with SCI at τ = 25 s. In the supine condition, short-term scales were greater in individuals with SCI for all q, and αSD(τ) did not differ between groups. Group differences were found in αs(q,τ) and not in αm(q,τ) or in traditional HRV indices. The surrogate analysis showed AB–SCI differences in linear HRV components at scales τ < 16 s and nonlinear components at larger scales. Significance: Complexity decomposition by DFA describes autonomic alterations in HRV in low-level paraplegia better than traditional indices, probably pointing out a loss of system complexity in the sitting posture and an impaired sympatho/vagal modulation in the supine position.

Manufacturing and analysis of carbon fiber knee ankle foot orthosis

Knee ankle foot orthoses (KAFOs) are used by paraplegia patients with low level spinal cord injury and having well control of the stem muscles. Four layers of carbon fiber with C- orthocryl lamination resin are used for manufacturing the knee ankle foot orthoses in this work. The mechanical properties of most of the components materials were estimated with the aid of fatigue and tensile test machines. Results of the tensile tests showed that the mechanical properties: yield stress, ultimate strength and modulus of elasticity were 92MPa, 105.7MPa and 2GPa respectively. The value of amidst pressure between the patient limb and the manufactured KAFO was measured using (F-socket) Mat scan sensor and these values of pressure were (663kPa) and (316kPa) for the thigh and calf regions respectively.

Hemodynamic Adaptations to Regular Exercise in People With Spinal Cord Injury.

ObjectiveTo investigate the real-time cardiovascular response to the progressive overload exercise in different levels of spinal cord injury (SCI), and to find out whether regular exercise has effect on these cardiovascular responses.MethodsThe study enrolled 8 able-bodied individuals in the control group plus 15 SCI subjects who were divided into two groups by their neurological level of injury: high-level SCI group (T6 or above) and low-level SCI group (T7 or below). Also, subjects were divided into exercise group and non-exercise group by usual exercise habits. We instructed the subjects to perform exercises using arm ergometer according to the protocol and checked plethysmograph for the real time assessment of blood pressure, heart rate, and cardiac output.ResultsSix subjects were included in high-level SCI group (3 cervical, 3 thoracic injuries), 9 subjects in low-level SCI group (9 thoracic injuries), and 8 able-bodied individuals in control group. During arm ergometer-graded exercise, mean arterial pressure (MAP) was significantly lower in high-level SCI subjects of non-exercise group, compared with high-level SCI subjects of exercise group. In addition, HR was significantly higher in low-level SCI group compared with control group.ConclusionThere are significant differences in mean arterial pressure of high-level SCI group according to usual exercise habits. We discovered that even in non-athlete high-level SCI, regular exercise can bring cardiac modulation through blood pressure control.

Application of Digital Volume Pulse Analysis in Patients with Spinal Cord Injury

Orthostatic hypotension is a common complication following spinal cord injury (SCI). However, an easy method to quantify the degree of vasomotor impairment below the level of injury is lacking. We postulated that SCI patients with different sympathetic reserves exhibited different digital volume pulse contours. Thirty-one patients with high chronic SCI (above the T6 neurologic level) and 28 low-level SCI patients (below T6) were recruited. Thirty-two age- and BMI-matched healthy participants were enrolled in the control group. All participants were positioned on a tilting table for five minutes in each of the following: supine rest (SR), 60-degree head-up tilt (HUT), and recovery to supine position. Digital volume pulse (DVP), heart rate variability (HRV), and blood pressure were measured. The reflection index (RI) was calculated as the amplitude of reflection wave divided by directly-transmitted wave. The RI ratio is the RI value in the fifth minute during the HUT position divided by RI in SR. Low frequency to high frequency power ratio (LF/HF), high frequency power (HFP), normalized low frequency power (LFn) and high frequency power (HFn) were recorded in HRV analysis. Our results revealed that patients with a higher level of injury had a reduced reflection wave of DVP in SR and HUT. High-level SCI patients also had a smaller RI ratio. Additionally, the increase of LF/HF during the transition from SR to HUT was attenuated in high SCI patients. However, the decrease of HF power was normally preserved in high SCI patients. We concluded that posture change alters the contour of the pulse wave, which is related to the level of injury. The RI ratio could be used to quantify the degree of vasoconstriction impairment below the injury level in SCI patients.

Remote inflammatory response in liver is dependent on the segmental level of spinal cord injury

Traumatic spinal cord injury (SCI) triggers a systemic inflammatory response (SIR) that contributes to a high incidence of secondary organ complications, particularly after a cervical or high-level thoracic injury. Because liver plays a key role in initiating and propagating the SIR, the aim of this study was to assess the effects that SCI at differing segmental levels has on the intensity of the inflammatory response in the liver. Using male Wistar rats, clip compression SCI was performed at the 4th thoracic (T4 SCI; high-level SCI) or the 12th thoracic (T12 SCI; low-level SCI) spinal cord segment. Sham-injured rats had a partial laminectomy, but no SCI. Leukocyte recruitment to the liver, hepatic blood flow, and hepatocellular injury/death were assessed using intravital microscopy and histology. Chemokine and cytokine concentrations were assessed in the liver. Outcomes were measured at 1.5 hours, 12 hours, and 24 hours after SCI. At 12 hours after injury, T4 SCI caused a threefold increase in hepatic leukocyte recruitment compared with T12 SCI (p < 0.05). T4 SCI induced 50% more hepatocyte injury than T12 SCI at 12 hours (p < 0.05). Hepatic blood flow decreased after SCI, but not after sham injury, and stayed decreased only after T4 SCI at 24 hours after injury. The T4 SCI-induced changes were accompanied by increases in the hepatic concentrations of interleukin-1β, leptin, interleukin 10, and cytokine-induced neutrophil chemoattractant-1 at 1.5 hours. Our findings indicate that traumatic SCI triggers an acute SIR that contributes to hepatocellular injury. SCI-induced remote injury/dysfunction to the liver appears to be transient and is more robust after an upper thoracic SCI compared with a lower thoracic SCI.

077 Cerebrovascular autoregulation during orthostatic stress after spinal cord injury

077 Cerebrovascular autoregulation during orthostatic stress after spinal cord injury

Heart Rate Variability And Complexity During Static Exercise In Active Individuals With Spinal Cord Injury

Spinal cord injury (SCI) adversely affects autonomic control of heart rate (HR) at rest and during dynamic exercise. This finding may be evidenced through differences in frequency domain measures of heart rate variability (HRV) and measures that quantify complexity. Many activities of daily living in persons with SCI require static contractions. Whether persons with SCI have cardiac autonomic dysfunction in response to static exercise is not well documented. PURPOSE: To examine whether cardiac autonomic modulation as measured by HRV and HR complexity at rest and during static handgrip exercise differs between active individuals with low-level SCI and active individuals without SCI. METHODS: HRV and HR complexity were examined in 20 active individuals with SCI below T6 (11 men, 9 women; 22 + 3 yrs) and 20 active individuals without SCI (12 men, 8 women; 26 + 4 yrs) during 3 minutes of rest and 2 minutes of static handgrip exercise at 30% of maximum isometric strength. Spectral decomposition of HRV was used to obtain total power, power in low frequency (LF) and high frequency (HF) ranges, and the LF/HF ratio. HF and LF/HF were taken as measures of vagal modulation and sympatho-vagal balance, respectively. HR complexity was quantified with sample entropy, a measure of signal irregularity. Between-group differences in all variables were evaluated using 2 × 2 factorial ANOVAs. RESULTS: HR at rest and during exercise was higher in participants with SCI than participants without SCI (P < 0.05), but it increased similarly in response to handgrip exercise for both groups. In response to exercise, total power and HF decreased (P < 0.05), LF/HF increased (P < 0.05), and sample entropy did not change. All of those variables did not differ between the groups, except for sample entropy which was lower (P < 0.05) at rest and during exercise in participants with SCI. CONCLUSION: The chronotropic response to handgrip exercise is similar between active individuals with and without SCI. For both groups, HR augmentation is due to vagal withdrawal and sympathoexcitation as evidenced by reductions in HF and increases in LF/HF. Frequency domain measures of HRV suggest similar autonomic control of HR at rest and during static handgrip exercise in active individuals with and without SCI. However, individuals with SCI show evidence of lower HR complexity.

Comparison of Heart Rate Response to Tennis Activity Between Persons With and Without Spinal Cord Injuries

The purpose of this study was to evaluate the ability of individuals with spinal cord injury (SCI) to reach a training threshold during on-court sport activity. Monitors collected heart rate (HR) data every 5 s for 11 wheelchair tennis players (WCT) with low paraplegia and 11 able-bodied controls matched on experience and skill level (ABT). Average HR was determined for time spent in practice (e.g., drills) and game (i.e., a competitive set), and the ability to surpass 50% peak HR (HRpeak) and 64% HRpeak in each condition was evaluated. Average exercise intensity (%HRpeak) was not significantly different between the groups during practice (M WCT = 68.18, SD = 7.53%, M ABT = 68.78, SD = 5.44%; t = .22, p = .83) or game (M WCT = 68.17, SD = .17%, M ABT = 71.55, SD = 4.75%; t = 1.12, p = .28). All participants averaged an intensity ≥ 50% HR-peak during practice and game, and the difference between group participants averaging an intensity ≥ 64% HRpeak was not significant during practice (ξ2 = .92, p = .34) or game (ξ2 = 3.85, p = .05). In terms of reaching a health and fitness training threshold during tennis, individuals with low-level SCI are similar to matched controls.

Impaired antibody synthesis after spinal cord injury is level dependent and is due to sympathetic nervous system dysregulation

Individuals with spinal cord injury (SCI) are highly susceptible to infection. This post-traumatic immune suppression is thought to occur via alterations in sympathetic nervous system (SNS) or hypothalamic–pituitary–adrenal (HPA) axis function. Normally, the HPA axis and SNS help coordinate proper immune function. After SCI, the HPA axis becomes activated and descending input to sympathetic preganglionic neurons (SPNs) is impaired. Because lymphoid organs are innervated by SPNs distributed throughout the thoracolumbar spinal cord, we predicted level-dependent immune suppression after SCI due to activation of the HPA axis and loss of descending input to SPNs. We tested this hypothesis by measuring indices of HPA (circulating corticosterone; CORT) and SNS function (norepinephrine (NE) in spleen) as well as antigen-specific antibody synthesis against an exogenous non-self protein following high- or low-level SCI. Using a mid-thoracic (T9) spinal contusion injury model, we found that CORT was elevated after SCI with aberrant patterns of diurnal CORT synthesis evident through at least the first 24 h post-injury. However, splenic NE and antibody synthesis were similar to uninjured controls. Injury severity did not change these parameters. Indeed, CORT, NE and antibody synthesis were similar after T9 contusion or transection SCI. In contrast, high-level SCI (T3) caused sustained increases in CORT and splenic NE along with impaired antibody synthesis and elevated splenocyte apoptosis. The immunosuppressive effects of T3 SCI were caused by NE acting at β2-adrenergic receptors (β2AR) and could be reversed using β2AR blockers. Interestingly, impaired antibody after T3 SCI could be mimicked after T9 SCI with a β2AR agonist. These data illustrate the immunosuppressive effects of the SNS after high-level SCI and indicate that immune deficits may be overcome using β-blockers.

Biomechanical analysis of a posterior transfer maneuver on a level surface in individuals with high and low-level spinal cord injuries

Objective. The purpose of this study was to determine the movement patterns and the muscular demand during a posterior transfer maneuver on a level surface in individuals with spinal cord injuries. Design. Six participants with high-level spinal cord injury (C7 to T6) were compared to five participants with low-level spinal cord injury (T11 to L2) with partial or complete control of abdominal musculature. Background. Developing an optimal level of independence for transfer activities figures among the rehabilitation goals of individuals with spinal cord injury. There has been no biomechanical study which specifically describes the posterior transfer maneuver. Methods. Tridimensional kinematics at the elbow, shoulder, head and trunk, as well as surface electromyographic data of the biceps, triceps, anterior deltoid, posterior deltoid, pectoralis major, latissimus dorsi, trapezius and rectus abdominus muscles were recorded during the posterior transfer. To quantify the muscular demand, the electromyographic data were amplitude normalized to the peak value obtained from maximum voluntary contractions. The transfer was divided into pre-lift, lift, and post-lift phases for analysis. Results. The duration of the lift phase was significantly shorter ( P<0.05) for the high-level spinal cord injury (1.24; SD, 0.37 s) when compared to the low-level spinal cord injury (1.74; SD, 0.39 s). The patterns and magnitudes of the angular displacements were found similar between groups ( P values: 0.45–0.98). However, the high-level spinal cord injury initiated the task from a forward flexed posture, whereas the low-level spinal cord injury adopted an almost upright alignment of the trunk. Higher muscular demands were calculated for all muscles among high-level spinal cord injury participants during the transfer when compared to the low-level spinal cord injury. However, only the anterior deltoid (high level = 92.4%; low level = 34.2%) and the pectoralis major (high level = 109.8%; low level = 25.6%) reached statistical significance during the lift phase. Conclusions. Participants with high-level spinal cord injury presented different movement characteristics and higher muscular demands during the posterior transfer than low-level spinal cord injury ones. This is probably to compensate for the additional trunk and upper limb musculature impairment. Relevance The findings of this study may help to develop guidelines of specific strengthening programs for the thoracohumeral, scapulothoracic and shoulder muscles designed to restore optimal transfer capacity in individuals with spinal cord injury. Furthermore, innovative rehabilitation programs targeting the ability to control the trunk could be beneficial for these individuals.

Baroreceptor sensitivity response to phase IV of the Valsalva maneuver in spinal cord injury.

Due to the increased prevalence of ischemic heart disease and hypertension reported in individuals with chronic spinal cord injury (SCI), we investigated whether subjects with low level SCI (paraplegia), without apparent evidence of coronary artery disease, exhibit normal baroreceptor and autonomic function. Eighteen males participated in this study: seven normotensive with paraplegia, five hypertensive with paraplegia and six normotensive non-SCI controls. The Valsalva maneuver was performed by maintaining a pressure of 40 mmHg over 15 s and R-R intervals (RRI) and arterial blood pressure were measured continuously. Phase IV of the Valsalva maneuver was determined by linear regression analysis between RRI and systolic pressure, with a final slope calculated. The power spectra for RRI and blood pressure variability parameters were also analyzed, in addition to the index alpha, a frequency domain estimate of the overall gain in baroreceptor control of the RRI-arterial blood pressure. The normotensive subjects with paraplegia were found to have an impaired baroreceptor response when compared with age-matched, non-SCI controls. In addition, the levels of both the low frequency and high frequency spectral components of RRI and the index alpha were reduced in these individuals at rest. These cumulative findings strongly suggest that the integrity of the sinoaortic baroreceptors, as well as efferent parasympathetic function, may be compromised in otherwise apparently healthy individuals with chronic paraplegia.