Patient Perceptions and Clinical Assessments of Cardiometabolic Disease After Subacute Spinal Cord Injury

OBJECTIVES

To investigate the effectiveness of health care team communication regarding cardiometabolic disease (CMD) risk factors with patients with subacute spinal cord injury (SCI).

DESIGN

Multi-site prospective cross-sectional study.

SETTING

Five National Institute on Disability, Independent Living, and Rehabilitation Research Model SCI Rehabilitation Centers.

PARTICIPANTS

Ninety-six patients with subacute SCI, aged 18-70 years, with SCI (neurologic levels of injury C2-L2, American Spinal Injury Association Impairment Scale grades A-D), and enrolled within 2 months of initial rehabilitation discharge (N=96).

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

Objective risk factors of CMD (body mass index, fasting glucose, insulin, high-density lipoprotein cholesterol, triglyceride levels, and resting blood pressure). Patient reported recall of these present risk factors being shared with them by their health care team. Medications prescribed to patients to address these present risk factors were checked against guideline- assessed risk factors.

RESULTS

Objective evidence of 197 CMD risk factors was identified, with patients recalling less than 12% of these (P<.0001) being shared with them by their health care team. Thirty-one individuals (32%) met criteria for a diagnosis of CMD, with only 1 of these patients (3.2%) recalling that this was shared by their health care team (P<.0001). Pharmacologic management was prescribed to address these risk factors only 7.2% of the time.

CONCLUSIONS

Despite high prevalence of CMD risk factors after acute SCI, patients routinely do not recall being told of their present risk factors. Multifaceted education and professionals' engagement efforts are needed to optimize treatment for these individuals.

Relationship of cardiometabolic disease risk factors with age and spinal cord injury duration

CONTEXT/OBJECTIVES

Cardiometabolic disease (CMD) is increased after spinal cord injury (SCI), with an increased number of CMD risk factors that relate to higher mortality. The study objective was to characterize the relationship of age and injury duration with CMD.

DESIGN

Retrospective cohort assessment of CMD risks using unbiased recursive partitioning to divide for group comparison: (1) Lowest Risk, (2) Moderate Risk, and (3) Highest Risk based on classification and regression trees predicting CMD diagnosis by age and injury duration.

SETTING

Academic rehabilitation center laboratory.

PARTICIPANTS

Adults (N = 103; aged 18-75) with traumatic SCI (C4-L2) of 3 months to 42 years duration.

INTERVENTIONS

NA.

OUTCOME MEASURES

CMD risk factors (obesity, insulin resistance, dyslipidemia, and hypertension) using Paralyzed Veterans of America SCI-specific guidelines.

RESULTS

Obesity was prevalent (82%) and co-occurred with most other risk factors present. Age increased odds for CMD diagnosis by 1.05 per year (P = 0.02) and was directly related to elevated body mass index (BMI, β = 0.42, P < 0.05), fasting glucose (β =  0.58, P < 0.01), and higher systolic blood pressure (β = 0.31, P < 0.10). In contrast, time since injury contributed to lower risk factor count (β = -0.29, P < 0.10) and higher HDL-C (β = 0.50, P < 0.01), and was not related to odds of CMD diagnosis.

CONCLUSION

While SCI is linked to an increased risk of CMD, age is associated with higher CMD risk. Increased SCI duration related to improvement in individual CMD risk factors but did not decrease overall risk for CMD diagnosis. SCI may not uniformly increase CMD risks and highlight a necessary focus on weight management for risk prevention.

Cardiorespiratory Effects of Yogic Versus Slow Breathing in Individuals with a Spinal Cord Injury: An Exploratory Cohort Study

Background: An intricate physiological and pathophysiological connection exists between the heart and lungs, which is especially important in individuals with spinal cord injury (SCI). While an exercise intervention may seem the best approach to leverage this relationship, the prior work has shown that, despite numerous health benefits, regular exercise training does not improve cardiorespiratory control in individuals with SCI. Breath training presents an alternative intervention that is uniquely accessible, with yogic breathing directly engaging linked fluctuations in respiration and cardiovascular control. In addition, there is evidence across a range of populations that regular yogic breathing reduces cardiovascular disease risk. It is possible that the chronic decrease in breathing frequency associated with regular yogic breathing, rather than the specific yogic breathing techniques themselves, is the primary contributor to the observed risk reduction. Methods: Therefore, in 12 individuals with traumatic SCI from C4 to T8, the authors compared Unpaced and conventional 0.083 Hz (Slow) paced breathing with various yogic breathing techniques including: (1) inspiratory-expiratory breath holds (i.e., Kumbhaka or "Box Breathing"), (2) extended exhalation (1:2 duty cycle), and (3) expiratory resistance via throat constriction (i.e., Ujjayi). Beat-to-beat heart rate and blood pressure were measured as well as end-tidal CO2 and O2 saturation were measured. Statistical analysis was performed using a one-way repeated-measures analysis of variance with post hoc pairwise t tests corrected for multiple comparisons. Results: As expected, all slow breathing patterns markedly increased respiratory sinus arrhythmia (RSA) compared with Unpaced in all (n = 12) individuals. More importantly, Ujjayi breathing appeared to improve ventilatory efficiency over Unpaced breathing in individuals with SCI by increasing O2 saturation (97.6% vs. 96.1%; p = 0.042) and tended to decrease end-tidal CO2 (32 mmHg vs. 35 mmHg; p = 0.08). While other slow breathing patterns demonstrated similar effects, only Ujjayi improved RSA while increasing heart rate and improving ventilatory efficiency. Conclusions: Hence, slow breathing per se can result in important cardiorespiratory changes, but the yogic breathing practice of Ujjayi, with glottic throat resistance, may hold the greatest promise for improving cardiorespiratory control in individuals with SCI (CTR ID No. NCT05480618).

Paradoxical breathing during sleep is associated with increased sleep apnea and reduced ventilatory capacities in high-level spinal cord injury

Sleep-disordered breathing is highly prevalent in individuals with high-level spinal cord injury. In addition, chest mechanics are known to be altered, leading to paradoxical breathing. Here we investigated the interaction between paradoxical breathing and sleep quality in these patients, and its association with measurements of respiratory function, hypercapnic ventilatory response and peak exercise ventilation. Home-based polysomnography was performed in 13 patients with spinal cord injury (C4 to T4) untreated for sleep-disordered breathing. We defined paradoxical breathing as counterphase between thoracic and abdominal movements during slow-wave and rapid eye movement sleep. Sleep quality, pulmonary function, hypercapnic ventilatory responses and peak exercise ventilation were compared between those with and without paradoxical breathing. Half of individuals presented with nocturnal paradoxical breathing. Despite similar age, body mass index, injury level, time since injury, and respiratory function, those with paradoxical breathing had higher apnea-hypopnea index (13 ± 8 versus 5 ± 3 events per hr) and average sleep heart rate (67 ± 12 versus 54 ± 4 bpm; p < 0.05). Moreover, paradoxical breathing was associated with lower hypercapnic ventilatory response (slope: 0.35 ± 0.17 versus 0.96 ± 0.38) and lower peak exercise ventilation (33 ± 4 versus 48 ± 12 L min-1 ; p < 0.05). Nocturnal respiratory muscle desynchronization could play a role in the pathophysiology of sleep apnea, and could relate to low ventilatory responses to both hypercapnia and exercise in high-level spinal cord injury. Polysomnography may be an important diagnostic tool for these patients for whom therapeutic approaches should be considered to treat this abnormality.

Nitric oxide-mediated vasodilation in human bone

OBJECTIVE

Regulation of blood flow to bone is critical but poorly understood, particularly in humans. This study aims to determine whether nitric oxide (NO), a major regulator of vascular tone to other tissues, contributes also to the regulation of blood flow to bone.

METHODS

In young healthy adults (n = 16, 8F, 8M), we characterized NO-mediated vasodilation in the tibia in response to sublingual nitroglycerin and contrasted it to lower leg. Blood flow responses were assessed in supine individuals by continuously measuring tibial total hemoglobin (tHb) via near-infrared spectroscopy and lower leg blood flow (LBF) as popliteal flow velocity via Doppler ultrasound in the same leg.

RESULTS

LBF increased by Δ9.73 ± 0.66 cm/s and peaked 4.4 min after NO administration and declined slowly but remained elevated (Δ3.63 ± 0.60 cm/s) at 10 min. In contrast, time to peak response was longer and smaller in magnitude in the tibia as tHb increased Δ2.08 ± 0.22 μM and peaked 5.3 min after NO administration and declined quickly but remained elevated (Δ0.87±0.22 μM) at 10 min (p = .01).

CONCLUSIONS

In young adults, the tibial vasculature demonstrates robust NO-mediated vasodilation, but tHb is delayed and diminishes faster compared to LBF, predominately reflective of skeletal muscle responses. Thus, NO-mediated vasodilation in bone may be characteristically different from other vascular beds.

Transcutaneous spinal cord stimulation and its impact on cardiovascular autonomic regulation after spinal cord injury

Individuals with spinal cord injury (SCI) have significant dysfunction in cardiovascular autonomic regulation. Although recent findings postulate that spinal cord stimulation improves autonomic regulation, limited scope of past methods have tested only above level sympathetic activation, leaving significant uncertainty. To identify whether transcutaneous spinal cord stimulation improves cardiovascular autonomic regulation, two pairs of well-matched individuals with and without high thoracic, complete SCI were recruited. Baseline autonomic regulation was characterized with multiple tests of sympathoinhibition and above/below injury level sympathoexcitation. At three subsequent visits, testing was repeated with the addition submotor threshold transcutaneous spinal cord stimulation at three previously advocated frequencies. Uninjured controls demonstrated no autonomic deficits at baseline and had no changes with any frequency of stimulation. As expected, individuals with SCI had baseline autonomic dysfunction. In a frequency-dependent manner, spinal cord stimulation enhanced sympathoexcitatory responses, normalizing previously impaired Valsalva's maneuvers. However, stimulation exacerbated already impaired sympathoinhibitory responses, resulting in significantly greater mean arterial pressure increases with the same phenylephrine doses compared with baseline. Impaired sympathoexcitatory response below the level of injury were also further exacerbated with spinal cord stimulation. At baseline, neither individual with SCI demonstrated autonomic dysreflexia with the noxious foot cold pressor test; the addition of stimulation led to a dysreflexic response in every trial, with greater relative hypertension and bradycardia indicating no improvement in cardiovascular autonomic regulation. Collectively, transcutaneous spinal cord stimulation demonstrates no improvements in autonomic regulation after SCI, and instead likely generates tonic sympathoexcitation which may lower the threshold for dangerous autonomic dysreflexia.NEW & NOTEWORTHY Spinal cord stimulation increases blood pressure after spinal cord injury, though it is unclear if this restores natural autonomic regulation or induces a potentially dangerous pathological reflex. We performed comprehensive autonomic testing batteries, with and without transcutaneous spinal cord stimulation at multiple frequencies. Across 96 independent tests, stimulation did not change uninjured control responses, though all frequencies facilitated pathological reflexes without improved autonomic regulation for those with spinal cord injuries.

Vascular deficits contributing to skeletal fragility in type 1 diabetes

Over 1 million Americans are currently living with T1D and improvements in diabetes management have increased the number of adults with T1D living into later decades of life. This growing population of older adults with diabetes is more susceptible to aging comorbidities, including both vascular disease and osteoporosis. Indeed, adults with T1D have a 2- to 3- fold higher risk of any fracture and up to 7-fold higher risk of hip fracture compared to those without diabetes. Recently, diabetes-related vascular deficits have emerged as potential risks factors for impaired bone blood flow and poor bone health and it has been hypothesized that there is a direct pathophysiologic link between vascular disease and skeletal outcomes in T1D. Indeed, microvascular disease (MVD), one of the most serious consequences of diabetes, has been linked to worse bone microarchitecture in older adults with T1D compared to their counterparts without MVD. The association between the presence of microvascular complications and compromised bone microarchitecture indicates the potential direct deleterious effect of vascular compromise, leading to abnormal skeletal blood flow, altered bone remodeling, and deficits in bone structure. In addition, vascular diabetic complications are characterized by increased vascular calcification, decreased arterial distensibility, and vascular remodeling with increased arterial stiffness and thickness of the vessel walls. These extensive alterations in vascular structure lead to impaired myogenic control and reduced nitric-oxide mediated vasodilation, compromising regulation of blood flow across almost all vascular beds and significantly restricting skeletal muscle blood flow seen in those with T1D. Vascular deficits in T1D may very well extend to bone, compromising skeletal blood flow control, and resulting in reduced blood flow to bone, thus negatively impacting bone health. Indeed, several animal and ex vivo human studies report that diabetes induces microvascular damage within bone are strongly correlated with diabetes disease severity and duration. In this review article, we will discuss the contribution of diabetes-induced vascular deficits to bone density, bone microarchitecture, and bone blood flow regulation, and review the potential contribution of vascular disease to skeletal fragility in T1D.

Longitudinal Changes in Cerebral Perfusion, Perivascular Space Volume, and Ventricular Volume in a Healthy Cohort Undergoing a Spaceflight Analog

BACKGROUND AND PURPOSE

A global decrease in brain perfusion has recently been reported during exposure to a ground-based spaceflight analog. Considering that CSF and glymphatic flow are hypothesized to be propelled by arterial pulsations, it is unknown whether a change in perfusion would impact these CSF compartments. The aim of the current study was to evaluate the relationship among changes in cerebral perfusion, ventricular volume, and perivascular space volume before, during, and after a spaceflight analog.

MATERIALS AND METHODS

Eleven healthy participants underwent 30 days of bed rest at 6° head-down tilt with 0.5% atmospheric CO2 as a spaceflight analog. For each participant, 6 MR imaging brain scans, including perfusion and anatomic-weighted T1 sequences, were obtained before, during, and after the analog period. Global perfusion, ventricular volume, and perivascular space volume time courses were constructed and evaluated with repeated measures ANOVAs.

RESULTS

Global perfusion followed a divergent time trajectory from ventricular and perivascular space volume, with perfusion decreasing during the analog, whereas ventricular and perivascular space volume increased (P < .001). These patterns subsequently reversed during the 2-week recovery period.

CONCLUSIONS

The patterns of change in brain physiology observed in healthy participants suggest a relationship between cerebral perfusion and CSF homeostasis. Further study is warranted to determine whether a causal relationship exists and whether similar neurophysiologic responses occur during spaceflight.

Calculation of Tissue Oxygenation via an Inverse Boundary Problem for Transcutaneous Oxygenation Wearable Applications

In this article, we present a toolset to fully leverage a previously developed transcutaneous oxygenation monitor (TCOM) wearable technology to accurately measure skin oxygenation values. We describe numerical models and experimental characterization techniques that allow for the extraction of precise tissue oxygenation measurements. The numerical model is based on an inverse boundary problem of the parabolic equation with Dirichlet boundary conditions. To validate this model and characterize the diffusion of oxygen through the oxygen sensing materials, we designed a series of control/calibration experiments modeled after the device's clinical application using oxygenation values in the physiological range expected for healthy tissue. Our results demonstrate that it is possible to obtain accurate tissue pO2 measurements without the need for long equilibration times with a small wearable device.

The Impact of Transcutaneous Spinal Cord Stimulation on Autonomic Regulation after Spinal Cord Injury: A randomized crossover trial

Importance

Individuals with spinal cord injury (SCI) have significant autonomic nervous system dysfunction. However, despite recent findings postulated to support that spinal cord stimulation improves dynamic autonomic regulation, limited scope of previous testing means the true effects remain unknown.

Objective

To determine whether transcutaneous spinal cord stimulation improves dynamic autonomic regulation after SCI.

Design

Single-blinded, randomized crossover trial with matched cohorts.

Setting

Academic autonomic physiology laboratory.

Participants

Two pairs of well-matched individuals with and without high-thoracic, complete SCI.

Interventions

Sub-motor threshold transcutaneous spinal cord stimulation delivered at T10-T11 using 120Hz, 30Hz, and 30Hz with 5kHz carrier frequency at separate autonomic testing sessions.

Main Outcomes and Measures

Baseline autonomic regulation was characterized with tests of above injury level sympathoexcitation (Valsalva's maneuver), sympathoinhibition (progressive doses of bolus intravenous phenylephrine), and below level sympathoexcitation (foot cold pressor test). At three subsequent visits, this testing battery was repeated with the addition of spinal cord stimulation at each frequency. Changes in autonomic regulation for each frequency were then analyzed relative to baseline testing for each individual and within matched cohorts.

Results

Uninjured controls demonstrated no autonomic deficits at baseline and had no changes with any frequency of stimulation. Contrasting this, and as expected, individuals with SCI had baseline autonomic dysfunction. In a frequency-dependent manner, spinal cord stimulation enhanced sympathoexcitatory responses, normalizing previously impaired Valsalva's maneuvers. However, stimulation exacerbated already impaired sympathoinhibitory responses, resulting in significantly greater mean arterial pressure increases with the same phenylephrine doses compared to baseline. Impaired sympathoexcitatory response below the level of injury were also further exacerbated with spinal cord stimulation. At baseline, neither individual with SCI demonstrated autonomic dysreflexia with the noxious foot cold pressor test; the addition of stimulation led to a dysreflexic response in every trial, with greater relative hypertension and bradycardia indicating no improvement in autonomic regulation.

Conclusions and Relevance

Transcutaneous spinal cord stimulation does not improve autonomic regulation after SCI, and instead likely generates tonic, frequency-dependent sympathoexcitation which may lower the threshold for autonomic dysreflexia.

Improved pulmonary function is associated with reduced inflammation after hybrid whole-body exercise training in persons with spinal cord injury

NEW FINDINGS

What is the central question of this study? Does 12 weeks of functional electrical stimulation (FES) rowing exercise training lead to suppressed systemic inflammation and an improvement in pulmonary function in persons with sub-acute spinal cord injury (SCI)? What is the main finding and its importance? Twelve weeks of FES rowing exercise improves pulmonary function and the magnitude of improvement is associated with reductions in inflammatory biomarkers. Thus, interventions targeting inflammation may lead to better pulmonary outcomes for person with sub-acute SCI.

ABSTRACT

The current study was designed to test the hypotheses that (1) reducing systemic inflammation via a 12-week functional electrical stimulation rowing exercise training (FESRT) prescription results in augmented pulmonary function, and (2) the magnitude of improvement in pulmonary function is inversely associated with the magnitude of systemic inflammation suppression in persons with sub-acute (≤2 years) spinal cord injury (SCI). We conducted a retrospective analysis of a randomized controlled trial (NCT#02139436). Twenty-one participants were enrolled (standard of care (SOC; n = 9) or FESRT (n = 12)). The exercise prescription was three sessions/week at 70-85% of peak heart rate. A two-way analysis of covariance and regression analysis was used to assess group differences and associations between pulmonary function, log transformed high-sensitivity C-reactive protein (hsCRPlog ) and white blood cell count (WBC). Following FESRT, clinically significant improvements in forced expiratory volume in 1 s (FEV1 ; 0.25 (0.08-0.43) vs. -0.06 (-0.26 to 0.15) litres) and forced vital capacity (0.22 (0.04-0.39) vs. 0.08 (-0.29 to 0.12) litres) were noted and systemic WBC (-1.45 (-2.48 to -0.50) vs. 0.41 (-0.74 to 1.56) μl) levels were suppressed compared to SOC (mean change (95% confidence interval); P < 0.05). Additionally, both ΔhsCRPlog and ΔWBC were predictors of ΔFEV1 (r2  = 0.89 and 0.43, respectively; P < 0.05). Twelve weeks of FESRT improves pulmonary function and reduces WBC in persons with sub-acute SCI. The potency of FESRT to augment pulmonary function may depend on adequate suppression of systemic inflammation.

Digital Interventions for Social Participation in Adults with Long-term Physical Conditions: A Systematic Review

This review aims to identify and evaluate digital interventions for social participation in the growing population of adults with long-term physical conditions. Articles were sourced from MEDLINE, EMBASE, CINAHL and PsycINFO databases using subject headings and keywords related to "social participation" and "digital technology". Studies that adopted digital technology interventions to improve social participation in adults with long-term physical conditions were included. Data on study methodology, participant and digital intervention characteristics, and findings related to social participation were extracted. The search yielded a total of 4646 articles and 14 articles met criteria for final review with five randomized controlled trials, two non-randomized clinical trials and seven one-group pretest-posttest clinical trials. Studies were organized based on the digital intervention strategy implemented to improve social participation: group support (n = 4), individual skill training or counseling (n = 6), education and support (n = 3), and mixed intervention (n = 1). The group support interventions developed a social network among participants through videoconference, app, or virtual reality platform. Three studies reported positive improvements in different aspects of social participation. Individual skill training or counseling mainly utilized phone calls to help participants cope with activity participation and interpersonal relationship issues. Only two studies demonstrated benefits for social participation. The education and support intervention, which used messages and website information to increase participants' knowledge and provide support, showed positive findings in three studies. This review suggests digital interventions for improving social participation in adults with long-term physical conditions are feasible and the effectiveness of different strategies may vary.Registration: This review was prospectively registered on the International Prospective Register of Systematic Reviews (PROSPERO) (registry number: CRD42021254105).

Exercise Training Does Not Attenuate Cardiac Atrophy or Loss of Function in Individuals With Acute Spinal Cord Injury: A Pilot Study

OBJECTIVE

To investigate the effects of 2 modes of exercise training, upper-body alone, and the addition of electrical stimulation of the lower body, to attenuate cardiac atrophy and loss of function in individuals with acute spinal cord injury (SCI).

DESIGN

Randomized controlled trial.

SETTING

Rehabilitation Hospital.

PARTICIPANTS

Volunteers (N=27; 5 women, 22 men) who were <24 months post SCI.

INTERVENTIONS

Volunteers completed either 6 months of no structured exercise (Control), arm rowing (AO), or a combination of arm rowing with electrical stimulation of lower body paralyzed muscle (functional electrical stimulation [FES] rowing).

MAIN OUTCOME MEASURES

Transthoracic echocardiography was performed on each subject prior to and 6 months after the intervention. The relations between time since injury and exercise type to cardiac structure and function were assessed via 2-way repeated-measures analysis of variance and with multilevel linear regression.

RESULTS

Time since injury was significantly associated with a continuous decline in cardiac structure and systolic function, specifically, a reduction in left ventricular mass (0.197 g/month; P=.049), internal diameter during systole (0.255 mm/month; P<.001), and diastole (0.217 mm/month; P=.019), as well as cardiac output (0.048 L/month, P=.019), and left ventricular percent shortening (0.256 %/month; P=.027). These associations were not differentially affected by exercise (Control vs AO vs FES, P>.05).

CONCLUSIONS

These results indicate that within the subacute phase of recovery from SCI there is a linear loss of left ventricular cardiac structure and systolic function that is not attenuated by current rehabilitative aerobic exercise practices. Reductions in cardiac structure and function may increase the risk of cardiovascular disease in individuals with SCI and warrants further interventions to prevent cardiac decline.

Methodologic implications for rehabilitation research: Differences in heart rate variability introduced by respiration

BACKGROUND

Heart rate variability is a measure of autonomic activity that is growing in popularity as a research outcome. However, despite its increased use, the known effects of respiration on heart rate variability measures are rarely accounted for in rehabilitation medicine research, leading to potential misinterpretation.

OBJECTIVE

To describe the effect that unpaced and paced breathing introduces to heart rate variability measures in a rehabilitation medicine relevant example of individuals with spinal cord injury.

DESIGN

Cross-sectional comparison of heart rate variability during unpaced and paced breathing (0.25 Hz, 15 breaths per minute) within the same individuals during the same lab session.

SETTING

Academic autonomic physiology laboratory.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Mean low frequency (LF) and high frequency (HF) heart rate variability power, percentage of total power derived from the LF spectrum, LF:HF ratio.

RESULTS

Fifty-nine individuals with spinal cord injury completed laboratory assessments using standardized protocols (NCT02139436). In repeated measures within individuals, mean LF power was significantly higher in unpaced breathing compared to paced breathing (1292 vs. 573 ms2 , p < .001). A Bland-Altman plot demonstrated significant positive proportional bias for LF power when comparing unpaced and paced breathing conditions (R2  = 0.39). Mean HF power was similar between unpaced and paced breathing conditions, although there were wide positive and negative differences between measures, leading to notable uncertainty when respiratory confounders were not accounted for. The percentages of total power derived from the LF spectrum and the mean LF:HF ratio were both significantly higher for unpaced breathing compared to paced breathing (64 vs. 42%, p < .001; and 3.2 vs. 1.1, p < .001, respectively).

CONCLUSION

Respiration has a significant effect on heart rate variability following spinal cord injury, and not accounting for this has serious consequences for accurate interpretation of unpaced data. Future studies of heart rate variability in rehabilitation medicine should accordingly consider paced breathing.

Serotonin 1A Receptor Pharmacotherapy and Neuroplasticity in Spinal Cord Injury

Spinal cord injury is associated with damage in descending and ascending pathways between brainstem/cortex and spinal neurons, leading to loss in sensory-motor functions. This leads not only to locomotor reduction but also to important respiratory impairments, both reducing cardiorespiratory engagement, and increasing cardiovascular risk and mortality. Moreover, individuals with high-level injuries suffer from sleep-disordered breathing in a greater proportion than the general population. Although no current treatments exist to restore motor function in spinal cord injury (SCI), serotoninergic (5-HT) 1A receptor agonists appear as pharmacologic neuromodulators that could be important players in inducing functional improvements by increasing the activation of spared motoneurons. Indeed, single therapies of serotoninergic 1A (5-HT_1A) agonists allow for acute and temporary recovery of locomotor function. Moreover, the 5-HT_1A agonist could be even more promising when combined with other pharmacotherapies, exercise training, and/or spinal stimulation, rather than administered alone. In this review, we discuss previous and emerging evidence showing the value of the 5HT_1A receptor agonist therapies for motor and respiratory limitations in SCI. Moreover, we provide mechanistic hypotheses and clinical impact for the potential benefit of 5-HT_1A agonist pharmacology in inducing neuroplasticity and improving locomotor and respiratory functions in SCI.

774 Digital Interventions for Social Participation in Adults with Long-term Physical Conditions: A Systematic Review

Introduction

Burn survivors experience significant social participation challenges in their recovery. However, enrolment and compliance with face-to-face interventions for such issues are often limited by time, location, and financial resources. Digital technologies are increasingly utilized in healthcare and provide a flexible, accessible, and low-cost treatment option. Given the sparse literature on this topic in the burn field, this review evaluated digital interventions for social participation in adults with long-term physical conditions to inform future use in the burn population.

Methods

MEDLINE, EMBASE, CINAHL and PsycINFO databases were searched using keywords and Medical Subject Headings (MeSH) terms related to ‘digital intervention’ and ‘social participation’ for studies published in English between January 2010 and May 2021. Studies that adopted digital technology interventions to improve social participation in adults with long-term physical conditions were included. Study quality was evaluated using Oxford Levels of Evidence. Data on study methodology, digital intervention and findings related to social participation were summarized.

Results

The search yielded a total of 4646 articles, of which 158 were full-text screened and 14 met inclusion and exclusion criteria. There were five randomized controlled trials, two non-randomized clinical trials and seven one-group pretest-posttest clinical trials. Twenty-five different measurement tools were utilized to assess social participation and two of them were used twice. Three types of digital interventions were implemented to improve social participation: group support, individual skill training or counselling, and education and support. The group support intervention developed a social network among affected people through videoconference, app, or virtual reality platform (3 of 4 studies with positive results). Individual skill training or counselling utilized phone calls or videoconference to help participants with activity participation and interpersonal relationships (2 of 6 studies with positive results). The education and support intervention used messages and website information to increase participants’ knowledge and provide support (3 of 3 studies with positive results).

Conclusions

This review presents evidence of different digital interventions’ effect on improving social participation in adults with long-term physical conditions. However, the existing literature is limited by the heterogeneity of outcome measures and varied methodology quality that preclude larger generalizations.

Effect of hybrid FES exercise on body composition during the sub-acute phase of spinal cord injury

Objectives

To determine the Effect of Hybrid functional electrically stimulated (FES) Exercise on Body Composition during the Sub-acute Phase of Spinal Cord Injury (SCI).

Design

Randomized Clinical Trial.

Setting

Rehabilitation Hospital.

Participants

Patients within sub-acute phase (3–24 months) of SCI.

Interventions

We investigated if high-intensity exercise training via the addition of functional electrically stimulated (FES) leg muscles, provides sufficient stimulus to mitigate against body composition changes in the sub-acute phase after SCI.

Main outcome measures

We explored potential effects of FES row training (FESRT) on body fat gain, lean mass loss, and cardiometabolic parameters and compared the effects of 6-month of FESRT (n = 18) to standard of care (SOC, n = 13). Those in SOC were crossed over to FESRT.

Results

FESRT resulted in greater exercise capacity and a tendency for lesser total body fat accumulation with a significant increase in total and leg lean mass (p<0.05). In addition pelvis and total bone mineral density declines were significantly less (p<0.05). Compared to SOC, FESRT did not lead to any significant difference in insulin sensitivity or serum lipids. However, HbA1C levels were significantly decreased in SOC participants who crossed over to 6-month FESRT.

Conclusion

FESRT early after SCI provides a sufficient stimulus to mitigate against detrimental body composition changes. This may lead to prevention of losses in lean mass, including bone.

Clinical Reasoning: A Young Man With Daily Episodes of Altered Awareness

Stretch syncope is a distinct entity characterized by transient alteration in awareness (TAA) induced by neck hyperextension during stretching. Few cases of stretch syncope have been reported in the literature. Nevertheless, this is a highly relevant diagnosis as it can be easily mistaken for epilepsy for a number of reasons. These include stereotypical motor activity associated with the events, development of ictal tachycardia, and presence of rhythmic/semirhythmic slowing on EEG in the context of transient cerebral hypoperfusion.

We present the case of a young man who was referred to our comprehensive epilepsy center for frequent episodes of TAA. After careful evaluation, the episodes were initially considered to be epileptic. Given that he had negligible clinical response to antiseizure medications, he underwent an experimental protocol at a cardiovascular research laboratory that ultimately confirmed the diagnosis of stretch syncope.

The present manuscript describes an approach to the evaluation of TAA and illustrates a typical case of stretch syncope. The importance of considering stretch syncope in the differential diagnosis of TAA is exemplified. Finally, our analyses help elucidate the pathophysiology of this rare entity.

Association of hysterectomy and invasive epithelial ovarian and tubal cancer: a cohort study within UKCTOCS

OBJECTIVE

To investigate the association between hysterectomy with conservation of one or both adnexa and ovarian and tubal cancer.

DESIGN

Prospective cohort study.

SETTING

Thirteen NHS Trusts in England, Wales and Northern Ireland.

POPULATION

A total of 202 506 postmenopausal women recruited between 2001 and 2005 to the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) and followed up until 31 December 2014.

METHODS

Multiple sources (questionnaires, hospital notes, Hospital Episodes Statistics, national cancer/death registries, ultrasound reports) were used to obtain accurate data on hysterectomy (with conservation of one or both adnexa) and outcomes censored at bilateral oophorectomy, death, ovarian/tubal cancer diagnosis, loss to follow up or 31 December 2014. Cox proportional hazards regression models were used to assess the association.

MAIN OUTCOME MEASURES

Invasive epithelial ovarian and tubal cancer (WHO 2014) on independent outcome review.

RESULTS

Hysterectomy with conservation of one or both adnexa was reported in 41 912 (20.7%; 41 912/202 506) women. Median follow up was 11.1 years (interquartile range 9.96-12.04), totalling >2.17 million woman-years. Among women who had undergone hysterectomy, 0.55% (231/41 912) were diagnosed with ovarian/tubal cancer, compared with 0.59% (945/160 594) of those with intact uterus. Multivariable analysis showed no evidence of an association between hysterectomy and invasive epithelial ovarian/tubal cancer (hazard ratio 0.98, 95% CI 0.85-1.13, P = 0.765).

CONCLUSIONS

This large cohort study provides further independent validation that hysterectomy is not associated with alteration of invasive epithelial ovarian and tubal cancer risk. These data are important both for clinical counselling and for refining risk prediction models.

TWEETABLE ABSTRACT

Hysterectomy does not alter risk of invasive epithelial ovarian and tubal cancer.

High-intensity, whole-body exercise improves blood pressure control in individuals with spinal cord injury: A prospective randomized controlled trial

Blood pressure regulation following spinal cord injury (SCI) is often compromised due to impaired vascular sympathetic control, leading to increased reliance on cardiovagal baroreflex sensitivity to maintain pressure. Whole-body exercise improves cardiovagal baroreflex sensitivity in uninjured individuals, though has not been explored in those with SCI. Our objective was to determine changes in cardiovagal baroreflex sensitivity following 6 months of high-intensity, whole-body exercise in individuals with SCI compared to lower-intensity, arms only exercise, or waitlist. This randomized controlled trial recruited individuals with SCI aged 18-40 years old. Sixty-one individuals were randomized, with 38 completing at least one cardiovagal baroreflex sensitivity assessment. Whole-body exercise was performed with hybrid functional electrical stimulation rowing prescribed as two to three times per week, for 30-60 minutes with a target heart rate of >75% of maximum. The arms only exercise group performed upper body rowing exercise with the same prescription as whole-body exercise. Waitlist controls were not enrolled in any explicit training regimen. After 6 months, those in arms only exercise or waitlist crossed over to whole-body exercise. Cardiovagal baroreflex sensitivity was assessed via the neck suction technique at baseline and at three-month intervals thereafter. Intention to treat analysis with a structured equation model demonstrated no significant effect of waitlist control or arms only exercise on cardiovagal baroreflex sensitivity. Whole-body exercise significantly improved cardiovagal baroreflex sensitivity at 6 months for those initially randomized (p = 0.03), as well as those who crossed over from arms only exercise or waitlist control (p = 0.03 for each). However, amount of exercise performed and aerobic gains (VO2max) each poorly correlated with increases in cardiovagal baroreflex sensitivity (R2<0.15). In post-hoc analyses, individuals with paraplegia made significantly greater gains in baroreflex sensitivity compared to those with tetraplegia (p = 0.02), though gains within this group were again poorly correlated to gains in aerobic capacity. Clinicaltrials.gov number NCT02139436.

Mechanisms of bone blood flow regulation in humans

Bone is a highly vascularized tissue. However, despite the importance of appropriate circulation for bone health, regulation of bone blood flow remains poorly understood. Invasive animal studies suggest that sympathetic activity plays an important role in bone flow control. However, it remains unknown if bone vasculature evidences robust vasoconstriction in response to sympathoexcitatory stimuli. Here, we characterized bone blood flow in young healthy individuals [n = 13, (four females)] in response to isometric handgrip exercise (IHE) and cold pressor test (CPT). These provide a strong stimulus for active vasoconstriction in the inactive muscle, and perhaps also in the bone. During sustained IHE to fatigue and CPT, we measured blood pressure, whole leg blood flow, and tibial perfusion using near-infrared spectroscopy. Tibia perfusion was determined as oxy- and deoxyhemoglobin. For both stimuli, tibial metabolism remained constant (i.e., no change in deoxyhemoglobin) and thus tibial arterial perfusion was represented by oxyhemoglobin. During IHE, oxyhemoglobin declined (beginning -0.20 ± 1.04 μM; end -1.13 ± 3.71 μM, both P < 0.01) slower than whole leg blood flow (beginning -0.85 ± 1.02 cm/s; end -2.72 ± 1.64 cm/s, both P < 0.01). However, during CPT, both oxyhemoglobin (beginning -0.46 ± 1.43 μM; end -0.60 ± 1.59 μM, both P < 0.01) and whole leg blood flow (beginning -1.52 ± 1.63 cm/s; end -0.69 ± 1.51 cm/s, both P < 0.01) declined with a similar timecourse, even though the magnitudes of decline were smaller than during IHE. These responses are likely due to the different timecourses of sympathetically mediated vasoconstriction in bone and muscle. These results indicate that sympathetic innervation of the bone vasculature serves a functional role in the control of flow in young healthy individuals.NEW & NOTEWORTHY The current study is the first one to noninvasively investigate control of bone blood perfusion in vivo in humans, on a moment-by-moment basis. Our results indicate that tibial bone vasculature demonstrates active vasoconstriction in response to sympathoexcitatory stimuli in young healthy individuals. Compared with whole leg vasculature, bone vasoconstrictor response seems to be smaller, delayed, and more variable.

Reductions in Cardiac Structure and Function 24 Months After Spinal Cord Injury: A Cross-Sectional Study

OBJECTIVE

To determine the alterations in cardiac structure and function that occur in the months after spinal cord injury (SCI).

STUDY DESIGN

Cross-sectional SETTING: Rehabilitation Hospital PARTICIPANTS: Volunteers (N=29; 4 women, 25 men) between 3 and 24 months after SCI.

MAIN OUTCOME MEASURES

Transthoracic echocardiography was performed on each volunteer. The relationships between time since injury and neurologic and sensory levels of injury to cardiac structure and function were assessed via multiple linear regression.

RESULTS

Time since injury was most strongly associated with reductions in left ventricular end diastolic volume (r²=0.156; P=.034), end systolic volume (r²=0.141; P=.045), and mass (r²=0.138; P=.047). These structural changes were paralleled by reduced stroke volume (r²=0.143; P=.043) and cardiac output (r²=0.317; P=<.001). The reductions in left ventricular structure and systolic function were not differentially affected by neurologic or sensory levels of injury (P=.084-.921).

CONCLUSIONS

These results suggest progressive reductions in left ventricular structure and systolic function between 3 and 24 months after SCI that occur independent of neurologic and sensory levels of injury.

Cardiac, Autonomic, and Cardiometabolic Impact of Exercise Training in Spinal Cord Injury: A QUALITATIVE REVIEW

INTRODUCTION

Direct and indirect effects of spinal cord injury lead to important cardiovascular (CV) complications that are further increased by years of injury and the process of "accelerated aging." The present review examines the current evidence in the literature for the potential cardioprotective effect of exercise training in spinal cord injury.

REVIEW METHODS

PubMed and Web of Science databases were screened for original studies investigating the effect of exercise-based interventions on aerobic capacity, cardiac structure/function, autonomic function, CV function, and/or cardiometabolic markers. We compared the effects in individuals <40 yr with time since injury <10 yr with those in older individuals (≥40 yr) with longer time since injury (≥10 yr), reasoning that the two can be considered individuals with low versus high CV risk factors.

SUMMARY

Studies showed similar exercise effects in both groups (n = 31 in low CV risk factors vs n = 15 in high CV risk factors). The evidence does not support any effect of exercise training on autonomic function but does support an increased peripheral blood flow, improved left ventricular mass, higher peak cardiac output, greater lean body mass, better antioxidant capacity, and improved endothelial function. In addition, some evidence suggests that it can result in lower blood lipids, systemic inflammation (interleukin-6, tumor necrosis factor α, and C-reactive protein), and arterial stiffness. Training intensity, volume, and frequency were key factors determining CV gains. Future studies with larger sample sizes, well-matched groups of subjects, and randomized controlled designs will be needed to determine whether high-intensity hybrid forms of training result in greater CV gains.

Digital Phenotyping to Quantify Psychosocial Well-Being Trajectories After Spinal Cord Injury

OBJECTIVE

The aim of the study was to explore feasibility of smartphone-based digital phenotyping methods to examine depression and its relation to psychosocial well-being indicators after spinal cord injury.

DESIGN

Smartphone research platform obtained smartphone sensor and survey data among community-living adult wheelchair users with spinal cord injury. Weekly measurements for 4 mos included Patient Health Questionnaire 8, Spinal Cord Injury-Quality of Life Satisfaction with and ability to participate in social roles and activities, global positioning system-derived community mobility metrics, health conditions, and physical activity.

RESULTS

Forty-three individuals were enrolled. Study retention was higher among individuals offered financial incentives (78%) compared with participants enrolled before incentives (50%). Participants who dropped out more commonly had nontraumatic or acute spinal cord injury, were older, and had less satisfaction and lower participation in social roles and activities. Among 15 individuals with complete data, half had 1 wk or more of mild depression. Those with depression had frequent health issues, less satisfaction, and lower participation in social roles and activities. Those without depression experienced increased social engagement over time. Average community mobility was similar across depression groups. Relationships were typically in-phase but also varied by individual.

CONCLUSIONS

Smartphone-based digital phenotyping of psychosocial well-being after spinal cord injury is feasible but not without attrition challenges. Individual differences in depression patterns highlight clinical utility of scaling these methods.

Cardiometabolic Effects of High-Intensity Hybrid Functional Electrical Stimulation Exercise after Spinal Cord Injury

INTRODUCTION

The prevalence of cardiometabolic disease following spinal cord injury is known to be high. However, it is unknown whether engaging in high-intensity exercise, which is advocated by recent guidelines, is beneficial or feasible for these individuals.

OBJECTIVE

To assess the effects of high-intensity, whole-body exercise on the prevalence of cardiometabolic disease in individuals with spinal cord injury.

DESIGN

Combination of a randomized controlled trial and an open label intervention study of functional electrical stimulation legs plus arms rowing.

SETTING

Outpatient academic rehabilitation hospital.

PARTICIPANTS

Forty individuals with spinal cord injury, with American Spinal Injury Association (ASIA) impairments scales A-D and neurological levels of injury C1-T12.

INTERVENTION

Six months of high-intensity, hybrid-functional electrical stimulation rowing.

MAIN OUTCOME MEASURES

Change in VO_2max , serum lipids, and insulin resistance, prevalence of cardiometabolic disease.

RESULTS

Individuals averaged 42.1 ± 22.0 minutes of hybrid-functional electrical stimulation rowing a week over an average of 1.69 sessions per week over the 6 months of intervention. This amounted to an average of 170.9 ± 100 km rowed, at a mean heart rate of 82.7% of individualized maximum. Only one of 40 individuals met current exercise guidelines for the full 6 months. VO_2max increased significantly (P < .001), yet prevalence of cardiometabolic disease did not change significantly (decrease from 22.5% to 20%, P = .70). Hemoglobin A1c did decrease significantly over this time (P = .01), although serum lipids and fasting glucose/insulin levels were unchanged. In exploratory subanalyses assessing individuals injured ≤12 months, those with more chronic injuries decreased their triglyceride-to-high-density lipoprotein (HDL) ratio (P = .04), a marker of cardiac mortality. Stratifying by neurological level of injury, individuals with paraplegia had worsened low-density lipoprotein (LDL) level (P = .02) and total cholesterol-to-HDL ratio (P = .04) over the 6-month intervention.

CONCLUSIONS

Sustained high-intensity exercise with hybrid functional electrical stimulation rowing does not decrease the prevalence of cardiometabolic disease after spinal cord injury.

Heart rate variability as a biomarker for anorexia nervosa: A review

OBJECTIVE

Anorexia nervosa (AN) typically begins in early adolescence and other than weight status has few reliable biomarkers. Early diagnosis is a critical prognostic factor, but this can be clinically challenging. Heart rate variability (HRV), the beat-by-beat variance in heart rate (HR), may provide a unique assessment for the presence of AN because it has clinical utility as a biomarker of cardiac autonomic control in various populations (e.g., athletes, the aged, those with cardiovascular diseases, etc.). We present a review of the literature examining HRV in those with AN.

METHOD

Relevant publications were selected from PubMed using the search terms 'anorexia nervosa AND (HR OR HRV)'. Twenty papers were selected and reviewed.

RESULTS

The majority of studies suggest that those with AN have markedly and consistently elevated HRV compared to controls, even greater than among young athletes. However, no studies have explored HRV as a biomarker for AN.

DISCUSSION

Future studies on HRV should elucidate its role as a diagnostic biomarker for AN as well as its responsiveness with serial measurement to track response rates and predict relapse.

Ventilatory support during whole-body row training improves oxygen uptake efficiency in patients with high-level spinal cord injury: A pilot study

High-level spinal cord injury (SCI) is characterized by profound respiratory compromise. One consequence is a limitation of whole-body exercise-based rehabilitation, reducing its cardioprotective effect. We investigated the use of ventilatory support during training on cardiorespiratory response to exercise. Nine subjects with high-level SCI (T3-C4) were included in this double-blind sham-controlled study. All had training adaptations plateauing for more than 6 months before enrolling in the study. After performing baseline assessment, participants were randomly assigned to continue training with non-invasive ventilation (NIV: n = 6: IPAP = 20 ± 2, EPAP: 3 cmH₂O) or sham (n = 3: IPAP = 5, EPAP: 3 cmH₂O) for 3 months and performed again maximal exercise tests. We compared the oxygen uptake efficiency slope (OUES, the rate of increases in VO₂ in relation to increasing VE) before and after training. Training with NIV increased OUES both compared to baseline (4.1 ± 1.1 vs. 3.4 ± 1.0, i.e. +20 ± 12%, p < 0.05) and Sham (p = 0.01), representing an increase in ability to uptake oxygen for a given ventilation. This result was sustained without NIV during the test, suggesting improved cardiopulmonary reserve. Best responders were the youngest whose characteristics were very similar to sham participants. In addition, NIV tended to increase weekly rowing distance by 24% (p = 0.09, versus 10% in sham). Our results are very suggestive of a positive effect of ventilatory support during whole-body exercise in high-level SCI. Training adaptations found are of great importance since this sub-population of patients have the greatest need for exercise-based cardio-protection.

Gains in aerobic capacity with whole-body functional electrical stimulation row training and generalization to arms-only exercise after spinal cord injury

STUDY DESIGN

Longitudinal study in adults (n = 27; 19-40 years old) with tetraplegic or paraplegic spinal cord injury (SCI).

OBJECTIVES

Determine physiological adaptations and generalizable fitness effects of 6 months of whole-body exercise training using volitional arm and functional electrical stimulation (FES) leg rowing.

SETTING

Outpatient hospital-based exercise facility and laboratory.

METHODS

Participants enrolled in hybrid FES-row training (FESRT) and performed peak exercise tests with arms-only (AO; baseline and 6 months) and FES rowing (baseline, 3, 6 months).

RESULTS

Participants demonstrated increased aerobic capacity (VO_2peak) after FESRT (p < 0.001, n_p² = 0.56) that tended to be higher when assessed with FES than AO rowing tests (0.15 ± 0.20 vs. 0.04 ± 0.22 L/min; p = 0.10). Changes in FES and AO VO_2peak were significantly correlated (r = 0.55; p < 0.01), and 11 individuals demonstrated improvements (>6%) on both test formats. Younger age was the only difference between those who showed generalization of training effects and those who did not (mean age 26.6 ± 5.6 vs. 32.0 ± 5.7 years; p < 0.05) but changes in FES VO_2peak correlated to time since injury in individuals <2 years post-SCI (r = -0.51, p < 0.01, n = 24). Lastly, VO_2peak improvements were greater during the first 3 months vs. months 4-6 (+7.0% vs. +3.9%; p < 0.01) which suggests early training adaptations during FESRT.

CONCLUSIONS

Gains in aerobic capacity after whole-body FESRT are better reflected during FES-row testing format. They relate to high-intensity exercise and appear early during training, but they may not generalize to equivalent increases in AO exercise in all individuals with SCI.

Techniques and results of palate fistula repair following palatoplasty: a 234-case multicenter study

INTRODUCTION

Palate fistula is the most frequent complication following palatoplasty. The objectives of this study were: to describe the most widely used repair techniques; to study results and recurrence rate; to analyze potentially predictive recurrence variables; and to assess whether a specific technique is superior according to fistula size and location.

MATERIALS AND METHODS

Retrospective study of patients undergoing palate fistula repair in 7 healthcare facilities from 2008 to 2018. All facilities had at least 20 new cases of cleft lift and palate annually (range: 20-80), with a fistula incidence of 14% (range: 1.5-20%). Minimum follow-up was 1 year. 8 variables were collected for statistical analysis purposes.

RESULTS

234 fistula patients underwent surgery. Most fistulas occurred in complete bilateral cleft lift and palate (Veau type IV). The most frequent location was the hard palate (Pittsburgh types IV and V (63.2%)), and fistulas were mostly large (42.1%) and medium (39.5%). The most frequent repair technique was re-palatoplasty (34.2%). Recurrence rate was 22%. The multivariate analysis demonstrated more recurrences in re-palatoplasty repaired type III fistulas in patients over 3 years old.

CONCLUSION

A tendency towards using flap repair in large hard palate fistulas, re-palatoplasty in medium hard palate and soft and hard palate junction fistulas, and local flaps or re-palatoplasty in small fistulas at any location was observed. However, it could not be statistically demonstrated whether a specific repair technique was superior in different clinical situations.

Systematic review of the use of "magnitude-based inference" in sports science and medicine

Magnitude-based inference (MBI) is a controversial statistical method that has been used in hundreds of papers in sports science despite criticism from statisticians. To better understand how this method has been applied in practice, we systematically reviewed 232 papers that used MBI. We extracted data on study design, sample size, and choice of MBI settings and parameters. Median sample size was 10 per group (interquartile range, IQR: 8-15) for multi-group studies and 14 (IQR: 10-24) for single-group studies; few studies reported a priori sample size calculations (15%). Authors predominantly applied MBI's default settings and chose "mechanistic/non-clinical" rather than "clinical" MBI even when testing clinical interventions (only 16 studies out of 232 used clinical MBI). Using these data, we can estimate the Type I error rates for the typical MBI study. Authors frequently made dichotomous claims about effects based on the MBI criterion of a "likely" effect and sometimes based on the MBI criterion of a "possible" effect. When the sample size is n = 8 to 15 per group, these inferences have Type I error rates of 12%-22% and 22%-45%, respectively. High Type I error rates were compounded by multiple testing: Authors reported results from a median of 30 tests related to outcomes; and few studies specified a primary outcome (14%). We conclude that MBI has promoted small studies, promulgated a "black box" approach to statistics, and led to numerous papers where the conclusions are not supported by the data. Amidst debates over the role of p-values and significance testing in science, MBI also provides an important natural experiment: we find no evidence that moving researchers away from p-values or null hypothesis significance testing makes them less prone to dichotomization or over-interpretation of findings.

Cardiovagal baroreflex gain relates to sensory loss after spinal cord injury

Spinal cord injury (SCI) leads to autonomic nervous system damage, resulting in loss of sympathetic control to the vasculature and the heart proportional to injury level. Given maintained cardiac parasympathetic control, we hypothesized that SCI demonstrates a compensatory, higher baroreflex gain compared to able-bodied that relates to injury level (neurological and/or sensory). We compared baroreflex gain (average and across 10-20, 20-30, and 30-40 mmHg input stimuli) derived from neck chamber technique in SCI (N = 29; neurological level C1-T10, sensory zone of partial preservation C4-S4/5; ≤2 yrs since injury) and able-bodied (N = 14). Average gain tended to be higher in able-bodied compared to SCI (p = 0.06), primarily due to higher gains at 10-20 and 20-30 mmHg (p = 0.03, p = 0.06). In SCI, although gain was not related to neurological level, average gain and gain at 10-20 mmHg was related to sensory zone of partial preservation and resting RR-interval (all p < 0.02). Multiple regression showed that both sensory level and RR-interval were strongly predictive of average baroreflex gain (r² = 0.41, p < 0.01) and gain at 10-20 mmHg (r² = 0.51, p < 0.01); gain decreased with higher sensory zone of partial preservation and lower resting RR-interval. Moreover, gain was significantly lower in those with high sensory level compared to both able-bodied (average gain and gain at 10-20 and 20-30 mmHg p < 0.01) and those with low level injury (all p < 0.05). In SCI, sensory zone of partial preservation is more predictive of gain than neurological level. This might reflect that those with high level sensory injuries may have the lowest likelihood of intact cardiac sympathetic innervation and therefore lesser cardiac vagal responsiveness due to vagal-sympathetic interactions.

The Role of Aerobic Exercise in Reducing Persistent Sport-related Concussion Symptoms

Aerobic exercise has received increasing attention in the scientific literature as a component of management for individuals who sustain a concussion. Because exercise training has been reported to reduce symptoms and improve function for those experiencing persistent postconcussion symptoms, it represents a potentially useful and clinically pragmatic rehabilitation technique. However, the specific exercise parameters that best facilitate recovery from concussion remain poorly defined and unclear. This review will provide a summary of the current understanding of the role of subsymptom exercise to improve outcomes after a concussion and will describe the exercise parameters that appear to be important. The latter will take into account the three pillars of exercise dose-frequency, duration, and intensity-to examine what is currently known. In addition, we identify important gaps in our knowledge of exercise as a treatment for those who develop persistent symptoms of concussion.

Acute Ventilatory Support During Whole-Body Hybrid Rowing in Patients With High-Level Spinal Cord Injury: A Randomized Controlled Crossover Trial

BACKGROUND

High-level spinal cord injury (SCI) results in profound spinal and supraspinal deficits, leading to substantial ventilatory limitations during whole-body hybrid functional electrical stimulation (FES)-rowing, a form of exercise that markedly increases the active muscle mass via electrically induced leg contractions. This study tested the effect of noninvasive ventilation (NIV) on ventilatory and aerobic capacities in SCI.

METHODS

This blinded, randomized crossover study enrolled 19 patients with SCI (level of injury ranging from C4 to T8). All patients were familiar with FES-rowing and had plateaued in their training-related increases in aerobic capacity. Patients performed two FES-rowing peak exercise tests with NIV or without NIV (sham).

RESULTS

NIV increased exercise tidal volume (peak, 1.50 ± 0.31 L vs 1.36 ± 0.34 L; P < .05) and reduced breathing frequency (peak, 35 ± 7 beats/min vs 38 ± 6 beats/min; P < .05) compared with the sham test, leading to no change in alveolar ventilation but a trend toward increased oxygen uptake efficiency (P = .06). In those who reached peak oxygen consumption (Vo₂peak) criteria (n = 13), NIV failed to significantly increase Vo₂peak (1.73 ± 0.66 L/min vs 1.78 ± 0.59 L/min); however, the range of responses revealed a correlation between changes in peak alveolar ventilation and Vo₂peak (r = 0.89; P < .05). Furthermore, those with higher level injuries and shorter time since injury exhibited the greatest increases in Vo₂peak.

CONCLUSIONS

Acute NIV can successfully improve ventilatory efficiency during FES exercise in SCI but may not improve Vo₂peak in all patients. Those who benefit most seem to be patients with cervical SCI within a shorter time since injury.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT02865343 and NCT03267212; URL: www.clinicaltrials.gov.

Muscle Fatigue in Response to Electrical Stimulation Pattern and Frequency in Spinal Cord Injury

BACKGROUND

Functional electrical stimulation (FES) is widely used to induce functional movements for paralyzed muscles. However, rapid muscle fatigue during FES-induced muscle contractions limits FES clinical efficacy.

OBJECTIVE

To investigate muscle fatigue response across stimulation patterns and frequencies during FES in able-bodied individuals and in those with spinal cord injury (SCI).

DESIGN

Four stimulation protocols combining 20 and 40 Hz average frequency with either constant frequency trains (CFTs) or with doublet frequency trains (DFTs) were applied to the quadriceps of seven adults with SCI and eight able-bodied participants.

SETTING

A FES-row training laboratory.

PARTICIPANTS

Seven individuals with SCI (one female; age range, 25 ± 6 years) and eight age-matched able-bodied participants (one female).

INTERVENTION

None.

MAIN OUTCOME MEASURES

Fatigue was defined as the number of contractions until force decreased by 20% from the target level of 25% maximal contraction force. The number of contractions and the stimulation current used during the four stimulation protocols were compared.

RESULTS

There was a significant effect of frequency, as well as interaction between group and stimulation pattern (P < .05). In both groups, 20-Hz trains increased the number of contractions to fatigue compared to 40-Hz trains. However, the responses to the pattern of stimulation differed. In the able-bodied participants, CFT increased the number of contractions to fatigue compared to DFT, whereas in those with SCI, DFT increased the number of contractions to fatigue. In fact, DFT resulted in similar number of contractions to fatigue in both populations.

CONCLUSIONS

These results indicate that DFT at 20 Hz may be a better stimulation protocol to delay fatigue onset in the SCI population than the other three protocols. In addition, this work implies that results from able-bodied persons may not be directly applicable to those with SCI.

Effects of FES-Rowing Exercise on the Time-Dependent Changes in Bone Microarchitecture After Spinal Cord Injury: A Cross-Sectional Investigation

Disuse osteoporosis is a serious, secondary consequence of spinal cord injury (SCI). Numerous pharmacological and exercise therapies have been implemented to mitigate bone loss after SCI. However, these therapies have not been shown to improve bone density, potentially because of insufficient duration and magnitude of loading and/or inability of imaging modalities to capture changes in bone microarchitecture. In this cross‐sectional study, we evaluated bone microstructure of the distal tibia and radius using HR‐pQCT in men with SCI (N = 13) who regularly trained with functional electrical stimulation‐ (FES‐) rowing. We aimed to determine whether the amount of FES‐rowing (total distance rowed and peak foot force) and/or time since injury (TSI) predict bone loss after SCI. We assessed volumetric density of the total, cortical, and trabecular compartments, cortical thickness, and trabecular thickness. Using linear regression analysis, we found that TSI was not associated with any of the tibial bone metrics. In fact, none of the variables (TSI, total distance rowed, and peak foot force) independently predicted bone loss. Using stepwise regression, when all three variables were considered together, we found a strong prediction for trabecular microstructure (trabecular vBMD: R² = 0.53; p = 0.06; trabecular thickness: R² = 0.72; p < 0.01), but not cortical bone metrics. In particular, trabecular vBMD and thickness were negatively associated with TSI and positively associated with distance rowed. Foot force contributed markedly less to trabecular bone than distance rowed or TSI. Our results suggest that regular FES‐rowing may have the capacity to alter the time‐dependent bone negative effects of SCI on trabecular bone density and microstructure. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Tests of General Relativity with GW170817

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due to large extra dimensions. Finally, the polarization content of the gravitational wave signal is studied. The results of all tests performed here show good agreement with GR.

Inspiratory threshold loading reduces lipoperoxidation in obese and normal-weight subjects

Obesity is related to increased oxidative stress. Although low-intensity physical exercise reduces oxidative stress, obese subjects may show exercise intolerance. For these subjects, inspiratory threshold loading could be an alternative tool to reduce oxidative stress. We investigated the effects of inspiratory threshold loading on biomarkers of oxidative stress in obese and normal-weight subjects. Twenty obese (31.4 ± 6 years old, 10 men and 10 women, 37.5 ± 4.7 kg/m²) and 20 normal-weight (29.4 ± 8 years old, 10 men and 10 women, 23.2 ± 1.5 kg/m²) subjects matched for age and gender participated in the study. Maximal inspiratory pressure (MIP) was assessed by a pressure transducer. Blood sampling was performed before and after loading and control protocols to assess thiobarbituric acid reactive substances (TBARS), protein carbonylation, and reduced glutathione. Inspiratory threshold loading was performed at 60% MIP and maintained until task failure. The 30-min control protocol was performed at 0 cmH₂O. Our results demonstrated that inspiratory threshold loading reduced TBARS across time in obese (6.21 ± 2.03 to 4.91 ± 2.14 nmol MDA/ml) and normal-weight subjects (5.60 ± 3.58 to 4.69 ± 2.80 nmol MDA/ml; p = 0.007), but no change was observed in protein carbonyls and glutathione in both groups. The control protocol showed no significant changes in TBARS and protein carbonyls. However, reduced glutathione was increased across time in both groups (obese: from 0.50 ± 0.37 to 0.56 ± 0.35 μmol GSH/ml; normal-weight: from 0.61 ± 0.11 to 0.81 ± 0.23 μmol GSH/ml; p = 0.002). These findings suggest that inspiratory threshold loading could be potentially used as an alternative tool to reduce oxidative stress in both normal-weight and obese individuals.

Combination Therapy With Zoledronic Acid and FES-Row Training Mitigates Bone Loss in Paralyzed Legs: Results of a Randomized Comparative Clinical Trial

Spinal cord injury (SCI) results in rapid, severe osteoporosis and an increased risk of lower extremity fractures. Despite the medical complications associated with these fractures, there is no standard of care to prevent osteoporotic fractures following SCI. Functional electrical stimulation- (FES-) assisted rowing is a promising intervention to improve bone health in SCI because of its ability to generate a muscular contraction in conjunction with mechanical loading of the lower extremity long bones. Combination therapy consisting of FES-rowing plus zoledronic acid (ZA) may be a superior treatment via inhibition of bone resorption and stimulation of new bone formation. We studied participants enrolled in a randomized clinical trial comparing FES-rowing alone with FES-rowing plus ZA to improve bone health in SCI. Volumetric CT scans at the distal femur and proximal tibial metaphyses were performed. Bone geometric properties (cortical thickness index [CTI], cortical compressive strength index [CSI], buckling ratio [BR], bending strength index) and mineral (cortical bone volume [CBV], cortical bone mineral density, cortical bone mineral content) indices were determined. In models adjusting for baseline values, we found that the CBV (p = 0.05 to 0.006), the CTI (p = 0.009), and the BR (p = 0.001) at both the distal femoral and proximal tibial metaphyses were greater in the ZA plus rowing group compared with the rowing-only group. Similarly, there was a significant positive association between the total rowing work completed and the BR at the proximal tibia (p = 0.05). A subgroup analysis of the rowing-only arm showed that gains in the CSI at the tibial metaphysis varied in a dose-dependent fashion based on the total amount of exercise performed (p = 0.009). These findings demonstrate that the osteogenic response to FES-rowing is dose-dependent. Combination therapy with ZA and FES-row training has therapeutic potential to improve bone quality, and perhaps reduce fracture risk at the most common fracture site following SCI. © 2019 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.