From Toxin to Treatment: A Narrative Review on the Use of Botulinum Toxin for Autonomic Dysfunction

Since its regulatory approval over a half-century ago, botulinum toxin has evolved from one of the most potent neurotoxins known to becoming routinely adopted in clinical practice. Botulinum toxin, a highly potent neurotoxin produced by Clostridium botulinum, can cause botulism illness, characterized by widespread muscle weakness due to inhibition of acetylcholine transmission at neuromuscular junctions. The observation of botulinum toxin's anticholinergic properties led to the investigation of its potential benefits for conditions with an underlying etiology of cholinergic transmission, including autonomic nervous system dysfunction. These conditions range from disorders of the integument to gastrointestinal and urinary systems. Several formulations of botulinum toxin have been developed and tested over time, significantly increasing the availability of this treatment for appropriate clinical use. Despite the accelerated and expanded use of botulinum toxin, there lacks an updated comprehensive review on its therapeutic use, particularly to treat autonomic dysfunction. This narrative review provides an overview of the effect of botulinum toxin in the treatment of autonomic dysfunction and summarizes the different formulations and dosages most widely studied, while highlighting reported outcomes and the occurrence of any adverse events.

REPORT-SCS: minimum reporting standards for spinal cord stimulation studies in spinal cord injury

Objective.Electrical spinal cord stimulation (SCS) has emerged as a promising therapy for recovery of motor and autonomic dysfunctions following spinal cord injury (SCI). Despite the rise in studies using SCS for SCI complications, there are no standard guidelines for reporting SCS parameters in research publications, making it challenging to compare, interpret or reproduce reported effects across experimental studies.Approach.To develop guidelines for minimum reporting standards for SCS parameters in pre-clinical and clinical SCI research, we gathered an international panel of expert clinicians and scientists. Using a Delphi approach, we developed guideline items and surveyed the panel on their level of agreement for each item.Main results.There was strong agreement on 26 of the 29 items identified for establishing minimum reporting standards for SCS studies. The guidelines encompass three major SCS categories: hardware, configuration and current parameters, and the intervention.Significance.Standardized reporting of stimulation parameters will ensure that SCS studies can be easily analyzed, replicated, and interpreted by the scientific community, thereby expanding the SCS knowledge base and fostering transparency in reporting.

Perspectives from the spinal cord injury community with teleSCI services during the COVID-19 pandemic: a qualitative study

PURPOSE

To explore individuals with spinal cord injury (SCI) experiences with and perceptions towards teleSCI services during the COVID-19 global pandemic in British Columbia, Canada.

METHOD

Using maximum variation sampling, we invited selected individuals from a larger quantitative dataset (n = 71) to partake in an interview. In total, 12 individuals participated in the study. Interviews were recorded and transcribed verbatim. Interview transcripts were then coded and analysed by team members using qualitative descriptive analysis.

RESULTS

Individuals with an SCI perceived teleSCI services to be convenient, accessible, affordable, and an effective way to access some healthcare services during the COVID-19 pandemic. However, in-person healthcare was still needed by many participants to effectively manage and treat their SCI-associated secondary conditions.

CONCLUSION

Our findings suggest that, in a post-pandemic world, the SCI community would benefit from blended models of healthcare delivery that leverage telecommunication technologies to increase accessibility to healthcare while still providing in-person care for assessments and treatments.Implications for RehabilitationIndividuals with an SCI perceived teleSCI services to be convenient, accessible, affordable, and an effective way to access some healthcare services during the COVID-19 pandemic. However, in-person healthcare was still needed and desired by those with an SCI to effectively manage and treat their SCI-associated secondary conditions.In a post-pandemic world, individuals with an SCI would benefit from blended models of healthcare delivery that leverage telecommunication technologies to increase accessibility to healthcare, while still providing in-person care for those requiring ongoing treatment and management of secondary conditions associated with the patient's SCI.TeleSCI services offer the potential to allow healthcare professionals and SCI specialists to collaborate (digitally) with patients at the same time. This patient-centered approach could not only help healthcare professionals strategize effective remedies to better manage secondary conditions associated with SCI but could result in overall better-quality care received by those within the SCI community.

Heart Rate Variability-Based Prediction of Autonomic Dysreflexia After Spinal Cord Injury

Autonomic dysreflexia (AD) is a common autonomic complication of spinal cord injury (SCI) characterized by a sudden increase is blood pressure triggered by peripheral stimulation, such as bladder distention. Iatrogenic AD events often occur during various medical procedures including urodynamic assessments (UDSs) used to evaluate lower urinary tract (LUT) function in individuals with SCI. To date, there are no established clinical practices that would allow early detection of the development of episodes of AD. Heart rate variability (HRV) is a reliable and non-invasive metric for evaluating autonomic regulation of the cardiovascular system, with demonstrated utility in people with SCI during UDSs. We aim to provide a comprehensive evaluation of cardiovascular function during UDS-induced AD using ultra-short-term HRV analysis and identify changes in cardiovascular dynamics to predict the onset of AD. We assessed cardiovascular data in a total of 24 participants with sensorimotor complete SCI above T6 (17 males, 7 females, median age = 43 [36-50] years) who experienced AD during UDS. We used continuous electrocardiographic recordings to evaluate HRV in 60 sec overlapping windows during filling cystometry. The mean of "normal-to-normal" heartbeats (meanNN), its standard deviation (SDNN), and the root mean square of successive differences (RMSSD) were calculated and used in all subsequent analyses. We found that SDNN and RMSSD diminished during the early phase of bladder filling and sharply increased during AD. Using the lowest point of statistical variability in heart rate (i.e., SDNN), we were able to predict AD events within 240 sec (percentile 25-percentile 75: 172-339 sec) before the first systolic blood pressure peak after AD onset (sensitivity = 0.667; specificity = 0.875). Our results indicated a temporary increase in sympathetic activity during the early phase of bladder filling, which is followed by an increase in parasympathetic outflow to the heart when AD occurs. These findings have significant clinical implications that extend beyond the context of UDS and demonstrate the importance of identifying early changes in HRV in order to accurately predict AD episodes in people living with SCI.

Heart Rate Variability Biofeedback in Adults with a Spinal Cord Injury: A Laboratory Framework and Case Series

Heart rate variability biofeedback (HRV-F) is a neurocardiac self-regulation therapy that aims to regulate cardiac autonomic nervous system activity and improve cardiac balance. Despite benefits in various clinical populations, no study has reported the effects of HRV-F in adults with a spinal cord injury (SCI). This article provides an overview of a neuropsychophysiological laboratory framework and reports the impact of an HRV-F training program on two adults with chronic SCI (T1 AIS A and T3 AIS C) with different degrees of remaining cardiac autonomic function. The HRV-F intervention involved 10 weeks of face-to-face and telehealth sessions with daily HRV-F home practice. Physiological (HRV, blood pressure variability (BPV), baroreflex sensitivity (BRS)), and self-reported assessments (Fatigue Severity Scale, Generalised Anxiety Disorder Scale, Patient Health Questionnaire, Appraisal of Disability and Participation Scale, EuroQol Visual Analogue Scale) were conducted at baseline and 10 weeks. Participants also completed weekly diaries capturing mood, anxiety, pain, sleep quality, fatigue, and adverse events. Results showed some improvement in HRV, BPV, and BRS. Additionally, participants self-reported some improvements in mood, fatigue, pain, quality of life, and self-perception. A 10-week HRV-F intervention was feasible in two participants with chronic SCI, warranting further investigation into its autonomic and psychosocial effects.

Construct validity of the international standards to document remaining autonomic function after spinal cord injury (ISAFSCI) (1st edition)

STUDY DESIGN

Observational study.

OBJECTIVES

To assess the construct validity of the International Standards to Document Remaining Autonomic Function after Spinal Cord Injury (ISAFSCI) (2012 1st Edition).

SETTING

Two Canadian spinal cord injury (SCI) centers.

METHODS

Data were collected between 2011-2014. Assessments included the ISAFSCI, standardized measures of autonomic function and a clinical examination. Construct validity of ISAFSCI was assessed by testing a priori hypotheses on expected ISAFSCI responses to standard measures (convergent hypotheses) and clinical variables (clinical hypotheses).

RESULTS

Forty-nine participants with an average age of 45 ± 12 years were included, of which 42 (85.7%) were males, 37 (77.6%) had a neurological level of injury at or above T6, and 23 (46.9%) were assessed as having motor and sensory complete SCI. For the six General Autonomic Function component hypotheses, two hypotheses (1 clinical, 1 convergent) related to autonomic control of blood pressure and one clinical hypothesis for temperature regulation were statistically significant. In terms of the Lower Urinary Tract, Bowel and Sexual Function component of the ISAFSCI, all the hypotheses (5 convergent, 3 clinical) were statistically significant except for the hypotheses on female sexual items (2 convergent, 2 clinical), likely due to small sample size.

CONCLUSION

The construct validity of ISAFSCI (2012 1st Edition) for the General Autonomic Function component was considered to be weak while it was much stronger for the Lower Urinary Tract, Bowel and Sexual Function component based on a priori hypotheses. These results can inform future psychometric studies of the ISAFSCI (2021 2nd Edition).

Exercise and aerobic capacity in individuals with spinal cord injury: A systematic review with meta-analysis and meta-regression

BACKGROUND

A low level of cardiorespiratory fitness [CRF; defined as peak oxygen uptake ([Formula: see text]O2peak) or peak power output (PPO)] is a widely reported consequence of spinal cord injury (SCI) and a major risk factor associated with chronic disease. However, CRF can be modified by exercise. This systematic review with meta-analysis and meta-regression aimed to assess whether certain SCI characteristics and/or specific exercise considerations are moderators of changes in CRF.

METHODS AND FINDINGS

Databases (MEDLINE, EMBASE, CENTRAL, and Web of Science) were searched from inception to March 2023. A primary meta-analysis was conducted including randomised controlled trials (RCTs; exercise interventions lasting >2 weeks relative to control groups). A secondary meta-analysis pooled independent exercise interventions >2 weeks from longitudinal pre-post and RCT studies to explore whether subgroup differences in injury characteristics and/or exercise intervention parameters explained CRF changes. Further analyses included cohort, cross-sectional, and observational study designs. Outcome measures of interest were absolute (A[Formula: see text]O2peak) or relative [Formula: see text]O2peak (R[Formula: see text]O2peak), and/or PPO. Bias/quality was assessed via The Cochrane Risk of Bias 2 and the National Institute of Health Quality Assessment Tools. Certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Random effects models were used in all meta-analyses and meta-regressions. Of 21,020 identified records, 120 studies comprising 29 RCTs, 67 pre-post studies, 11 cohort, 7 cross-sectional, and 6 observational studies were included. The primary meta-analysis revealed significant improvements in A[Formula: see text]O2peak [0.16 (0.07, 0.25) L/min], R[Formula: see text]O2peak [2.9 (1.8, 3.9) mL/kg/min], and PPO [9 (5, 14) W] with exercise, relative to controls (p < 0.001). Ninety-six studies (117 independent exercise interventions comprising 1,331 adults with SCI) were included in the secondary, pooled meta-analysis which demonstrated significant increases in A[Formula: see text]O2peak [0.22 (0.17, 0.26) L/min], R[Formula: see text]O2peak [2.8 (2.2, 3.3) mL/kg/min], and PPO [11 (9, 13) W] (p < 0.001) following exercise interventions. There were subgroup differences for R[Formula: see text]O2peak based on exercise modality (p = 0.002) and intervention length (p = 0.01), but there were no differences for A[Formula: see text]O2peak. There were subgroup differences (p ≤ 0.018) for PPO based on time since injury, neurological level of injury, exercise modality, and frequency. The meta-regression found that studies with a higher mean age of participants were associated with smaller changes in A[Formula: see text]O2peak and R[Formula: see text]O2peak (p < 0.10). GRADE indicated a moderate level of certainty in the estimated effect for R[Formula: see text]O2peak, but low levels for A[Formula: see text]O2peak and PPO. This review may be limited by the small number of RCTs, which prevented a subgroup analysis within this specific study design.

CONCLUSIONS

Our primary meta-analysis confirms that performing exercise >2 weeks results in significant improvements to A[Formula: see text]O2peak, R[Formula: see text]O2peak, and PPO in individuals with SCI. The pooled meta-analysis subgroup comparisons identified that exercise interventions lasting up to 12 weeks yield the greatest change in R[Formula: see text]O2peak. Upper-body aerobic exercise and resistance training also appear the most effective at improving R[Formula: see text]O2peak and PPO. Furthermore, acutely injured, individuals with paraplegia, exercising for ≥3 sessions/week will likely experience the greatest change in PPO. Ageing seemingly diminishes the adaptive CRF responses to exercise training in individuals with SCI.

REGISTRATION

PROSPERO: CRD42018104342.

The temporal burden of preparing catheters for re-use in adults with spinal cord injury: a cross-sectional study

STUDY DESIGN

Cross-sectional OBJECTIVES: Neurogenic lower urinary tract dysfunction is common among people with spinal cord injury (SCI). Although single-use clean intermittent catheterization is recommended to facilitate routine bladder emptying, catheter re-use is common. Barriers associated with the preparation (i.e., cleaning) of catheters for re-use are unknown. This study examined barriers to catheter re-use in adult individuals with SCI by assessing (1) the time needed to clean a catheter, and (2) the perceived difficulty of the catheter cleaning routine.

SETTING

Laboratory METHODS: Twenty individuals with chronic SCI ( ≥ 1 year since injury; Group 1 = 10 with tetraplegia; Group 2 = 10 with paraplegia) completed the study. Using a standardized cleaning procedure (i.e., Milton method), catheter cleaning was timed for each participant. Perceived difficulty was assessed using a 5-point Likert scale. Functional impairment was assessed with the Upper Extremity Motor Score (UEMS).

RESULTS

Significant between-group differences were observed for total cleaning time (Group 1 = 1584.1 ± 179.8 s; Group 2 = 1321.0 ± 93.8 s, p = 0.004) and perceived difficulty [Group 1 = 2.6 (2, 3); Group 2 = 2 (1.7, 2.3), p = 0.028]. Total cleaning time was significantly correlated with UEMS (ρ = -0.709, p ≤ 0.001) and perceived difficulty (ρ = 0.468, p = 0.037). UEMS emerged as an independent predictor of total cleaning time (R² = 0.745, β = -0.833, p ≤ 0.001).

CONCLUSIONS

Preparing catheters for re-use is time-intensive and difficult for people with higher SCI level, severity and more pronounced upper limb motor impairment, which was independently associated with total cleaning time. Performing this routine on a consistent basis would require a substantial time commitment and would have a profoundly negative impact on overall quality of life.

sPinal cOrd neUromodulatioN to treat Cerebral palsy in pEdiatrics: POUNCE Multisite Randomized Clinical Trial

Introduction

Cerebral palsy (CP) affects up to 4 children in 1,000 live births, making it the most common motor disorder in children. It impairs the child's ability to move voluntarily and maintain balance and posture, and results in a wide range of other functional disorders during early development impairments in various sensory modalities, e.g., vision, hearing ability and proprioception. Current standard of care therapy focuses on symptom management and does not mitigate the progression of many of these underlying neurological impairments. The goal of this trial is to conduct a prospective multicenter, double-blinded, sham-controlled, crossover, randomized control trial to demonstrate the safety and efficacy of noninvasive spinal cord neuromodulation (SCiP™, SpineX Inc.) in conjunction with activity-based neurorehabilitation therapy (ABNT) to improve voluntary sensorimotor function in children with cerebral palsy.

Methods and analysis

Sixty participants (aged 2-13 years) diagnosed with CP classified as Gross Motor Function Classification Scale Levels I-V will be recruited and divided equally into two groups (G1 and G2). Both groups will receive identical ABNT 2 days/wk. G1 will initially receive sham stimulation, whereas G2 will receive therapeutic SCiP™ therapy for 8 weeks. After 8 weeks, G1 will cross over and receive therapeutic SCiP™ therapy for 8 weeks, whereas G2 will continue to receive SCiP™ therapy for another 8 weeks, for a total of 16 weeks. Primary and secondary outcome measures will include Gross Motor Function Measure-88 and Modified Ashworth Scale, respectively. Frequency and severity of adverse events will be established by safety analyses.

Ethics and dissemination

The trial is registered on clinicaltrials.gov (NCT05720208). The results from this trial will be reported on clinicaltrials.gov, published in peer-reviewed journals and presented at scientific and clinical conferences.

Motor and autonomic concomitant health improvements with neuromodulation and exercise (MACHINE) training: a randomised controlled trial in individuals with spinal cord injury

INTRODUCTION

Motor and autonomic dysfunctions are widespread among people with spinal cord injury (SCI), leading to poor health and reduced quality of life. Exercise interventions, such as locomotor training (LT), can promote sensorimotor and autonomic recovery post SCI. Recently, breakthroughs in SCI research have reported beneficial effects of electrical spinal cord stimulation (SCS) on motor and autonomic functions. Despite literature supporting the independent benefits of transcutaneous SCS (TSCS) and LT, the effect of pairing TSCS with LT is unknown. These therapies are non-invasive, customisable and have the potential to simultaneously benefit both sensorimotor and autonomic functions. The aim of this study is to assess the effects of LT paired with TSCS in people with chronic SCI on outcomes of sensorimotor and autonomic function.

METHODS AND ANALYSIS

Twelve eligible participants with chronic (>1 year) motor-complete SCI, at or above the sixth thoracic segment, will be enrolled in this single-blinded, randomised sham-controlled trial. Participants will undergo mapping for optimisation of stimulation parameters and baseline assessments of motor and autonomic functions. Participants will then be randomly assigned to either LT+TSCS or LT+Sham stimulation for 12 weeks, after which postintervention assessments will be performed to determine the effect of TSCS on motor and autonomic functions. The primary outcome of interest is attempted voluntary muscle activation using surface electromyography. The secondary outcomes relate to sensorimotor function, cardiovascular function, pelvic organ function and health-related quality of life. Statistical analysis will be performed using two-way repeated measures Analysis of variance (ANOVAs) or Kruskal-Wallis and Cohen's effect sizes.

ETHICS AND DISSEMINATION

This study has been approved after full ethical review by the University of British Columbia's Research Ethics Board. The stimulator used in this trial has received Investigation Testing Authorisation from Health Canada. Trial results will be disseminated through peer-reviewed publications, conference presentations and seminars.

TRIAL REGISTRATION NUMBER

NCT04726059.

The Microbiological Burden of Short-Term Catheter Reuse in Individuals with Spinal Cord Injury: A Prospective Study

Despite the risk of developing catheter-associated urinary tract infections (CAUTI), catheter reuse is common among people with spinal cord injury (SCI). This study examined the microbiological burden and catheter surface changes associated with short-term reuse. Ten individuals with chronic SCI reused their catheters over 3 days. Urine and catheter swab cultures were collected daily for analysis. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses were used to assess catheter surface changes. Catheter swab cultures showed no growth after 48 h (47.8%), skin flora (28.9%), mixed flora (17.8%), or bacterial growth (5.5%). Asymptomatic bacteriuria was found for most participants at baseline (n = 9) and all at follow-up (n = 10). Urine samples contained Escherichia coli (58%), Klebsiella pneumoniae (30%), Enterococcus faecalis (26%), Acinetobacter calcoaceticus-baumannii (10%), Pseudomonas aeruginosa (6%) or Proteus vulgaris (2%). Most urine cultures showed resistance to one or more antibiotics (62%). SEM images demonstrated structural damage, biofilm and/or bacteria on all reused catheter surfaces. XPS analyses also confirmed the deposition of bacterial biofilm on reused catheters. Catheter surface changes and the presence of antibiotic-resistant bacteria were evident following short-term reuse, which may increase susceptibility to CAUTI in individuals with SCI despite asymptomatic bacteriuria.

Epidural stimulation restores muscle synergies by modulating neural drives in participants with sensorimotor complete spinal cord injuries

Multiple studies have corroborated the restoration of volitional motor control after motor-complete spinal cord injury (SCI) through the use of epidural spinal cord stimulation (eSCS), but rigorous quantitative descriptions of muscle coordination have been lacking. Six participants with chronic, motor and sensory complete SCI underwent a brain motor control assessment (BMCA) consisting of a set of structured motor tasks with and without eSCS. We investigated how muscle activity complexity and muscle synergies changed with and without stimulation. We performed this analysis to better characterize the impact of stimulation on neuromuscular control. We also recorded data from nine healthy participants as controls. Competition exists between the task origin and neural origin hypotheses underlying muscle synergies. The ability to restore motor control with eSCS in participants with motor and sensory complete SCI allows us to test whether changes in muscle synergies reflect a neural basis in the same task. Muscle activity complexity was computed with Higuchi Fractal Dimensional (HFD) analysis, and muscle synergies were estimated using non-negative matrix factorization (NNMF) in six participants with American Spinal Injury Association (ASIA) Impairment Score (AIS) A. We found that the complexity of muscle activity was immediately reduced by eSCS in the SCI participants. We also found that over the follow-up sessions, the muscle synergy structure of the SCI participants became more defined, and the number of synergies decreased over time, indicating improved coordination between muscle groups. Lastly, we found that the muscle synergies were restored with eSCS, supporting the neural hypothesis of muscle synergies. We conclude that eSCS restores muscle movements and muscle synergies that are distinct from those of healthy, able-bodied controls.

Spinal Cord Stimulation Prevents Autonomic Dysreflexia in Individuals with Spinal Cord Injury: A Case Series

Spinal cord injury (SCI) results in severe cardiovascular dysfunction due to the disruption of supraspinal control. Autonomic dysreflexia (AD), an uncontrolled rise in blood pressure in response to peripheral stimuli including common bowel routine, digital anorectal stimulation (DARS), reduces the quality of life, and increases morbidity and mortality. Recently, spinal cord stimulation (SCS) has emerged as a potential intervention to mitigate unstable blood pressure following SCI. The objective of this case series was to test the real-time effect of epidural SCS (eSCS) at the lumbosacral spinal cord, the most common implant location, on mitigating AD in individuals with SCI. We recruited three individuals with cervical and upper thoracic motor-complete SCI who have an implanted epidural stimulator. We demonstrated that eSCS can reduce the elevation in blood pressure and prevent DARS-induced AD. The blood pressure variability analysis indicated that eSCS potentially reduced vascular sympathetic nervous system activity during DARS, compared to without eSCS. This case series provides evidence to support the use of eSCS to prevent AD episodes during routine bowel procedures, improving the quality of life for individuals with SCI and potentially reducing cardiovascular risks.

Cannabis health survey on usage in women with spinal cord injury and knowledge among physicians: A cross-sectional study

OBJECTIVE

Individuals with spinal cord injury (SCI) report using cannabis to self-manage chronic pain and spasticity. However, its safety and efficacy are not well understood. As more women with SCI are pursuing motherhood, clinicians must consider the possibility of maternal cannabis use and its impact on fetal development. Moreover, due to the lack of current evidence for cannabis, it is important to characterize the perceptions and knowledge of physicians towards both recreational and synthetic cannabinoids.

DESIGN

Two anonymous surveys (10-items each) were conducted.

SETTING AND PARTICIPANTS

Women with SCI (n = 20) completed an anonymous, online survey regarding cannabis use. Physicians at a Canadian SCI rehabilitation center (n = 15) completed a survey on their knowledge of recreational and synthetic cannabinoids among individuals with SCI.

OUTCOME MEASURES

Survey 1 evaluated cannabis use patterns and perceptions before/after SCI in women, including during pregnancy and breastfeeding. The aim of Survey 2 was to understand the perception and current knowledge of physicians regarding recreational cannabis and synthetic cannabinoid use by patients with SCI.

RESULTS

At the time of survey, 7 women with SCI reported use of cannabis, only 4 of them used prior to injury. Managing tone/spasticity (n = 5) was the major reported benefit of cannabis use. Women used cannabis during pregnancy and/or breastfeeding as a sleep aid or relief for morning sickness (n = 1 pregnancy, n = 1 breastfeeding, n = 1 both). The most-reported challenge with cannabis use was difficulty obtaining consistent, desirable effects (n = 5). Almost all physicians (n = 13) described their knowledge on recreational cannabis products as "none, very little or poor", with greater overall comfort and knowledge of synthetic cannabinoids.

CONCLUSION

Due to the reported use of cannabis during pregnancy/breastfeeding and current impoverishment of physicians' knowledge (particularly regarding recreational cannabis products), it is imperative to further investigate the safety and efficacy of cannabis use in women with SCI.

Mapping the Iceberg of Autonomic Recovery: Mechanistic Underpinnings of Neuromodulation following Spinal Cord Injury

Spinal cord injury leads to disruption in autonomic control resulting in cardiovascular, bowel, and lower urinary tract dysfunctions, all of which significantly reduce health-related quality of life. Although spinal cord stimulation shows promise for promoting autonomic recovery, the underlying mechanisms are unclear. Based on current preclinical and clinical evidence, this narrative review provides the most plausible mechanisms underlying the effects of spinal cord stimulation for autonomic recovery, including activation of the somatoautonomic reflex and induction of neuroplastic changes in the spinal cord. Areas where evidence is limited are highlighted in an effort to guide the scientific community to further explore these mechanisms and advance the clinical translation of spinal cord stimulation for autonomic recovery.

Characterization of heart rate changes associated with autonomic dysreflexia during penile vibrostimulation and urodynamics

STUDY DESIGN

Secondary data analysis.

OBJECTIVES

To characterize autonomic dysreflexia (AD) associated heart rate (HR) changes during penile vibrostimulation (PVS) and urodynamic studies (UDS).

SETTING

University-based laboratory.

METHODS

We analyzed blood pressure (BP) and HR data, recorded continuously, from 21 individuals (4 females; median age 41 years [lower and upper quartile, 37; 47]; median time post-injury 18 years [7; 27]; all motor-complete spinal cord injury (SCI) except one; cervical SCI = 15, thoracic [T1-T6] SCI = 6), who underwent PVS (11/21) or UDS (10/21).

RESULTS

Overall, 47 AD episodes were recorded (i.e. PVS = 37, UDS = 10), with at least one AD episode in each participant. At AD threshold, bradycardia was observed during PVS and UDS in 43% and 30%, respectively. At AD peak (i.e., maximum increase in systolic BP from baseline), bradycardia was observed during PVS and UDS in 65% and 50%, respectively. Tachycardia was detected at AD peak only once during UDS. Our study was limited by a small cohort of participants and the distribution of sex and injury characteristics.

CONCLUSIONS

Our findings reveal that AD-associated HR changes during PVS and UDS appear to be related to the magnitude of systolic BP increases. Highly elevated systolic BP associated with bradycardia suggests the presence of severe AD. Therefore, we recommend cardiovascular monitoring (preferably with continuous beat-to-beat recordings) during PVS and UDS to detect AD early. Stopping assessments before systolic BP reaches dangerously elevated levels, could reduce the risk of life-threatening complications in this cohort.

Post-processing of peak oxygen uptake data obtained during cardiopulmonary exercise testing in individuals with spinal cord injury: A scoping review and analysis of different post- processing strategies

OBJECTIVES

To review the evidence regarding the most common practices adopted with cardiopulmonary exercise testing (CPET) in individuals with spinal cord injury (SCI), with the following specific aims to: (1) determine the most common averaging strategies of peak oxygen uptake (V̇O_2peak), (2) review the endpoint criteria adopted to determine a valid V̇O_2peak, and (3) investigate the effect of averaging strategies on V̇O_2peak values in a convenience sample of individuals with SCI (between the fourth cervical and sixth thoracic segments).

DATA SOURCES

Searches for this scoping review were conducted in MEDLINE (PubMed), EMBASE, and Web Science.

STUDY SELECTION

Studies were included if (1) were original research on humans published in English, (2) recruited adults with traumatic and non-traumatic SCI, and (3) V̇O_2peak reported and measured directly during CPET to volitional exhaustion. Full-text review identified studies published before April 2021 for inclusion.

DATA EXTRACTION

Extracted data included authors, journal name, publication year, participant characteristics, and comprehensive information relevant to CPET.

DATA SYNTHESIS

We extracted data from a total of 200 studies involving 4,928 participants. We found that more than 50% of studies adopted a 30-sec averaging strategy. A wide range of endpoint criteria were used to confirm the attainment of maximal effort. In the convenience sample of individuals with SCI (n=30), the mean V̇O_2peak decreased as epoch (i.e., time) lengths increased. Reported V̇O_2peak values differed significantly (P<.001) between averaging strategies, with epoch length explaining 56% of the variability.

CONCLUSIONS

The adoption of accepted and standardized methods for processing and analyzing CPET data is needed to ensure high-quality, reproducible research, and inform population-specific normative values for individuals with SCI.

Effects of non-invasive spinal cord stimulation on lower urinary tract, bowel, and sexual functions in individuals with chronic motor-complete spinal cord injury: Protocol for a pilot clinical trial

INTRODUCTION

Electrical spinal cord neuromodulation has emerged as a leading intervention for restoring autonomic functions, such as blood pressure, lower urinary tract (LUT), bowel, and sexual functions, following spinal cord injury (SCI). While a few preliminary studies have shown the potential effect of non-invasive transcutaneous spinal cord stimulation (tSCS) on autonomic recovery following SCI, the optimal stimulation parameters, as well as real-time and long-term functional benefits of tSCS are understudied. This trial entitled "Non-invasive Neuromodulation to Treat Bladder, Bowel, and Sexual Dysfunction following Spinal Cord Injury" is a pilot trial to examine the feasibility, dosage effect and safety of tSCS on pelvic organ function for future large-scale randomized controlled trials.

METHODS AND ANALYSIS

Forty eligible participants with chronic cervical or upper thoracic motor-complete SCI will undergo stimulation mapping and assessment batteries to determine the real-time effect of tSCS on autonomic functions. Thereafter, participants will be randomly assigned to either moderate or intensive tSCS groups to test the dosage effect of long-term stimulation on autonomic parameters. Participants in each group will receive 60 minutes of tSCS per session either twice (moderate) or five (intensive) times per week, over a period of six weeks. Outcome measures include: (a) changes in bladder capacity through urodynamic studies during real-time and after long-term tSCS, and (b) resting anorectal pressure determined via anorectal manometry during real-time tSCS. We also measure assessments of sexual function, neurological impairments, and health-related quality of life using validated questionnaires and semi-structured interviews.

ETHICS AND DISSEMINATION

Ethical approval has been obtained (CREB H20-01163). All primary and secondary outcome data will be submitted to peer-reviewed journals and disseminated among the broader scientific community and stakeholders.

Common carotid artery responses to the cold-pressor test are impaired in individuals with cervical spinal cord injury

Cervical spinal cord injury (SCI) leads to autonomic cardiovascular dysfunction that underlies the three- to fourfold elevated risk of cardiovascular disease in this population. Reduced common carotid artery (CCA) dilatory responsiveness during the cold-pressor test (CPT) is associated with greater cardiovascular disease risk and progression. The cardiovascular and CCA responses to the CPT may provide insight into cardiovascular autonomic dysfunction and cardiovascular disease risk in individuals with cervical SCI. Here, we used CPT to perturb the autonomic nervous system in 14 individuals with cervical SCI and 12 uninjured controls, while measuring cardiovascular responses and CCA diameter. The CCA diameter responses were 55% impaired in those with SCI compared with uninjured controls (P = 0.019). The CCA flow, velocity, and shear response to CPT were reduced in SCI by 100% (P < 0.001), 113% (P = 0.001), and 125% (P = 0.002), respectively. The association between mean arterial pressure and CCA dilation observed in uninjured individuals (r = 0.54, P = 0.004) was absent in the SCI group (r = 0.22, P = 0.217). Steady-state systolic blood pressure (P = 0.020), heart rate (P = 0.003), and cardiac contractility (P < 0.001) were reduced in those with cervical SCI, whereas total peripheral resistance was increased compared with uninjured controls (P = 0.042). Relative cerebral blood velocity responses to CPT were increased in the SCI group and reduced in controls (middle cerebral artery, P = 0.010; posterior cerebral artery, P = 0.026). The CCA and cardiovascular responsiveness to CPT are impaired in those with cervical SCI.NEW & NOTEWORTHY This is the first study demonstrating that CCA responses during CPT are suppressed in SCI. Specifically, CCA diameter, flow, velocity, and shear rate were reduced. The relationship between changes in MAP and CCA dilatation in response to CPT was absent in individuals with SCI, despite similar cardiovascular activation between SCI and uninjured controls. These findings support the notion of elevated cardiovascular disease risk in SCI and that the cardiovascular responses to environmental stimuli are impaired.

Effect of the COVID-19 pandemic on individuals with spinal cord injury: Mental health and use of telehealth

INTRODUCTION

Limited access to health care services and the self-isolation measures due to the coronavirus disease 2019 (COVID-19) pandemic may have had additional unintended negative effects, affecting the health of individuals with spinal cord injury (SCI).

OBJECTIVES

To examine the perceived influence of the COVID-19 pandemic on individuals with SCI. First, this study looked to understand how the pandemic affected the use and perception of telehealth services for these individuals. Second, it investigated the effect of COVID-19 on mental health.

DESIGN

Cross-sectional online survey.

SETTING

Individuals with SCI living in the community in British Columbia, Canada.

PATIENTS

This survey was offered to individuals with SCI and had 71 respondents, with 34% living in a rural setting and 66% in an urban setting.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Telehealth utility, Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder 7 (GAD-7), Fear of COVID-19 scale (FCV-19S), and Perceived Vulnerability to Disease (PVD).

RESULTS

Telehealth use in the SCI population has increased from 9.9% to 25.4% over the pandemic, with rates of telehealth use in urban centers nearing those of rural participants. Thirty-one percent of respondents had probable depression and 7.0% had probable generalized anxiety disorder as measured by a score of ≥10 on the PHQ-9 and GAD-7, respectively. The mean scores on FCV-19S and PVD were 17.0 (6.6 SD) and 4.29 (1.02 SD), respectively.

CONCLUSION

Telehealth use during COVID-19 has more than doubled. It is generally well regarded by respondents, although only a fourth of the SCI population has reported its use. With this in mind, it is important to understand the barriers to further adoption. In addition, higher rates of probable depression were seen than those estimated by pre-pandemic studies in other countries.

May I Have This Dance: A Case-Series on the Acute Cardiometabolic Demand of Wheelchair Dancing in Recreational Dancers with Spinal Cord Injury

OBJECTIVES

This case-series investigated energy expenditure, cardiovascular responses, and psychosocial outcomes during two wheelchair dancing routines with different tempos.

METHODS

Three individuals with chronic, non-traumatic spinal cord injuries [males, mean age 42 (13) years, C3-T12, AIS D, schwannoma=1, poliomyelitis=1, ependymoma=1] performed slow (rumba, 80 bpm) and fast (salsa, 170 bpm) wheelchair dance routines. Physiological [heart rate, blood pressure, relative oxygen consumption (VO2), metabolic task equivalent] and psychosocial parameters [ratings of perceived exertion, enjoyment and Brunel Mood Score] were measured pre, during, and post-dancing.

RESULTS

All participants showed an elevation in heart rate and relative VO2 from rest to dancing with a subsequent decrease in these parameters post-dance for both routines. Relative to the slow dance routine, two out of three participants demonstrated greater heart rate, relative VO2, ratings of perceived exertion, and enjoyment during the fast dance routine. For all three participants, metabolic task equivalents ranged from 1.7-2.4 (slow) and 2.1-3.8 (fast), suggesting the intervention was of light to moderate intensity for slow and fast dance routines, respectively. Enjoyment ratings ranged from "quite a bit" to "extremely." No differences in Brunel mood subscales were observed.

CONCLUSION

This case-series offers a preliminary understanding of the acute cardiometabolic and psychosocial responses to wheelchair dance routines of differing intensities per¬formed by individuals with spinal cord injury. Responsiveness observed among these participants suggests the potential use of wheelchair dance for promoting physical activity and improving psychological well-being.

Accidental boosting in an individual with tetraplegia - considerations for the interpretation of cardiopulmonary exercise testing

CONTEXT

Autonomic dysreflexia (AD), characterized by a transient increase in systolic blood pressure (BP), is experienced by individuals with spinal cord injury (SCI) and can be purposefully induced ('boosting') to counteract autonomic dysfunction that impairs cardiovascular responses to exercise. Herein, we demonstrate the impact of unintentional boosting observed during cardiopulmonary exercise testing (CPET) in an inactive male with SCI (C5, motor-complete).

FINDINGS

On two separate occasions the individual performed a standard arm-crank CPET (1-min stages, 7W increase in resistance) following by a longer CPET (4-min stages, 12W increase in resistance), both to volitional exhaustion. The second CPET was performed to confirm the accuracy of exercise intensity prescription and verify peak exercise parameters. Immediately following the second CPET on the initial visit, the individual reported symptoms of AD, verified as a 58mmHg increase in systolic BP from baseline. Relative to the first CPET, performed only 35 min earlier, there were pronounced differences in peak exercise responses. In comparison to the longer CPET performed on the second visit without a concomitant episode of AD (thereby controlling for the type of CPET protocol administered), peak exercise outcomes were considerably elevated: power output (Δ19W), oxygen uptake (Δ3.61 ml·kg·^-1min^-1), ventilation (Δ11.4 L ·min^-1) and heart rate (Δ9 b·min^-1).

CONCLUSION/CLINICAL RELEVANCE

This case raises important considerations around the nuances of CPET in this population. In individuals susceptible to BP instability, the physiologically boosted state may explain a significant proportion of the variance in peak aerobic capacity and should be closely monitored before and after clinical CPET.

How to learn the International Standards to document remaining Autonomic Function after Spinal Cord Injury (ISAFSCI) content: Self-study through booklet is not enough

OBJECTIVE

To investigate the baseline knowledge of autonomic functions and specifically the International Standards to document remaining Autonomic Function after Spinal Cord Injury (ISAFSCI) among medical students and to present the effective methods in learning of the ISAFSCI.

DESIGN

Interventional training session.

SETTING

A tertiary hospital.

PARTICIPANTS

37 medical students.

INTERVENTIONS

Before training, a self-rating questionnaire including 24 concepts extracted from the ISAFSCI was administrated to the students. Then students were divided into two groups. One group (N = 19) had a one-hour ISAFSCI booklet self-study (BSS), while the other group (N = 18) received a one-hour lecture-based learning (LBL) about the ISAFSCI. After BSS/LBL, all students were examined by a 15-question written test on the knowledge of ISAFSCI.

MAIN OUTCOME MEASURES

Baseline knowledge self-rating questionnaire before training and comparison of post-training performance on the written test between the BSS and LBL groups.

RESULTS

Before training, students were familiar with only 8 out of the 24 concepts within the questionnaire (demonstrating baseline knowledge rate beyond 50%). Significant difference in post-training performance (P<0.05) between BBS and LBL groups was noted for 5 of 15 items tested, including hypohydrosis, broncho-pulmonary system, lower urinary tract function, bowel function and female sexual function. All questions except the one regarding hypohydrosis were answered with greater than 80% accuracy by LBL group.

CONCLUSION

Use of ISAFSCI booklet alone for self-study by medical students is not sufficient to obtain bassline knowledge of autonomic discussions after SCI. It is recommended that formal lecture or presentation should be used to improve the effectiveness of learning the ISAFSCI for medical students.

When the whole is greater than the sum of its parts: Activity-based therapy paired with spinal cord stimulation following spinal cord injury

Spinal cord injuries (SCI) result in both motor and autonomic impairments, which can negatively affect independence and quality of life and increase morbidity and mortality. Despite emerging evidence supporting the benefits of activity-based training and spinal cord stimulation as two distinct interventions for sensorimotor and autonomic recovery, the combined effects of these modalities are currently uncertain. This scoping review evaluated the effectiveness of paired interventions (exercise + spinal neuromodulation) for improving sensorimotor and autonomic functions in individuals with SCI. Four electronic databases were searched for peer-reviewed manuscripts (Medline, Embase, CINAHL and EI-compedex Engineering Village) and data were independently extracted by two reviewers using pre-established extraction tables. A total of 15 studies representing 79 participants were included in the review, of which 73% were conducted within the last five years. Only two of the studies were randomized controlled studies, while the other 13 studies were case or case-series designs. Compared to activity-based training alone, spinal cord stimulation combined with activity-based training improved walking and voluntary muscle activation, and augmented improvements in lower urinary tract, bowel, resting metabolic rate, peak oxygen consumption, and thermoregulatory function. Spinal neuromodulation in combination with use-dependent therapies may provide greater neurorecovery and induce long-term benefits for both motor and autonomic function beyond the capacity of traditional activity-based therapies. However, evidence for combinational approaches is limited and there is no consensus for outcome measures or optimal protocol parameters, including stimulation settings. Future large-scale randomized trials into paired interventions are warranted to further investigate these preliminary findings.

Fesoterodine ameliorates autonomic dysreflexia while improving lower urinary tract function and urinary incontinence-related quality of life in individuals with spinal cord injury: A prospective phase IIa study

The aim of this prospective phase IIa, open-label exploratory, pre-post study was to determine the efficacy of fesoterodine (i.e., 12-week treatment period) to ameliorate autonomic dysreflexia (AD) in individuals with chronic SCI (>1-year post-injury) at or above the sixth thoracic spinal segment, with confirmed history of AD and neurogenic detrusor overactivity (NDO). Twelve participants (4 females, 8 males; median age 42 years) completed this study and underwent urodynamics, 24-hour ambulatory-blood-pressure-monitoring (ABPM), and urinary incontinence-related quality of life (QoL) measures at baseline and on-treatment. The Montreal Cognitive Assessment (MoCA) and Neurogenic Bowel Dysfunction (NBD) score were used to monitor cognitive and bowel function, respectively. Compared to baseline, fesoterodine improved lower urinary tract (LUT) function, i.e., increased cystometric capacity (205 vs 475mL, p = 0.002) and decreased maximum detrusor pressure (44 vs 12cmH2O, p = 0.009). NDO was eliminated in seven (58%) participants. Severity of AD events during urodynamics (40 vs 27mmHg, p = 0.08) and 24-hour ABPM (59 vs. 36mmHg, p = 0.05) were both reduced, yielding a large effect size (r = -0.58). AD Frequency (14 vs. 3, p = 0.004) during 24-hour ABPM was significantly reduced. Urinary incontinence-related QoL improved (68 vs. 82, p = 0.02), however, cognitive (p = 0.2) and bowel function (p = 0.4) did not change significantly. In conclusion, fesoterodine reduces the magnitude and frequency of AD, while improving LUT function and urinary incontinence-related QoL in individuals with chronic SCI without negatively affecting cognitive or bowel function.

Cardiac arrhythmias six months following traumatic spinal cord injury

OBJECTIVE

To investigate the incidence of cardiac arrhythmias at six months following traumatic spinal cord injury (SCI) and to compare the prevalence of arrhythmias between participants with cervical and thoracic SCI.

DESIGN

A prospective observational study using continuous twenty-four-hour Holter monitoring.

SETTING

Inpatient rehabilitation unit of a university research hospital and patient home setting.

PARTICIPANTS

Fifty-five participants with acute traumatic SCI were prospectively included. For each participant, the SCI was characterized according to the International Standards for Neurological Classification of SCI by the neurological level and severity according to the American Spinal Injury Association Impairment Scale.

OUTCOME MEASURES

Comparisons between demographic characteristics and arrhythmogenic occurrences as early as possible after SCI (4 ± 2 days) followed by 1, 2, 3, 4 weeks and 6 month time points of Holter monitoring.

RESULTS

Bradycardia (heart rate [HR] <50 bpm) was present in 29% and 33% of the participants with cervical (C1-C8) and thoracic (T1-T12) SCI six months after SCI, respectively. The differences in episodes of bradycardia between the two groups were not significant (P < 0.54). The mean maximum HR increased significantly from 4 weeks to 6 months post-SCI (P < 0.001), however mean minimum and maximum HR were not significantly different between the groups at the six-month time point. There were no differences in many arrhythmias between recording periods or between groups at six months.

CONCLUSIONS

At the six-month timepoint following traumatic SCI, there were no significant differences in occurrences of arrhythmias between participants with cervical and thoracic SCI compared to the findings observed in the first month following SCI.

Temporal Changes of Cardiac Structure, Function, and Mechanics During Sub-acute Cervical and Thoracolumbar Spinal Cord Injury in Humans: A Case-Series

Individuals with cervical spinal cord injury (SCI) experience deleterious changes in cardiac structure and function. However, knowledge on when cardiac alterations occur and whether this is dependent upon neurological level of injury remains to be determined. Transthoracic echocardiography was used to assess left ventricular structure, function, and mechanics in 10 male individuals (median age 34 years, lower and upper quartiles 32–50) with cervical (n = 5, c-SCI) or thoracolumbar (n = 5, tl-SCI) motor-complete SCI at 3- and 6-months post-injury. Compared to the 3-month assessment, individuals with c-SCI displayed structural, functional, and mechanical changes during the 6-month assessment, including significant reductions in end diastolic volume [121 mL (104–139) vs. 101 mL (99–133), P = 0.043], stroke volume [75 mL (61–85) vs. 60 mL (58–80), P = 0.042], myocardial contractile velocity (S') [0.11 m/s (0.10–0.13) vs. 0.09 m/s (0.08–0.10), P = 0.043], and peak diastolic longitudinal strain rate [1.29°/s (1.23–1.34) vs. 1.07°/s (0.95–1.15), P = 0.043], and increased early diastolic filling over early myocardial relaxation velocity (E/E') ratio [5.64 (4.71–7.72) vs. 7.48 (6.42–8.42), P = 0.043]. These indices did not significantly change in individuals with tl-SCI between time points. Ejection fraction was different between individuals with c-SCI and tl-SCI at 3 [61% (57–63) vs. 54% (52–55), P &lt; 0.01] and 6 months [58% (57–62) vs. 55% (52–56), P &lt; 0.01], though values were considered normal. These results demonstrate that individuals with c-SCI exhibit significant reductions in cardiac function from 3 to 6 months post-injury, whereas individuals with tl-SCI do not, suggesting the need for early rehabilitation to minimize cardiac consequences in this specific population.

The safety of epidural spinal cord stimulation to restore function after spinal cord injury: post-surgical complications and incidence of cardiovascular events

STUDY DESIGN

Cohort prospective study.

OBJECTIVES

Epidural spinal cord stimulation (eSCS) improves volitional motor and autonomic function after spinal cord injury (SCI). While eSCS has an established history of safety for chronic pain, it remains unclear if eSCS in the SCI population presents the same risk profile. We aimed to assess safety and autonomic monitoring data for the first 14 participants in the E-STAND trial.

SETTING

Hennepin County Medical Center, Minneapolis and Minneapolis Veterans Affairs Medical Center, Minnesota, USA.

METHODS

Monthly follow-up visits assessed surgical and medical device-related safety outcomes as well as stimulation usage. Beat-by-beat blood pressure (BP) and continuous electrocardiogram data were collected during head-up tilt-table testing with and without eSCS.

RESULTS

All participants had a motor-complete SCI. Mean (SD) age and time since injury were 38 (10) and 7 (5) years, respectively. There were no surgical complications but one device malfunction 4 months post implantation. Stimulation was applied for up to 23 h/day, across a broad range of parameters: frequency (18-700 Hz), pulse width (100-600 µs), and amplitude (0.4-17 mA), with no adverse events reported. Tilt-table testing with eSCS demonstrated no significant increases in the incidence of elevated systolic BP or a greater frequency of arrhythmias.

CONCLUSIONS

eSCS to restore autonomic and volitional motor function following SCI has a similar safety profile as when used to treat chronic pain, despite the prevalence of significant comorbidities and the wide variety of stimulation parameters tested.

Spinal cord injury impairs cardiac function due to impaired bulbospinal sympathetic control

Spinal cord injury chronically alters cardiac structure and function and is associated with increased odds for cardiovascular disease. Here, we investigate the cardiac consequences of spinal cord injury on the acute-to-chronic continuum, and the contribution of altered bulbospinal sympathetic control to the decline in cardiac function following spinal cord injury. By combining experimental rat models of spinal cord injury with prospective clinical studies, we demonstrate that spinal cord injury causes a rapid and sustained reduction in left ventricular contractile function that precedes structural changes. In rodents, we experimentally demonstrate that this decline in left ventricular contractile function following spinal cord injury is underpinned by interrupted bulbospinal sympathetic control. In humans, we find that activation of the sympathetic circuitry below the level of spinal cord injury causes an immediate increase in systolic function. Our findings highlight the importance for early interventions to mitigate the cardiac functional decline following spinal cord injury.

By combining experimental models with prospective clinical studies, the authors show that spinal cord injury causes a rapid reduction in cardiac function that precedes structural changes, and that the loss of descending sympathetic control is the major cause of reduced cardiac function following spinal cord injury.

Test-retest reliability of the Valsalva maneuver in spinal cord injury

Objective: To determine the test-retest reliability of quantitative and qualitative baroreflex sensitivity (BRS) parameters derived from the Valsalva maneuver (VM) in individuals with traumatic cervical SCI.Design: Test-retest reliability.Setting: Tertiary rehabilitation center.Participants: Fourteen participants with cervical SCI (ranging from C3-C8 neurological level).Outcome Measurements: Beat-to-beat systolic blood pressure (SBP) traces (finger photoplethysmography) were obtained during a 15-second forced expiration at two time points (7.6 ± 2.9 days between sessions) to assess VM reliability. Test-retest reliability of BRS metrics from derived from the VM (Valsalva ratio; VR, pressure recovery time; PRT, vagal baroreflex sensitivity; BRSv, adrenergic baroreflex sensitivity; BRSa₁, and total recovery; TR) were assessed by intra-class correlation coefficient (ICC, with 95% confidence interval; CI) and by qualitative reproducibility (V, N, or M pattern).Results: ICCs for quantitative parameters were (CI): VR = 0.894 (0.703-0.965), TR = 0.927 (0.789-0.976), BRSa₁ = 0.561 (0.149-0.911), PRT = 0.728 (0.343-0.904), BRSv = 0.243 (-0.309-0.673). Qualitatively, 12 subjects (85.7%) demonstrated reproducible VM patterns at both time points (3 "M" pattern, 8 "V" pattern and one "N" pattern).Conclusion: VR (a measure of cardiovagal function) and TR (a measure of sympathetic adrenergic function) are reliable quantitative parameters that can be derived from SBP response to VM in participants with SCI. Qualitative waveform analysis was reproducible in 12/14 participants. This provides the foundational evidence required to pursue further validity testing to establish a role for VM in the assessment of autonomic functions in SCI.

Reduced Reflex Autonomic Responses Following Intradetrusor OnabotulinumtoxinA Injections: A Pre-/Post-study in Individuals With Cervical and Upper Thoracic Spinal Cord Injury

Urodynamic studies (UDS) can provoke autonomic dysreflexia (AD) in individuals with spinal cord injury (SCI) at and above the sixth thoracic spinal segment potentially leading to profound vagally mediated heart rate (HR) reductions. In this study,¹ we test the hypothesis that intradetrusor onabotulinumtoxinA injections will improve HR and its variability (HRV) responses to UDS in individuals with cervical and thoracic SCI. A total of 19 participants with chronic SCI (5 women, mean age 42.5 ± 7.9 years) with confirmed neurogenic detrusor overactivity underwent UDS before (i.e., baseline) and 1 month after intradetrusor onabotulinumtoxinA (200 U) injections (post-treatment). Continuous electrocardiography and blood pressure (BP) recordings were used to assess RR-interval, time, and frequency domain metrics of HRV (a surrogate marker of autonomic nervous system activity), and AD pre- and post-treatment. UDS pre-treatment resulted in increased RR-interval as well as time and frequency domain metrics of HRV. Vagally mediated increases in high-frequency (HF) power during UDS were larger in participants with cervical compared to upper thoracic SCI. Post-treatment, UDS had no effect on RR-interval and significantly reduced instances of bradycardia. Furthermore, intradetrusor onabotulinumtoxinA injections significantly reduced time domain metrics of HRV and HF power responses to UDS across all participants. Changes in HRV during UDS could be a potential indicator of improved autonomic cardiovascular function following interventions such as intradetrusor onabotulinumtoxinA injections.

Exercise Improves Cardiorespiratory Fitness, but Not Arterial Health, after Spinal Cord Injury: The CHOICES Trial

Arterial stiffness, as measured by carotid-femoral pulse wave velocity (cfPWV), is elevated after spinal cord injury (SCI). In the uninjured population, exercise training has been shown to reduce arterial stiffness. In a randomized, multi-center clinical trial, we evaluated the impact of two exercise interventions on cardiovascular disease risk factors in persons with chronic SCI. A total of 46 adults with motor-complete SCI with neurological levels of injury between the fourth cervical and sixth thoracic spinal cord segments (C4-T6) were randomly assigned to either body-weight-supported treadmill training (BWSTT) or arm-cycle ergometer training (ACET). Participants trained 3 days per week for 24 weeks. Exercise session duration progressed gradually to reach 30 and 60 min for ACET and BWSTT, respectively. The primary outcome was arterial stiffness, assessed by cfPWV, and was measured at baseline, 12 weeks of training, and at 24 weeks. Secondary outcomes included cardiorespiratory fitness (CRF) and cardiometabolic health measures and were measured before and after completion of training. Fourteen participants per intervention arm completed the exercise intervention. Our results show no effect of either exercise intervention on arterial stiffness (p = 0.07) and cardiometabolic health measures (p > 0.36). However, peak oxygen uptake increased with ACET compared with BWSTT (p = 0.04). The findings of this trial demonstrate that although 24 weeks of upper-body exercise improved CRF in persons with motor-complete SCI ≥T6, neither intervention resulted in improvements in arterial stiffness or cardiometabolic health measures. ClinicalTrials.gov identifier: NCT01718977.

Long-term neurogenic lower urinary tract dysfunction: A case of cardiovascular nightmares

CONTEXT

Individuals with spinal cord injury (SCI) suffering from autonomic dysreflexia (AD) due to neurogenic detrusor overactivity (NDO) can effectively be treated with intradetrusor onabotulinumtoxinA. We present a complex case to highlight the treatment's potential limitations to ameliorate AD and improve lower urinary tract (LUT) function in this population.

FINDINGS

A 46-year old man, who was relying on an indwelling urethral catheter for bladder emptying due to severely impaired hand function following a SCI (C5, AIS B) sustained 30 years ago, underwent intradetrusor onabotulinumtoxinA injections for treatment of refractory NDO and associated AD. Although LUT function slightly improved (i.e. cystometric capacity increased while detrusor pressure was reduced), severe bladder-related AD persisted post-treatment.

CONCLUSIONS

This case raises awareness of serious considerations when treating NDO-related AD in individuals with longstanding neurogenic LUT dysfunction and compromised dexterity following SCI. Given the limited improvement in LUT function and persisting bladder-related AD following treatment, urinary diversion as advocated in the wider literature should be considered to protect an individual's urinary tract from further deterioration and thus eliminate bladder-related AD consequences long-term. Early treatment and management of NDO and AD is crucial to minimize complications associated with these two major health risks in this population.

Effects of early exercise training on the severity of autonomic dysreflexia following incomplete spinal cord injury in rodents

Hemodynamic instability and cardiovascular (CV) dysfunction are hallmarks of patients living with cervical and high thoracic spinal cord injuries (SCI). Individuals experience bouts of autonomic dysreflexia (AD) and persistent hypotension which hamper the activities of daily living. Despite the widespread use of exercise training to improve health and CV function after SCI, little is known about how different training modalities impact hemodynamic stability and severity of AD in a model of incomplete SCI. In this study, we used implantable telemetry devices to assess animals with T2 contusions following 3.5 weeks of exercise training initiated 8 days post-injury: passive hindlimb cycling (T2-CYC, n = 5) or active forelimb swimming (T2-SW, n = 6). Uninjured and non-exercised SCI control groups were also included (CON, n = 6; T2-CON, n = 7; T10-CON, n = 6). Five weeks post-injury, both T2-CON and T2-CYC presented with resting hypotension compared to uninjured CON and T10-CON groups; no differences were noted in resting blood pressure in T2-SW versus CON and T10-CON. Furthermore, pressor responses to colorectal distention (AD) were larger in all T2-injured groups compared to T10-CON, and were not attenuated by either form of exercise training. Interestingly, when T2-injured animals were re-stratified based on terminal BBB scores (regardless of training group), animals with limited hindlimb recovery (T2-LOW, n = 7) had more severe AD responses. Our results suggest that the spontaneous recovery of locomotor and autonomic function after severe but incomplete T2 SCI also influences the severity of AD, and that short periods (3.5 weeks) of passive hindlimb cycling or active forelimb swimming are ineffective in this model.

Neurogenic Bowel in Acute Rehabilitation Following Spinal Cord Injury: Impact of Laxatives and Opioids

Objective: To explore the association between bowel dysfunction and use of laxatives and opioids in an acute rehabilitation setting following spinal cord injury (SCI). Methods: Data was collected regarding individuals with acute traumatic/non-traumatic SCI over a two-year period (2012–2013) during both the week of admission and discharge of their inpatient stay. Results: An increase in frequency of bowel movement (BM) (p = 0.003) and a decrease in frequency of fecal incontinence (FI) per week (p < 0.001) between admission and discharge was found across all participants. There was a reduction in the number of individuals using laxatives (p = 0.004) as well as the number of unique laxatives taken (p < 0.001) between admission and discharge in our cohort. The number of individuals using opioids and the average dose of opioids in morphine milligram equivalents (MME) from admission to discharge were significantly reduced (p = 0.001 and p = 0.02, respectively). There was a positive correlation between the number of laxatives and frequency of FI at discharge (r = 0.194, p = 0.014), suggesting that an increase in laxative use results in an increased frequency of FI. Finally, there was a significant negative correlation between average dose of opioids (MME) and frequency of BM at discharge, confirming the constipating effect of opioids (r = −0.20, p = 0.009).

Noninvasive Neuroprosthesis Promotes Cardiovascular Recovery After Spinal Cord Injury

Spinal cord injury (SCI) leads to severe impairment in cardiovascular control, commonly manifested as a rapid, uncontrolled rise in blood pressure triggered by peripheral stimuli-a condition called autonomic dysreflexia. The objective was to demonstrate the translational potential of noninvasive transcutaneous stimulation (TCS) in mitigating autonomic dysreflexia following SCI, using pre-clinical evidence and a clinical case report. In rats with SCI, we show that TCS not only prevents the instigation of autonomic dysreflexia, but also mitigates its severity when delivered during an already-triggered episode. Furthermore, when TCS was delivered as a multisession therapy for 6 weeks post-SCI, the severity of autonomic dysreflexia was significantly reduced when tested in the absence of concurrent TCS. This treatment effect persisted for at least 1 week after the end of therapy. More importantly, we demonstrate the clinical applicability of TCS in treatment of autonomic dysreflexia in an individual with cervical, motor-complete, chronic SCI. We anticipate that TCS will offer significant therapeutic advantages, such as obviating the need for surgery resulting in reduced risk and medical expenses. Furthermore, this study provides a framework for testing the potential of TCS in improving recovery of other autonomic functions such lower urinary tract, bowel, and sexual dysfunction following SCI.

Prevalence of postpartum depression and anxiety among women with spinal cord injury

Objective: To examine the prevalence of postpartum depression (PPD) and postpartum anxiety (PPA) in mothers with spinal cord injury (SCI).Design: Retrospective, cross-sectional study.Setting: Online multi-national study.Participants: We surveyed an international sample of 102 women who gave birth following cervical SCI (C1-C8, n = 30), upper thoracic SCI (T1-T6, n = 12) or lower level SCI (T7 & below, n = 60). Participants were primarily from Canada and Sweden, and mean age at childbirth was 30 ± 6 years.Outcome Measures: Subscales from the Pregnancy Risk Assessment Monitoring System (PRAMS) were used to measure PPD (PRAMS-3D) and PPA (PRAMS-2A).Results: PPD and PPA were most prevalent in women with cervical SCI, followed by upper thoracic SCI then lower SCI. Self-reported PPD was more prevalent than clinically diagnosed PPD in women with cervical SCI (P = 0.03) and upper thoracic SCI (P = 0.03). With cervical SCI, 75% of women diagnosed with MDD before pregnancy scored >9 on the PRAMS PPD subscale, indicating clinically relevant PPD. However, only 10% were diagnosed with PPD. Of women with lower SCI diagnosed with MDD before pregnancy, 25% had a clinically relevant score for self-reported PPD; 7% were diagnosed.Conclusions: This is currently the largest study examining PPD and PPA after SCI. Clinicians should be aware that mothers with SCI (particularly high-level SCI) may have increased risk of PPD and PPA. PPD is poorly understood in women with SCI and may even be underdiagnosed. SCI-related risk factors for PPD and PPA should be explored.

The Therapeutic Potential and Usage Patterns of Cannabinoids in People with Spinal Cord Injuries: A Systematic Review

BACKGROUND

People with spinal cord injuries (SCI) commonly experience pain and spasticity; limitations of current treatments have generated interest in cannabis as a possible therapy.

OBJECTIVES

We conducted this systematic review to: 1) examine usage patterns and reasons for cannabinoid use, and 2) determine the treatment efficacy and safety of cannabinoid use in people with SCI.

METHODS

PubMed, Embase, Web of Science and Cumulative Index to Nursing and Allied Health Literature databases were queried for keywords related to SCI and cannabinoids.

RESULTS

7,232 studies were screened, and 34 were included in this systematic review. Though 26 studies addressed cannabinoid usage, only 8 investigated its therapeutic potential on outcomes such as pain and spasticity. The most common method of use was smoking. Relief of pain, spasticity and recreation were the most common reasons for use. A statistically significant reduction of pain and spasticity was observed with cannabinoid use in 83% and 100% of experimental studies, respectively. However, on examination of randomized control trials (RCTs) alone, effect sizes ranged from - 0.82 to 0.83 for pain and -0.95 to 0.09 for spasticity. Cannabinoid use was associated with fatigue and cognitive deficits.

CONCLUSION

Current evidence suggests that cannabinoids may reduce pain and spasticity in people with SCI, but its effect magnitude and clinical significance are unclear. Existing information is lacking on optimal dosage, method of use, composition and concentration of compounds. Long-term, double-blind, RCTs, assessing a wider range of outcomes should be conducted to further understand the effects of cannabinoid use in people with SCI.

Prevalence of self-reported complications associated with intermittent catheterization in wheelchair athletes with spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To identify the prevalence of complications associated with intermittent catheterization in wheelchair athletes with spinal cord injury (SCI).

SETTING

International and national sporting events.

METHODS

A total 130 competitive wheelchair athletes living with SCI completed a self-reported questionnaire during international or national sporting events. The questionnaire collected information regarding demographics, injury characteristics, method of bladder emptying, and complications related to intermittent catheterization.

RESULTS

Overall, 84% (109/130) of wheelchair athletes used intermittent catheterization. Within this group, 77% of athletes (84/109) experienced at least one complication associated with intermittent catheterization. Twenty-seven percent (29/109) sustained urethral injuries and 63% (69/109) had at least one episode of urinary tract infection during the last 12 months. Almost one-fourth of male athletes (22/95, 23%) had a history of inflammation / infection of genital organs associated with intermittent catheterization.

CONCLUSIONS

Here we report a high prevalence of self-reported complications associated with intermittent catheterization in wheelchair athletes with SCI. Considering their potential impact on lower urinary tract function, athletic performance, and health, further studies are needed to assess the role of preventative strategies to reduce complications related to intermittent catheterization in wheelchair athletes with SCI.

SPONSORSHIP

Coloplast Brazil and Instituto Lado a Lado pela Vida (a nongovernmental, nonprofit organization based in São Paulo) and Wellspect provided funding for this study.

Intradetrusor OnabotulinumtoxinA Injections Ameliorate Autonomic Dysreflexia while Improving Lower Urinary Tract Function and Urinary Incontinence-Related Quality of Life in Individuals with Cervical and Upper Thoracic Spinal Cord Injury

Pilot data of our phase IV clinical trial (pre/post study design) highlighted a beneficial effect of intradetrusor onabotulinumtoxinA (200 IU) injections to reduce autonomic dysreflexia (AD) in individuals with chronic spinal cord injury (SCI) at T6 or above. After trial completion, we assessed whether our primary expectation (i.e., decrease of AD severity in 50% of participants during urodynamics [UDS]) was met. Secondary outcome measures were reduction of spontaneous AD in daily life as well as amelioration of AD-related and urinary incontinence-related quality of life (QoL). In addition, we conducted injury-level–dependent analysis—i.e., cervical and upper thoracic—to explore group-specific treatment efficacy. Post-treatment, AD severity decreased in 82% (28/34) of all participants during UDS and in 74% (25/34) in daily life assessed with 24-h ambulatory blood pressure monitoring. In addition, urinary incontinence-related QoL was improved, cystometric capacity was increased, and maximum detrusor pressure during storage was reduced (all p < 0.001). Further, the treatment was well tolerated, with only minor complications (grade I [n = 7] and II [n = 7]) in accordance with the Clavien-Dindo classification recorded in 11 individuals (cervical n = 9, upper thoracic n = 2). Injury-level–dependent analysis revealed lower incidence (cervical n = 15/23, upper thoracic n = 6/11) and lesser severity (cervical p = 0.009; upper thoracic p = 0.06 [Pearson r = −0.6, i.e., large effect size]) of AD during UDS. Further, reduced AD severity in daily life, improved urinary incontinence-related QoL, greater cystometric capacity, and lower maximum detrusor pressure during storage (all p < 0.05) were found in both groups post-treatment. Intradetrusor onabotulinumtoxinA injections are an effective and safe second-line treatment option that ameliorates AD while improving lower urinary tract function and urinary incontinence-related QoL in individuals with cervical and upper thoracic SCI.

Vascular-Cognitive Impairment following High-Thoracic Spinal Cord Injury Is Associated with Structural and Functional Maladaptations in Cerebrovasculature

Individuals living with chronic spinal cord injury (SCI) often exhibit impairments in cognitive function, which impede their rehabilitation and transition into the community. Although a number of clinical studies have demonstrated the impact of impaired cardiovascular control on cognitive impairment, the mechanistic understanding of this deleterious relationship is still lacking. The present study investigates whether chronic disruption of cardiovascular control following experimental SCI results in cerebrovascular decline and vascular cognitive impairment. Fourteen weeks following a high thoracic SCI (at the third thoracic segment), rats were subjected to a battery of in vivo and in vitro physiological assessments, cognitive-behavioral tests, and immunohistochemical approaches to investigate changes in cerebrovascular structure and function in the middle cerebral artery (MCA). We show that in the MCA of rats with SCI, there is a 55% (SCI vs. control: 13.4 ± 1.9% vs. 29.63 ± 2.8%, respectively) reduction in the maximal vasodilator response to carbachol, which is associated with reduced expression of endothelial marker cluster of differentiation 31 (CD31) and transient receptor potential cation channel 4 (TRPV 4) channels. Compared with controls, MCAs in rats with SCI were found to have 50% (SCI vs. control: 1.5 ± 0.2 vs. 1 ± 0.1 a.u., respectively) more collagen 1 in the media of vascular wall and 37% (SCI vs. control: 30.5 ± 2.9% vs. 42.0 ± 4.0%, respectively) less distensibility at physiological intraluminal pressure. Further, the cerebral blood flow (CBF) in the hippocampus was reduced by 32% in the SCI group (SCI vs. control: 44.3 ± 4.5 mL/100 g/min vs. 65.0 ± 7.2 mL/100 g/min, respectively) in association with impairment of short-term memory based on a novel object recognition test. There were no changes in the sympathetic innervation of the vasculature and passive structure in the SCI group. Chronic experimental SCI is associated with structural alterations and endothelial dysfunction in cerebral arteries that likely contribute to significantly reduced CBF and vascular cognitive impairment.

Acute Cardiovascular Responses to Vagus Nerve Stimulation after Experimental Spinal Cord Injury

Pairing vagus nerve stimulation (VNS) with rehabilitation has emerged as a potential strategy to enhance plasticity and improve recovery in a range of neurological disorders. A recent study highlights the therapeutic promise of VNS in promoting motor recovery after spinal cord injury (SCI). We investigated the safety of acute VNS in a rat model of chronic SCI. We measured the cardiovascular response to various VNS paradigms following chronic high-thoracic SCI that is known to deleteriously impact cardiovascular control. Dose-response experiments with continuous VNS revealed an SCI-dependent increase in sensitivity for heart rate (HR) and blood pressure (BP) compared with controls. A clinically relevant intermittent VNS resulted in transient reduction in HR in rats with SCI; however, BP remained unaltered. In all experiments, the effect lasted only while the VNS stimulus train was present, as HR and BP restored to baseline values as soon as VNS ended. No prolonged episodes of persisting hypotension were seen in either group. Further, VNS did not trigger autonomic dysreflexia or exacerbate the severity of autonomic dysreflexia when induced during or after stimulation sessions. Overall, these findings provide initial evidence that intermittent VNS at parameters used for targeted plasticity therapy (30 Hz, 0.8 mA) appears safe and supports further investigation of this potential therapy for use following SCI.

Morphological maladaptations in sympathetic preganglionic neurons following an experimental high-thoracic spinal cord injury

Spinal cord injury (SCI) disrupts the supraspinal vasomotor pathways to sympathetic preganglionic neurons (SPNs) leading to impaired blood pressure (BP) control that often results in episodes of autonomic dysreflexia and orthostatic hypotension. The physiological cardiovascular consequences of SCI are largely attributed to the plastic changes in spinal SPNs induced by their partial deafferentation. While multiple studies have investigated the morphological changes in SPNs following SCI with contrasting reports. Here we investigated the morphological changes in SPNs rostral and caudal to a high thoracic (T3) SCI at 1-, 4- and 8-weeks post injury. SPNs were identified using Nicotinamide adenine dinucleotide hydrogen phosphate-diaphorase (NADPH- diaphorase) staining and were quantified for soma size and various dendritic measurements. We show that rostral to the lesion, soma size was increased at 1 week along with increased dendritic arbor. The total dendritic length was also increased at chronic stage (8 weeks post SCI). Caudal to the lesion, the soma size or dendritic lengths did not change with SCI. However, dendritic branching was enhanced within a week post SCI and remained elevated throughout the chronic stages. These findings demonstrate that SPNs undergo significant structural changes form sub-acute to chronic stages post-SCI that likely determines their functional consequences. These changes are discussed in context of physiological cardiovascular outcomes post-SCI.

Lifestyle modifications and pharmacological approaches to improve sexual function and satisfaction in men with spinal cord injury: a narrative review

STUDY DESIGN

A narrative review describing various components of sexual dysfunction in men with spinal cord injury (SCI), as well as addressing potential therapeutic approaches.

OBJECTIVES

Restoration of sexual function is considered one of the most important health priorities for individuals with SCI. The purpose of this review is to provide information regarding the factors that are less appreciated when considering changes to sexual function in men with SCI. We also propose therapeutic approaches, with a focus on lifestyle modifications, which have been shown to improve sexual function.

METHODS

A literature search was performed and limited evidence for therapeutic approaches in individuals with SCI was supplemented by consistent findings from the able-bodied population.

RESULTS

We evaluated the less addressed factors known to contribute to sexual dysfunction in men with SCI, including hormonal influences (i.e., testosterone deficiency, thyroid hormone, and cortisol), psychological factors (i.e., pain, fatigue, depression, and body image), and secondary SCI complications (i.e., urinary tract infection, pressure sores, and autonomic dysreflexia). To address these factors beyond standard medical treatments for sexual dysfunction, options include physical activity/exercise, diet, and specific medications for symptom relief (i.e., testosterone replacement therapy and selective serotonin reuptake inhibitors for depression).

CONCLUSIONS

Physical activity's potential application, efficacy across multiple aspects of sexuality, and the lack of side effects, suggests that long-term exercise is a viable solution to directly or indirectly improve sexual function in males with SCI. Diet and supplemental medications may further promote body composition changes, which more broadly affect sexuality.

Diverse cognitive impairment after spinal cord injury is associated with orthostatic hypotension symptom burden

This study: 1) compared cognitive functioning between individuals with chronic (>1 year) spinal cord injury (SCI) and non-injured controls and, 2) assessed associations between symptoms of autonomic dysreflexia and orthostatic hypotension with cognitive functioning in SCI participants with a history of unstable blood pressure (BP). Thirty-two individuals with SCI (C4-L2, American Spinal Injury Association Impairment Scale A-D) and thirty age, sex-matched non-injured controls participated in this study. Participants completed a motor-free neuropsychological test battery assessing 1) memory, 2) attention/concentration/psychomotor speed and, 3) executive function. Nineteen participants with SCI who had injuries ≥T6 and a history of unstable BP also completed the Autonomic Dysfunction Following Spinal Cord Injury (ADFSCI) questionnaire. Cognitive function was significantly lower in people with SCI across measures of memory and executive function compared to non-injured controls. Significant, moderate-to-large associations were observed between cumulative (frequency x severity) orthostatic hypotension and total BP instability symptoms scores, with measures of attention/concentration/psychomotor speed and executive function. These data demonstrate a 10 - 65% reduced performance across specific realms of cognitive functioning in individuals with SCI relative to non-injured controls. Furthermore, cumulative subjective scores for symptoms of unstable BP were associated with diverse cognitive deficits. These findings, in individuals without co-occurring traumatic brain injury, imply cardiovascular dysregulation plays a role in cognitive deficits observed in this population.