Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology

Comparison of the prevalence of metabolic syndrome between individuals with spinal cord injury and the general population based on the cutoff values of abdominal obesity

BACKGROUND

Metabolic syndrome (MetS) is a cluster of cardiovascular disease (CVD) risk factors. Accurate diagnosis, in spinal cord injury (SCI) patients, is vital for effective CVD prevention.

OBJECTIVE

This study aimed to identify factors related to MetS prevalence by comparing MetS prevalence trends in SCI and the general population (GP) and to examine differences in MetS prevalence in patients with SCI according to the cutoff reference value for abdominal obesity.

METHODS

This retrospective cohort study analyzed data from the National Health Insurance Corporation from 2015 to 2019. MetS was defined using the National Cholesterol Education Program criteria with an adjusted waist circumference of 81.3 cm for patients with SCI. Data were collected on age, gender, smoking, alcohol consumption, BMI, waist circumference, lipid profiles, blood pressure, fasting glucose, and socioeconomic status. Each year, SCI patients (n = 3,140, n = 3,201, n = 3,503, n = 1,590, n = 1544) were matched with GP individuals (m = 31,400, m = 32,040, m = 35,030, m = 15,900, m = 15,440).

RESULTS

Over 5 years, MetS prevalence increased in both groups, consistently higher in the SCI group. Older age and lower income were risk factors in both groups (p < 0.05). Smoking and alcohol intake were significant only in the GP (p < 0.0001). Using the adjusted obesity criterion, MetS prevalence was 1.4 times higher in SCI patients than in the GP (p < 0.0001).

CONCLUSIONS

Exclusively relying on GP criteria for diagnosing MetS in patients with SCI may lead to an underestimation of MetS prevalence and overlooked opportunities for CVD prevention. Therefore, the development of diagnostic and preventive strategies for MetS considering SCI characteristics is needed.

The Prevalence of Adrenal Insufficiency in Individuals with Traumatic Spinal Cord Injury: A Systematic Review and Meta-Analysis

Background/Objectives: Spinal cord injury (SCI) causes profound autonomic and endocrine dysfunctions, giving rise to adrenal insufficiency (AI), which is marked by a reduction in steroid hormone production. Left unaddressed, SCI-related AI (SCI-AI) can lead to life-threatening consequences such as severe hypotension and shock (i.e., adrenal crisis). However, symptoms are often non-specific, making AI challenging to distinguish from similar or overlapping cardiovascular conditions (e.g., orthostatic hypotension). Additionally, the etiology of SCI-AI remains unknown. This review aimed to synthesize the current literature reporting the prevalence, symptomology, and management of SCI-AI. Methods: A systematic search was performed to identify studies reporting AI following the cessation of glucocorticoid treatments in individuals with traumatic SCI. A random-effects meta-analysis was conducted to investigate the overall prevalence of SCI-AI. Results: Thirteen studies involving 545 individuals with traumatic SCI, most with cervical level injuries (n = 256), met the review criteria. A total of 4 studies were included in the meta-analysis. Primary analysis results indicated an SCI-AI pooled prevalence of 24.3% (event rate [ER] = 0.243, 95% confidence interval [CI] = 0.073-0.565, n = 4). Additional sensitivity analyses showed a pooled prevalence of 46.3% (ER = 0.463, 95%CI = 0.348-0.582, n = 2) and 10.8% (ER = 0.108, 95%CI = 0.025-0.368, n = 2) for case-control and retrospective cohort studies, respectively. High-dose glucocorticoid administration after SCI as well as the injury itself appear to contribute to the development of AI. Conclusions: The estimated prevalence of AI in people with traumatic SCI was high (24%). Prevalence was also greater among individuals with cervical SCI than those with lower-level lesions. Clinicians should be vigilant in recognizing the symptomatology and onset of SCI-AI. Further research elucidating its underlying pathophysiology is needed to optimize glucocorticoid administration for remediating AI in this vulnerable population.

Sit-up test to assess orthostatic hypotension in individuals with spinal cord injury

AIM

Individuals with spinal cord injury (SCI) have an increased prevalence of orthostatic hypotension (OH). Diagnosis of OH is made with active standing or tilt table testing, with limited the use in individuals with SCI.

METHODS

An alternative approach to assess OH is the sit-up test, which involves passive repositioning from the supine to the seated position. The purpose of this study was to document the reliability and validity of the sit-up test, and determine whether the level or severity of injury related to orthostatic blood pressure (BP) responses in a large, diverse group of individuals with SCI.

RESULTS

A total of 166 participants-119 individuals with SCI and 47 uninjured control-completed two sit-up tests, and 36 individuals who completed the sit-up tests also underwent a head-up tilt test. Change in BP from sit-up test 1 to sit-up test 2 was not significantly different for either systolic BP or diastolic BP. Neither level nor severity of injury contributed to the reliability assessments, which showed disappointing results with generally low interclass correlation coefficients (ICC), with values ranging from 0 to 0.63, and large standard error of measurements (SEM), ranging from 5.2 to 13.7 mmHg. Comparison between BP responses to the sit-up test and the head-up tilt showed good sensitivity and specificity, with positive predictive values > 75%.

CONCLUSION

Prevalent BP instability likely contributed to the poor reliability of the sit-up test, but the test is easy to perform with a high likelihood ratio for the valid assessment of OH in individuals with SCI.

CLINICAL TRIAL REGISTRATION

NCT01758692.

The Effect of a Low-Glycemic Index Diet on Postprandial Hypotension in Individuals With Chronic Spinal Cord Injury: Results From a Pilot Study

Background

One in two individuals with spinal cord injury (SCI) experiences postprandial hypotension (PPH), a decline (>20 mm Hg) in systolic blood pressure (SBP) within 2 hours after eating. Consuming meals with a low glycemic index (GI) could prevent or lessen PPH.

Objectives

To determine the effect of a low-GI diet on PPH and postprandial glucose and insulin in individuals with chronic SCI (>1 year postinjury).

Methods

Eleven participants (6 males, 5 females; age 43 ± 11 years) with chronic SCI (C4-C7, 7; T4-T12, 4) took part in a randomized crossover study (low GI vs. high GI). On each occasion, BP, glucose, and insulin were measured in the fasted state and for 2 hours after consuming a breakfast meal (60% carbohydrate, 28% fat, 12% protein) in laboratory-controlled conditions. Participants wore an ambulatory BP monitor and continuous glucose monitor for 3 days at home, and consumed study meals that were macronutrient-matched across conditions.

Results

The maximum decrease in systolic blood pressure (SBP) following the laboratory-controlled breakfast meals tended to be lower in the low-GI (14 ± 12 mm Hg) compared to the high-GI (24 ± 25 mm Hg) diet (d = 0.52, P = .056). Serum glucose (P < .01) and insulin (P = .026) concentrations were lower at 30 minutes in the low-GI diet. In the home setting, peak glucose concentrations were lower after lunch (P = .011) and dinner (P < .01) in the low-GI diet.

Conclusion

A low-GI meal may be an effective solution to reduce the magnitude of PPH and peak glucose concentrations in individuals with chronic SCI.

Effects of Gait Rehabilitation Robot Combined with Electrical Stimulation on Spinal Cord Injury Patients' Blood Pressure

BACKGROUND

Orthostatic hypotension can occur during acute spinal cord injury (SCI) and subsequently persist. We investigated whether a gait rehabilitation robot combined with functional electrical stimulation (FES) stabilizes hemodynamics during orthostatic stress in SCI.

METHODS

Six intermediate-phase SCI patients (five males and one female; mean age: 49.5 years; four with quadriplegia and two with paraplegia) participated. The participants underwent robotic training (RT), with a gait rehabilitation robot combined with FES, and tilt table training (TT). Hemodynamics were monitored using a laser Doppler flowmeter for the earlobe blood flow (EBF) and non-invasive blood pressure measurements. The EBF over time and the resting and exercise blood pressures were compared between each session. Adverse events were also evaluated.

RESULTS

The EBF change decreased in TT but increased in RT at the 0.5-min slope (p = 0.03). Similarly, the pulse rate change increased in TT but decreased in RT at the 1-min slope (p = 0.03). Systolic and mean blood pressures were slightly higher in RT than in TT but not significantly (p = 0.35; 0.40). No adverse events occurred in RT, but two TT sessions were incomplete due to dizziness.

CONCLUSIONS

RT with FES can reduce symptoms during orthostatic stress in intermediate-phase SCI. Future studies require a larger number of cases to generalize this study.

Making the Invisible Visible: Understanding Autonomic Dysfunctions Following Spinal Cord Injury

Autonomic dysfunctions are a major challenge to individuals following spinal cord injury. Despite this, these consequences receive far less attention compared with motor recovery. This review will highlight the major autonomic dysfunctions following SCI predominantly based on our present understanding of the anatomy and physiology of autonomic control and available clinical data.

A novel method for the measurement of cardiovascular responses to lower body negative pressure in the awake instrumented rat

Lower body negative pressure (LBNP) has been used for decades in humans to model arterial baroreceptor unloading and represents a powerful tool for evaluating cardiovascular responses to orthostatic challenges. However, LBNP studies in animals have been limited to conditions of anesthesia or sedation, where cardiovascular reflexes are altered. Given the consequent uncertainties, the usefulness of LBNP studies in these preclinical models has been severely hampered. Here, we developed an approach using a novel system to study LBNP responses in awake rats instrumented for telemetric blood pressure (BP) measurement. BP responses to progressive levels of LBNP (-3 to -15 mmHg) were first made in awake rats, followed by measurements under various treatments. In awake untreated rats, BP was well maintained up to -15 mmHg LBNP and there was a robust baroreceptor response in heart rate (HR). Under anesthesia with 3% isoflurane, BP was not maintained at LBNP below -3 mmHg and baroreceptor responses in HR were completely blocked, confirming the limited usefulness of this method under anesthesia. Interrogation of the autonomic pathways involved in the response revealed that muscarinic (atropine) and β1-adrenergic (atenolol) blockade, separately or together, blocked the HR responses, but BP remained well maintained. α1-adrenergic blockade (prazosin) severely blunted the ability to maintain BP in response to LBNP. These data are consistent with findings in human subjects in that the vascular component of the orthostatic reflex predominates in preserving BP. Validation of this novel method provides a valuable tool for investigating orthostatic (in)tolerance in a facile preclinical model.NEW & NOTEWORTHY Orthostatic hypotension or intolerance is a common but often underappreciated disorder that is associated with a variety of neurological comorbidities. LBNP studies provide a valuable tool to study these conditions, but heretofore could only be used in human subjects, since animal subjects needed to be anesthetized or sedated, which blunts or eliminates neurocardiovascular reflexes. This novel method allowing LBNP studies in awake rats will provide a valuable preclinical model for studying these disorders.

The effect of abdominal functional electrical stimulation on blood pressure in people with high level spinal cord injury

STUDY DESIGN

Single centre training study.

OBJECTIVES

To investigate, in a group of people with spinal cord injury (SCI), the effect of transcutaneous functional electrical stimulation of the abdominal muscles (abdominal FES) during cough training on blood pressure (BP), and how it is affected by injury characteristics and alters over time.

SETTING

Laboratory and community.

METHODS

Sixteen participants with SCI (C4-T5) underwent 25 of abdominal FES cough training (5 sets of 10 stimulated coughs) over 6 weeks as part of a previously published study on the effect of abdominal FES training on cough. Systolic BP (SBP), diastolic BP (DBP) and calculated mean arterial pressure (MAP) were measured at the completion of each set.

RESULTS

Abdominal FES coughing resulted in an average ~30% acute increase in BP from initial resting BP across all sessions in almost all participants (p < 0.001). However, the increase in BP during abdominal FES coughs from rest reduced over the 25 sessions of training by ~35% for SBP, MAP and DBP (p = 0.024, p = 0.013 and p = 0.042, respectively). There was no meaningful change in resting BP over time (p = 0.935, p = 0.705 and p = 0.988, respectively). Overall, increases in BP during abdominal FES coughs were greatest for those with chronic injuries and cervical injuries.

CONCLUSIONS

Transcutaneous abdominal FES during cough training acutely increases BP. However, the magnitude of the increase is reduced after 25 sessions of training. Abdominal FES may offer a solution to combat orthostatic hypotension, but its effectiveness may diminish over time.

A Scoping Review of Acute Sedentary Behaviour Studies of People with Spinal Cord Injury

People with a spinal cord injury (SCI) report less physical activity than other populations and may engage in more sedentary behaviour (SB), especially sitting time. SB negatively impacts physiological and psychosocial outcomes in the general population, yet minimal research has explored the effects in people with SCI. The goal of this scoping review was to catalogue and describe the effects of acute SB among people with SCI. We searched four databases before February 2024 for studies in which people with any SCI sat, laid, or reclined for more than one hour in a day, and any physiological, psychological, or behavioural (i.e., SB time) outcome was measured. In total, 2021 abstracts were screened, and eight studies were included (n = 172 participants). The studies were characterized by varied definitions, manipulations, and measures of SB. Most measured outcomes were physiological (e.g., metabolic, blood pressure), followed by behavioural (e.g., SB time) and psychological (e.g., well-being, affect). When SB was interrupted, only postprandial glucose and affect improved. Based on two studies, participants engaged in 1.6 to 12.2 h of SB per day. Average uninterrupted wheelchair sitting bouts lasted 2.3 h. Based on the very limited body of research, it is impossible to draw any conclusions regarding the nature, extent, or impact of SB in people with SCI. There is much work to carry out to define SB, test its effects, and determine if and how people with SCI should reduce and interrupt SB.

Computational modelling of cardiovascular pathophysiology to risk stratify commercial spaceflight

For more than 60 years, humans have travelled into space. Until now, the majority of astronauts have been professional, government agency astronauts selected, in part, for their superlative physical fitness and the absence of disease. Commercial spaceflight is now becoming accessible to members of the public, many of whom would previously have been excluded owing to unsatisfactory fitness or the presence of cardiorespiratory diseases. While data exist on the effects of gravitational and acceleration (G) forces on human physiology, data on the effects of the aerospace environment in unselected members of the public, and particularly in those with clinically significant pathology, are limited. Although short in duration, these high acceleration forces can potentially either impair the experience or, more seriously, pose a risk to health in some individuals. Rather than expose individuals with existing pathology to G forces to collect data, computational modelling might be useful to predict the nature and severity of cardiovascular diseases that are of sufficient risk to restrict access, require modification, or suggest further investigation or training before flight. In this Review, we explore state-of-the-art, zero-dimensional, compartmentalized models of human cardiovascular pathophysiology that can be used to simulate the effects of acceleration forces, homeostatic regulation and ventilation-perfusion matching, using data generated by long-arm centrifuge facilities of the US National Aeronautics and Space Administration and the European Space Agency to risk stratify individuals and help to improve safety in commercial suborbital spaceflight.

Effects of exercise on autonomic cardiovascular control in individuals with chronic, motor-complete spinal cord injury: an exploratory randomised clinical trial

STUDY DESIGN

Secondary analysis of a clinical trial.

OBJECTIVE

To assess the impact of 6 months of arm cycle ergometry training (ACET), or body weight-supported treadmill training (BWSTT), on autonomic cardiovascular responses to a laboratory sit-up test (SUT) in individuals with chronic (≥1-year post-injury) spinal cord injury (SCI).

SETTING

Tertiary Rehabilitation Centre, Vancouver, Canada.

METHODS

Sixteen individuals with motor-complete (American Spinal Injury Association Impairment Scale A-B) SCI between the fourth cervical and sixth thoracic spinal cord segments, aged 39 ± 11 years, were assessed. Participants were randomized to receive 72 sessions of moderate-to-vigorous intensity ACET (n = 8) or passive BWSTT (n = 8). Changes in mean arterial pressure (finger plethysmography), hemodynamics (Modelflow® method), and heart rate/heart rate variability (HR/HRV; electrocardiography) were measured in response to a  SUT before and after 6 months of exercise training. Spontaneous cardiovagal baroreflex sensitivity (cvBRS) was assessed using the sequence method.

RESULTS

Neither ACET nor BWSTT impacted hemodynamic responses to SUT or the incidence of orthostatic hypotension (all P > 0.36). ACET increased HR (P < 0.01, ηp2 = 0.34) and high frequency (HF) power HRV responses (P < 0.01, ηp2 = 0.42) to SUT following 6 months of training while BWSTT did not. Consistent with this, cvBRS improved (P < 0.05, ηp2 = 0.16) only following ACET. Improvements in cvBRS were correlated with both the HR (r = 0.726, P < 0.0001) and HF power (r = -0.484, P < 0.01) responses to SUT.

CONCLUSION

Six months of ACET, but not BWSTT, improved cardiovagal baroreflex control of HR but had no effect on BP responses to SUT in individuals with chronic, motor-complete SCI.

SPONSORSHIP

Canadian Institutes of Health Research (CIHR) CLINICAL TRIAL REGISTRATION: NCT01718977.

Enhancing upper extremity muscle strength in individuals with spinal cord injury using low-intensity blood flow restriction exercise

OBJECTIVES

This study explores the feasibility and effects of low-intensity blood flow restriction exercise on forearm muscle strength and function in individuals with spinal cord injury.

STUDY DESIGN

Pilot randomized clinical trial.

PATIENTS AND METHODS

Ten male and female adult participants with chronic cervical and thoracic spinal cord injury underwent an 8-week low-intensity blood flow restriction exercise programme that targeted forearm muscles. Each participant's contralateral forearm served as the control. Grip strength was the primary outcome measure, and participants also provided qualitative feedback on their experiences.

RESULTS

The study revealed a significant increase in participants' forearm muscle strength on the experimental side engaged in low-intensity blood flow restriction training, with an average strength gain of 7.5 ± 0.36 kg after 16 exercise sessions (Cohen's d = -6.32, 95% CI -8.34, -6.68). In comparison, the control side, following a conventional high- intensity exercise regimen without BFR, showed a more modest strength increase of 4.4 ± 0.67 kg. A mean Patient's Global Impression of Change score of 2.2 reflected overall improvements in participants' daily activities and health status.

CONCLUSION

This study highlights the feasibility and effectiveness of low-intensity blood flow restriction exercise as a safe and promising approach to enhancing forearm muscle strength in individuals with spinal cord injury. The observed positive outcomes, coupled with a high level of participant satisfaction, underscore the potential of this innovative method to significantly improve limb muscle strength, thereby contributing to greater functional independence in this population.

Rehabilitation to Improve Outcomes after Cervical Spine Surgery: Narrative Review

PURPOSE

The increasing elderly patient population is contributing to the rising worldwide load of cervical spinal disorders, which is expected to result in a global increase in the number of surgical procedures in the foreseeable future. Cervical rehabilitation plays a crucial role in optimal recovery after cervical spine surgeries. Nevertheless, there is no agreement in the existing research regarding the most suitable postsurgical rehabilitation program. Consequently, this review assesses the ideal rehabilitation approach for adult patients following cervical spine operations.

MATERIALS AND METHODS

This review covers activities of daily living and encompasses diverse treatment methods, including physiotherapy, specialized tools, and guidance for everyday activities. The review is organized under three headings: (1) historical perspectives, (2) patient-reported functional outcomes, and (3) general and disease-specific rehabilitation.

RESULTS

Rehabilitation programs are determined on the basis of patient-reported outcomes, performance tests, and disease prognosis. CSM requires strengthening of the neck and shoulder muscles that have been surgically invaded. In contrast, the CCI requires mobility according to the severity of the spinal cord injury and functional prognosis. The goal of rehabilitation for CCTs, as for CCIs, is to achieve ambulation, but the prognosis and impact of cancer treatment must be considered.

CONCLUSIONS

Rehabilitation of the cervical spine after surgery is essential for improving physical function and the ability to perform daily activities and enhancing overall quality of life. The rehabilitation process should encompass general as well as disease-specific exercises. While current rehabilitation protocols heavily focus on strengthening muscles, they often neglect the crucial aspect of spinal balance. Therefore, giving equal attention to muscle reinforcement and the enhancement of spinal balance following surgery on the cervical spine is vital.

Cardiorespiratory Responses to Acute Intermittent Hypoxia in Humans With Chronic Spinal Cord Injury

Brief exposure to repeated episodes of low inspired oxygen, or acute intermittent hypoxia (AIH), is a promising therapeutic modality to improve motor function after chronic, incomplete spinal cord injury (SCI). Although therapeutic AIH is under extensive investigation in persons with SCI, limited data are available concerning cardiorespiratory responses during and after AIH exposure despite implications for AIH safety and tolerability. Thus, we recorded immediate (during treatment) and enduring (up to 30 min post-treatment) cardiorespiratory responses to AIH in 19 participants with chronic SCI (>1 year post-injury; injury levels C1 to T6; American Spinal Injury Association Impairment Scale A to D; mean age = 33.8 ± 14.1 years; 18 males). Participants completed a single AIH (15, 60-sec episodes, inspired O2 ≈ 10%; 90-sec intervals breathing room air) and Sham (inspired O2 ≈ 21%) treatment, in random order. During hypoxic episodes: (1) arterial oxyhemoglobin saturation decreased to 82.1 ± 2.9% (p < 0.001); (2) minute ventilation increased 3.83 ± 2.29 L/min (p = 0.008); and (3) heart rate increased 4.77 ± 6.82 bpm (p = 0.010). Considerable variability in cardiorespiratory responses was found among subjects; some individuals exhibited large hypoxic ventilatory responses (≥0.20 L/min/%, n = 11), whereas others responded minimally (<0.20 L/min/%, n = 8). Apneas occurred frequently during AIH and/or Sham protocols in multiple participants. All participants completed AIH treatment without difficulty. No significant changes in ventilation, heart rate, or arterial blood pressure were found 30 min post-AIH p > 0.05). In conclusion, therapeutic AIH is well tolerated, elicits variable chemoreflex activation, and does not cause persistent changes in cardiorespiratory control/function 30 min post-treatment in persons with chronic SCI.

Valsalva maneuver pressure recovery time is prolonged following spinal cord injury with correlations to autonomically-influenced secondary complications

PURPOSE

This work's purpose was to quantify rapid sympathetic activation in individuals with spinal cord injury (SCI), and to identify associated correlations with symptoms of orthostatic hypotension and common autonomically mediated secondary medical complications.

METHODS

This work was a cross-sectional study of individuals with SCI and uninjured individuals. Symptoms of orthostatic hypotension were recorded using the Composite Autonomic Symptom Score (COMPASS)-31 and Autonomic Dysfunction following SCI (ADFSCI) survey. Histories of secondary complications of SCI were gathered. Rapid sympathetic activation was assessed using pressure recovery time of Valsalva maneuver. Stepwise multiple linear regression models identified contributions to secondary medical complication burden.

RESULTS

In total, 48 individuals (24 with SCI, 24 uninjured) underwent testing, with symptoms of orthostatic hypotension higher in those with SCI (COMPASS-31, 3.3 versus 0.6, p < 0.01; ADFSCI, 21.2 versus. 3.2, p < 0.01). Pressure recovery time was prolonged after SCI (7.0 s versus. 1.7 s, p < 0.01), though poorly correlated with orthostatic symptom severity. Neurological level of injury after SCI influenced pressure recovery time, with higher injury levels associated with more prolonged time. Stepwise multiple linear regression models identified pressure recovery time as the primary explanation for variance in number of urinary tract infections (34%), histories of hospitalizations (12%), and cumulative secondary medical complication burden (24%). In all conditions except time for bowel program, pressure recovery time outperformed current clinical tools for assessing such risk.

CONCLUSIONS

SCI is associated with impaired rapid sympathetic activation, demonstrated here by prolonged pressure recovery time. Prolonged pressure recovery time after SCI predicts higher risk for autonomically mediated secondary complications, serving as a viable index for more "autonomically complete" injury.

Use of an upright power wheelchair in spinal cord injury: a case series

Objective

To explore independence, usability, and self-reported quality of life (QOL) in eligible persons with spinal cord injury (SCI) who used a standing powered wheelchair over a 12-week period. Setting: VA SCI research facility.

Participants

Four participants with chronic SCI who use a wheelchair as the primary means of mobility.

Intervention

A standing power wheelchair was used three times a week (3.5 h/session) for 12 weeks in a supervised setting. Main Outcome Measures: safety, usability and feasibility, blood pressure in seated and standing positions, bowel, bladder, and pain item banks from the SCI-QOL Physical-Medical-Health domain, and overall user satisfaction with the device.

Results

Participants consistently maintained normal blood pressure responses between seated and standing positions throughout the training sessions and learned to perform all the mobility tasks safely and independently. Participants reported improvements on the SCI-QOL and were generally satisfied with the upright standing power wheelchair.

Conclusions

In this small case series of chronic, non-ambulatory individuals with SCI, the standing powered wheelchair was shown to be safe and efficacious.

Vasoplegia Following Complex Spine Surgery: Incidence and Risk

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Vasoplegia is a life-threatening form of distributive or vasodilatory shock that is characterized by reduced systemic vascular resistance with resultant hypotension and normal to elevated cardiac output affecting morbidity and mortality. Vasoplegia in the context of Spine Surgery has not been described previously. The purpose of this case series is to determine incidence, risk factors, complications and postoperative outcome in patients with vasoplegia after complex multi-level thoraco-lumbar spine surgery.

METHODS

A retrospective review of the electronic medical records at our institution was conducted between January 2014 and June 2018. All patients undergoing multi-level spine surgery (>6 levels) were screened for intraoperative hypotension. Patient demographics, surgical characteristics, neurological status, blood loss, risk factors, medical treatment, complications, hospital course and mortality were collected. All patients included in this study had a minimum follow-up period of 3 months.

RESULTS

Out of 8521 surgically treated patients, 994 patients with multi-level thoraco-lumbar spine surgery were identified. A total of 41 patients had intraoperative hypotensive events. Of those, 5 patients with vasoplegia could be identified after elimination of all other potential contributing factors. Vasoplegia did not influence the neurological outcome. One major and three minor complications occurred. All patients showed full recovery. The risk factors identified for vasoplegia include prolonged surgery with osteotomies.

CONCLUSIONS

Vasoplegia is a rare condition with an incidence of .6%. Patients experiencing vasoplegia did not appear to experience worse surgical outcomes. The use of special intraoperative hemodynamic monitoring should be considered in selected cases.

Effects of Adaptations in an Interdisciplinary Follow-Up Clinic for People with Spinal Cord Injury in the Chronic Phase: A Prospective Cohort Study

People with spinal cord injury (SCI) often experience secondary health conditions (SHCs), which are addressed during interdisciplinary follow-up clinics. We adapted the design of our clinic, by introducing a questionnaire concerning functioning and SHCs, additional measurements of blood pressure and saturation, and participants were seen by either a specialized nurse or rehabilitation physician. In this study, we investigated the effects of these adaptations and the experienced satisfaction of the participants. The results showed an increased number of recommendations in the adapted design, compared to the initial design. Further, the nature of the recommendations shifted from somatic issues to recommendations regarding psychosocial functioning and regarding (the use of) devices. The added measurements revealed an average high systolic blood pressure, which led to more referrals to the general practitioner. The clinical weight and pulmonary functions stayed stable over time. The current adaptations in design expanded and optimized the number and nature of recommendations regarding SHCs to participants. The questionnaire helps the participant to prepare for the clinic and the professionals to tailor their recommendations, resulting in highly satisfied participants.

Safety and efficacy of continuous intravenous labetalol for blood pressure control in neurosurgical patients

OBJECTIVES

Current evidence supporting the use of continuous intravenous labetalol for blood pressure (BP) control in neurosurgical patients is limited. This study aims to assess the efficacy and safety of labetalol in neurosurgical patients and identify potential contributing factors to these outcomes.

METHODS

We retrospectively reviewed the medical records of neurosurgical patients who received continuous labetalol infusion for BP control. Efficacy was assessed based on the time needed to achieve the target BP (systolic BP ≤ 140 mmHg or diastolic BP ≤ 90 mmHg). Safety was assessed according to adverse events that occurred during labetalol administration. Factors associated with efficacy and safety were analyzed using a logistic regression model.

RESULTS

Among 79 patients enrolled in this study, 47 (59.49%) achieved the target BP within 1 hour (early response). No factors were significantly associated with an early response. Hypotension was observed in 11 patients (13.9%), and bradycardia was observed in 8 patients (10.1%). Hypotension was significantly associated with patient age and motor impairment, while bradycardia was significantly associated with diabetes mellitus.

CONCLUSION

The efficacy and safety profiles of labetalol infusion suggest this treatment as a promising option for BP control in neurosurgical patients.

Item Banks for Measuring the Effect of Blood Pressure Dysregulation on Health-Related Quality of Life in Persons With Spinal Cord Injury

OBJECTIVE

To report on the development and calibration of the new Blood Pressure Dysregulation Measurement System (BPD-MS) item banks that assess the effect of BPD on health-related quality of life (HRQOL) and the daily activities of Veterans and non-Veterans with spinal cord injury (SCI).

DESIGN

Cross-sectional survey study.

SETTING

Two Veteran Affairs medical centers and a SCI model system site.

PARTICIPANTS

454 respondents with SCI (n=262 American Veterans and n=192 non-Veterans; N=454).

INTERVENTIONS

Not applicable MAIN OUTCOME MEASURES: The BPD-MS item banks.

RESULTS

BPD item pools were developed and refined using literature reviews, qualitative data from focus groups, and cognitive debriefing of persons with SCI and professional caregivers. The item banks then underwent expert review, reading level assessment, and translatability review prior to field testing. The items pools consisted of 180 unique questions (items). Exploratory and confirmatory factor analyses, item response theory modeling, and differential item function investigations resulted in item banks that included a total of 150 items: 75 describing the effect of autonomic dysreflexia on HRQOL, 55 describing the effect of low blood pressure (LBP) on HRQOL, and 20 describing the effect of LBP on daily activities. In addition, 10-item short forms were constructed based on item response theory-derived item information values and the clinical relevance of item content.

CONCLUSIONS

The new BPD-MS item banks and corresponding 10-item short forms were developed using established rigorous measurement development standards, which represents the first BPD-specific patient-reported outcomes measurement system unique for use in the SCI population.

At-Home Blood Pressure Measurements Provide Better Assessments of Orthostatic Hypotension in Parkinson's Disease

Orthostatic hypotension (OH) is common in Parkinson's Disease (PD). It is intermittent, exacerbated by stressors including meals, medications, and dehydration, and frequently is unrecognized. Although intermittent, assessment is usually by a single "in clinic" BP measurement. This study examines whether 10 home measurements are more sensitive in detecting OH than a single "in clinic" measurement. Participants (44 people with PD and 16 controls) were instructed to measure lying and standing BP at home. BP was measured on five consecutive days upon waking and before bedtime. Symptoms were also assessed using the Movement Disorder Society United Parkinson's Disease Rating Scale and the Non-Motor Questionnaire. While a postural drop in systolic BP (≥20 mmHg) was recorded "in clinic" in thirteen of the forty-four PD participants, a postural drop was found in at least one of the ten home measurements in twenty-eight of the forty-four participants. Morning hypertension and variability in lying systolic BP was more common in these subjects than in those without a postural drop or the controls. A greater number of measurements of lying and standing BP are more likely to reveal orthostatic hypotension, variation in systolic BP, and hypertension than a single office measurement in people with PD.

Diagnosis and Management of Cardiovascular Risk in Individuals With Spinal Cord Injury: A Narrative Review

More than 16 000 Americans experience spinal cord injury (SCI), resulting in chronic disability and other secondary sequelae, each year. Improvements in acute medical management have increased life expectancy. Cardiovascular disease is a leading cause of death in this population, and seems to occur earlier in individuals with SCI compared with the general population. People with SCI experience a high burden of traditional cardiovascular disease risk factors, including dyslipidemia and diabetes, and demonstrate anatomic, metabolic, and physiologic changes alongside stark reductions in physical activity after injury. They also experience multiple, complex barriers to care relating to disability and, in many cases, compounding effects of intersecting racial and socioeconomic health inequities. Given this combination of risk factors, some investigators have proposed that people with SCI are at increased risk for cardiovascular disease, beyond that associated with traditional risk factors, and SCI could be considered a risk-enhancing factor, analogous to other risk-enhancing factors defined by the 2019 American Heart Association/American College of Cardiology Primary Prevention Guidelines. However, more research is needed in this population to clarify the role of traditional risk factors, novel risk factors, health care access, social determinants of health, and intersectionality of disability, race, and socioeconomic status. There is an urgent need for primary care physicians and cardiologists to have awareness of the importance of timely diagnosis and management of cardiac risk factors for people with SCI.

Autogenic biofeedback training improves autonomic responses in a participant with cervical motor complete spinal cord injury- case report

STUDY DESIGN

Single-subject case design OBJECTIVE: To evaluate the Autogenic Feedback Training Exercise (AFTE) on autonomic nervous system responses.

INTRODUCTION

AFTE combines specific autogenic exercises with biofeedback of multiple physiological responses. Originally developed by the National Aeronautics and Space Administration (NASA), AFTE is used to improve post-flight orthostatic intolerance and motion sickness in astronauts. Individuals with cervical or upper thoracic spinal cord injury (SCI) often present symptoms of autonomic dysfunction similar to astronauts. We hypothesize that AFTE challenges nervous system baroreflex, gastric and vascular responses often impaired after SCI.

METHODS

Using a modified AFTE protocol, we trained a hypotensive female participant with cervical motor complete (C5/6-AIS A) SCI, and a male non-injured control participant (NI) and measured blood pressure (BP), heart rate (HR), gastric electrical activity, and microvascular blood volume before, during and after AFTE. The participants were instructed to complete breathing and imagery exercises to help facilitate relaxation. Subsequently, they were instructed to use stressful imagery and breathing exercises during arousal trials.

RESULTS

Both participants completed 8 sessions of approximately 45 min each. Microvascular blood volume decreased 23% (SCI) and 54% (NI) from the beginning to the end of the stimulation cycles. The participant with SCI became progressively more normotensive and improved levels of gastric electrical activity, while the NI participant's changes in HR, gastric electrical activity, and BP were negligible.

CONCLUSIONS

AFTE may offer a novel non-pharmacologic intervention to minimize symptoms of dysautonomia in people with SCI.

Recurrent syncope secondary to autonomic dysfunction in spinal cord injury: a case report

High-level spinal cord injuries are often associated with autonomic impairment, which can result in orthostatic hypotension and syncope. Persistent autonomic dysfunction can manifest with disabling symptoms including recurrent syncopal events. We describe a case of autonomic failure resulting in recurrent syncopal events in a tetraplegic 66-year-old man.

Intractable postural hypotension resulting from cervical pseudomeningocele after a posterior cervical spinal surgery: a case report

INTRODUCTION

Postural hypotension (PH) is common in patients with spinal cord injury (SCI), especially those with tetraplegia. To effectively treat PH, identifying and eliminating treatable predisposing factors of PH are prerequisites before applying any interventions.

CASE PRESENTATION

We report a patient with post-acute cervical SCI who suffered from intractable PH resulting from pseudomeningocele causing unfavorable rehabilitation outcomes. A previously healthy 34-year-old man with complete C6 SCI resulting from C6-C7 fracture dislocation developed PH in the first week of the rehabilitation program. No specific predisposing factors including anemia, hyponatremia, and dehydration were identified. Non-pharmacological interventions and pharmacological treatment were administered to the patient without satisfactory result, causing a delay in rehabilitation progression. In the fourth week of rehabilitation program, a mass at the surgical site was detected. A cervical MRI revealed a large fluid collection at the posterior aspect of cervical spines with a size of 7.9 × 6.8 × 5.0 cm. A diagnosis of pseudomeningocele was made and surgical site debridement with closing dura by grafting was immediately conducted. One day after surgery, PH disappeared, and the patient could progress in his rehabilitation program and achieve his short-term goal within three weeks.

CONCLUSION

Pseudomeningocele could be one of the precipitating factors of PH in patients with tetraplegia. Healthcare providers should consider investigating pseudomeningocele in patients who have intractable and unexplainable PH.

Tamsulosin-induced life-threatening hypotension in a patient with spinal cord injury: A case report

BACKGROUND

Tamsulosin, a selective α1-adrenergic receptor antagonist, is commonly used for treating neurogenic bladder in patients with spinal cord injury (SCI). No severe adverse events have been described with such tamsulosin use. To our knowledge, we report the first case of severe life-threatening hypotension as an adverse effect of tamsulosin in a person with SCI. Therefore, we report this case to inform that this severe adverse effect of tamsulosin can occur when treating patients with SCI.

CASE SUMMARY

A 59-year-old woman was diagnosed with cervical spinal cord myelopathy and was classified as American Spinal Injury Association Impairment Scale D, neurological level of injury C3. Because she suffered from voiding difficulty due to neurogenic bladder, we prescribed tamsulosin. Her vital signs remained stable, but occasional hypotensive symptoms followed defecation. We reduced the dose of tamsulosin, but after administering tamsulosin for 9 d, she experienced life-threatening hypotension with no evidence of hypovolemic shock, neurogenic shock, cardiogenic shock, or septic shock. A hypotensive condition induced by tamsulosin was the suspected cause, and her symptoms could be associated with adverse effects of tamsulosin. As symptoms resolved after stopping tamsulosin, and no other reason was found, we concluded that tamsulosin was the cause of her symptoms.

CONCLUSION

Caution for severe hypotension is needed when administering tamsulosin for neurogenic bladder in a patient with 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.

Atrial Natriuretic Peptide and the Epithelial Sodium Channel Contribute to Spinal Cord Injury-Induced Polyuria in Mice

Polyuria is found in patients with spinal cord injury (SCI). However, the underlying cellular and molecular mechanism is unknown. Here, we show that mice had elevated urine for 7 days after T10 contusion. Using multi-photon confocal microscopy, we performed intra-vital imaging experiments to evaluate water reabsorption in kidney tubules by examining fluorescent intensity in the lumen of the distal tubule from live mice. The data show that SCI significantly reduced the concentrating function of kidney tubules. The reduced water reabsorption appears to be mediated by atrial natriuretic peptide (ANP) because SCI increased the expression levels of both ANP and natriuretic peptide receptor A (NPR-A) in the kidney cortex. Our patch-clamp single-channel recordings from split-open distal tubules show that SCI decreased the activity of the epithelial sodium channel (ENaC). Western blot combined with confocal microscopy data show that the levels of 70 kD γ-ENaC, which is an active isoform because of proteolytic cleavage, were significantly reduced in distal tubule principal cells. An NPR-A inhibitor (A71915) given intravenously eliminated the effects of SCI on ENaC and polyuria. These data together with previous studies suggest that SCI causes polyuria, probably by reducing ENaC activity through elevating ANP and NPR-A. Further investigation of the signal transduction pathways may provide useful information for discovering an efficient drug to treat SCI-induced polyuria.

Targeted delivery of acrolein scavenger hydralazine in spinal cord injury using folate-linker-drug conjugation

Oxidative stress has been shown to play a critical pathogenic role in functional loss after spinal cord injury (SCI). As a direct result of oxidative stress, lipid peroxidation-derived aldehydes have emerged as key culprits that sustain secondary injury and contribute significantly to pathological outcomes. Acrolein, a neurotoxin, has been shown to be elevated in SCI and can result in post-SCI neurological deficits. Reducing acrolein has therefore emerged as a novel and effective therapeutic strategy in SCI. Previous studies have revealed that hydralazine, an FDA approved blood pressure lowering medication, when administered after SCI shows strong acrolein scavenging capabilities and significantly improves cellular and behavioral outcomes. However, while effective at scavenging acrolein, hydralazine's blood pressure lowering activity can have a detrimental impact on neurotrauma patients. Here, our goal was to preserve the acrolein scavenging capability while mitigating the effect of hydralazine on blood pressure. We accomplished this using a folate-targeted delivery system to deploy hydralazine to the folate receptor positive inflammatory site of the cord injury. Using a model of rat SCI, we found that this system is effective for targeting the injury site, and that folate targeted hydralazine can scavenge acrolein without significantly impacting blood pressure.

Toward rebalancing blood pressure instability after spinal cord injury with spinal cord electrical stimulation: A mini review and critique of the evolving literature

High-level spinal cord injury commonly leads to blood pressure instability. This manifests clinically as orthostatic hypotension (OH), where blood pressure can drop to the point of loss of consciousness, and autonomic dysreflexia (AD), where systolic blood pressure can climb to over 300 mmHg in response to an unperceived noxious stimulus. These blood pressure fluctuations can occur multiple times a day, contributing to increased vessel shear stress and heightened risk of cardiovascular disease. The pathophysiology of both of these conditions is rooted in impairments in regulation of spinal cord sympathetic preganglionic neurons, which control blood pressure by mediating vascular resistance and catecholamine release. Recently, spinal cord electrical stimulation has provided evidence that it may modulate these blood pressure imbalances. Early proposed mechanisms suggest activation of spinal cord dorsal horn neurons that ultimately act upon the sympathetic preganglionic neuronal pathways. For OH, spinal cord stimulation likely induces local activation of these neurons to generate baseline sympathetic tone and accompanying vasoconstriction. The mechanisms for spinal stimulation regulating AD are less clear, though some suggest it activates inhibitory circuits to dampen the overactive sympathetic response. While questions remain, spinal cord electrical stimulation is an intriguing new modality that may restore blood pressure regulation following spinal cord injury.

Impact of tetraplegia vs. paraplegia on venoarteriolar, myogenic and maximal cutaneous vasodilation responses of the microvasculature: Implications for cardiovascular disease

Objective: Cardiovascular disease (CVD) is a leading cause of mortality in persons with SCI. While macrovascular remodeling and function after SCI is well documented, changes in the microvascular structure and function are comparably understudied, but importantly predict CVD risk. Specifically, the integrity of venoarteriolar (VAR), myogenic (MYO) and maximal vasodilation responses are largely unknown after SCI, especially in persons with tetraplegia (TP) at highest risk of CVD. This is the first to examine the differences in VAR (cuff inflation), MYO (limb dependency) and maximal vasodilation responses of the microvasculature between able bodied (AB) versus those with TP and paraplegia (PP).Design: Observational.Setting: Laboratory.Participants: Eight AB, 6 TP, and 8 PP persons.Interventions: One forearm and calf were treated topically with lidocaine 2.5%/prilocaine 2.5% while contralateral limb served as a control. Laser doppler flowmeters were applied over treated and control sites during limb dependency, cuff inflation and local skin heating (Tloc) up to 42°C.Outcome measures: Skin vascular resistance (SkVR) change with cuff inflation and limb dependency and maximal cutaneous vascular conductance (CVC) during local heating.Results: Change in SkVR was not significantly different between groups or extremity (upper vs. lower) during cuff inflation or limb dependency. However, CVC at Tloc 42°C was significantly different in the lower extremity (LE) of TP and PP (P = 0.007, 0.35) compared to AB.Conclusion: Increases in SkVR during cuff inflation (VAR) and limb dependency (VAR and MYO) are unaltered after SCI, however maximal vasodilation in the LE post-SCI is higher than AB persons.

An investigation to the prolonged requirement (>7 days) of vasopressors in cervical spinal cord injury patients-a retrospective analysis

STUDY DESIGN

Retrospective chart review.

OBJECTIVES

The primary aim was to identify the number of patients requiring vasopressors beyond the first week of cervical spinal cord injury (SCI). Secondary objectives were to note the type, duration and doses of vasopressors and any association between prolonged vasopressors use and outcome.

SETTING

Neurosurgical intensive care of a tertiary trauma care centre.

METHODS

After Ethical approval we retrospectively collected the data of patients of isolated cervical SCI admitted to neurosurgical intensive care from January to December 2017. Vasopressor requirement for sepsis or cardiac arrest was excluded.

RESULTS

Out of 80 patients analysed, 54 (67.5%) received vasopressors. The prolonged requirement of vasopressors was observed in 77.7%. Our preferred agent was dopamine (64.8%). We found out that longer requirement (in days) of high dose of dopamine was associated with higher survival (p = 0.03).

CONCLUSION

Our results describe a significant portion of cervical SCI patients need ongoing vasopressor to maintain a mean arterial pressure >65 mm of Hg beyond first week. We observed patients who required longer duration of high dose dopamine had a higher chance of survival suggesting some unknown mechanism of high dose of dopamine. This is first such observation, further studies are needed to substantiate.

Intraoperative Monitoring of Spinal Cord Perfusion using Ultrasound in an Ovine Model

Ultrasound imaging can be used to visualize the spinal cord and assess localized cord perfusion. We present in vivo data in an ovine model undergoing spinal cord stimulation and propose development of transcutaneous US imaging as a potential non-invasive imaging modality in spinal cord injury.Clinical Relevance- Ultrasound imaging can be used to aid in prognosis and diagnosis by providing qualitative and quantitative characterization of the spinal cord. This modality can be developed as a low cost, portable, and non-invasive imaging technique in spinal injury patients.

Development of a Spinal Cord Injury Model Permissive to Study the Cardiovascular Effects of Rehabilitation Approaches Designed to Induce Neuroplasticity

Simple Summary

People living with high-level spinal cord injury experience worse cardiovascular health than the general population. In most spinal cord injuries, there are some remaining functioning pathways leading from the brain through the spinal cord to the organs and muscles, but not enough to sustain normal levels of function. Recently, therapies that aim to increase the strength of connections in these remaining pathways have shown great potential in restoring walking, hand, and breathing function in the spinal cord injured population. In order to test these therapies for their effects on cardiovascular function, we developed a new type of spinal cord injury rat model that spares enough pathways for these therapies to act upon but still produces measurable reductions in heart and blood vessel function that can be targeted with interventions/treatments.

Abstract

As primary medical care for spinal cord injury (SCI) has improved over the last decades there are more individuals living with neurologically incomplete (vs. complete) cervical injuries. For these individuals, a number of promising therapies are being actively researched in pre-clinical settings that seek to strengthen the remaining spinal pathways with a view to improve motor function. To date, few, if any, of these interventions have been tested for their effectiveness to improve autonomic and cardiovascular (CV) function. As a first step to testing such therapies, we aimed to develop a model that has sufficient sparing of descending sympathetic pathways for these interventions to target yet induces robust CV impairment. Twenty-six Wistar rats were assigned to SCI (n = 13) or naïve (n = 13) groups. Animals were injured at the T3 spinal segment with 300 kdyn of force. Fourteen days post-SCI, left ventricular (LV) and arterial catheterization was performed to assess in vivo cardiac and hemodynamic function. Spinal cord lesion characteristics along with sparing in catecholaminergic and serotonergic projections were determined via immunohistochemistry. SCI produced a decrease in mean arterial pressure of 17 ± 3 mmHg (p < 0.001) and left ventricular contractility (end-systolic elastance) of 0.7 ± 0.1 mmHg/µL (p < 0.001). Our novel SCI model produced significant decreases in cardiac and hemodynamic function while preserving 33 ± 9% of white matter at the injury epicenter, which we believe makes it a useful pre-clinical model of SCI to study rehabilitation approaches designed to induce neuroplasticity.

Experimental high thoracic spinal cord injury impairs the cardiac and cerebrovascular response to orthostatic challenge in rats

Spinal cord injury (SCI) impairs the cardiovascular responses to postural challenge, leading to the development of orthostatic hypotension (OH). Here, we apply lower body negative pressure (LBNP) to rodents with high-level SCI to demonstrate the usefulness of LBNP as a model for experimental OH studies, and to explore the effect of simulated OH on cardiovascular and cerebrovascular function following SCI. Male Wistar rats (n = 34) were subjected to a sham or T3-SCI surgery and survived into the chronic period postinjury (i.e., 8 wk). Cardiac function was tracked via ultrasound pre- to post-SCI to demonstrate the clinical utility of our model. At study termination, we conducted left-ventricular (LV) catheterization and insonated the middle cerebral artery to investigate the hemodynamic, cardiac, and cerebrovascular response to a mild dose of LBNP that is sufficient to mimic clinically defined OH in rats with T3-SCI but not sham animals. In response to mimicked OH, there was a greater decline in stroke volume, cardiac output, maximal LV pressure, and blood pressure in SCI compared with sham (P < 0.034), whereas heart rate was increased in sham but decreased in SCI (P < 0.029). SCI animals also had an exaggerated reduction in peak, minimum and mean middle cerebral artery flow, for a given change in blood pressure, in response to LBNP (P < 0.033), implying impaired dynamic cerebral autoregulation. Using a preclinical SCI model of OH, we demonstrate that complete high thoracic SCI impairs the cardiac response to OH and disrupts dynamic cerebral autoregulation.NEW & NOTEWORTHY This is the first use of LBNP to interrogate the cardiac and cerebrovascular responses to simulated OH in a preclinical study of SCI. Here, we demonstrate the utility of our simulated OH model and use it to demonstrate that SCI impairs the cardiac response to simulated OH and disrupts dynamic cerebrovascular autoregulation.

Autonomic cardiovascular dysfunction during simple arithmetic test in a patient with cervical spinal cord injury-a case report

INTRODUCTION

Spinal cord injury (SCI) disrupts autonomic control of the cardiovascular system, which may lead to autonomic dysfunction. Growing amounts of evidence support the possibility that systemic and cerebral hemodynamic dysfunctions may contribute to cognitive deficits in patients with SCI.

CASE PRESENTATION

We present a case of autonomic cardiovascular dysfunction in a 55-year old female patient following non-traumatic cervical SCI. This case illustrates how a simple arithmetic test may elicit fluctuations in blood pressure causing cognitive disturbances.

DISCUSSION

Clinical awareness of autonomic dysfunction and cognitive deficits is relevant in neurorehabilitation of patients with SCI. Assessment of autonomic function should be evaluated according to recommendation from International Standards to document remaining Autonomic Function after Spinal Cord Injury (ISAFSCI) [1].

Cerebral Autoregulation during Postural Change in Patients with Cervical Spinal Cord Injury-A Carotid Duplex Ultrasonography Study

Patients with a spinal cord injury (SCI) frequently experience sudden falls in blood pressure during postural change. Few studies have investigated whether the measurement of blood flow velocity within vessels can reflect brain perfusion during postural change. By performing carotid duplex ultrasonography (CDU), we investigated changes in cerebral blood flow (CBF) during postural changes in patients with a cervical SCI, determined the correlation of CBF change with presyncopal symptoms, and investigated factors affecting cerebral autoregulation. We reviewed the medical records of 100 patients with a cervical SCI who underwent CDU. The differences between the systolic blood pressure, diastolic blood pressure, and CBF volume in the supine posture and after 5 min at 50° tilt were evaluated. Presyncopal symptoms occurred when the blood flow volume of the internal carotid artery decreased by ≥21% after tilt. In the group that had orthostatic hypotension and severe CBF decrease during tilt, the body mass index and physical and functional scores were lower than in other groups, and the proportion of patients with a severe SCI was high. The higher the SCI severity and the lower the functional score, the higher the possibility of cerebral autoregulation failure. CBF should be assessed by conducting CDU in patients with a high-level SCI.

The Role of Lipids, Lipid Metabolism and Ectopic Lipid Accumulation in Axon Growth, Regeneration and Repair after CNS Injury and Disease

Axons in the adult mammalian nervous system can extend over formidable distances, up to one meter or more in humans. During development, axonal and dendritic growth requires continuous addition of new membrane. Of the three major kinds of membrane lipids, phospholipids are the most abundant in all cell membranes, including neurons. Not only immature axons, but also severed axons in the adult require large amounts of lipids for axon regeneration to occur. Lipids also serve as energy storage, signaling molecules and they contribute to tissue physiology, as demonstrated by a variety of metabolic disorders in which harmful amounts of lipids accumulate in various tissues through the body. Detrimental changes in lipid metabolism and excess accumulation of lipids contribute to a lack of axon regeneration, poor neurological outcome and complications after a variety of central nervous system (CNS) trauma including brain and spinal cord injury. Recent evidence indicates that rewiring lipid metabolism can be manipulated for therapeutic gain, as it favors conditions for axon regeneration and CNS repair. Here, we review the role of lipids, lipid metabolism and ectopic lipid accumulation in axon growth, regeneration and CNS repair. In addition, we outline molecular and pharmacological strategies to fine-tune lipid composition and energy metabolism in neurons and non-neuronal cells that can be exploited to improve neurological recovery after CNS trauma and disease.

Subacute Post-Traumatic Ascending Myelopathy (SPAM) in a Spinal Cord Injured Patient - a Rare Presentation: A Case Report

The optimisation of blood pressure management is critical in managing hypotensive episodes in patients with spinal cord injury. Improper handling of this preventable factor will negatively impact the patient recovery prognosis. A 42-year-old man was admitted for a complete spinal cord injury after fell from height. He developed subacute neurological deterioration unrelated to the mechanical instability but due to multiple episodes of hypotension occurring one month after the initial injury. After proper management of blood pressure, his deterioration was halted and no further progression. Spinal cord haemodynamics play an important role in mediating the onset of subacute post-traumatic ascending myelopathy. Better education and awareness on Subacute Post-traumatic Ascending Myelopathy (SPAM) especially to the junior healthcare providers are important to hinder this rare but avoidable condition.

Effectiveness of non-pharmacological interventions to treat orthostatic hypotension in elderly people and people with a neurological condition: a systematic review

OBJECTIVE

The objective of this review was to summarize the best available evidence regarding the effectiveness of non-pharmacological interventions to treat orthostatic hypotension (OH) in elderly people and people with a neurological condition.

INTRODUCTION

Orthostatic hypotension is common in elderly people and people with a neurological condition and can interfere with or limit rehabilitation. Non-pharmacological interventions to treat OH could allow for longer and earlier mobilization, which is recommended in national clinical guidelines for rehabilitation in the acute or sub-acute phase following stroke or other neurological conditions.

INCLUSION CRITERIA

The review considered people aged 50 years and older, and people aged 18 years and elderly people with a neurological condition. Non-pharmacological interventions to treat OH included compression garments, neuromuscular stimulation, physical counter-maneuvers, aerobic or resistance exercises, sleeping with head tilted up, increasing fluid and salt intake, and timing and size of meals. The comparator was usual care, no intervention, pharmacological interventions, or other non-pharmacological interventions. Outcome measures included systolic blood pressure, diastolic blood pressure, heart rate, cerebral blood flow, observed/perceived symptoms, duration of standing or sitting in minutes, tolerance of therapy, functional ability, and adverse events/effects.

METHODS

Databases for published and unpublished studies available in English up to April 2018 with no lower date limit were searched. Critical appraisal was conducted using standardized instruments from JBI. Data were extracted using standardized tools designed for quantitative studies. Where appropriate, studies were included in a meta-analysis; otherwise, data were presented in a narrative form due to heterogeneity.

RESULTS

Forty-three studies - a combination of randomized controlled trials (n = 13), quasi-experimental studies (n = 28), a case control study (n = 1), and a case report (n = 1) - with 1069 participants were included. Meta-analyses of three interventions (resistance exercise, electrical stimulation, and lower limb compression bandaging) showed no significant effect of these interventions. Results from individual studies indicated physical maneuvers such as leg crossing, leg muscle pumping/contractions, and bending forward improved orthostatic hypotension. Abdominal compression improved OH. Sleeping with head up in combination with pharmacological treatment was more effective than sleeping with head up alone. Eating smaller, more frequent meals was effective. Drinking 480 mL of water increased blood pressure.

CONCLUSIONS

The review found mixed results for the effectiveness of non-pharmacological interventions to treat OH in people aged 50 years and older, and people with a neurological condition. There are several non-pharmacological interventions that may be effective in treating OH, but not all have resulted in clinically meaningful changes in outcome. Some may not be suitable for people with moderate to severe disability; therefore, it is important for clinicians to consider the patient's abilities and impairments when considering which non-pharmacological interventions to implement.

Robotic Locomotor Training Leads to Cardiovascular Changes in Individuals With Incomplete Spinal Cord Injury Over a 24-Week Rehabilitation Period: A Randomized Controlled Pilot Study

OBJECTIVE

To describe the effect of robotic locomotor training (RLT) and activity-based training (ABT) on cardiovascular indices during various physiological positions in individuals with spinal cord injury.

DESIGN

Randomized controlled pilot study.

SETTING

Private practice: Therapy & Beyond Centre - Walking with Brandon Foundation, Sports Science Institute of South Africa, Cape Town, South Africa.

PARTICIPANTS

Participants with chronic traumatic motor incomplete tetraplegia (N=16) who resided in the Western Cape, South Africa.

INTERVENTION

Robotic locomotor training (Ekso GT) and activity-based training over a 24-week intervention.

MAIN OUTCOME MEASURES

Brachial and ankle blood pressure, heart rate, heart rate variability, and cardiovascular efficiency during 4 physiological positions.

RESULTS

No differences between groups or over time were evident in resting systolic and diastolic blood pressure, ankle systolic pressure, ankle brachial pressure index, and heart rate variability. Standing heart rate at 24 weeks was significantly higher in the ABT group (95.58±12.61 beats/min) compared with the RLT group (75.14±14.96 beats/min) (P=.05). In the RLT group, no significant changes in heart rate variability (standard deviation R-R interval and root mean square of successive differences) was found between the standing and 6-minute walk test physiological positions throughout the intervention. Cardiovascular efficiency in the RLT group during the 6-minute walk test improved from 11.1±2.6 at baseline to 7.5±2.8 beats per meter walked at 6 weeks and was maintained from 6 to 24 weeks.

CONCLUSIONS

Large effect sizes and significant differences between groups found in this pilot study support the clinical effectiveness of RLT and ABT for changing cardiovascular indices as early as 6 weeks and up to 24 weeks of rehabilitation. RLT may be more effective than ABT in improving cardiac responses to orthostatic stress. Based on heart rate variability metrics, the stimulus of standing has comparable effects to RLT on the parasympathetic nervous system. Cardiovascular efficiency of exoskeleton walking improved, particularly over the first 6 weeks. Both the RLT and ABT interventions were limited in their effect on brachial and ankle blood pressure. A randomized controlled trial with a larger sample size is warranted to further examine these findings.

Medical emergency: rash, headache and spinal cord injury

A 49-year-old consultant medical oncologist, with a medical history of complete T5 spinal cord injury (March 1992) and long-term paralysis from the chest down, presented with shingles affecting the T7 dermatome. He also had a dull frontal headache, a feeling of agitation and increased blood pressure of 135/90 on a home blood pressure machine (higher than his usual blood pressure of 90/70). Having been taught about autonomic dysreflexia at the time of his initial spinal cord injury, he self-diagnosed autonomic dysreflexia caused by the noxious stimulus of shingles below his level of spinal cord injury. He self-administered a nifedipine 5 mg sublingual capsule to decrease his blood pressure before urgently seeing his general practitioner. Treatment of the shingles with acyclovir and analgesia successfully managed the problem and avoided hospital admission. This case highlights key aspects in treating autonomic dysreflexia and the value of doctor-patient partnership in doing so.

Postprandial Hypotension and Spinal Cord Injury

Postprandial hypotension (PPH) is defined as a fall of ≥20 mmHg in systolic blood pressure (SBP) or a SBP of <90 mmHg after having been >100 mmHg before the meal within two hours after a meal. The prevalence of PPH among persons with spinal cord injury (SCI) is unknown. Ambulatory blood pressure measurement was performed in 158 persons with SCI, 109 men, median age was 59.1 years (min.:13.2; max.: 86.2). In total, 78 persons (49.4%) had PPH after 114 out of 449 meals (25.4%). The median change in SBP during PPH was −28 mmHg (min.: −87; max.: −15 mmHg) and 96% of the PPH episodes were asymptomatic. The occurrence of PPH was correlated to older age (p = 0.001), level of injury (p = 0.023), and complete SCI (p = 0.000), but not, gender or time since injury. Further studies are needed to elucidate if PPH contributes to the increased cardiovascular mortality in the SCI population.

Spinal cord injury and vascular function: evidence from diameter-matched vessels

The effect of a spinal cord injury (SCI) on vascular function has been clouded by both the physiological and mathematical bias of assessing vasodilation in arteries with differing diameters both above and below the lesion and when comparing with healthy, nondisabled controls (CTRL). Thus, we measured vascular function, with flow-mediated vasodilation (FMD), in 10 SCI and 10 CTRL with all arteries matched for diameter (≈0.5 cm): brachial artery (BA, arm, functional limb in both groups) and popliteal artery (PA, leg, disused limb in SCI, functional limb in CTRL). PA %FMD was significantly attenuated in SCI (5.6 ± 0.6%) compared with CTRL (8.4 ± 1.3%), with no difference in the BA (SCI: 8.6 ± 0.9%; CTRL: 8.7 ± 0.7%). However, unlike the arm, where muscle mass was preserved, the legs of the SCI were significantly smaller than CTRL (∼70%). Thus, reactive hyperemia (RH), which is heavily dependent on the volume of muscle occluded, in the PA was attenuated in the SCI (144 ± 22 mL) compared with CTRL (258 ± 16 mL) but not different in the BA. Consequently, shear rate was significantly diminished in the PA of the SCI, such that %FMD/shear rate (vascular responsiveness) was actually greater in the SCI (1.5 ± 0.1% · s^-1) than CTRL (1.2 ± 0.1% · s^-1). Of note, this was significantly greater than both their own BA (0.9 ± 0.1% · s^-1) and that of the CTRL (0.9 ± 0.1% · s^-1). Therefore, examining vessels of similar size, this study reveals normal vascular function above the lesion and vascular dysfunction below the lesion. However, below the lesion there was, actually, evidence of increased vascular responsiveness in this population.NEW & NOTEWORTHY This study examined the effect of a spinal cord injury (SCI) and subsequent limb disuse on vascular function, assessed by %FMD, in diameter-matched vessels above and below the lesion in subjects with SCI and controls. The results reveal normal vascular function above the lesion and vascular dysfunction below the lesion (%FMD). However, below the lesion there was, actually, evidence of increased vascular responsiveness (%FMD/shear rate) in this population.

Multidimensional review of cognitive impairment after spinal cord injury

Cognitive impairment is highly prevalent in the population with spinal cord injury (SCI) and exerts a significant impact on functional independence and quality of life in this population. A number of neuroscientists have conducted preliminary investigations of cognitive deficits after SCI, but achieved marginally contradictory results due to some limitations such as the heterogeneity in the sample population, sample size, types of tests utilized, study design, and time since SCI. Therefore, this review mainly focuses on the characteristics, assessments, potential causality and treatment of cognitive impairment for better understanding such deficits in the SCI population.