Alterations in cardiac autonomic control in spinal cord injury

Influence of Blood Pressure on Acute Cervical Spinal Cord Injury Without Fracture and Dislocation: Results From a Retrospective Analysis

OBJECTIVE

The objective of this study was to investigate the influence of blood pressure on the severity and functional recovery of patients with acute cervical spinal cord injury (SCI) without fracture and dislocation.

METHODS

A retrospective case control study analyzed the data of 40 patients admitted to our orthopedics department (Beijing Tiantan Hospital, Capital Medical University) from January 2013 to February 2021. They were diagnosed as acute cervical SCI without fracture and dislocation. Gender, age, height, weight, history of hypertension, postinjury American Spinal Injury Association grade, postinjury modified Japanese Orthopaedic Association (mJOA) score, postoperative mJOA score, 1-year follow-up mJOA score, preoperative mean arterial pressure (MAP), intramedullary T2 hyperintensity, and hyponatremia were collected. The patients were divided into groups and subgroups based on their history of hypertension and preoperative MAP. The effects of history of hypertension and preoperative MAP on the incidence of T2 hyperintensity, hyponatremia, the improvement rate of the postoperative mJOA and 1-year follow-up mJOA scores were analyzed.

RESULTS

Patients with history of hypertension had a lower incidence of intramedullary T2 hyperintensity than patients without history of hypertension (P < 0.05). Patients with history of hypertension and patients with a higher preoperative MAP had better neurological recovery at 1 year of follow-up (P < 0.05).

CONCLUSIONS

Blood pressure has great influence on acute cervical SCI without fracture and dislocation. Maintaining a higher preoperative MAP is advantageous for better recovery after SCI. Attention should be paid to the dynamic management of blood pressure to avoid the adverse effects of hypotension after SCI.

Spinal decompression surgery may alleviate vasopressor-induced spinal hemorrhage and extravasation during acute cervical spinal cord injury in rats

BACKGROUND

Cervical spinal injury often disrupts the supraspinal vasomotor pathways projecting to the thoracic sympathetic preganglionic neurons, leading to cardiovascular dysfunction. The current guideline is to maintain the mean arterial blood pressure at 85 to 90 mmHg using a vasopressor during the first week of the injury. Some studies have demonstrated that this treatment might be beneficial to alleviate secondary injury and improve neurological outcomes; however, elevation of blood pressure may exacerbate spinal hemorrhage, extravasation, and edema, exacerbating the initial injury.

PURPOSE

The present study was designed to (1) examine whether vasopressor administration exacerbates spinal hemorrhage and extravasation; (2) evaluate whether spinal decompression surgery relieves vasopressor-induced spinal hemorrhage and extravasation.

STUDY DESIGN

In vivo animal study.

METHODS

Animals received a saline solution or a vasopressor (phenylephrine hydrochloride, 500 or 1000 μg/kg, 7 mL/kg/h) after mid-cervical contusion with or without spinal decompression (ie, incision of the dura and arachnoid mater). Spinal cord hemorrhage and extravasation were examined by expression of Evans blue within the spinal cord section.

RESULTS

The results demonstrated that cervical spinal contusion significantly reduced the mean arterial blood pressure and induced spinal hemorrhage and extravasation. Phenylephrine infusion significantly elevated the mean arterial blood pressure to the preinjury level within 15 to 60 minutes postcontusion; however, spinal hemorrhage and extravasation were more extensive in animals that received phenylephrine than in those that received saline. Notably, spinal decompression mitigated spinal hemorrhage and extravasation in contused rats who received phenylephrine.

CONCLUSIONS

These data indicate that, although phenylephrine can prevent hypotension after cervical spinal injury, it also causes excess spinal hemorrhage and extravasation.

CLINICAL SIGNIFICANCE

Spinal decompressive surgery seemed to minimize the side effect of phenylephrine as vasopressor treatment during acute spinal cord injury.

Polymorphic Ventricular Tachycardia in Acute Cervical Spinal Cord Injury: A Rare Occurrence in the Setting of Normal QTc

Cardiovascular manifestations like bradycardia, hypotension, fluctuation of blood pressure, and supraventricular arrhythmia are common in acute spinal cervical injury above the C6 level and are the major cause of mortality and morbidity in them. Ventricular tachycardia (VT) and fibrillation have only been reported in a few cases, but polymorphic VT (PMVT) has not been reported. We report a very rare case of acute cervical spinal cord injury patient who developed PMVT in the setting of normal QT interval degenerating to ventricular fibrillation, causing cardiac arrest before surgery.

Closed reduction of fracture-dislocation of the sub-axial cervical spine with Gardner-Wells tongs. Technical note

Study design

Technical note.

Purpose

To provide a technical description of the placement of Gardner-Wells tongs and the performance of awake cranio-cervical traction to reduce AO type C injuries of the sub-axial cervical spine with Gardner-Wells tongs.

Methods

In this technical note, the authors present the indications, the contraindications, the pull-out of the pins, a detailed description of the technique for its proper placement, traction reduction technique, reduction maneuvers, complications and post-reduction care.

Results

Awake reduction of AO type C injuries of the sub-axial cervical spine can be successfully performed using Gardner-Wells tongs.

Conclusions

There is sufficient evidence to recommend the use of cranio-cervical traction in these vertebral injuries; however, we lack a detailed technical note to guide its proper placement.

Test-retest reliability of short- and long-term heart rate variability in individuals with spinal cord injury

STUDY DESIGN

Cross-sectional.

OBJECTIVES

To investigate test-retest reliability of heart rate variability (HRV) metrics in SCI without restriction of activity over long (24-h) and shorter durations (5-min, 10-min, 1-h, 3-h and 6-h).

SETTINGS

University hospital in Khon Kaen, Thailand.

METHODS

Forty-five participants (11 with tetraplegia and 34 with paraplegia) underwent two 24-h recordings of RR-intervals to derive time and frequency HRV metrics. Relative reliability was assessed by intraclass correlation coefficient (ICC) and absolute reliability by coefficient of variation (CV) and Bland-Altman limits of agreement (LoA).

RESULTS

For 5- and 10-min durations, eight of eleven HRV metrics had moderate to excellent reliability (ICC 0.40-0.76); the remaining three were poor (ICC < 0.4). HRV values from 1-h and 3-h durations showed moderate to excellent reliability (ICC of 0.46-0.81), except for 1-h reliability of ULF and TP (ICC of 0.06 and 0.30, respectively). Relative reliability was excellent (ICC of 0.77-0.92) for 6-h and 24-h durations in all HRV metrics. Absolute reliability improved as recording duration increased (lower CVs and narrower LoAs). Participants with high AD risk (SCI level at or above T6) showed lower test-retest reliability of HF and LF values than participants with low AD risk.

CONCLUSION

Relative reliability of HRV was excellent for 6-h and 24-h. The best absolute reliability values were for 24-h duration. Time-domain outcomes were more reliable than frequency domain outcomes. Participants with high risk of AD, particularly those with tetraplegia, showed lower reliability, especially for HF and LF.

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.

Postural Orthostatic Tachycardia Syndrome in Spinal Cord Injury

Spinal cord injury (SCI), in addition to motor and sensory problems, may also lead to autonomic dysfunction. Postural orthostatic tachycardia syndrome (POTS) is one of them and has often been reported in traumatic brain injuries, multiple sclerosis, and other spinal cord pathologies. However, there is not much data on POTS in SCI even in extensive databases. We present a case of an adolescent female with paraplegia due to traumatic SCI. During her tilt table training, she started having episodes of sinus tachycardia associated with fatigue, dizziness, headache, palpitations, and presyncope with no orthostatic hypotension, after achieving 60 degrees of head tilt. After ruling out the common causes of tachycardia and syncope, a diagnosis of POTS was established. With pharmacologic and non-pharmacological measures, including metoprolol, increased fluid intake, and compression stockings, her symptoms resolved, and she was able to continue rehabilitation.

Latent Autonomic Dysfunction in a Chronic Cervical Spinal Injury

Latent autonomic dysfunction has been identified in recent years among patients with chronic cervical lesions. This paper further illustrates a precautionary case of symptomatic manifestation with an elusive trigger. A 64-year-old male, who had shown excellent neurological recovery after decompression surgery for a cervical spinal injury (modified Frankel classification from C1 to D3), complained of recurrent syncope in the chronic phase. The cause remained unidentified for two years, but it was finally discovered that the syncope was induced by a transient sympathetic overactivation that was concurrent with mental strain and alcohol intake. Abstinence completely suppressed the episodes thereafter. The case suggests the possibility that patients with a history of cervical spinal injury, no matter how normal they appear, may have asymptomatic autonomic dysfunction. Additionally, identification of the trigger can be challenging due to its dynamic and protean nature. More emphasis should be paid to autonomic evaluation for chronic cervical spinal injuries.

Cardiac autonomic modulation in response to postural transition during a virtual reality task in individuals with spinal cord injury: A cross-sectional study

PURPOSE

The postural transition from sitting to standing is a moment of dysautonomic occurrence in individuals with Spinal Cord Injury (SCI). Different tools can be used to minimize this event, such as virtual reality. Thus, we aimed to analyze cardiac autonomic modulation in individuals with SCI during postural transition from the sitting to orthostatism position using a cognitive virtual reality (VR) task.

METHODS

Individuals with and without SCI were positioned on the Easy Stand® device, sitting at rest, at 0° considering the angle between the seat and the floor, elevation at 45°, and orthostatism at 90°, for 5 minutes in each position. Heart rate variability (HRV) measures of sympathovagal balance were collected (heart rate receiver: Polar V800). The groups were subdivided into two groups, one that performed VR as an intervention during the postural angle changes and another group that did not perform VR.

RESULTS

We evaluated 76 individuals, 40 with a medical diagnosis of SCI and 36 who composed the able-bodied control group without SCI, matched by age and sex. The HRV results showed that the SCI group who performed the task in VR demonstrated no significant difference in parasympathetic activation and global variability between the sitting versus 90° positions. There was better sympathovagal balance in SCI and able-bodied control groups who performed the VR task between the sitting versus 90° positions.

CONCLUSION

The use of a VR task seems to contribute to better sympathovagal balance, with the potential to reduce dysautonomia during postural changes.

Effects of C2 hemisection on respiratory and cardiovascular functions in rats

High cervical spinal cord injuries induce permanent neuromotor and autonomic deficits. These injuries impact both central respiratory and cardiovascular functions through modulation of the sympathetic nervous system. So far, cardiovascular studies have focused on models of complete contusion or transection at the lower cervical and thoracic levels and diaphragm activity evaluations using invasive methods. The present study aimed to evaluate the impact of C2 hemisection on different parameters representing vital functions (i.e., respiratory function, cardiovascular, and renal filtration parameters) at the moment of injury and 7 days post-injury in rats. No ventilatory parameters evaluated by plethysmography were impacted during quiet breathing after 7 days post-injury, whereas permanent diaphragm hemiplegia was observed by ultrasound and confirmed by diaphragmatic electromyography in anesthetized rats. Interestingly, the mean arterial pressure was reduced immediately after C2 hemisection, with complete compensation at 7 days post-injury. Renal filtration was unaffected at 7 days post-injury; however, remnant systolic dysfunction characterized by a reduced left ventricular ejection fraction persisted at 7 days post-injury. Taken together, these results demonstrated that following C2 hemisection, diaphragm activity and systolic function are impacted up to 7 days post-injury, whereas the respiratory and cardiovascular systems display vast adaptation to maintain ventilatory parameters and blood pressure homeostasis, with the latter likely sustained by the remaining descending sympathetic inputs spared by the initial injury. A better broad characterization of the physiopathology of high cervical spinal cord injuries covering a longer time period post-injury could be beneficial for understanding evaluations of putative therapeutics to further increase cardiorespiratory recovery.

Comparison of in-hospital and out-of-hospital cardiac arrest of trauma patients in Qatar

Background

Cardiac arrests in admitted hospital patients with trauma have not been described in the literature. We defined “in-hospital cardiac arrest of a trauma” (IHCAT) patient as “cessation of circulatory activity in a trauma patient confirmed by the absence of signs of circulation or abnormal cardiac arrest rhythm inside a hospital setting, which was not cardiac re-arrest.” This study aimed to compare epidemiology, clinical presentation, and outcomes between in- and out-of-hospital arrest resuscitations in trauma patients in Qatar. It was conducted as a retrospective cohort study including IHCAT and out-of-hospital trauma cardiac arrest (OHTCA) patients from January 2010 to December 2015 utilizing data from the national trauma registry, the out-of-hospital cardiac arrest registry, and the national ambulance service database.

Results

There were 716 traumatic cardiac arrest patients in Qatar from 2010 to 2015. A total of 410 OHTCA and 199 IHCAT patients were included for analysis. The mean annual crude incidence of IHCAT was 2.0 per 100,000 population compared to 4.0 per 100,000 population for OHTCA. The univariate comparative analysis between IHCAT and OHTCA patients showed a significant difference between ethnicities (p=0.04). With the exception of head injury, IHCAT had a significantly higher proportion of localization of injuries to anatomical regions compared to OHTCA; spinal injury (OR 3.5, 95% CI 1.5–8.3, p<0.004); chest injury (OR 2.62, 95% CI 1.62–4.19, p<0.00), and abdominal injury (OR 2.0, 95% CI 1.0–3.8, p<0.037). IHCAT patients had significantly higher hypovolemia (OR 1.66, 95% CI 1.18–2.35, p=0.004), higher mean Glasgow Coma Scale (GCS) score (OR 1.4, 95% CI 1.3–1.6, p<0.00), and a greater proportion of initial shockable rhythm (OR 3.51, 95% CI 1.6–7.7, p=0.002) and cardiac re-arrest (OR 6.0, 95% CI 3.3–10.8, p=<0.00) compared to OHTCA patients. Survival to hospital discharge was greater for IHCAT patients compared to OHTCA patients (OR 6.3, 95% CI 1.3–31.2, p=0.005).

Multivariable analysis for comparison after adjustment for age and gender showed that IHCAT was associated with higher odds of spinal injury, abdominal injury, higher pre-hospital GCS, higher occurrence of cardiac re-arrest, and better survival than for OHTCA patients.

IHCAT patients had a greater proportion of anatomically localized injuries indicating solitary injuries compared to greater polytrauma in OHTCA. In contrast, OHTCA patients had a higher proportion of diffuse blunt non-localizable polytrauma injuries that were severe enough to cause immediate or earlier onset of cardiac arrest.

Conclusion

In traumatic cardiac arrest patients, IHCAT was less common than OHTCA and might be related to a greater proportion of solitary localized anatomical blunt injuries (head/abdomen/chest/spine). In contrast, OHTCA patients were associated with diffuse blunt non-localizable polytrauma injuries with increased severity leading to immediate cardiac arrest. IHCAT was associated with a higher mean GCS score and a higher rate of initial shockable rhythm and cardiac re-arrest, and improved survival rates.

Evaluation of Cardiovascular Autonomic Function during Inpatient Rehabilitation following Traumatic Spinal Cord Injury

Assessment of the degree of impaired autonomic nervous system (ANS) function is not part of routine clinical practice during inpatient rehabilitation following traumatic spinal cord injury (SCI). The goal of this investigation was to determine the utility of the International Standards for Neurologic Classification of SCI (ISNCSCI) and the recently revised International Standards to document remaining Autonomic Function after SCI (ISAFSCI) in documenting cardiovascular ANS impairment during inpatient rehabilitation following traumatic SCI. Beat-to-beat recording of supine heart rate (HR) and blood pressure (BP) were collected at the bedside for estimation of total cardiovascular ISAFSCI score, cardio-vagal modulation (i.e., high frequency HR variability [HFHRV]) and sympathetic vasomotor regulation (i.e., Mayer wave component of systolic BP [SBPmayer]). A total of 41 participants completed baseline testing, which was conducted 11 ± 5 days from the admission ISNCSCI examination. There were no differences in supine HR or BP based on the ISNCSCI or ISAFSCI assessments. The HFHRV was generally lower with more distal lesions (r2 = 0.15; p = 0.01), and SBPmayer was significantly lower in those with American Spinal Injury Association Impairment Scale (AIS) A compared with AIS B, C, D (Cohen's d = -1.4; p < 0.001). There were no significant differences in HFHRV or SBPmayer in patients with or without ISAFSCI evidence of cardiovascular ANS impairment. These preliminary data suggest that neither the ISNCSCI nor the ISAFSCI are sensitive to changes in ANS cardiovascular function following traumatic SCI. Bedside assessment of HR and BP variabilities may provide insight, but are not readily available in the clinical setting. Further research is required to evaluate methods that accurately assess the degree of ANS impairment following traumatic SCI.

Early insights of the COVID-19 pandemic in the Veterans' Affairs spinal cord injury and disorders population

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

The primary outcome of the study was to identify patient characteristics associated with a positive COVID-19 test. The secondary outcome was to identify patient characteristics associated with mortality from COVID-19.

SETTING

Veterans Health Administration (VHA) National Spinal Cord Injury and Disorders (SCI) Registry, created by the National Spinal Cord Injury and Disorders SCI Program Office in March 2020.

METHODS

Data was analyzed in the form of descriptive statistics and then subsequent regression analysis was performed.

RESULTS

A total of 4,562 persons with SCI were tested for COVID-19 between March and July 2020, and 290 were positive. The study found that African Americans had increased odds of testing positive for COVID-19 (OR 1.53 (1.18-2.00), p &lt; 0.01). Increased age correlated with increased odds of mortality after testing positive for COVID-19 (1.046 (1.003-1.090)). Non-smokers had lower odds of mortality following positive COVID-19 test (0.15 (0.04-0.52)). No association was found between neurologic level of injury (NLI) and positive COVID-19 test or increased mortality. Increased Body Mass Index (BMI) did correlate with positive COVID-19 test but not increased mortality. The case fatality rate for persons with SCI and a positive test for COVID-19 was 12%.

CONCLUSIONS

It is important to define the risk factors for patients with SCI to elucidate and mitigate individual and population risks. These risk factors also can play a role in determining the allocation of critical healthcare resources.

Psychosocial aspects of sports medicine in pediatric athletes: Current concepts in the 21st century

Behavioral aspects of organized sports activity for pediatric athletes are considered in a world consumed with winning at all costs. In the first part of this treatise, we deal with a number of themes faced by our children in their sports play. These concepts include the lure of sports, sports attrition, the mental health of pediatric athletes (i.e., effects of stress, anxiety, depression, suicide in athletes, ADHD and stimulants, coping with injuries, drug use, and eating disorders), violence in sports (i.e., concepts of the abused athlete including sexual abuse), dealing with supervisors (i.e., coaches, parents), peers, the talented athlete, early sports specialization and sports clubs. In the second part of this discussion, we cover ergolytic agents consumed by young athletes in attempts to win at all costs. Sports doping agents covered include anabolic steroids (anabolic-androgenic steroids or AAS), androstenedione, dehydroepiandrostenedione (DHEA), human growth hormone (hGH; also its human recombinant homologue: rhGH), clenbuterol, creatine, gamma hydroxybutyrate (GHB), amphetamines, caffeine and ephedrine. Also considered are blood doping that includes erythropoietin (EPO) and concepts of gene doping. In the last section of this discussion, we look at disabled pediatric athletes that include such concepts as athletes with spinal cord injuries (SCIs), myelomeningocele, cerebral palsy, wheelchair athletes, and amputee athletes; also covered are pediatric athletes with visual impairment, deafness, and those with intellectual disability including Down syndrome. In addition, concepts of autonomic dysreflexia, boosting and atlantoaxial instability are emphasized. We conclude that clinicians and society should protect our precious pediatric athletes who face many challenges in their involvement with organized sports in a world obsessed with winning. There is much we can do to help our young athletes find benefit from sports play while avoiding or blunting negative consequences of organized sport activities.

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.

Polarity-Differentiated Dielectric Materials in Monolayer Graphene Charge-Regulated Field-Effect Transistors for an Artificial Reflex Arc and Pain-Modulation System of the Spinal Cord

The nervous system is a vital part of organisms to survive and it endows them with remarkable abilities, such as perception, recognition, regulation, learning, and decision-making, by intertwining myriad neurons. To realize such outstanding efficacies and functions, many artificial devices and systems have been investigated to emulate the operating principles of the nervous system. Here, an artificial reflex arc (ARA) and artificial pain modulation system (APMS) are proposed to imitate the unconscious behaviors of the spinal cord. Gd_x O_y - and Al_x O_y -based charge-regulated field-effect transistors (CRFETs) with a monolayer graphene channel are fabricated and adopted as inhibitory and excitatory synapses, respectively, under the same pulse signals to mimic the biological reflex arc through a connection with a poly(vinylidene fluoride-co-trifluoroethylene)-based actuator. Additionally, a memristor is integrated with a CRFET as the interneuron to regulate the Dirac point by controlling the voltage drop on the graphene channel, analogous to the descending pain-inhibition system in the spinal cord, to prevent excessive pain perception. The proposed ARA and APMS provide a significant step forward to realizing the functions of the nervous system, giving promising potential for developing future intelligent alarm systems, neuroprosthetics, and neurorobotics.

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.

Heart rate changes associated with autonomic dysreflexia in daily life of individuals with chronic spinal cord injury

STUDY DESIGN

Secondary data analysis.

OBJECTIVE

To characterize heart rate (HR) changes during autonomic dysreflexia (AD) in daily life for individuals with chronic spinal cord injury (SCI).

SETTING

University-based laboratory/community-based outpatient.

METHODS

Cardiovascular data, previously collected during a 24-h ambulatory surveillance period in individuals with chronic SCI, were assessed. Any systolic blood pressure (SBP) increase ≥20 mmHg from baseline was identified and categorized into confirmed AD (i.e., diarized trigger), unknown (i.e., no diary entry), or unlikely AD (i.e., potential exertion driven SBP increase) groups. SBP-associated HR changes were categorized as unchanged, increased or decreased compared to baseline.

RESULTS

Forty-five individuals [8 females, median age and time since injury of 43 years (lower and upper quartiles 36-50) and 17 years (6-23), respectively], were included for analysis. Overall, 797 episodes of SBP increase above AD threshold were identified and classified as confirmed (n = 250, 31.4%), unknown (n = 472, 59.2%) or unlikely (n = 75, 9.4%). The median number of episodes per individual within the 24-h period was 13 (8-28). HR-decrease/increase ratio was 3:1 for confirmed and unknown, and 1.5:1 for unlikely episodes. HR changes resulting in brady-/tachycardia were 34.4%/2.8% for confirmed, 39.6%/3.4% unknown, and 26.7%/9.3% for unlikely episodes, respectively.

CONCLUSIONS

Our findings suggest that the majority of confirmed AD episodes are associated with a HR decrease. Using wearable-sensors-derived measures of physical activity in future studies could provide a more detailed characterization of HR changes during AD and improve AD identification.

Case series on the Charcot neuroarthropathy in hands after cervical central cord syndrome

Background

Charcot neuroarthropathy (CNA) of the upper extremity occurs most frequently in shoulders. However, CNA in the hands is uncommon and seldom be reported. The onset of CNA is usually insidious. If this process continues undetected, it can result in joint deformity, ulceration and/or superinfection, loss of function, and amputation or even death. In this article, we are going to present three cases of CNA in the hands of individuals with cervical spinal cord injury (SCI) with central cord syndrome.

Case presentation

Three male individuals with cervical spinal stenosis contracted tetraplegia (American Spinal Injury Association Impairment Scale Grade D, D, and B) due to spinal cord contusion after a trauma and developed hand swelling without pain 2 to 3 months after their SCI. X-ray showed degenerative joint changes in the hands. CNA was considered due to the patient’s history of cervical SCI, loss of motor function and sensation, symptoms of painless swelling, physical examination, and X-ray findings. The self-care sub scores of Spinal Cord Independence Measure III improved slightly only during rehabilitation and follow-up due to poor hand function.

Conclusions

CNA may develop after a central or peripheral neurological disorder. Nearly every joint of the body can be affected and the lower limbs are the most frequently involved. However, CNA of the hand is rare. We present three patients with CNA in the hands after cervical SCI and review the features and early differential diagnosis of CNA. Currently there is no specific treatment available. Therefore, early identification of CNA and adequate protection to the affected joints seem important.

Leveraging Continuous Vital Sign Measurements for Real-Time Assessment of Autonomic Nervous System Dysfunction After Brain Injury: A Narrative Review of Current and Future Applications

Subtle and profound changes in autonomic nervous system (ANS) function affecting sympathetic and parasympathetic homeostasis occur as a result of critical illness. Changes in ANS function are particularly salient in neurocritical illness, when direct structural and functional perturbations to autonomic network pathways occur and may herald impending clinical deterioration or intervenable evolving mechanisms of secondary injury. Sympathetic and parasympathetic balance can be measured quantitatively at the bedside using multiple methods, most readily by extracting data from electrocardiographic or photoplethysmography waveforms. Work from our group and others has demonstrated that data-analytic techniques can identify quantitative physiologic changes that precede clinical detection of meaningful events, and therefore may provide an important window for time-sensitive therapies. Here, we review data-analytic approaches to measuring ANS dysfunction from routine bedside physiologic data streams and integrating this data into multimodal machine learning-based model development to better understand phenotypical expression of pathophysiologic mechanisms and perhaps even serve as early detection signals. Attention will be given to examples from our work in acute traumatic brain injury on detection and monitoring of paroxysmal sympathetic hyperactivity and prediction of neurologic deterioration, and in large hemispheric infarction on prediction of malignant cerebral edema. We also discuss future clinical applications and data-analytic challenges and future directions.

Effects of Vitamin D Deficiency on the Function of the Cardiac Autonomic Nervous System in Rats

Background

Previous studies have shown that autonomic nervous system (ANS) dysfunction was closely related to vitamin D (VD) deficiency, but the mechanism remained unclear. The purpose of this study was to evaluate the mechanism of VD^def on the function of cardiac ANS in rats.

Methods

After 10 weeks of VD deficiency feeding, we successfully established a VD-deficient rat model. The body weight of rats was recorded, and the levels of calcium (Ca), phosphorus (P), creatinine (CRE), triglyceride (TG), hemoglobin (HG), and 25(OH)VD3 in serum were detected by corresponding kits. Short-time frequency domain analysis was used to evaluate the heart rate variability (HRV) of all rats. The expression of tyrosine hydroxylase (TH) in the atria and ventricle were detected by IHC. ELISA was used to determine the levels of acetyl choline (Ach) and nitric oxide (NO). HPLC was used for the detection of norepinephrine (NE). The expressions of KIR3.1, HERG, KVLQT1, and Mink were detected by qRT-PCR and western blot.

Results

After 10 weeks of VD deficiency feeding, serum 25(OH)VD3 levels were markedly reduced in the VD^def group, and sera Ca and P, as well as body weight, were notably decreased in the VD^def group. In resting and motion states, VD deficiency resulted in a decline in HF levels and a mark increase in VLF and LF/HF levels. VD deficiency caused a reduction in the release of the local cardiac neurotransmitters TH and Ach. NE and NO levels were also remarkably depressed in the VD^def group. In addition, VD deficiency resulted in severely impaired expression of potassium channel proteins.

Conclusion

VD deficiency leads to cardiac ANS dysfunction. The imbalance in heart rate variability, impaired release and secretion of neurotransmitters and local plasma hormones in the heart, and downregulation of potassium channel protein expression caused by VD deficiency may be closely related to this dysfunction.

Physiological parameters and the use of compression stockings in individuals with spinal cord injuries: a scoping review

STUDY DESIGN

Scoping review.

OBJECTIVE

To summarize information on the physiological effects of compression stockings (CS) in individuals with spinal cord injuries (SCI) and suggest areas for future research.

METHODS

We asked, "What are the physiological effects of CS use in individuals with SCI?" Original studies of patients with SCI regardless of sex and age that focused on SCI and CS were included. Five biomedical databases were searched. Studies were selected by three researchers in two stages, starting with an abstract and title screening and continuing with a full text review for application of the inclusion and exclusion criteria. A narrative synthesis was then performed.

RESULTS

An initial search yielded 283 titles, of which five met the inclusion criteria and were subjected to the full text review. Among them, there were 78 individuals with SCI. The studies found that the use of CS at rest reduced deep vein thrombosis (DVT) and vascular capacitance but increased systolic blood pressure and norepinephrine level., three studies tested the use of CS During exercise; one found that time of the last lap in a standard court test was negatively affected; however, the greatest benefits were observed after exercises, such as reduced blood lactate level, improved autonomic function, and increased blood flow to the upper limbs.

CONCLUSION

We conclude that future research should examine the physiological effects and relationship of CS with: (a) pharmacological interventions, (b) body position changes, (c) physical fitness level, (d) wheelchair use duration, (e) exercise-induced thermal stress, (f) thermal stress mitigation, and (g) edema reduction.

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.

A neuro-cardiac self-regulation therapy to improve autonomic and neural function after SCI: a randomized controlled trial protocol

BACKGROUND

Spinal cord injury (SCI) is associated with autonomic imbalance and significant secondary conditions, including cardiac and brain dysfunction that adversely impact health and wellbeing. This study will investigate the effectiveness (intention-to-treat) of a neuro-cardiac self-regulation therapy to improve autonomic and neural/brain activity in adults with SCI living in the community.

METHODS

A two-arm parallel, randomised controlled trial in which adults with SCI living in the community post-rehabilitation will be randomly assigned to a treatment or control group. The treatment group (N = 60) aged 18-70 years with a chronic traumatic or non-traumatic SCI, will receive intervention sessions once per week for 10 weeks, designed to regulate autonomic activity using computer-based feedback of heart rate variability and controlled breathing (called HRV-F). Comprehensive neurophysiological and psychological assessment will occur at baseline, immediate post-treatment, and 6 and 12-months post-treatment. Primary outcome measures include electrocardiography/heart rate variability (to assess autonomic nervous system function) and transcranial doppler sonography (to assess cerebral blood circulation in basal cerebral arteries). Secondary outcomes measures include continuous blood pressure, electroencephalography, functional near-infrared spectroscopy, respiration/breath rate, electrooculography, cognitive capacity, psychological status, pain, fatigue, sleep and quality of life. Controls (N = 60) will receive usual community care, reading material and a brief telephone call once per week for 10 weeks and be similarly assessed over the same time period as the HRV-F group. Linear mixed model analysis with repeated measures will determine effectiveness of HRV-F and latent class mixture modelling used to determine trajectories for primary and selected secondary outcomes of interest.

DISCUSSION

Treatments for improving autonomic function after SCI are limited. It is therefore important to establish whether a neuro-cardiac self-regulation therapy can result in improved autonomic functioning post-SCI, as well as whether HRV-F is associated with better outcomes for secondary conditions such as cardiovascular health, cognitive capacity and mental health.

TRIAL REGISTRATION

The study has been prospectively registered with the Australian and New Zealand Clinical Trial Registry ( ACTRN12621000870853 .aspx). Date of Registration: 6th July 2021. Trial Sponsor: The University of Sydney, NSW 2006. Protocol version: 22/07/2021.

Local and Systemic Factors Drive Ectopic Osteogenesis in Regenerating Muscles of Spinal-Cord-Injured Mice in a Lesion-Level-Dependent Manner

Neuroimmune dysfunction is thought to promote the development of several acute and chronic complications in spinal cord injury (SCI) patients. Putative roles for adrenal stress hormones and catecholamines are increasingly being recognized, yet how these adversely affect peripheral tissue homeostasis and repair under SCI conditions remains elusive. Here, we investigated their influence in a mouse model of SCI with acquired neurogenic heterotopic ossification. We show that spinal cord lesions differentially influence muscular regeneration in a level-dependent manner and through a complex multi-step process that creates an osteopermissive environment within the first hours of injury. This cascade of events is shown to critically involve adrenergic signals and drive the acute release of the neuropeptide, substance P. Our findings generate new insights into the kinetics and processes that govern SCI-induced deregulations in skeletal muscle homeostasis and regeneration, thereby aiding the development of sequential therapeutic strategies that can prevent or attenuate neuromusculoskeletal complications in SCI patients.

Spinal cord injury: A multisystem physiological impairment/dysfunction

Spinal cord injury (SCI) is a complex disease that affects not only sensory and motor pathways below the neurological level of injury (NLI) but also all the organs and systems situated below this NLI. This multisystem impairment implies comprehensive management in dedicated SCI specialized centers, by interdisciplinary and multidisciplinary teams, able to treat not only the neurological impairment, but also all the systems and organs affected. After a brief history of the Spinal Cord Medicine, the author describes how to determine the level and severity of a SCI based on the International Standards for Neurological Classification of Spinal Cord Injury and the prognosis factors of recovery. This article provides also a review of the numerous SCI-related impairments (except for urinary, sexual problems and pain treated separately in this issue), their principles of management and related complications.

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.

Substrate metabolism during recovery from circuit resistance exercise in persons with spinal cord injury

INTRODUCTION

Whole body energy expenditure and lipid oxidation (Lox) are upregulated during and after exercise. Persons with spinal cord injury (SCI) generally have a blunted ability to utilize fat during exercise, but it is unknown if their substrate partitioning is affected during recovery from exercise.

PURPOSE

To determine the effect of a single session of upper body circuit resistance exercise (CRE) on energy expenditure and Lox during exercise recovery in persons with and without SCI.

METHODS

Twenty four persons (3 groups; 7 male and 1 female per group) without paralysis (neurologically intact; N) or with chronic (≥ 1 yr) paraplegia (P) or tetraplegia (T) participated. Energy expenditure and substrate partitioning were assessed via indirect calorimetry before, during, and three times after (up to 120 min after) a single session of CRE, or time-matched seated control (CON).

RESULTS

During CRE, all groups experienced a similar relative increase in oxygen consumption (49 ± 13, 55 ± 11, and 48 ± 15% VO_2peak for N, P, and T, respectively). The Post_0-120 energy expenditure was greater following CRE vs. CON (P < 0.01) and independent of injury characteristics (10.6, 22.6, and 14.3% higher than CON for N, P, and T; P = 0.21). The absolute increase in Lox above CON during recovery was similar for N, P, and T (5.74 ± 2.81, 6.62 ± 3.10, and 4.50 ± 3.91 g, respectively; P = 0.45).

CONCLUSIONS

Energy expenditure and lipid utilization was increased similarly following circuit exercise in persons without and with spinal cord injury in a manner independent of level of injury.

Cardiovascular safety of mirabegron in individuals treated for spinal cord injury- or multiple sclerosis-induced neurogenic detrusor overactivity

PURPOSE

To analyze cardiovascular safety of mirabegron in patients with spinal cord injury (SCI)- and multiple sclerosis (MS)-induced neurogenic detrusor overactivity (NDO) in a prospective, randomized, double-blind, placebo-controlled study.

METHODS

Seventy-eight patients were enrolled into the study, and 66 of them were included into the final analysis. In 49 (74.2%), NDO developed due to suprasacral SCI, 17 (25.8%) suffered from NDO due to MS. Eleven patients were previously treated for hypertension and one for arrhythmia. All study participants received placebo for 2 weeks run-in period. Subsequently, eligible subjects were randomized for 4 weeks of active treatment with mirabegron 50 mg once daily (Group A; n = 32) or placebo (Group B; n = 34). Data from resting electrocardiography (ECG), 24-h ECG and blood pressure monitoring, and echocardiographic examination, were used for cardiovascular safety assessment. All reported variables were evaluated at time of randomization and at the end of the study. Longitudinal changes of variables within the groups and differences between the groups were assessed using nonparametric Kruskal-Wallis test, and p ≤ 0.05 was considered statistically significant.

RESULTS

No statistically significant longitudinal changes were found in safety variables, except for prolongation of QT interval in placebo group (p = 0.0328) recorded by resting ECG. No significant difference between the Groups A and B, in any of the variables, was observed. A single cardiovascular study drug-related adverse event was recorded in a patient with cervical SCI (3.13%).

CONCLUSIONS

Our results suggest that mirabegron can be safely used in the treatment of patients with SCI- and MS-induced NDO.

A review of sleep research in patients with spinal cord injury

Study design: Systematic review. Objectives: Sleep disturbances are a common complaint among individuals with spinal cord injury (SCI) and were not usually present before the SCI. Their sleep disturbances, including disrupted sleep, spasms, and problems with initiating and sustaining sleep through the night, affect SCI individuals' overall quality of life due to excessive tiredness and low energy levels during the day. Despite the high prevalence of sleep complaints in this population, current knowledge about sleep in the SCI population has not been systematically assessed. Setting: Capital Region of Denmark. Methods: We systematically reviewed literature identified from the PubMed and EMBASE databases following PRISMA guidelines.Thirty-seven articles met our inclusion criteria, as only controlled studies were included. This could be a comparison of (1) SCI individuals and able-bodied controls, (2) cervical with thoracolumbar SCI individuals, or (3) cervical, thoracolumbar SCI individuals and able-bodied controls. Results: Individuals with SCI have a higher prevalence of sleep-disordered breathing and periodic leg movements during sleep (PLMS), lower heart rate, but no nocturnal lowering of blood pressure. 24-hour energy expenditure and sleeping metabolic rate were significantly lower, and bowel movements were altered. Endocrine alterations were found in investigations of melatonin, cortisol and antidiuretic hormone. Questionnaires revealed a high prevalence of subjectively poorer sleep quality in individuals with SCI compared with able-bodied controls. Conclusions: There are significant differences between groups with SCI and able-bodied controls. SCI objectively and subjectively markedly affects an individual's sleep.

Longitudinal Assessment of Autonomic Function during the Acute Phase of Spinal Cord Injury: Use of Low-Frequency Blood Pressure Variability as a Quantitative Measure of Autonomic Function

High-level spinal cord injury (SCI) can disrupt cardiovascular autonomic function. However, the evolution of cardiovascular autonomic function in the acute phase following injury is unknown. We evaluated the timing, severity, progression, and implications of cardiovascular autonomic injury following acute SCI. We tested 63 individuals with acute traumatic SCI (aged 48 ± 2 years) at five time-points: <2 weeks, and 1, 3, 6-12, and >12 months post-injury. Supine beat-to-beat systolic arterial pressure (SAP) and R-R interval (RRI) were recorded and low-frequency variability (LF SAP and LF RRI) determined. Cross-spectral analyses were used to determine baroreflex function (low frequency) and cardiorespiratory interactions (high frequency). Known electrocardiographic (ECG) markers for arrhythmia and self-reported symptoms of cardiovascular dysfunction were determined. Comparisons were made with historical data from individuals with chronic SCI and able-bodied controls. Most individuals had high-level (74%) motor/sensory incomplete (63%) lesions. All participants had decreased LF SAP at <2 weeks (2.22 ± 0.65 mm Hg²). Autonomic injury was defined as high-level SCI with LF SAP <2 mm Hg². Two distinct groups emerged by 1 month: autonomically complete SCI with sustained low LF SAP (0.76 ± 0.17 mm Hg²) and autonomically incomplete SCI with increased LF SAP (5.46 ± 1.0 mm Hg², p < 0.05). Autonomically complete injuries did not recover over time. Cardiovascular symptoms were prevalent and worsened with time, especially in those with autonomically complete lesions, and chronic SCI. Baroreflex function and cardiorespiratory interactions were impaired after SCI. Risk of arrhythmia increased immediately after SCI, and remained elevated throughout the acute phase. Acute SCI is associated with severe cardiovascular dysfunction. LF SAP provides a simple, non-invasive, translatable, quantitative assessment of autonomic function, and is most informative 1 month after injury.

Cardiovascular Autonomic Dysfunction in Spinal Cord Injury: Epidemiology, Diagnosis, and Management

Spinal cord injury (SCI) disrupts autonomic circuits and impairs synchronistic functioning of the autonomic nervous system, leading to inadequate cardiovascular regulation. Individuals with SCI, particularly at or above the sixth thoracic vertebral level (T6), often have impaired regulation of sympathetic vasoconstriction of the peripheral vasculature and the splanchnic circulation, and diminished control of heart rate and cardiac output. In addition, impaired descending sympathetic control results in changes in circulating levels of plasma catecholamines, which can have a profound effect on cardiovascular function. Although individuals with lesions below T6 often have normal resting blood pressures, there is evidence of increases in resting heart rate and inadequate cardiovascular response to autonomic provocations such as the head-up tilt and cold face tests. This manuscript reviews the prevalence of cardiovascular disorders given the level, duration and severity of SCI, the clinical presentation, diagnostic workup, short- and long-term consequences, and empirical evidence supporting management strategies to treat cardiovascular dysfunction following a SCI.

A Patient With Acute Cervical Cord Injury and COVID-19: A First Case Report

During the pandemic of Coronavirus disease 2019 (COVID-19), it is possible for rehabilitation physicians and personnel to take care of patients with concurrent spinal cord injury (SCI) and COVID-19. Here, we describe a case of acute cervical SCI resulting in complete tetraplegia C5 American Spinal Injury Association (ASIA) Impairment Scale (AIS) A with unrecognized, acute respiratory syndrome coronavirus 2 (SAR-CoV-2) infection. This resulted in large-scale quarantines of related surgical and rehabilitation staff, and the unexpected death of the patient despite receiving the treatments according to the standard guideline. Rehabilitation personnel who take care of acute SCI patients with COVID-19 should consider the effect of SCI on the course of COVID-19, the effect of COVID-19 and its treatments on the course of SCI, and risks of SAR-CoV2 transmission between patients and rehabilitation staff, to continue providing safe and effective rehabilitation programs.

COVID-19: Screening and triage challenges in people with disability due to Spinal Cord Injury

An outbreak of a novel coronavirus disease (COVID-19) that emerged in the Chinese city of Wuhan has rapidly become a global public health pandemic. As of March 2020, the Centers for Disease Control and Prevention (CDC) has described priority levels for testing patients with suspected COVID-19 and information on when to seek medical attention. However, there is a paucity of further guidance for people with spinal cord injury (SCI) who may not present with typical symptoms of COVID-19 due to altered physiology. This may pose challenges with surveillance, risk stratification, and initial management of this vulnerable population. In this point-counterpoint discussion, we outline important differences in presentation along with COVID-19 cases co-morbid with SCI.

Diffuse midline glioma in the spinal cord with rapid respiratory deterioration

Background

Neurogenic acute respiratory failure is usually caused by either infection or vascular insufficiency. We report the case of a patient who developed acute respiratory failure secondary to a spinal tumor.

Case Presentation

A 32‐year‐old man, presenting with numbness and muscle weakness in his legs for 2 weeks, was transferred to our hospital with worsening quadriplegia and development of respiratory symptoms. We carried out emergent spinal decompression and initiated steroid pulse therapy, with no resolution of symptoms; a tumor incision biopsy after contrast cervical magnetic resonance imaging revealed an intraspinal tumor with a pathological diagnosis of World Health Organization grade IV glioma. The patient developed bradycardia, severe sepsis, status epilepticus, and cardiopulmonary arrest due to hypoxemia and was treated with chemoradiotherapy under mechanical ventilation. He was later transferred to another hospital for subacute care.

Conclusion

Acute respiratory failure caused by spinal tumors is uncommon. However, acute care practitioners should be mindful of neoplastic lesions as a potential cause.

Clinical guidelines for the diagnosis and treatment of lower urinary tract dysfunction in patients with spinal cord injury

The present article is an abridged English translation of the Japanese clinical guidelines for the diagnosis and treatment of lower urinary tract dysfunction in patients with spinal cord injury updated as of July 2019. The patients are adult spinal cord injured patients with lower urinary tract dysfunction; special consideration of pediatric and elderly populations is presented separately. The target audience is healthcare providers who are engaged in the medical care of patients with spinal cord injury. The mandatory assessment includes medical history, physical examination, frequency-volume chart, urinalysis, blood chemistry, transabdominal ultrasonography, measurement of post-void residual urine, uroflowmetry and video-urodynamic study. Optional assessments include questionnaires on the quality of life, renal scintigraphy and cystourethroscopy. The presence or absence of risk factors for renal damage and symptomatic urinary tract infection affects urinary management, as well as pharmacological treatments. Further treatment is recommended if the maximum conservative treatment fails to improve or prevent renal damage and symptomatic urinary tract infection. In addition, management of urinary incontinence should be considered individually in patients with risk factors for urinary incontinence and decreased quality of life.

Effect of acetazolamide on susceptibility to central sleep apnea in chronic spinal cord injury

Spinal cord injury (SCI) is an established risk factor for central sleep apnea. Acetazolamide (ACZ), a carbonic anhydrase inhibitor, has been shown to decrease the frequency of central apnea by inducing mild metabolic acidosis. We hypothesized that ACZ would decrease the propensity to develop hypocapnic central apnea and decrease the apneic threshold. We randomized 16 participants with sleep-disordered breathing (8 SCI and 8 able-bodied controls) to receive ACZ (500 mg twice a day for 3 days) or placebo with a 1-wk washout before crossing over to the other drug arm. Study nights included polysomnography and determination of the hypocapnic apneic threshold and CO₂ reserve using noninvasive ventilation. For participants with spontaneous central apnea, CO₂ was administered until central apnea was abolished, and CO₂ reserve was measured as the difference in end-tidal Pco₂ (PETCO2) before and after. Steady-state plant gain, the response of end-tidal Pco₂ to changes in ventilation, was calculated from PETCO2 and V̇e ratio during stable sleep. Controller gain, the response of ventilatory drive to changes in end-tidal Pco₂, was defined as the ratio of change in V̇e between control and hypopnea to the ΔCO₂ during stable non-rapid eye movement sleep. Treatment with ACZ for three days resulted in widening of the CO₂ reserve (-4.0 ± 1.2 vs. -3.0 ± 0.7 mmHg for able-bodied, -3.4 ± 1.9 vs. -2.2 ± 2.2 mmHg for SCI, P < 0.0001), and a corresponding decrease in the hypocapnic apnea threshold (28.3 ± 5.2 vs. 37.1 ± 5.6 mmHg for able-bodied, 29.9 ± 5.4 vs. 34.8 ± 6.9 mmHg for SCI, P < 0.0001), respectively. ACZ significantly reduced plant gain when compared with placebo (4.1 ± 1.7 vs. 5.4 ± 1.8 mmHg/L min for able-bodied, 4.1 ± 2.0 vs. 5.1 ± 1.7 mmHg·L^-1·min for SCI, P < 0.01). Acetazolamide decreased apnea-hypopnea index (28.8 ± 22.9 vs. 39.3 ± 24.1 events/h; P = 0.05), central apnea index (0.6 ± 1.5 vs. 6.3 ± 13.1 events/h; P = 0.05), and oxyhemoglobin desaturation index (7.5 ± 8.3 vs. 19.2 ± 15.2 events/h; P = 0.01) compared with placebo. Our results suggest that treatment with ACZ decreases susceptibility to hypocapnic central apnea due to decreased plant gain. Acetazolamide may attenuate central sleep apnea and improve nocturnal oxygen saturation, but its clinical utility requires further investigation in a larger sample of patients.NEW & NOTEWORTHY Tetraplegia is a risk factor for central sleep-disordered breathing (SDB) and is associated with narrow CO₂ reserve (a marker of susceptibility to central apnea). Treatment with high-dose acetazolamide for 3 days decreased susceptibility to hypocapnic central apnea and reduced the frequency of central respiratory events during sleep. Acetazolamide may play a therapeutic role in alleviating central SDB in patients with cervical spinal cord injury, but larger clinical trials are needed.

A Provider's Guide to Vascular Disease, Dyslipidemia, and Glycemic Dysregulation in Chronic Spinal Cord Injury

Individuals with chronic spinal cord injury (SCI) are predisposed to accelerated atherogenesis, dyslipidemia, and glycemic dysregulation, although not enough is known about the etiologies or clinical consequences of these secondary effects of paralysis. While guidelines for the detection and treatment of cardiometabolic disease in SCI have recently been published, there has been a historical paucity of data-driven approaches to these conditions. This article will describe what is and not known about the cardiovascular disease and glycemic dysregulation that frequently attend SCI. It will conclude with a review of both guideline-driven and informal recommendations addressing the clinical care of people living with SCI.

Posteroanterior cervical transcutaneous spinal stimulation targets ventral and dorsal nerve roots

OBJECTIVE

We aim to non-invasively facilitate activation of spared neural circuits after cervical spinal cord injury (SCI) and amyotrophic lateral sclerosis (ALS). We developed and tested a novel configuration for cervical transcutaneous spinal stimulation (cTSS).

METHODS

cTSS was delivered via electrodes placed over the midline at ~T2-T4 levels posteriorly and ~C4-C5 levels anteriorly. Electromyographic responses were measured in arm and hand muscles across a range of stimulus intensities. Double-pulse experiments were performed to assess homosynaptic post-activation depression (PAD). Safety was closely monitored.

RESULTS

More than 170 cTSS sessions were conducted without major safety or tolerability issues. A cathode-posterior, 2 ms biphasic waveform provided optimal stimulation characteristics. Bilateral upper extremity muscle responses were easily obtained in subjects with SCI and ALS. Resting motor threshold at the abductor pollicis brevis muscle ranged from 5.5 to 51.0 mA. As stimulus intensity increased, response latencies to all muscles decreased. PAD was incomplete at lower stimulus intensities, and decreased at higher stimulus intensities.

CONCLUSIONS

Posteroanterior cTSS has the capability to target motor neurons both trans-synaptically via large-diameter afferents and non-synaptically via efferent motor axons.

SIGNIFICANCE

Posteroanterior cTSS is well tolerated and easily activates upper extremity muscles in individuals with SCI and ALS.

Critical Care Management of Acute Spinal Cord Injury-Part II: Intensive Care to Rehabilitation

Spinal cord injury is devastating to those affected due to the loss of motor and sensory function, and, in some cases, cardiovascular collapse, ventilatory failure, and bowel and bladder dysfunction. Primary trauma to the spinal cord is exacerbated by secondary insult from the inflammatory response to injury. Specialized intensive care of patients with acute spinal cord injury involves the management of multiple systems and incorporates evidence-based practices to reduce secondary injury to the spinal cord. Patients greatly benefit from early multidisciplinary rehabilitation for neurologic and functional recovery. Treatment of acute spinal cord injury may soon incorporate novel molecular agents currently undergoing clinical investigation to assist in neuroprotection and neuroregeneration.

Early Management of Acute Spinal Cord Injury-Part I: Initial Injury to Surgery

Acute spinal cord injury is a devastating event associated with substantial morbidity worldwide. The pathophysiology of spinal cord injury involves the initial mechanical trauma and the subsequent inflammatory response, which may worsen the severity of neurologic dysfunction. Interventions have been studied to reduce the extent of primary injury to the spinal cord through preventive measures and to mitigate secondary insult through early specialized care. Management, therefore, is multifold, interdisciplinary, and begins immediately at the time of injury. It includes the trauma triage, acute management of the circulatory and respiratory systems, and definitive treatment, mainly with surgical decompression and stabilization.