Cardiovascular consequences of loss of supraspinal control of the sympathetic nervous system after spinal cord injury

Impact of Bladder Management Strategies on Autonomic Dysreflexia Severity in People With Spinal Cord Injuries

PURPOSE

We investigated whether severity of autonomic dysreflexia (AD) was associated with more patient-reported bladder and bowel symptoms and compared AD severity by bladder management strategy in people with spinal cord injury (SCI).

METHODS

The Neurogenic Bladder Research Group SCI Registry is a prospective study which evaluated quality of life after SCI. Bladder and bowel symptoms were assessed through Neurogenic Bladder Symptom Score and Neurogenic Bowel Dysfunction score, respectively. AD severity was assessed with the Autonomic Dysreflexia Following Spinal Cord Injury (ADFSCI) instrument. Bladder management was classified as volitional voiding, clean intermittent catheterization (CIC), indwelling catheter (IDC), and surgery (augmentation and diversion).

RESULTS

AD scores were identified for 1473 people. The mean age was 45. Bladder management was CIC in 754 (51%), IDC in 271 (18%), surgery in 195 (13%) and voiding in 259 (18%). On univariate analysis, higher ADFSCI scores occurred with complete injuries (3.1 vs 3.4, p = 0.03), cervical/thoracic injuries (3.8 vs 1.5, p < 0.0001), and chronic pain (3.9 vs 2.9, p = 0.0004). IDC (5.2) and surgery (4.5) had higher ADFSCI scores than CIC (3.0) and volitional voiding (2.8) (p < 0.0001). Sub-analysis showed bladder augmentation had significantly higher ADSCI scores than diversion (4.7 vs 3.7, p = 0.03). On multivariate analysis, level of injury, bladder management, and bowel and bladder symptoms remained associated with worse AD.

CONCLUSION

Level of injury, age, worse bowel and bladder symptoms and bladder management type were associated with higher AD scores. Bladder management with surgery, particularly bladder augment, and IDC had associated greater AD symptoms compared to CIC or voiding.

TRIAL REGISTRATION

clinicaltrials.gov NTC06216081 and HSRP20153564, U.S. National Library of Medicine, wwwcf.nlm.nih.gov.

Acute intermittent hypoxia elicits sympathetic neuroplasticity independent of peripheral chemoreflex activation and spinal cord tissue hypoxia in a rodent model of high-thoracic spinal cord injury

The loss of medullary control of spinal circuits controlling the heart and blood vessels is a unifying mechanism linking both hemodynamic instability and the risk for cardiovascular diseases (CVD) following spinal cord injury (SCI). As such, new avenues to regulate sympathetic activity are essential to mitigate CVD in this population. Acute intermittent hypoxia (AIH) induces a type of neuroplasticity known as long-term facilitation (LTF), a persistent increase in nerve activity post-AIH in spinal motor circuits. Whether LTF occurs within the sympathetic circuit following SCI is largely unknown. We aimed to test whether AIH elicits sympathetic LTF (i.e., sLTF) and attenuates hypoactivity in sub-lesional splanchnic sympathetic circuits in a male rat model of SCI. In 3 experimental series, we tested whether 1) high-thoracic contusion SCI induces hypoactivity in splanchnic sympathetic nerve activity, 2) AIH elicits sLTF following SCI, and 3) sLTF requires carotid chemoreflex activation or spinal cord tissue hypoxia. Our results indicate that a single-session of AIH therapy (10 × 1 min of FiO2 = 0.1, interspersed with 2 min of FiO2 = 1.0) delivered at 2 weeks following SCI attenuates SCI-induced sympathetic hypoactivity by eliciting sLTF 90 min post-treatment that is independent of peripheral chemoreflex activation and/or spinal cord hypoxia. These findings advance our mechanistic understanding of AIH in the field and yield new insights into factors underpinning AIH-induced sLTF following SCI in a rat model. Our findings also set the stage for the chronic application of AIH to alleviate secondary complications resulting from sympathetic hypoactivity following SCI.

Measured and Predicted Resting Metabolic Rate of Dutch and Norwegian Paralympic Athletes

BACKGROUND

Although resting metabolic rate (RMR) is crucial for understanding athletes' energy requirements, limited information is available on the RMR of Paralympic athletes.

OBJECTIVE

The aim of this study was to determine RMR and its predictors in a diverse cohort of Paralympic athletes and evaluate the agreement between measured and predicted RMR from both newly developed and pre-existing equations.

DESIGN

This cross-sectional study, conducted between September 2020 and September 2022 in the Netherlands and Norway, assessed RMR in Paralympic athletes by means of ventilated hood indirect calorimetry and body composition by means of dual-energy x-ray absorptiometry.

PARTICIPANTS

Sixty-seven Paralympic athletes (male: n = 37; female: n = 30) competing in various sports, with a spinal cord disorder (n = 22), neurologic condition (n = 8), limb deficiency (n = 18), visual or hearing impairment (n = 7), or other disability (n = 12) participated.

MAIN OUTCOME MEASURES

RMR, fat-free mass (FFM), body mass, and triiodothyronine (T3) concentrations were assessed.

STATISTICAL ANALYSES

Multiple regression analyses were conducted with height, FFM, body mass, sex, T3 concentration, and disabilities as potential predictors of RMR. Differences between measured and predicted RMRs were analyzed for individual accuracy, root mean square error, and intraclass correlation.

RESULTS

Mean ± SD RMR was 1386 ± 258 kcal/d for females and 1686 ± 302 kcal/d for males. Regression analysis identified FFM, T3 concentrations, and the presence of a spinal cord disorder, as the main predictors of RMR (adjusted R2 = 0.71; F = 50.3; P < .001). The novel prediction equations based on these data, as well as pre-existing equations of Chun and colleagues and Nightingale and Gorgey performed well on accuracy (>60% of participants within 10% of measured RMR), had good reliability (intraclass correlation >0.78), and low root mean square error (≤141 kcal).

CONCLUSIONS

FFM, total T3 concentrations, and presence of spinal cord disorder are the main predictors of RMR in Paralympic athletes. Both the current study's prediction equations and those from Chun and colleagues and Nightingale and Gorgey align well with measured RMR, offering accurate prediction equations for the RMR of Paralympic athletes.

Neuroprotective agents ineffective in mitigating autonomic dysreflexia following experimental spinal cord injury

BACKGROUND AND OBJECTIVES

Loss of supraspinal cardiovascular control and secondary damage following spinal cord injury (SCI) lead to cardiovascular dysfunction, where autonomic dysreflexia (AD), triggered by stimuli below the injury, can cause uncontrolled blood pressure (BP) surges, posing severe health risks such as stroke and seizures. While anti-inflammatory neuroprotective agents have been studied for motor recovery, their impact on cardiovascular function remains under investigated. The objective was to assess the efficacy of four clinically approved neuroprotective agents in promoting cardiovascular recovery following SCI.

METHODS

Male Wistar rats received contusion at the third thoracic spinal segment (T3). Fluoxetine, Glyburide, Valproic acid, and Indomethacin were first administered at 1 h or 6 h post-SCI, and every 12 h for two weeks thereafter. Four weeks following SCI, hemodynamics were measured at rest and during colorectal distension. Locomotor function was assessed prior to SCI and weekly for four weeks after SCI, using the Basso-Beattie-Bresnahan (BBB) locomotor scale. Quantitative comparisons of lesion area were performed.

RESULTS

Contrary to the published literature, Indomethacin and Valproic acid resulted in high morbidity and mortality rates 60 % and 40 % respectively) within 2-3 days of administration. Fluoxetine, and Glyburide were well-tolerated. There were no differences in change in systolic BP with colorectal distension compared to control i.e., all experimental groups experienced severe episodes of AD [F(6, 67) = 0.94, p = 0.47]. There was no significant difference in BBB scores in any experimental group compared to control [F(18, 252) = 0.3, p = 0.99]. No between-group differences were observed in tissue sparing at the lesion epicentre [F(6, 422) = 6.98, p = 0.29].

DISCUSSION

Despite promising beneficial effect reported in previous studies, none of the drugs demonstrated improvement in cardiovascular or motor function. Indomethacin and Valproic acid exhibited unexpected high mortality at doses deemed safe in the literature. This emphasizes the necessity for reproducibility studies in pre-clinical research and underscores the importance of publishing null findings to guide future investigations.

BP-Net: Monitoring "Changes" in Blood Pressure Using PPG With Self-Contrastive Masking

Estimating blood pressure (BP) values from physiological signals (e.g., photoplethysmogram (PPG)) using deep learning models has recently received increased attention, yet challenges remain in terms of models' generalizability. Here, we propose taking a new approach by framing the problem as tracking the "changes" in BP over an interval, rather than directly estimating its value. Indeed, continuous monitoring of acute changes in BP holds promising implications for clinical applications (e.g., hypertensive emergencies). As a solution, we first present a self-contrastive masking (SCM) model, designed to perform pair-wise temporal comparisons within the input signal. We then leverage the proposed SCM model to introduce BP-Net, a model trained to detect elevations/drops greater than a given threshold in the systolic blood pressure (SBP) over an interval, from PPG. Using data from PulseDB, 1) we evaluate the performance of BP-Net on previously unseen subjects, 2) we test BP-Net's ability to generalize across domains by training and testing on different datasets, and 3) we compare the performance of BP-Net with existing PPG-based BP-estimation models in detecting over-threshold SBP changes. Formulating the problem as a binary classification task (i.e., over-threshold SBP elevation/drop or not), BP-Net achieves 75.97%/73.19% accuracy on data from subjects unseen during training. Additionally, the proposed BP-Net outperforms SBP estimations derived from existing PPG-based BP-estimation methods. Overall, by shifting the focus from estimating the value of SBP to detecting over-threshold "changes" in SBP, this work introduces a new potential for using PPG in clinical BP monitoring, and takes a step forward in addressing the challenges related to the generalizability of PPG-based BP-estimation models to unseen subjects.

Outcomes of odontoid fractures with associated cardiac arrest: retrospective bi-center case series and systematic literature review

BACKGROUND

Odontoid fractures from high-energy trauma are associated with significant morbidity and mortality, including spinal cord injury, neurological damage, and cardiac arrest. The literature on odontoid fractures leading to cardiac arrest is limited to isolated case reports. This study aims to conduct a retrospective bi-center case series and a systematic review of existing literature.

METHODS

We conducted a retrospective bi-center case series on patients with odontoid fractures from high-energy trauma who experienced post-traumatic cardiac arrest with return of spontaneous circulation (ROSC) after CPR from two Level 1 Trauma Centers (2008-2024). The primary outcome was in-hospital mortality; secondary outcomes included epidemiological, pre-hospital, and in-hospital data, and CT and MRI findings. Additionally, we performed a systematic literature review to summarize existing evidence.

RESULTS

The study included 25 patients (mean age 71.1 ± 12.3 years, SD; 8 females). The mortality rate was 92% (23 patients). Median downtime before CPR was 5.0 min (IQR: 7.0), with CPR lasting 17.0 min (IQR: 13.0), primarily initiated by professionals (60%). All patients were quadriplegic. Type II Anderson d'Alonzo fractures were most common (88%), with all patients showing myelopathy on MRI. Only three patients (12%) underwent surgical intervention due to favorable prognosis. Our literature review identified seven case reports, with two patients surviving and one achieving full recovery.

CONCLUSIONS

In this case series, patients experiencing cardiac arrest after odontoid fractures exhibited high mortality rates despite comprehensive management at Level 1 trauma centers. Survivors faced significant and enduring morbidity.

A Study of Hypertension and Fitness of Individuals with Spinal Cord Injury: A Cross-Sectional Study

Background/Objectives: Individuals with spinal cord injuries have a higher incidence of chronic conditions such as hypertension and cardiovascular diseases due to a sedentary lifestyle and low levels of physical activity caused by their disability. Additionally, their physical fitness levels are lower compared to those without disabilities. This cross-sectional study aimed to investigate the relationship between hypertension and the fitness of individuals with spinal cord injuries in South Korea while considering differences across sexes and spinal cord injury levels. Methods: This study used data for 835 individuals with spinal cord injuries aged 20-64 years who visited the Korea Paralympic Committee fitness standard test centers from 2018 to 2022, obtained from the Korea Culture Information Sports Association's big data market. The data were analyzed using a series of t-tests, a one-way analysis of variance, a logistic regression analysis, and the four-quartile method. Results: The prevalence of hypertension was 24.4%, and it was different according to the spinal cord injury impairment level. A lower grip strength, a lower arm curl, and a higher body mass index were associated with increased blood pressure. Conclusions: Therefore, a high level of physical strength in people with spinal cord injuries is thought to contribute to lowering blood pressure.

Autonomic dysreflexia in patients with cancer and spinal cord injury: a case series

INTRODUCTION

Autonomic dysreflexia (AD) is a potentially life-threatening syndrome that can occur in patients with traumatic injury to the spinal cord; however, it has not been well described in patients with non-traumatic spinal cord injury (SCI) from cancer and its treatments.

CASE PRESENTATION

We report four cases of autonomic dysreflexia secondary to primary spinal cord tumors and metastatic disease to the spine, and as sequela to cancer treatment. The clinical characteristics, diagnostic considerations, and therapeutic strategies used to mitigate the symptoms are discussed.

DISCUSSION

The case series shows that AD is a rare but important condition to consider among patients with cancer-related SCI. There is a need for close monitoring and early identification of this syndrome in this population. Therapeutic strategies are available to mitigate these symptoms and risks of complications.

Elucidating mechanisms of attenuated skin vasodilation during passive heat stress in persons with spinal cord injury

OBJECTIVE

Persons with spinal cord injury (SCI) are unable to efficiently dissipate heat via thermoregulatory vasodilation as efficiently as able-bodied persons during whole body passive heat stress (PHS). Skin blood flow (SkBF) is controlled by dual sympathetic vasomotor systems: noradrenergic vasoconstrictor (VC) nerves and cholinergic vasodilator (VD) nerves. Thus, impaired vasodilation could result from inappropriate increases in noradrenergic VC tone that compete with cholinergic vasodilation or diminished cholinergic tone. To address this issue, we used bretylium (BR) which selectively blocks neural release of norepinephrine, thereby reducing noradrenergic VC tone. If impaired vasodilation during PHS is due to inappropriate increase in VC tone, BR treatment will improve SkBF responses during PHS.

DESIGN

Prospective interventional trial.

SETTING

laboratory.

PARTICIPANTS

22 veterans with SCI.

INTERVENTIONS

Skin surface areas with previously defined intact vs. impaired thermoregulatory vasodilation were treated with BR iontophoresis with a nearby untreated site serving as control/CON. Participants underwent PHS until core temperature rose 1°C.

OUTCOME MEASURES

Laser doppler flowmeters measured SkBF over BR and CON sites in areas with impaired and intact thermoregulatory vasodilation. Cutaneous vascular conductance (CVC) was calculated for all sites. Peak-PHS CVC was normalized to baseline (BL): (CVC peak-PHS/CVC BL) to quantify SkBF change.

RESULTS

CVC rise in BR sites was significantly less than CON sites in areas with intact (P = 0.03) and impaired (P = 0.04) thermoregulatory vasodilation.

CONCLUSION

Cutaneous blockade of neural release of noradrenergic neurotransmitters affecting vasoconstriction did not enhance thermoregulatory vasodilation during PHS in persons with SCI; rather BR attenuated the response. Cutaneous blockade of neural release of noradrenergic neurotransmitters affecting vasoconstriction did not restore cutaneous active vasodilation during PHS in persons with SCI.

Comparison of autonomic nervous system dysfunction, arterial stiffness, and heart rate recovery according to spinal cord injury level

OBJECTIVE

To investigate the differences in autonomic nervous system (ANS) dysfunction, arterial stiffness, and the degree of delay in post-exercise heart rate recovery (HRR) according to the level of spinal cord injury (SCI), and propose preventive measures against cardiovascular diseases after SCI.

METHODS

This retrospective study included 51 patients with SCI. Based on the neurological level of injury (NLI), patients were divided into two groups: Group A (NLI at and above T6) and Group B (NLI below T6). To assess ANS dysfunction, the head-up tilt test and 24-hour ambulatory blood pressure monitoring were conducted. Arterial stiffness was measured using the pulse wave velocity test. The exercise tolerance test was conducted to measure post-exercise HRR.

RESULTS

Group A had significantly higher values in the head-up tilt test and 24-hour ambulatory blood pressure monitoring. In the pulse wave velocity test, both sides (left and right) had significantly higher values in Group B. One minute after the exercise tolerance test, Group A had significantly slower HRR (18.8 ± 11.1 beats/minute) than Group B.

CONCLUSION

Understanding the impact of ANS dysfunction and arterial stiffness on HRR in SCI according to NLI may provide insights for clinical management and preventative strategies for cardiovascular diseases.

Preliminary feasibility and acute physiological effects of a single session of upper limb vibration training for persons with spinal cord injury

CONTEXT

Strong upper limb musculature is essential for persons with spinal cord injury (SCI) to operate a manual wheelchair and live independently. Targeted upper limb vibration may be a viable exercise modality to build muscle efficiently while eliminating some of the barriers associated with exercise for persons with SCI.

OBJECTIVE

The purpose of this study was to assess preliminary feasibility of completing a single exercise session of upper limb vibration and compare the acute physiological effects to a single session of standard dumbbell resistance exercise.

METHODS

Individuals with SCI performed seven upper limb exercises (1) isometrically using a vibrating dumbbell at 30 Hz for 60 s (n = 22) and (2) using a standard isotonic resistance protocol (n = 15).

RESULTS

Nineteen (86.4%) of 22 participants were able to perform all vibration exercises at 30 Hz but hold time success rates varied from 33% (side flies and front raises) to 95% (internal rotation). No significant differences were found between vibration exercise and standard resistance protocol for blood lactate, power output, and heart rate (P > 0.05). Perceptions of the training were positive, with most participants (>70%) expressing interest to train with vibration in the future.

CONCLUSIONS

Vibration training was not feasible for all participants, suggesting an individualized approach to starting weight and progression may be necessary. Similar acute physiological changes were seen between vibration exercise and standard resistance protocol, suggesting they could have similar benefits. Additional research is needed to determine if vibration exercise is feasible and beneficial to incorporate into a long-term training program.

Autonomic impairment is not explained by neurological level of injury or motor-sensory completeness

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

Determine how well common clinical assessments of level and completeness of injury are correlated with symptoms of autonomic blood pressure instability and secondary medical complications after spinal cord injury (SCI).

SETTING

Academic medical center, United States.

METHODS

Eighty-two individuals with (n = 48) and without (n = 34) SCI had symptoms of autonomic blood pressure instability quantified with the Autonomic Dysfunction Following SCI (ADFSCI) survey. Health histories quantified the secondary medical complications through number of urinary tract infections and hospitalizations in the past year, time to complete bowel program, and lifetime pressure injuries. Regression models were completed to identify strengths of associated correlations.

RESULTS

ADFSCI scores were significantly higher in individuals with SCI than controls. Neurological level of injury and ASIA impairment scale were both minimally correlated to symptoms of autonomic blood pressure instability, accounting for only 11.5% of variability in regression models. Secondary medical complications had similar, minimal correlations to level and motor/sensory completeness of SCI (R2 = 0.07 and R2 = 0.03 respectively). Contrasting this, symptoms of blood pressure instability on ADFSCI far outperformed the common clinical motor/sensory bedside exam, with moderately strong correlations to the ranked number of secondary medical complications after SCI (R2 = 0.31).

CONCLUSION

Neurological level of injury and motor/sensory completeness provided limited insights into which individuals with SCI would have blood pressure instability or secondary medical complications. Interestingly, symptoms of blood pressure instability outperform the clinical motor/sensory bedside exam, with higher correlations to secondary medical complications after SCI.

Successful recovery from cardiac arrest due to atlantoaxial subluxation in Down syndrome: a case report

INTRODUCTION

Down syndrome is the most common chromosomal abnormality associated with intellectual impairments. Unexpected deaths are common with this disease. There are certain difficulties in clarifying the cause of death because the manifestations may be quite diverse and involve many organ systems. Atlantoaxial subluxation is a dangerous complication of Down syndrome, as it may lead to cervical cord-medullary compression.

CASE PRESENTATION

Herein, we present a case of Down syndrome in a patient who completely recovered from cardiac arrest due to atlantoaxial subluxation. The neck was immobilized during post-cardiac arrest care, and the patient underwent surgery after 14 days. The patient could walk independently and was discharged 3 months later. At the last follow-up 5 years after surgery, the patient's general condition was good.

DISCUSSION

Physicians should be aware that atlantoaxial instability can cause cardiac arrest in patients with genetic syndromes.

Intravesical injection of botulinum toxin type a may be an effective treatment option for autonomic dysreflexia in patients with high-level spinal cord injury

OBJECTIVE

To evaluate the efficacy of intravesical injection of botulinum toxin type A (BTX-A) for neurogenic detrusor overactivity (DO) in reducing the frequency and severity of autonomic dysreflexia (AD).

DESIGN

A cross-sectional nonrandomized trial with before (baseline) and after (follow-up) assessments.

SETTING

A single spinal cord injury (SCI) rehabilitation center in China.

PARTICIPANTS

Twenty-five patients with SCI at or above T6 and a history of AD who underwent urodynamic studies (UDS) before and 3 months after BTX-A injection.

INTERVENTIONS

Received bladder injection treatment wtih 200 U BTX-A.

OUTCOME MEASURES

The maximum detrusor pressure(Pdetmax) and voume at first DO(VFIDC), baseline and overall maximum systolic blood pressure (SBP) during UDS, and scores of Incontinence Specific Quality of Life Instrument (IQoL) were recorded before and 3 months after the injection. The change in SBP (ΔSBP) from baseline to maximum SBP during UDS was calculated to assess the severity. The frequency of AD was recorded using ambulatory blood pressure monitoring during a 24 h period before and 3 months after the injection.

RESULTS

BTX-A injection decreased the Pdetmax and increased the VFIDC and mean urine volume per catheterization increased. The maximum SBP and the ΔSBP during UDS decreased significantly decreased after the injection (151.44 ± 13.92 vs 133.32 ± 9.20 mmHg and 49.44 ± 12.81 vs 33.08 ± 9.11 mmHg respectively, P < 0.05). The frequency of bladder-related ADs (i.e. performed a clean intermittent catheterization or leakage) during a 24-h period significantly decreased from 11.04 ± 1.81-7.88 ± 2.15 (P < 0.001).

CONCLUSIONS

BTX-A decreases the severity of SBP increase and the number of AD episodes 3 months after intravesical injection.

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

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

Autonomic Cardiovascular Control, Psychological Well-Being, and Cognitive Performance in People With Spinal Cord Injury

PURPOSE

To examine associations between parameters of psychological well-being, injury characteristics, cardiovascular autonomic nervous system (ANS) control, and cognitive performance in persons with spinal cord injury (SCI) compared with age-matched uninjured controls. This is an observational, cross-sectional study including a total of 94 participants (52 with SCI and 42 uninjured controls: UIC). Cardiovascular ANS responses were continuously monitored at rest and during administration of the Paced Auditory Serial Addition Test (PASAT). Self-report scores on the SCI-Quality of Life questionnaires are reported for depression, anxiety, fatigue, resilience, and positive affect. Participants with SCI performed significantly more poorly on the PASAT compared with the uninjured controls. Although not statistically significant, participants with SCI tended to report more psychological distress and less well-being than the uninjured controls. In addition, when compared with uninjured controls, the cardiovascular ANS responses to testing were significantly altered in participants with SCI; however, these responses to testing did not predict PASAT performance. Self-reported levels of anxiety were significantly related to PASAT score in the SCI group, but there was no significant relationship between PASAT and the other indices of SCI-Quality of Life. Future investigations should more closely examine the relationship among cardiovascular ANS impairments, psychological disorders, and cognitive dysfunction to better elucidate the underpinnings of these deficits and to guide interventions aimed at improving physiological, psychological, and cognitive health after SCI. Tetraplegia, paraplegia, blood pressure variability, cognitive, mood.

Functional and structural impairments of the pulmonary system in middle-aged people with cervical and upper thoracic spinal cord injuries

OBJECTIVES

To describe functional and structural impairments of the pulmonary system in middle-aged people with cervical and upper thoracic spinal cord injuries (SCI), and compare findings to the general population. To determine if the neurological level of injury (NLI) is related to functional and structural impairments, and if age is related to structural impairments.

DESIGN

Cross-sectional study with matched controls. Data from the Swedish SPinal Cord Injury Study on Cardiopulmonary and Autonomic Impairment (SPICA). Matched control data were obtained from the Swedish CArdioPulmonary bioImage Study (SCAPIS).

SETTING

Outpatient SCI unit in southern Sweden.

PARTICIPANTS

25 people (20% women, mean age 58 years, mean time since injury 28 years, NLIs C2-T6, American Spinal Injury Association Impairment Scale A-C).

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

Lung function was assessed with spirometry, diffusing capacity and impulse oscillometry. Structural assessments were performed with computed tomography.

RESULTS

Pulmonary function was generally worse compared to the controls. Structural impairments were common (75% of the participants and 65% of the controls; P = 0.36, NS). NLI was significantly related to some of the functional and structural impairments.

CONCLUSIONS

Middle-aged people with long-term cervical and upper thoracic SCI can have substantial pulmonary functional impairments, whereas structural impairments do not differ considerably from the general population. Further larger and longitudinal studies should focus on the clinical impact of these impairments over time.

Effect of GR205171 on autonomic dysreflexia induced by colorectal distension in spinal cord injured rats

STUDY DESIGN

Preclinical pharmacology.

OBJECTIVES

To determine whether blocking substance P signaling attenuates the hypertension and bradycardia evoked by colorectal distension (CRD) in spinal cord injured (SCI) rats.

SETTING

University laboratory in Pennsylvania, U.S.A.

METHODS

Tachykinin NK1 receptor antagonists were administered 30 min prior to CRD three weeks after complete spinal cord transection at the 4th thoracic (T4) level. The dose range, route of administration, and pretreatment time was based on published data demonstrating occupancy of brain NK1 receptors in rodents.

RESULTS

Subcutaneous (SC) administration of 10-30 mg/kg GR205171 ((2S,3S)-N-[[2-methoxy-5-[5-(trifluoromethyl)tetrazol-1-yl]phenyl]methyl]-2-phenylpiperidin-3-amine dihydrochloride) reduced CRD-induced hypertension and bradycardia by 55 and 49%, respectively, compared with pretreatment values. There was no effect of GR205171 on resting blood pressure or heart rate. In contrast, the same dose range of CP-99,994 ((2S,3S)-N-[(2-methoxyphenyl)methyl]-2-phenyl-3-piperidinamine dihydrochloride) had no effect on CRD-induced cardiovascular responses.

CONCLUSIONS

The effective dose range of GR205171 to alleviate autonomic dysreflexia is consistent with the blockade of NK1 receptors on pelvic sensory afferents in the lumbosacral spinal cord, which may in turn prevent the over-excitation of sympathetic preganglionic neurons (SPNs) that regulate blood pressure and heart rate. The findings provide preclinical support for the utility of NK1 receptor antagonists to treat autonomic dysreflexia in people with SCI. The difference in the effects of the two NK1 receptor antagonists may reflect the ~200-fold lower affinity of CP-99,994 than GR205171 for the rat NK1 receptor.

Impaired Glucose Tolerance and Visceral Adipose Tissue Thickness among Lean and Non-Lean People with and without Spinal Cord Injury

After spinal cord injury (SCI), multiple adaptations occur that influence metabolic health and life quality. Prolonged sitting and inactivity predispose people with SCI to body composition changes, such as increased visceral adipose tissue (VAT) thickness, which is often associated with impaired glucose tolerance. Our goal is to understand whether VAT is an index of leanness, and, secondarily, whether mobility methods influence glucose tolerance for people living with SCI. A total of 15 people with SCI and 20 people without SCI had fasting oral glucose tolerance tests (OGTT) and VAT thickness (leanness) measured during a single session. Glucose was 51% and 67% greater for individuals with SCI relative to those without SCI after 60 and 120 min of an OGTT (p < 0.001). Glucose area under the curve (AUC) was 28%, 34%, and 60% higher for non-lean people with SCI than lean people with SCI and non-lean and lean people without SCI, respectively (p = 0.05, p = 0.009, p < 0.001). VAT was associated with glucose AUC (R2 = 0.23, p = 0.004). Taken together, these findings suggest that leanness, as estimated from VAT, may be an important consideration when developing rehabilitation programs to influence metabolism among people with SCI.

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

Importance

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

Objective

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

Design

Single-blinded, randomized crossover trial with matched cohorts.

Setting

Academic autonomic physiology laboratory.

Participants

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

Interventions

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

Main Outcomes and Measures

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

Results

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

Conclusions and Relevance

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

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

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

Muscarinic cholinergic modulation of cardiovascular variables in spinal cord injured rats

Spinal cord injury (SCI) leads not only to major impairments in sensorimotor control but also to dramatic dysregulation of autonomic functions including major cardiovascular disturbances. Consequently, individuals with SCI endure daily episodic hypo/hypertension and are at increased risk for cardiovascular disease. Several studies have suggested that an intrinsic spinal coupling mechanism between motor and sympathetic neuronal networks exist and that propriospinal cholinergic neurons may be responsible for a synchronized activation of both somatic and sympathetic outputs. We therefore investigated in the present study, the effect of cholinergic muscarinic agonists on cardiovascular parameters in freely moving adult rats after SCI. Female Sprague-Dawley rats were implanted with radiotelemetry sensors for long-term in vivo monitoring of blood pressure (BP). From BP signal, we calculated heart rate (HR) and respiratory frequency. We first characterized the physiological changes occurring after a SCI performed at the T3-T4 level in our experimental model system. We then investigated the effects on BP, HR and respiration, of the muscarinic agonist oxotremorine using one variant that crossed the blood brain barrier (Oxo-S) and one that does not (Oxo-M) in both Pre- and Post-SCI animals. After SCI, both HR and respiratory frequency increased. BP values exhibited an immediate profound drop before progressively increasing over the three-week post-lesion period but remained below control values. A spectral analysis of BP signal revealed the disappearance of the low frequency component of BP (0.3-0.6 Hz) referred to as Mayer waves after SCI. In Post-SCI animals, central effects mediated by Oxo-S led to an increase in HR and MAP, a slowdown in respiratory frequency and to an increased power in the 0.3-0.6 Hz frequency band. This study unravels some of the mechanisms by which muscarinic activation of spinal neurons could contribute to partial restoration of BP after SCI.

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.

Primary Care in the Spinal Cord Injury Population: Things to Consider in the Ongoing Discussion

Purpose of Review

Spinal cord injury (SCI) creates unique needs that if not recognized and addressed timely can have detrimental effects on the health and quality of life (QOL) of people living with a SCI. Primary preventive health care is shown to decrease morbidity and mortality, yet the SCI population reportedly faces challenges getting access to this care. This area in SCI health care is still largely understudied with no consensus on the ideal way or which health care provider is best to provide primary care for this population.

Findings

Preventive care is generally provided by general primary care providers, but not all primary care providers are trained in recognizing and addressing spinal cord injury-specific needs. SCI providers generally are not trained in addressing all aspects of preventive care. Knowing the recommended preventive care screenings, recognizing and managing specific conditions seen after a SCI, and seamless coordination of care between general practitioners and SCI specialists are some of the interventions to help prevent health complications, decrease morbidity and mortality, improve health outcomes, and promote QOL in this patient population.

Summary

Prioritized focus on preventive care is necessary for a positive impact on the overall health and QOL in this population. Addressing the knowledge gap reported by primary care providers and SCI providers may help increase the probability of SCI patients getting their preventive and specialty care needs addressed. We present a "cheat sheet" of recommendations for the preventive care evaluation of a person living with a SCI.

Porcine spinal cord injury model for translational research across multiple functional systems

Animal models are necessary to identify pathological changes and help assess therapeutic outcomes following spinal cord injury (SCI). Small animal models offer value in research in terms of their easily managed size, minimal maintenance requirements, lower cost, well-characterized genomes, and ability to power research studies. However, despite these benefits, small animal models have neurologic and anatomical differences that may influence translation of results to humans and thus limiting the success of their use in preclinical studies as a direct pipeline to clinical studies. Large animal models, offer an attractive intermediary translation model that may be more successful in translating to the clinic for SCI research. This is largely due to their greater neurologic and anatomical similarities to humans. The physical characteristics of pig spinal cord, gut microbiome, metabolism, proportions of white to grey matter, bowel anatomy and function, and urinary system are strikingly similar and provide great insight into human SCI conditions. In this review, we address the variety of existing porcine injury models and their translational relevance, benefits, and drawbacks in modeling human systems and functions for neurophysiology, cardiovascular, gastrointestinal and urodynamic functions.

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

INTRODUCTION

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

METHODS AND ANALYSIS

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

ETHICS AND DISSEMINATION

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

The role of arousal and motivation in emotional conflict resolution: Implications for spinal cord injury

Under many conditions, emotional information is processed with priority and it may lead to cognitive conflict when it competes with task-relevant information. Accordingly, being able to ignore emotional information relies on cognitive control. The present perspective offers an integrative account of the mechanism that may underlie emotional conflict resolution in tasks involving response activation. We point to the contribution of emotional arousal and primed approach or avoidance motivation in accounting for emotional conflict resolution. We discuss the role of arousal in individuals with impairments in visceral pathways to the brain due to spinal cord lesions, as it may offer important insights into the “typical” mechanisms of emotional conflict control. We argue that a better understanding of emotional conflict control could be critical for adaptive and flexible behavior and has potential implications for the selection of appropriate therapeutic interventions.

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.

Spinal Tumors: Diagnosis and Treatment

Tumors that present in or around the spine can be challenging to diagnose and treat. A proper workup involves a complete history and physical examination, appropriate staging studies, appropriate imaging of the entire spine, and a tissue biopsy. The biopsy defines the lesion and guides treatment, but in some rare instances, rapid neurological decline may lead to urgent or emergent surgery before it can be analyzed. "Enneking-appropriate" margins should remain the goal for primary tumors while adequate debulking/separation/stabilization are often the goals in metastatic disease. Primary tumors of the spine are rare and often complex tumors to operate on-achieving Enneking-appropriate margins provides the greatest chance of survival while decreasing the chance of local recurrence. Metastatic tumors of the spine are increasingly more common, and timing of surgery must be considered within the greater framework of the patient and the patient's disease, deficits, stability, and other treatments available. The specific tumor type will dictate what other multidisciplinary approaches are available, allowing for chemotherapy and radiation as needed.

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.

Inflammation and Oxidative Stress as Common Mechanisms of Pulmonary, Autonomic and Musculoskeletal Dysfunction after Spinal Cord Injury

Simple Summary

When a spinal cord injury occurs, the neurons that regulate our voluntary movements, those involved in environment and somatic perception and those that regulate vegetative functions are affected. Once neuronal damage is established, the cells of other tissues are also affected in their functions, altering the interaction between organs and altering the proper functioning of the organism. Multiple studies in animal models, as well as in humans, have recognized as factors involved in organ damage the imbalance between the formation of highly reactive molecules called pro-oxidants and defensive mechanisms called antioxidants. Closely associated with this phenomenon, the inflammatory response is also pathologically activated. In this narrative review, we have analyzed the information involving these pathological processes at the level of the lung, the autonomic nervous system and the skeletal musculature after spinal cord injury. Knowing the abnormal functioning mechanisms that occur after a spinal cord injury not only offers a better understanding of the organic events but also offers future possibilities for therapeutic interventions that may benefit the thousands of patients suffering this pathology.

Abstract

One of the etiopathogenic factors frequently associated with generalized organ damage after spinal cord injury corresponds to the imbalance of the redox state and inflammation, particularly of the respiratory, autonomic and musculoskeletal systems. Our goal in this review was to gain a better understanding of this phenomenon by reviewing both animal and human studies. At the respiratory level, the presence of tissue damage is notable in situations that require increased ventilation due to lower thoracic distensibility and alveolar inflammation caused by higher levels of leptin as a result of increased fatty tissue. Increased airway reactivity, due to loss of sympathetic innervation, and levels of nitric oxide in exhaled air that are similar to those seen in asthmatic patients have also been reported. In addition, the loss of autonomic control efficiency leads to an uncontrolled release of catecholamines and glucocorticoids that induce immunosuppression, as well as a predisposition to autoimmune reactions. Simultaneously, blood pressure regulation is altered with vascular damage and atherogenesis associated with oxidative damage. At the muscular level, chronically elevated levels of prooxidants and lipoperoxidation associated with myofibrillar atrophy are described, with no reduction or reversibility of this process through antioxidant supplementation.

Incidence of and factors associated with hyponatremia in traumatic cervical spinal cord injury patients

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate the incidence of and factors associated with hyponatremia among traumatic cervical spinal cord injury (SCI) patients.

SETTING

Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

METHODS

This retrospective study included traumatic cervical SCI patients that were admitted to the Siriraj Spinal Unit during January 2002 to May 2013. Patient demographic and clinical data were collected.

RESULTS

One hundred and twenty-three patients (98 males, 25 females) were enrolled. The mean age of patients was 47.2 ± 16.9 years (range: 11-84). There were 38 complete and 85 incomplete cord injuries. Seventy-six patients were treated surgically, and all others received conservative treatment. Hyponatremia developed in 54 patients (43.9%), and 74.1% of all cases of hyponatremia presented within 9 days after SCI. Hyponatremia occurred on the first day in 10 patients (18.5%), on the fifth day in 6 patients (11.1%), and on the eighth day in 5 patients (9.26%). Hyponatremia occurred in 6/10 patients (60.0%) with upper cervical spine injury (C1-2), and in 48/113 patients (42.5%) with lower cervical spine injury (C3-7) (odds ratio [OR]: 2.031, 95% confidence interval [CI]: 0.543-7.596; p = 0.292). The incidence of hyponatremia was 65.8% in complete SCI patients, and 34.1% in incomplete SCI patients. Logistic regression analysis revealed complete SCI to be the only factor significantly associated with hyponatremia (OR: 3.714, 95% CI: 1.658-8.317; p < 0.001).

CONCLUSION

Hyponatremia was found to be common in post-traumatic cervical SCI patients. Complete SCI was identified as the only factor significantly associated with hyponatremia in traumatic cervical SCI patients.

Accuracy of Heart Rate Measurement by the Fitbit Charge 2 During Wheelchair Activities in People With Spinal Cord Injury: Instrument Validation Study

Background

Heart rate (HR) is an important and commonly measured physiological parameter in wearables. HR is often measured at the wrist with the photoplethysmography (PPG) technique, which determines HR based on blood volume changes, and is therefore influenced by blood pressure. In individuals with spinal cord injury (SCI), blood pressure control is often altered and could therefore influence HR accuracy measured by the PPG technique.

Objective

The objective of this study is to investigate the HR accuracy measured with the PPG technique with a Fitbit Charge 2 (Fitbit Inc) in wheelchair users with SCI, how the activity intensity affects the HR accuracy, and whether this HR accuracy is affected by lesion level.

Methods

The HR of participants with (38/48, 79%) and without (10/48, 21%) SCI was measured during 11 wheelchair activities and a 30-minute strength exercise block. In addition, a 5-minute seated rest period was measured in people with SCI. HR was measured with a Fitbit Charge 2, which was compared with the HR measured by a Polar H7 HR monitor used as a reference device. Participants were grouped into 4 groups—the no SCI group and based on lesion level into the <T5 (midthoracic and lower) group, T5-T1 (high-thoracic) group, and >T1 (cervical) group. Mean absolute percentage error (MAPE) and concordance correlation coefficient were determined for each group for each activity type, that is, rest, wheelchair activities, and strength exercise.

Results

With an overall MAPE_{all lesions} of 12.99%, the accuracy fell below the standard acceptable MAPE of –10% to +10% with a moderate agreement (concordance correlation coefficient=0.577). The HR accuracy of Fitbit Charge 2 seems to be reduced in those with cervical lesion level in all activities (MAPE_{no SCI}=8.09%; MAPE_<T5=11.16%; MAPE_T1−T5=10.5%; and MAPE_>T1=20.43%). The accuracy of the Fitbit Charge 2 decreased with increasing intensity in all lesions (MAPE_rest=6.5%, MAPE_activity=12.97%, and MAPE_strength=14.2%).

Conclusions

HR measured with the PPG technique showed lower accuracy in people with SCI than in those without SCI. The accuracy was just above the acceptable level in people with paraplegia, whereas in people with tetraplegia, a worse accuracy was found. The accuracy seemed to worsen with increasing intensities. Therefore, high-intensity HR data, especially in people with cervical lesions, should be used with caution.

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.

Topological network analysis of patient similarity for precision management of acute blood pressure in spinal cord injury

Background:

Predicting neurological recovery after spinal cord injury (SCI) is challenging. Using topological data analysis, we have previously shown that mean arterial pressure (MAP) during SCI surgery predicts long-term functional recovery in rodent models, motivating the present multicenter study in patients.

Methods:

Intra-operative monitoring records and neurological outcome data were extracted (n = 118 patients). We built a similarity network of patients from a low-dimensional space embedded using a non-linear algorithm, Isomap, and ensured topological extraction using persistent homology metrics. Confirmatory analysis was conducted through regression methods.

Results:

Network analysis suggested that time outside of an optimum MAP range (hypotension or hypertension) during surgery was associated with lower likelihood of neurological recovery at hospital discharge. Logistic and LASSO (least absolute shrinkage and selection operator) regression confirmed these findings, revealing an optimal MAP range of 76–[104-117] mmHg associated with neurological recovery.

Conclusions:

We show that deviation from this optimal MAP range during SCI surgery predicts lower probability of neurological recovery and suggest new targets for therapeutic intervention.

Funding:

NIH/NINDS: R01NS088475 (ARF); R01NS122888 (ARF); UH3NS106899 (ARF); Department of Veterans Affairs: 1I01RX002245 (ARF), I01RX002787 (ARF); Wings for Life Foundation (ATE, ARF); Craig H. Neilsen Foundation (ARF); and DOD: SC150198 (MSB); SC190233 (MSB); DOE: DE-AC02-05CH11231 (DM).

Spinal cord injury is a devastating condition that involves damage to the nerve fibers connecting the brain with the spinal cord, often leading to permanent changes in strength, sensation and body functions, and in severe cases paralysis. Scientists around the world work hard to find ways to treat or even repair spinal cord injuries but few patients with complete immediate paralysis recover fully.

Immediate paralysis is caused by direct damage to neurons and their extension in the spinal cord. Previous research has shown that blood pressure regulation may be key in saving these damaged neurons, as spinal cord injuries can break the communication between nerves that is involved in controlling blood pressure. This can lead to a vicious cycle of dysregulation of blood pressure and limit the supply of blood and oxygen to the damaged spinal cord tissue, exacerbating the death of spinal neurons. Management of blood pressure is therefore a key target for spinal cord injury care, but so far, the precise thresholds to enable neurons to recover are poorly understood.

To find out more, Torres-Espin, Haefeli et al. used machine learning software to analyze previously recorded blood pressure and heart rate data obtained from 118 patients that underwent spinal cord surgery after acute spinal cord injury.

The analyses revealed that patients who suffered from either low or high blood pressure during surgery had poorer prospects of recovery. Statistical models confirming these findings showed that the optimal blood pressure range to ensure recovery lies between 76 to 104-117 mmHg. Any deviation from this narrow window would dramatically worsen the ability to recover.

These findings suggests that dysregulated blood pressure during surgery affects to odds of recovery in patients with a spinal cord injury. Torres-Espin, Haefeli et al. provide specific information that could improve current clinical practice in trauma centers. In the future, such machine learning tools and models could help develop real-time models that could predict the likelihood of a patient’s recovery following spinal cord injury and related neurological conditions.

The Impact of Sub-maximal Exercise on Neuropathic Pain, Inflammation, and Affect Among Adults With Spinal Cord Injury: A Pilot Study

Introduction: Persons with spinal cord injury (SCI) often report high levels of neuropathic pain (NP) and poor well-being, which may result from increased inflammation. This study examined the impact of sub-maximal aerobic exercise on NP, inflammation and psychological affect among adults with SCI. Methods: Eight active adults with tetraplegia (n-4, AIS A-C) and paraplegia (n = 4, AIS A-C) performed 30-min of arm-crank aerobic exercise and reported their ratings of perceived exertion (RPE) each minute. Measures of NP, affect, and inflammatory cytokines (IL-6, IL-10, IL-1ra, TNF-α) were taken pre-(T0), immediately post-(T1), and 90-min post-exercise (T2). Results: NP decreased between T0 and T1 for tetraplegics (-60%, d = 0.47; CI = -0.32, 2.02) and paraplegics (-16%, d = 0.15; CI = -0.30, 0.90). Correlations between change in cytokines and change in NP were medium-to large for tetraplegics (rs ranged from -0.820 to 0.965) and paraplegics (rs ranged from -0.598 to 0.833). However, the pattern of correlations between change in cytokines and affect was inconsistent between groups. Lower baseline levels of IL-1ra predicted greater decreases in NP immediately post-exercise (r = 0.83, p = 0.01). Conclusion: Sub-maximal exercise can positively impact NP for some persons with SCI. Further experimental research should identify the optimal exercise intensity to reduce NP for persons with SCI, in addition to understanding biomarkers which may predict changes in NP. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03955523.

Noninvasive spinal stimulation safely enables upright posture in children with spinal cord injury

In children with spinal cord injury (SCI), scoliosis due to trunk muscle paralysis frequently requires surgical treatment. Transcutaneous spinal stimulation enables trunk stability in adults with SCI and may pose a non-invasive preventative therapeutic alternative. This non-randomized, non-blinded pilot clinical trial (NCT03975634) determined the safety and efficacy of transcutaneous spinal stimulation to enable upright sitting posture in 8 children with trunk control impairment due to acquired SCI using within-subject repeated measures study design. Primary safety and efficacy outcomes (pain, hemodynamics stability, skin irritation, trunk kinematics) and secondary outcomes (center of pressure displacement, compliance rate) were assessed within the pre-specified endpoints. One participant did not complete the study due to pain with stimulation on the first day. One episode of autonomic dysreflexia during stimulation was recorded. Following hemodynamic normalization, the participant completed the study. Overall, spinal stimulation was well-tolerated and enabled upright sitting posture in 7 out of the 8 participants.

Scoliosis due to trunk muscle paralysis frequently requires surgical treatment in children with spinal cord injury. The authors demonstrate the safety and efficacy of transcutaneous spinal stimulation to enable upright sitting posture in 7/8 children with trunk control impairment in a within-subjects, repeated measures pilot clinical trial.

Spinal abscess in a patient with undiagnosed Gerbode defect: a case report

Background

Gerbode defect (GD) is a rare cardiac defect in which an abnormal communication occurs between the left ventricle and right atrium. The aetiology is usually congenital but acquired defects can occur.

Case summary

We report on a 47-year-old male with atrioventricular block prior to decompression of an epidural abscess extending from the skull base to the 7th thoracic vertebrae. Following positive blood cultures for Staphylococcus aureus, a transoesophageal echocardiogram performed revealed a small GD with associated endocarditis. In our case, the defect was small and there was no evidence of heart failure, there was little guidance or literature available on how to best manage our patient. A multidisciplinary decision was taken to treat the endocarditis medically and to not close the defect in the acute setting. He recovered well and did not suffer any further cardiac complications. A repeat transthoracic echocardiogram did not reveal any evidence of endocarditis.

Conclusion

Gerbode defects are rare but have been known to increase the risk of developing endocarditis. It is important to have a high clinical suspicion of endocarditis in patients with evidence of conduction disorders and systemic infection.

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.

Core Temperature Lability Predicts Sympathetic Interruption and Cognitive Performance during Heat Exposure in Persons with Spinal Cord Injuries

Among persons with high spinal cord injury (Hi-SCI: > T5), changes in core body temperature (Tcore) and cognitive performance during heat exposure appear related to degree of sympathetic interruption. Twenty men with Hi-SCI (C4-T4, American Spinal Injury Association Impairment Scale [AIS] A-B) and 19 matched, able-bodied controls were acclimated to 27°C baseline (BL) before exposure to 35°C heat challenge (HC). Two groups, differentiated by increase in Tcore during HC, were identified: high responders (HR-SCI: ΔTcore ≥0.5°C; n = 13, C4-T2) and low responders (LR-SCI: ΔTcore <0.5°C; n = 7, C4-T4). Tcore, distal skin temperatures (Tskavg), and distal microvascular perfusion (LDFboth feet) were measured, as were indices of sympathetic integrity, mean arterial pressure (MAP), and extremity sweat rate (SRavg). Cognitive performance was assessed at BL and post-HC, using the Stroop Color and Word and Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) Digit Span tests. At BL, Tcore of the HR-SCI group (36.6 ± 0.4°C) was lower than that for the LR-SCI (37.1 ± 0.3°C; p = 0.011) and control groups (37.3 ± 0.3°C; p < 0.001). After HC, Tcore was not different among groups. MAP of the HR-SCI group (70.9 ± 9.8 mm Hg) was lower than that of the LR-SCI (81.8 ± 7.0 mm Hg; p = 0.048) and control groups (89.9 ± 9.9 mm Hg; p < 0.001). SRavg increased more in the control group (77.0 ± 52.5 nL/cm2/min) than in the HR-SCI group (15.5 ± 22.0 nL/cm2/min; p = 0.001). Only the HR-SCI group had significant increases in T-Scores of Stroop Word (7.5 ± 4.4; p < 0.001), WAIS-IV Digit Span Sequence (1.9 ± 1.8; p = 0.002), and WAIS-IV Digit Span Total (1.4 ± 1.6; p = 0.008). Persons with SCI who responded to HC with a greater change in Tcore demonstrated evidence of greater sympathetic interruption and had an associated improvement in cognitive performance.

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

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

Intrathecal baclofen as emergency treatment alleviates severe intractable autonomic dysreflexia in cervical spinal cord injury

Context: Episodic attacks of autonomic dysreflexia (AD) are regularly experienced by patients with a spinal cord injury (SCI) on T6 or higher levels. The episodes can result in a pounding headache, flushing, blurred vision, anxiety, a stroke, posturing, hyperthermia, retinal bleeding, seizures, myocardial ischemia, cardiac arrhythmias, and death. The observed associated bradycardia is explained as a baroreceptor reflex response to the high blood pressure. Intrathecal baclofen (ITB) has been used to treat chronic AD. This case highlights the occurrence of intractable AD after removal of the ITB delivery system because of a pump pocket infection. We describe the benefit of ITB as an emergency treatment for intractable AD.Findings: A 53-year-old male suffered from spasticity and AD after a C5 ASI B SCI in 2002 was successfully treated with ITB for 14 years. He developed Staphylococcus aureus and Pseudomonas aeruginosa cellulitis at the orifice of his suprapubic catheter, which caused an abscess in the pump pocket. To prevent a withdrawal syndrome, the medication was reduced in three steps of 25%, and the pump was explanted. Postoperatively, he experienced severe AD and was treated with clonazepam, clonidine, and urapidil. The next day, the severely fluctuating blood pressure and pulse rate were no longer controllable with the medication. At L2-3, a temporary external intrathecal catheter for reinitiating ITB was inserted. With this treatment, the AD and the spasticity symptoms could be controlled.Conclusion/Clinical Relevance: The case demonstrated that refractory AD could be managed with ITB in an emergency.

Autonomic dysreflexia associated with cervical spinal cord gliofibroma: case report

BACKGROUND

Autonomic dysreflexia (AD) is an abnormal reflex of the autonomic nervous system normally observed in patients with spinal cord injury from the sixth thoracic vertebra and above. AD causes various symptoms including paroxysmal hypertension due to stimulus. Here, we report a case of recurrent AD associated with cervical spinal cord tumor.

CASE PRESENTATION

The patient was a 57-year-old man. Magnetic resonance imaging revealed an intramedullary lesion in the C2, C6, and high Th12 levels. During the course of treatment, sudden loss of consciousness occurred together with abnormal paroxysmal hypertension, marked facial sweating, left upward conjugate gaze deviation, ankylosis of both upper and lower extremities, and mydriasis. Seizures repeatedly occurred, with symptoms disappearing after approximately 30 min. AD associated with cervical spinal cord tumor was diagnosed. Histological examination by tumor biopsy confirmed the diagnosis of gliofibroma. Radiotherapy was performed targeting the entire brain and spinal cord. The patient died approximately 3 months after treatment was started.

CONCLUSIONS

AD is rarely associated with spinal cord tumor, and this is the first case associated with cervical spinal cord gliofibroma. AD is important to recognize, since immediate and appropriate response is required.

Design and characterisation of an amorphous formulation of nifedipine for the treatment of autonomic dysreflexia

OBJECTIVES

Current treatment for autonomic dysreflexia (AD) involves rupturing a liquid-filled soft capsule of nifedipine to aid rapid drug release and absorption, however, this application is not covered under the manufacturer's license. The objective of the current work was to design a rapidly dissolving solid dosage formulation for the treatment of AD as an alternative to the off-license "bite and swallow" use of currently available commercial products.

METHODS

Amorphous solid dispersions (ASDs) of nifedipine were prepared by spray-drying using three different polymers: hydroxypropyl methyl cellulose (HPMC), polyvinyl pyrrolidone (PVP) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus), at a 15% w/w drug loading and were formulated and compressed into tablets. Dissolution testing was performed in the paddle dissolution apparatus using either a monophasic or biphasic medium.

KEY FINDINGS

The PVP-nifedipine ASD tablets exhibited rapid dissolution, with 35% of the total nifedipine dose dissolving within 15 min in the monophasic dissolution medium. The HPMC-nifedipine ASD exhibited a very slow dissolution, while the Solupus-nifedipine system exhibited no nifedipine release over 120 min. When tested in the biphasic dissolution medium, the PVP-nifedipine ASD tablets exhibited a release profile comparable to that of the pre-split/ruptured nifedipine soft capsule product.

CONCLUSIONS

This study demonstrates that a nifedipine-PVP ASD is a promising formulation strategy in the treatment of AD.

Aerobic fitness is a potential crucial factor in protecting paralympic athletes with locomotor impairments from atherosclerotic cardiovascular risk

Purpose

To test the hypothesis that aerobic fitness is inversely related to the risk of atherosclerotic cardiovascular disease (ACVD) in athletes with locomotor impairments deriving from health conditions, such as spinal cord injury (SCI), lower limb amputation, cerebral palsy, poliomyelitis, and other health conditions different from the previous ones.

Methods

A total of 68 male athletes who competed in either summer or winter Paralympic games were divided in two health conditions groups (35 with SCI, mean age 37.2 ± 8.0 years, and 33 with different health conditions, mean age 37.8 ± 9.9 years) and in four sport type groups (skill, power, intermittent—mixed metabolism—and endurance). They were evaluated through anthropometric and blood pressure measurements, laboratory blood tests, and graded cardiopulmonary maximal arm cranking exercise test, with oxygen uptake peak (VO2peak) measurement. Cardiovascular risk profile was assessed in each athlete.

Results

The prevalence of ACVD-risk factors in the overall population was 20.6% for hypertension; 47% and 55.9% for high values of total and LDL cholesterol, respectively; 22.1% for reduce glucose tolerance; and 8.8% for obesity. No difference was found between athletes with and without SCI, while the prevalence of obesity was significantly higher in those practicing skill sports (22.7%, p = 0.035), which was the sport type group with Paralympic athletes with the lowest VO2peak (22.5 ± 5.70 ml kg−1 min−1). VO2peak was lower in athletes with SCI than those with different health conditions (28.6 ± 10.0 vs 33.6 ± 8.9 ml kg−1 min−1p = 0.03), and in those with 3–4 risk factors (19.09 ± 5.34 ml kg−1 min−1) than those with 2 risk factors (27.1 ± 5.50 ml kg−1 min−1), 1 risk factor (31.6 ± 8.55 ml kg−1 min−1), or none (36.4 ± 8.76 ml kg−1 min−1) (p < 0.001).

Conclusions

The present study suggests that having higher VO2peak seems to offer greater protection against ACVD in individuals with a locomotor impairment. Prescribing physical exercise at an intensity similar to that of endurance and intermittent sports should become a fundamental tool to promote health among people with a locomotor impairment.