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

Online training improves paramedics' knowledge of autonomic dysreflexia management guidelines

STUDY DESIGN

Single-group pre-/post-test with 3- and 6-month follow-ups.

OBJECTIVES

To test the effects of the 'ABCs of AD' educational module on immediate and longer-term changes in paramedics' knowledge and beliefs about using the autonomic dysreflexia clinical practice guidelines (AD-CPGs).

SETTING

Canada.

METHODS

A total of 119 paramedics completed an AD knowledge test and measures of attitudes, perceived control, self-efficacy, social pressure from patients and health-care professionals, and intentions to use the AD-CPGs before and 1 week, 3 months and 6 months after viewing 'ABCs of AD'.

RESULTS

There were significant improvements in AD knowledge, attitudes and social pressure from patients to use the AD-CPGs from baseline to 1 week, 3 months and 6 months post viewing (all P<0.001). Self-efficacy and intentions increased 1 week post viewing (P<0.001), but returned to baseline levels at 3 and 6 months (P>0.05). There was no change in perceived control or social pressure from health-care professionals. AD knowledge and beliefs explained 50-61% of the variance in intentions to use the AD-CPGs. Attitudes, social pressure from patients and perceived behavioural control were significant unique predictors of intentions at all time points (P<0.05); AD knowledge was a significant predictor at 6 months only (P=0.048). No other predictors were significant.

CONCLUSION

'ABCs of AD' has immediate and sustained effects on paramedics' knowledge of attitudes toward and perceived pressure from patients to use the AD-CPGs. Updates to paramedic patient care guidelines and standards are needed to increase paramedics' perceived control and self-efficacy to implement the guidelines, and their intentions to use the AD-CPGs.

SPONSORSHIP

Canadian Institutes of Health Research (2011-CIHR- 260877).

Development of an Algorithm to Perform a Comprehensive Study of Autonomic Dysreflexia in Animals with High Spinal Cord Injury Using a Telemetry Device

Spinal cord injury (SCI) is a debilitating neurological condition characterized by somatic and autonomic dysfunctions. In particular, SCI above the mid-thoracic level can lead to a potentially life-threatening hypertensive condition called autonomic dysreflexia (AD) that is often triggered by noxious or non-noxious somatic or visceral stimuli below the level of injury. One of the most common triggers of AD is the distension of pelvic viscera, such as during bladder and bowel distension or evacuation. This protocol presents a novel pattern recognition algorithm developed for a JAVA platform software to study the fluctuations of cardiovascular parameters as well as the number, severity and duration of spontaneously occurring AD events. The software is able to apply a pattern recognition algorithm on hemodynamic data such as systolic blood pressure (SBP) and heart rate (HR) extracted from telemetry recordings of conscious and unrestrained animals before and after thoracic (T3) complete transection. With this software, hemodynamic parameters and episodes of AD are able to be detected and analyzed with minimal experimenter bias.

[Anesthesiological approach for patients with spinal cord injuries]

Spinal cord injuries (SCI) are serious medical conditions, which are associated with severe and potentially fatal risks and complications depending on the location and extent of injury. Traffic accidents, falls and recreational activities are the leading causes for traumatic SCI (TSCI) worldwide whereas non-traumatic spinal cord injuries (NTSCI) are mostly due to tumors and congenital diseases. As chronification of the injuries progresses other organ systems are affected including anatomical changes, the respiratory and cardiovascular systems and endocrinological pathways. All these effects have to be considered in the anesthesiological management of patients with SCI. Autonomic dysreflexia (AD) is the most dangerous and life-threatening complication in patients with chronic SCI above T6 that results from an overstimulation of sympathetic reflex circuits in the upper thoracic spine and can be fatal. This article summarizes the specific pathophysiology of SCI and how AD can be avoided as well as also providing anesthetists with strategies for perioperative and intensive care management of patients with SCI.

Physical fitness in people with a spinal cord injury: the association with complications and duration of rehabilitation

Objective: To assess the association between physical fitness and its recovery over time on the one hand, and complications and duration of phases of rehabilitation on the other.

Design and setting: Prospective cohort study at eight rehabilitation centres. Subjects: People with a spinal cord injury were assessed four times: at the start of active rehabilitation (n = 110), three months later (n = 92), at discharge (n = 137) and a year after discharge from inpatient rehabilitation (n = 91).

Main measures: Physical fitness was defined as aerobic capacity, determined at each occasion by the peak oxygen uptake (peak Vo2; L/min) and the peak power output (peak PO; W) during a maximal exercise test. On these occasions, spasticity, musculoskeletal and neurogenic pain were determined (1 = present; 0 = absent). During inpatient rehabilitation, complications (urinary tract infection, pulmonary infection or pressure sore) and bed rest were registered (1 = complication; 0 = no complications, and 1 = bed rest; 0 = no bed rest). Complications and bed rest occurring during the year after discharge were registered similarly.

Results: Multilevel random coefficient analyses revealed associations in multivariate models (P ≤ 0.05). The peak oxygen uptake was negatively associated with complications after discharge. The recovery of peak power output over time was negatively associated with bed rest and spasticity. Both physical fitness and its recovery were negatively associated with the duration of active rehabilitation.

Conclusion: Results suggest that limiting complications, spasticity or bed rest may improve fitness. A longer duration of active rehabilitation is not associated with an increase in physical fitness.

The Effect of Different Physiological Stimuli on Skin Vasomotor Reflexes above and below the Lesion in Human Chronic Spinal Cord Injury

Objective. Spinal cord injury (SCI) results in disruption of descending tonic activation of sympathetic circuits in the spinal cord. The authors determined whether different stimuli that increase sympathetic activity induced cutaneous vasoconstriction (skin vasomotor reflex, SkVR) above and below the level of lesion in subjects with clinically complete SCI. Methods. Baseline skin blood flow (SkBF) and SkVR reduction rate in the pulp of the finger and great toe was measured by laser Doppler probes in chronic complete SCI and in controls. Results. In the finger, baseline SkBF was similar in SCI and controls. The SkVR was elicited by all stimuli in controls but was significantly diminished to gasp, mental arithmetic, tactile stimulation, cutaneous cold, and deep breathing in high SCI compared to controls. In the toe, baseline SkBF was less stable in both controls and SCI. SkVR trends were identified in controls, and responses were not present or greatly reduced in high and low SCI. Conclusions. Measurements of skin vasomotor reflexes to physiological stimuli may be a noninvasive method to evaluate the extent of sympathetic adrenergic pathways in chronic SCI. This is of clinical relevance in monitoring recovery of sympathetic adrenergic function either spontaneously or following repair interventions.

Cardiovascular Responses to Sexual Activity in Able-Bodied Individuals and Those Living with Spinal Cord Injury

Sexuality is an integral part of the human experience and persists in health and disability. The cardiovascular system is crucial to sexual function and can be affected profoundly by spinal cord injury (SCI). The effects of sexual activity on the cardiovascular system in SCI have not been summarized and compared with sexual activity in able-bodied individuals. A keyword search of Embase, PubMed, and Medline was conducted. From 471 retrieved studies for able-bodied individuals, 11 were included that met the strict criteria of medically uncomplicated participants. In the SCI literature, 117 studies were screened, with 18 meeting criteria. In able-bodied persons, sexual activity resulted in modest increases in systolic blood pressure peaking at orgasm (males of 163 mm Hg and females of 142 mm Hg) and returning to baseline shortly afterward. In persons with SCI, results varied from minimal changes to significant elevations in systolic blood pressure because of episodes of autonomic dysreflexia, especially in those with high thoracic and cervical lesions. Peak systolic blood pressure in these individuals was measured to be as high as 325 mm Hg. In the SCI population, more intense stimuli (including penile vibrostimulation and electroejaculation) tended to result in a greater increase in systolic blood pressure compared with self-stimulation. Studies that used continuous versus intermittent monitoring were more likely to report greater changes in systolic blood pressure. In able-bodied persons, sexual activity results in modest increases in blood pressure. In those with SCI, intense stimulation and higher injury levels result in a higher likelihood of autonomic dysreflexia and elevated blood pressure. Because of rapid changes in blood pressure, continuous monitoring is more advantageous than intermittent measurement, because the latter may miss peak values.

Pulmonary edema and hemorrhage after acute spinal cord injury in rats

BACKGROUND CONTEXT

Respiratory complications are a major cause of morbidity and mortality during the first days after acute spinal cord injury (ASCI). However, the pathophysiology of respiratory insufficiency resulting from spinal cord injury that involves lower levels is less well understood.

PURPOSE

The aim of the present study was to investigate pulmonary pathophysiology after ASCI.

STUDY DESIGN

This is an experimental animal study of ASCI investigating pulmonary pathophysiology after ASCI.

METHODS

Eighty-four (N=84) rats were divided into two groups: a sham surgery (n=42) and an injury group (n=42). In the injury group, ASCI was induced at the level of the tenth thoracic vertebra by a modified Allen method. Rats were sacrificed 6 hours, 12 hours, 24 hours, 3 days, 1 week, 2 weeks, and 4 weeks after surgery. Pulmonary edema was assessed by calculating the ratio of the wet-to-dry lung weight (W:D). Pulmonary edema and hemorrhage were evaluated by observing gross and microscopic morphology. The study was funded by Natural Science Foundation of China (NSFC, 81272172). The funder of the present study had no capacity to influence the scholarly conduct of the research, interpretation of results, or dissemination of study outcomes.

RESULTS

In the injury group, W:D was significantly increased 12 hours after surgery compared with the sham surgery group; W:D peaked 3 days after ASCI (p<.05). Gross morphologic observations showed hemorrhagic lesions on the lung tissue 12 hours after ASCI and pulmonary edema 24 hours after ASCI. Pulmonary edema peaked 3 days after ASCI and was obviously decreased 1 week after ASCI. Hemorrhage was apparent until 2 weeks after ASCI. Light microscopy showed congestion of pulmonary capillaries 6 hours after ASCI. The pulmonary alveoli were filled with erythrocytes and serous extravasate 12 hours after ASCI. Hemorrhage and edema were observed in the interstitium and lung alveoli 24 hours after ASCI.

CONCLUSIONS

Early pathologic changes such as pulmonary congestion, hemorrhage, and edema after injury may be the basis for early respiratory dysfunction following ASCI.

Perioperative complications associated with spine surgery in patients with established spinal cord injury

BACKGROUND CONTEXT

Only a small percentage of patients with spinal cord injury (SCI) require consideration for reconstructive surgery after their initial injury. For those who do, perioperative complications can be frequent and significant. There has been very little published literature examining treatment of these patients and essentially nothing to guide the surgeon in perioperative decision making and management.

PURPOSE

To identify some of the common challenges associated with surgery in this patient population and review the literature to highlight the perioperative concerns in patients with chronic SCI.

STUDY DESIGN

Review article.

METHODS

A primary PubMed literature search was performed and reviewed for patients with chronic SCI with emphasis on the complications and difficulties encountered during surgical treatment of patients with chronic SCI.

RESULTS

For those who do proceed with surgery in this patient population, preoperative nutrition, bone density, and skin should be evaluated and optimized. Preoperative inferior vena cava filters should be considered. The integrity of the reconstruction will be extensively challenged. In addition, augmented fixation and bracing should be contemplated.

CONCLUSIONS

Patients with chronic SCI who require spinal reconstruction provide many unique challenges. Indications for surgery must be strong as perioperative complications can be frequent and long-term outcomes unpredictable. Close monitoring for postoperative complications is essential.

"The ABCs of AD": A prospective evaluation of the efficacy of an educational intervention to increase knowledge of autonomic dysreflexia management among emergency health care professionals

CONTEXT/OBJECTIVE

Despite the availability of consensus-based resources, first responders and emergency room (ER) health care professionals (HCPs) have limited knowledge regarding autonomic dysreflexia (AD) recognition and treatment. The purpose of this study was to assess the efficacy of "The ABCs of AD" educational seminar for improving HCPs' short- and long-term knowledge of AD recognition, diagnosis, and management.

DESIGN

Multi-center prospective pre, post, and follow-up questionnaire study.

SETTING

Level I trauma centers with emergency departments in British Columbia, Manitoba, and Ontario.

METHODS

ER professionals completed measures immediately before and after (n = 108), as well as 3-months following (n = 23), attendance at "The ABCs of AD" seminar.

OUTCOME MEASURES

AD knowledge test; seminar feedback.

RESULTS

Following the seminar, participants had higher ratings of their AD knowledge and had significantly higher AD knowledge test scores (M ± SD pre = 11.85 ± 3.88, M ± SD post = 18.95 ± 2.39, out of 22; P < 0.001, d = 2.21). Most participants believed the seminar changed their AD knowledge, and rated the seminar information as having the potential to influence and change their practice. AD knowledge test scores significantly decreased between post-seminar and 3-month follow-up (M ± SD 3mo = 17.04 ± 3.28; P = 0.004, d = -0.70); however, 3-month scores remained significantly higher than baseline.

CONCLUSION

"The ABCs of AD" seminar improves HCPs' perceived and actual AD knowledge in the short-term. To enhance knowledge retention in both the short- and long-term, the inclusion of additional active learning strategies and follow-up activities are recommended. The seminar is being translated into an online training module to enhance the dissemination of the AD clinical practice guidelines among first responders, ER staff, and SCI practitioners.

Cerebral Blood Flow Responses to Autonomic Dysreflexia in Humans with Spinal Cord Injury

Autonomic dysreflexia (AD) is a life-threatening episode of transient hypertension affecting up to 90% of those with high-level spinal cord injury (SCI), and can lead to cerebral hemorrhage. Due to the nature of this medical emergency, cerebral blood flow (CBF) has not been recorded during AD. Beat-by-beat blood pressure (BP) and CBF velocity of the middle cerebral artery were measured during spontaneous AD episodes in four motor complete cervical SCI patients. Mean arterial BP increased during AD (66 ± 11 vs. 83 ± 10 mm Hg; p = 0.004), whereas CBF (76 ± 4 vs. 74 ± 4 cm · sec(-1)) and end-tidal partial pressure of carbon dioxide (PETCO2) (35 ± 1 vs. 34 ± 3 mm Hg) were maintained. These preliminary data indicate that the brain may effectively buffer moderate episodes of AD.

Respiratory Training Improves Blood Pressure Regulation in Individuals With Chronic Spinal Cord Injury

OBJECTIVE

To investigate the effects of respiratory motor training (RMT) on pulmonary function and orthostatic stress-mediated cardiovascular and autonomic responses in individuals with chronic spinal cord injury (SCI).

DESIGN

Before-after intervention case-controlled clinical study.

SETTING

SCI research center and outpatient rehabilitation unit.

PARTICIPANTS

A sample of (N=21) individuals with chronic SCI ranging from C3 to T2 diagnosed with orthostatic hypotension (OH) (n=11) and healthy, noninjured controls (n=10).

INTERVENTIONS

A total of 21±2 sessions of pressure threshold inspiratory-expiratory RMT performed 5d/wk during a 1-month period.

MAIN OUTCOME MEASURES

Standard pulmonary function test: forced vital capacity, forced expiratory volume in one second, maximal inspiratory pressure, maximal expiratory pressure, beat-to-beat arterial blood pressure, heart rate, and respiratory rate were acquired during the orthostatic sit-up stress test before and after the RMT program.

RESULTS

Completion of RMT intervention abolished OH in 7 of 11 individuals. Forced vital capacity, low-frequency component of power spectral density of blood pressure and heart rate oscillations, baroreflex effectiveness, and cross-correlations between blood pressure, heart rate, and respiratory rate during the orthostatic challenge were significantly improved, approaching levels observed in noninjured individuals. These findings indicate increased sympathetic activation and baroreflex effectiveness in association with improved respiratory-cardiovascular interactions in response to the sudden decrease in blood pressure.

CONCLUSIONS

Respiratory training increases respiratory capacity and improves orthostatic stress-mediated respiratory, cardiovascular, and autonomic responses, suggesting that this intervention can be an efficacious therapy for managing OH after SCI.

Targeted Treatment of Experimental Spinal Cord Glioma With Dual Gene-Engineered Human Neural Stem Cells

BACKGROUND

There are currently no satisfactory treatments or experimental models showing autonomic dysfunction for intramedullary spinal cord gliomas (ISCG).

OBJECTIVE

To develop a rat model of ISCG and investigate whether genetically engineered human neural stem cells (F3.hNSCs) could be developed into effective therapies for ISCG.

METHODS

Immunodeficient/Rowett Nude rats received C6 implantation of G55 human glioblastoma cells (10K/each). F3.hNSCs engineered to express either cytosine deaminase gene only (i.e., F3.CD) or dual genes of CD and thymidine kinase (i.e., F3.CD-TK) converted benign 5-fluorocytosine and ganciclovir into oncolytic 5-fluorouracil and ganciclovir-triphosphate, respectively. ISCG rats received injection of F3.CD-TK, F3.CD, or F3.CD-TK debris near the tumor epicenter 7 days after G55 seeding, followed with 5-FC (500 mg/kg/5 mL) and ganciclovir administrations (25 mg/kg/1 mL/day × 5/each repeat, intraperitoneal injection). Per humane standards for animals, loss of weight-bearing stepping in the hindlimb was used to determine post-tumor survival. Also evaluated were autonomic functions and tumor growth rate in vivo.

RESULTS

ISCG rats with F3.CD-TK treatment survived significantly longer (37.5 ± 4.78 days) than those receiving F3.CD (21.5 ± 1.75 days) or F3.CD-TK debris (19.3 ± 0.85 days; n = 4/group; P &lt;.05, median rank test), with significantly improved autonomic function and reduced tumor growth rate. F3.DC-TK cells migrated diffusively into ISCG clusters to mediate oncolytic effect.

CONCLUSION

Dual gene-engineered human neural stem cell regimen markedly prolonged survival in a rat model that emulates somatomotor and autonomic dysfunctions of human cervical ISCG. F3.CD-TK may provide a novel approach to treating clinical ISCG.

Effect of Alpha-1-Adrenergic Agonist, Midodrine for the Management of Long-Standing Neurogenic Shock in Patient with Cervical Spinal Cord Injury: A Case Report

We report a rare case of a 71-year-old male patient who had suffered from long-lasting neurogenic shock for 13 weeks after cervical spinal cord injury (SCI) caused by a bicycle accident. The neurogenic shock was resolved dramatically 2 weeks after the administration of alpha-1-adrenergic agonist, midodrine hydrochloride. In usual cases, neurogenic shock tends to improve between 2 and 6 weeks after SCI; however, in a few cases, the shock lasts for several months. In our case, spinal shock lasted for 13 weeks and exhibited very sensitive decline of blood pressure for even a slight decrease of dopamine despite recovered bulbospongiosus reflex. Three days after midodrine hydrochloride was added, hypotension improved dramatically. We discuss our rare case with pertinent literatures.

Contemporary Cardiovascular Concerns after Spinal Cord Injury: Mechanisms, Maladaptations, and Management

Cardiovascular (CV) issues after spinal cord injury (SCI) are of paramount importance considering they are the leading cause of death in this population. Disruption of autonomic pathways leads to a highly unstable CV system, with impaired blood pressure (BP) and heart rate regulation. In addition to low resting BP, on a daily basis the majority of those with SCI suffer from transient episodes of aberrantly low and high BP (termed orthostatic hypotension and autonomic dysreflexia, respectively). In fact, autonomic issues, including resolution of autonomic dysreflexia, are frequently ranked by individuals with high-level SCI to be of greater priority than walking again. Owing to a combination of these autonomic disturbances and a myriad of lifestyle factors, the pernicious process of CV disease is accelerated post-SCI. Unfortunately, these secondary consequences of SCI are only beginning to receive appropriate clinical attention. Immediately after high-level SCI, major CV abnormalities present in the form of neurogenic shock. After subsiding, new issues related to BP instability arise, including orthostatic hypotension and autonomic dysreflexia. This review describes autonomic control over the CV system before injury and the mechanisms underlying CV abnormalities post-SCI, while also detailing the end-organ consequences, including those of the heart, as well as the systemic and cerebral vasculature. The tertiary impact of CV dysfunction will also be discussed, such as the potential impediment of rehabilitation, and impaired cognitive function. In the recent past, our understanding of autonomic dysfunctions post-SCI has been greatly enhanced; however, it is vital to further develop our understanding of the long-term consequences of these conditions, which will equip us to better manage CV disease morbidity and mortality in this population.

Tetraplegia is associated with enhanced peripheral chemoreflex sensitivity and ventilatory long-term facilitation

Cardiorespiratory plasticity induced by acute intermittent hypoxia (AIH) may contribute to recovery following spinal cord injury (SCI). We hypothesized that patients with cervical SCI would demonstrate higher minute ventilation (V̇e) following AIH compared with subjects with thoracic SCI and able-bodied subjects who served as controls. Twenty-four volunteers (8 with cervical SCI, 8 with thoracic SCI, and 8 able-bodied) underwent an AIH protocol during wakefulness. Each subject experienced 15 episodes of isocapnic hypoxia using mixed gases of 100% nitrogen (N2), 8% O2, and 40% CO2 to achieve oxygen saturation ≤90% followed by room air (RA). Measurements were obtained before, during, and 40 min after AIH to obtain ventilation and heart rate variability data [R-R interval (RRI) and low-frequency/high-frequency power (LF/HF)]. AIH results were compared with those of sham studies conducted in RA during the same time period. Individuals with cervical SCI had higher V̇e after AIH compared with able-bodied controls (117.9 ± 23.2% vs. 97.9 ± 11.2%, P < 0.05). RRI decreased during hypoxia in all individuals (those with cervical SCI, from 1,009.3 ± 65.0 ms to 750.2 ± 65.0 ms; those with thoracic SCI, from 945.2 ± 65.0 ms to 674.9 ± 65.0 ms; and those who were able-bodied, from 949 ± 75.0 to 682.2 ± 69.5 ms; P < 0.05). LH/HF increased during recovery in individuals with thoracic SCI and those who were able-bodied (0.54 ± 0.22 vs. 1.34 ± 0.22 and 0.67 ± 0.23 vs. 1.82 ± 0.23, respectively; P < 0.05) but remained unchanged in the group with cervical SCI. Our conclusion is that patients with cervical SCI demonstrate ventilatory long-term facilitation following AIH compared with able-bodied controls. Heart rate responses to hypoxia are acutely present in patients with cervical SCI but are absent during posthypoxic recovery.

Autonomic consequences of spinal cord injury

Spinal cord injury (SCI) results not only in motor and sensory deficits but also in autonomic dysfunctions. The disruption of connections between higher brain centers and the spinal cord, or the impaired autonomic nervous system itself, manifests a broad range of autonomic abnormalities. This includes compromised cardiovascular, respiratory, urinary, gastrointestinal, thermoregulatory, and sexual activities. These disabilities evoke potentially life-threatening symptoms that severely interfere with the daily living of those with SCI. In particular, high thoracic or cervical SCI often causes disordered hemodynamics due to deregulated sympathetic outflow. Episodic hypertension associated with autonomic dysreflexia develops as a result of massive sympathetic discharge often triggered by unpleasant visceral or sensory stimuli below the injury level. In the pelvic floor, bladder and urethral dysfunctions are classified according to upper motor neuron versus lower motor neuron injuries; this is dependent on the level of lesion. Most impairments of the lower urinary tract manifest in two interrelated complications: bladder storage and emptying. Inadequate or excessive detrusor and sphincter functions as well as detrusor-sphincter dyssynergia are examples of micturition abnormalities stemming from SCI. Gastrointestinal motility disorders in spinal cord injured-individuals are comprised of gastric dilation, delayed gastric emptying, and diminished propulsive transit along the entire gastrointestinal tract. As a critical consequence of SCI, neurogenic bowel dysfunction exhibits constipation and/or incontinence. Thus, it is essential to recognize neural mechanisms and pathophysiology underlying various complications of autonomic dysfunctions after SCI. This overview provides both vital information for better understanding these disorders and guides to pursue novel therapeutic approaches to alleviate secondary complications.

Pediatric Spinal Cord Injury: Recognition of Injury and Initial Resuscitation, in Hospital Management, and Coordination of Care

Spinal cord injury is uncommon in the pediatric population with a lifelong impact for the patient and family. Knowledge of spine embryology, mechanisms of injury that lead to specific injuries, appropriate utilization of radiographic imaging based on suspected injury, prehospital and hospital management of various spinal cord injuries is essential for providers attending to traumatically injured patients. In addition to patients who present with soft tissue and bony injuries diagnosed with clinical examination and confirmed with computed tomography or magnetic resonance imaging, it is important to note that the pediatric population is at a higher risk for spinal cord injury without radiographic abnormality than the adult population. Patients who survive the acute phase of injury face long-term rehabilitation and have an increased risk of depression and mortality. Understanding the long-term sequelae of spinal cord injuries is also an essential management component of traumatically injured children. A program that provides long-term rehabilitation, psychosocial and spiritual support, and adaptive environmental supports gives patients and their families the best opportunity for long-term recovery. A review of the current literature on the diagnosis, management, and follow-up of pediatric spinal cord injury is presented.

Passive Hind-Limb Cycling Reduces the Severity of Autonomic Dysreflexia After Experimental Spinal Cord Injury

Background. Spinal cord injury (SCI) induces alterations in cardio-autonomic control of which autonomic dysreflexia (AD), a condition characterized by life-threatening hypertension, is arguably the most insidious. Passive hind-limb cycling represents a low-cost therapeutic intervention with demonstrable cardiovascular, sensory, and motor benefits. Objective. To investigate the effect of passive hind-limb cycling on AD in rodents with T3 SCI. Methods. Forty-five male Wistar rats were evenly assigned to either uninjured control (CON), SCI, or SCI plus hind-limb cycling exercise (SCI-EX). At the end of the experimental period (day 32), rats were randomly assigned to stream 1 (n = 24) or stream 2 (n = 21). Stream 1 rats were assessed for AD severity (pressor response to colorectal distension) and were then perfused for tissue dissection and immunohistochemistry. Stream 2 rats underwent excision of the superior mesenteric artery for in vitro myography assessments. Results. From 2 weeks post-SCI onwards, SCI-EX rats exhibited a significant reduction in the pressor response to colorectal distension versus SCI ( P < .001). Reduced AD severity in SCI-EX rats was accompanied by a prevention of the SCI-induced increase in density of CGRP+ afferents in the dorsal horn ( P = .001). Conversely, both SCI and SCI-EX rats exhibited a similar degree of mesenteric endothelial dysfunction and α-adrenoceptor hypersensitivity versus CON. Conclusion. Passive hind-limb cycling reduces the severity of AD in SCI, and is correlated with changes in primary afferent morphology, but has limited effects on the peripheral vasculature.

The influence of cervical spinal cord compression and vertebral displacement on somatosympathetic reflexes in the rat

BACKGROUND CONTEXT

One theory within chiropractic proposes that vertebral subluxation in the upper cervical region induces spinal cord compression sufficient to alter spinal cord efferent output. We report on the feasibility of three different experimental approaches to test this theory.

METHODS

A high threshold electrical-evoked somatosympathetic reflex was recorded in adrenal or renal nerves of 10 anaesthetized adult male rats before and after (1) graded pressure was applied directly to the C1/C2 spinal cord segment in eight rats by the use of either direct compression or inflation of an extradural balloon and (2) displacement, less than a dislocation applied posterior to anterior, to the C2 vertebra in two rats. The latency and amplitude of the pre- and postintervention reflex responses were compared.

RESULTS

The reflex amplitude was not significantly changed by pressure (26 mmHg) from an extra-dural balloon or direct compression of the dura mater onto the dorsal spinal cord. Additional pressure, at least sufficient to occlude the dorsal vessels, induced a significant reduction in the amplitude of the reflex, and this reduction persisted for 20 minutes after removal of the pressure (Dunn's method for all pairwise multiple comparison Q stat=3.437; critical value for k=6 with α=0.05 is 2.936). Maximal vertebral (C2) displacement (4 mm), without dislocation did not induce significant changes compared with the control period.

CONCLUSIONS

Although this feasibility study suggests it is unlikely that upper cervical vertebral subluxation, displacement less than a dislocation, compromises the sympathetic outflow in the adrenal or renal nerves, further vertebral displacement studies are necessary to formally test this.

Prevalence of abnormal systemic hemodynamics in veterans with and without spinal cord injury

OBJECTIVE

Increased prevalence of heart rate and blood pressure abnormalities are evident in persons with spinal cord injury (SCI), but age, comorbid medical conditions, and prescription medication use may contribute. To determine differences in the prevalence of cardiac acceleration (heart rate ≥80 beats per minute), hypotension (blood pressure ≤110/70mmHg), orthostatic hypotension (OH) (-20/-10mmHg with upright positioning), and hypertension (HTN) (blood pressure ≥140/90mmHg) in veterans with and without SCI.

DESIGN

Observational trial.

SETTING

Medical center.

PARTICIPANTS

Subjects included veterans with SCI (n=62; cervical: tetraplegia, C3-8; high thoracic, T1-5; low thoracic, T7-L2) and veterans without SCI (n=160).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

We assessed medical history, prescription medication use, and heart rate and blood pressure during a routine clinical visit. Prevalence rates of cardiac acceleration, hypotension, OH, and HTN were calculated using binary logistic regression analysis with 95% confidence intervals. The influence of SCI status, age, smoking status, cardiovascular diagnoses, and use of prescribed antihypertensive medications on the prevalence of abnormal heart rate and blood pressure recordings was determined.

RESULTS

The diagnosis of HTN was reduced in the high thoracic and tetraplegia groups compared with the non-SCI and low thoracic groups. Use of antihypertensive medications was increased in the low thoracic group compared with the other 3 groups and was increased in the non-SCI group compared with the tetraplegia group. The prevalence of cardiac acceleration was reduced, and the prevalence of systolic hypotension was increased in the tetraplegia group. The prevalence of diastolic hypotension was increased in all SCI groups compared with the non-SCI group. For all analyses, increased prevalence of abnormal heart rate and blood pressure recordings was not further explained by the covariates, with the exception of age, cardiovascular diagnoses, and antihypertensive medications in the cardiac acceleration model; however, SCI status remained significant and was the dominant predictor variable.

CONCLUSIONS

Our data suggest that SCI status contributes to the prevalence of cardiac acceleration and systolic and diastolic hypotension regardless of cardiovascular medical conditions or prescription antihypertensive medication use.

The role of autonomic function on sport performance in athletes with spinal cord injury

Devastating paralysis, autonomic dysfunction, and abnormal cardiovascular control present significant hemodynamic challenges to individuals with spinal cord injury (SCI), especially during exercise. In general, resting arterial pressure after SCI is lower than with able-bodied individuals and is commonly associated with persistent orthostatic intolerance along with transient episodes of life-threatening hypertension, known as "autonomic dysreflexia." During exercise, the loss of central and reflexive cardiovascular control attenuates maximal heart rate and impairs blood pressure regulation and blood redistribution, which ultimately reduces venous return, stroke volume, and cardiac output. Thermoregulation also is severely compromised in high-lesion SCI, a problem that is compounded when competing in hot and humid conditions. There is some evidence that enhancing venous return via lower body positive pressure or abdominal binding improves exercise performance, as do cooling strategies. Athletes with SCI also have been documented to self-induce autonomic dysreflexia before competition with a view of increasing blood pressure and improving their performance, a technique known as "boosting." For health safety reasons, boosting is officially banned by the International Paralympics Committee. This article addresses the complex issue of how the autonomic nervous system affects sports performance in athletes with SCI, with a specific focus on the potential debilitating effects of deranged cardiovascular control.

Patient-identified factors that influence spasticity in people with stroke and multiple sclerosis receiving botulinum toxin injection treatments

PURPOSE

To describe the nature, extent, and impact of spasticity; determine factors that are perceived to influence its severity; and examine the relationship between time since diagnosis and impact of spasticity on daily activities in people with stroke and multiple sclerosis (MS) who are receiving botulinum toxin injection treatments.

METHODS

After a cross-sectional telephone survey, descriptive statistics and correlations were analyzed separately for the stroke and MS groups.

RESULTS

A total of 29 people with stroke and 10 with MS were surveyed. Both groups perceived increased spasticity with outdoor cold (69% stroke, 60% MS), muscle fatigue (59% stroke, 80% MS), and mental stress (59% stroke, 90% MS). No statistically significant correlations were found between time since diagnosis and perceived impact of spasticity on function in the stroke (r=0.07, p=0.37) or MS (r=0.16, p=0.33) groups. The MS group experienced bilateral and more severe perception of spasticity in the legs than the stroke group and identified more factors as worsening their spasticity (p<0.05). Severity of leg (but not arm) spasticity was significantly correlated with severity of impact of the following factors in the MS group only: lying on the back (r=0.70, p<0.05), outdoor heat (r=0.61, p<0.05), and morning (r=0.59, p<0.05).

CONCLUSION

Intrinsic and extrinsic triggers can influence the perception of spasticity differently depending on individual factors, severity, location (arm vs. leg), and distribution of spasticity (unilateral vs. bilateral). Clinicians can use the findings to better understand, educate, and treat people with stroke and MS.

Energy expenditure and heart rate responses to increased loading in individuals with motor complete spinal cord injury performing body weight-supported exercises

OBJECTIVE

To examine acute metabolic and heart rate responses in individuals with motor complete spinal cord injury (SCI) during stepping and standing with body weight support (BWS).

DESIGN

Cohort study.

SETTING

Therapeutic exercise research laboratory.

PARTICIPANTS

Nonambulatory individuals with chronic, motor complete SCI between T5 and T12 (n=8) and healthy, able-bodied controls (n=8).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Oxygen consumption (V˙o2) and heart rate.

RESULTS

Individuals with motor complete SCI performed standing and stepping exercises in a BWS system with manual assistance of lower body kinematics. V˙o2 and heart rate responses were assessed in relation to level of BWS. Weight support was provided by an overhead lift at high (≥50% BWS) or low (20%-35% BWS) levels during stepping and standing. Although participants with motor complete SCI were unable to stand or step without assistance, levels of V˙o2 and heart rate were elevated by 38% and 37%, respectively, when load was maximized during stepping (ie, low BWS). Participants without an SCI (able-bodied group) had a similar acute response to exercise. None of the participants met the target range for V˙o2 response in any of the tasks. However, stepping was sufficient to enable half of the participants in the SCI group to attain the target range for heart rate response to exercise.

CONCLUSIONS

Individuals with motor complete SCI exhibit cardiovascular responses during body weight-supported exercise. Findings indicate that body weight-supported stepping provides a minimal cardiovascular challenge for individuals with paraplegia. Emphasis on low weight support during locomotor training can trigger additional heart rate adaptations.

Iatrogenic urological triggers of autonomic dysreflexia: a systematic review

STUDY DESIGN

This is a systematic review.

OBJECTIVE

The objective of this study was to review the literature on iatrogenic urological triggers of autonomic dysreflexia (AD).

SETTING

This study was conducted in an international setting.

METHODS

A systematic review was conducted from PubMed search using AD/ autonomic hyperreflexia and spinal cord injury (SCI). Studies selected for review involved iatrogenic urological triggers of AD in individuals with SCI, including original articles, previous practice guidelines, case reports and literature reviews. Studies that did not report AD or blood pressure (BP) assessments during urological procedures were excluded.

RESULTS

Forty studies were included for analysis and categorized into four groups: (1) urodynamics and cystometry; (2) cystoscopy and transurethral litholapaxy; (3) extracorporeal shock-wave lithotripsy (ESWL); and (4) other procedures. During urodynamics, the incidence of AD ranged from 36.7% to 77.8%. The symptomatic rate ranged from 50% to 65%, with AD symptoms seen predominantly in cervical SCI patients. The studies imply no consensus regarding the relationship between AD, neurogenic detrusor overactivity and detrusor sphincter dyssynergia. Without anesthesia, the majority of individuals develop AD during cystoscopy, transurethral litholapaxy and ESWL. The effectiveness of different anesthesia methods relies on blocking the nociceptive signals from the lower urinary tract (LUT) below the level of the neurological lesion. Other iatrogenic urological triggers were commonly associated with bladder filling.

CONCLUSION

The LUT triggers of episodes of AD are often associated with iatrogenic urological procedures. AD was more prevalent in cervical SCI than in thoracic SCI. To detect this potential life-threatening complication following cervical and high thoracic SCI, routine BP monitoring during urological procedures is highly recommended.

Preserved cardiac autonomic dynamics during sleep in subjects with spinal cord injuries

BACKGROUND

Spinal cord injuries (SCI) are associated with altered cardiovascular autonomic control (CAC). Sleep is characterized by modifications of autonomic control across sleep stages; however, no data are available in SCI subjects on CAC during sleep. We aim to assess cardiac autonomic modulation during sleep in subjects with SCI.

PATIENTS AND METHODS

27 participants with a neurological and radiological diagnosis of cervical (Cerv, n = 12, ie, tetraplegic) and thoracic SCI (Thor, n = 15, ie, paraplegic) and healthy subjects (Controls) were enrolled. Overnight polysomnographic (PSG) recordings were obtained in all participants. Electrocardiography and respiration were extracted from PSG, divided into sleep stages [wakefulness (W), non-REM sleep (NREM) and REM] for assessment of CAC, using symbolic analysis (SA) and corrected conditional entropy (CCE). SA identified indices of sympathetic and parasympathetic modulation and CCE evaluated the degree of complexity of the heart period time series.

RESULTS

SA revealed a reduction of sympathetic and predominant parasympathetic control during NREM compared to W and REM in SCI patients, independent of the level of the lesion, similar to the Controls. In all three groups, complexity of autonomic regulation was higher in NREM compared to W and REM.

CONCLUSIONS

In subjects with SCI, cardiac autonomic control changed across sleep stages, with a reduction of sympathetic and an increase of parasympathetic modulation during NREM compared to W and REM, and a parallel increase of complexity during NREM, which was similar to the Controls. Cardiac autonomic dynamics during sleep are maintained in SCI, independent of the level of the lesion.

Cardiovascular dysfunction due to sympathetic hypoactivity after complete cervical spinal cord injury: a case report and literature review

Spinal cord injury (SCI) is one of the most devastating of all traumatic events; it may cause permanent dysfunction in several organ systems and lead to motor and sensory impairment. Cardiovascular dysfunction has been recognized to be the leading cause of morbidity and mortality in the acute and chronic stages following SCI. Although cardiovascular dysfunction causes the deaths of many SCI patients, most clinicians are unfamiliar with the phenomenon. The purpose of reporting our case is to remind clinicians to consider the possibility of cardiovascular dysfunction in patients with complete SCI. The patient signed informed consent for publication of this case report and any accompanying image. The ethical approval of this study was waived by the ethics committee of the Chonbuk National University Hospital, Jeonju, Korea, because this study was a case report and the number of patients was <3. A 63-year-old man was transferred to our emergency room after a fall. He complained of weakness and numbness of the lower extremity. Radiologic evaluation revealed C7/T1 unilateral facet dislocation with spinal cord contusion. On neurologic examination, the patient exhibited a paraplegic state below the T4 dermatome because of complete SCI. His vital signs were stable, but respiration was shallow. We performed intraoperative manual reduction and anterior interbody fusion. On the second postoperative day, the patient experienced sudden cardiac arrest after he was shifted from a supine to a semilateral position. Upon position change, heart rate was decreased <40 beats/min and blood pressure could not be checked. We immediately started cardiac massage and administered atropine 0.5 mg and epinephrine 1 mg, and the patient was successfully resuscitated. Cardiac arrest recurred when we performed endotracheal suction or changed patient's position. Echocardiographic and Holter monitoring findings demonstrated normal heart function and sinus bradycardia, and there was no evidence of pulmonary thromboembolism. We concluded that cardiac arrest was induced by sympathetic hypoactivity following complete SCI. Two months later, this phenomenon had resolved, and 4 months after presentation, he was discharged reliant on a home ventilator. Through this report, we emphasize that a thorough understanding of cardiovascular dysfunction following SCI is important for establishing a diagnosis and optimizing clinical outcomes.

Refined assessment of blood pressure instability after spinal cord injury

BACKGROUND

This study determined whether the Autonomic Dysfunction Following Spinal Cord Injury (ADFSCI) questionnaire, a measure of self-reported frequency and severity of symptoms during hypo- and hypertensive episodes, correlates with blood pressure (BP) instability. In addition, test-retest reliability of the ADFSCI questionnaire was assessed.

METHODS

Thirty individuals with spinal cord injury (SCI) (aged 42±12 years; level of lesion = C3-L1; American Spinal Injury Association Impairment Scale = A-C; lesion duration = 1 month to 30 years after injury) participated in this study. Twenty-four-hour ambulatory BP monitoring (ABPM) was used to assess BP instability. ABPM recorded systolic BP (SBP), diastolic BP (DBP), and heart rate at 15-minute intervals during the daytime and 1-hour intervals during the nighttime. Test-retest reliability was performed by completion of the ADFSCI questionnaire on 2 occasions (i.e., 9±4 days in between).

RESULTS

Individuals with SCI who self-reported autonomic dysreflexia (AD) episodes showed significantly higher SBP coefficient of variation (CV) (14%) and more AD events (n = 11) than individuals who reported never having AD symptoms (CV = 9%; AD events = 1). Both the number of AD events over the 24-hour period and the BP variability (SBP CV) were significantly related to the patients' self-reported total AD score (rho = 0.522, P = 0.005; rho = 0.584, P = 0.001, respectively) and daily AD frequency (rho = 0.553, P = 0.003; rho = 0.586, P = 0.001, respectively). Conversely, no significant correlations existed between the number of hypotensive events over the 24-hour period and self-reported frequency and severity in the ADFSCI questionnaire.

CONCLUSIONS

This study provides evidence that ABPM offers a strong clinical basis for documenting and understanding BP instability, such as AD, and related symptoms in individuals with SCI.

The association between spinal cord injury and acute myocardial infarction in a nationwide population-based cohort study

STUDY DESIGN

A spinal cord injury (SCI) retrospective cohort study was derived from the National Health Insurance Research Database of Taiwan.

OBJECTIVE

We evaluated risk of acute myocardial infarction (AMI) in patients newly diagnosed with SCI.

SUMMARY OF BACKGROUND DATA

According to information of the World Health Organization, cardiovascular diseases are the most frequent causes of death in patients with SCI compared with those in the general population.

METHODS

We obtained claims data from the National Health Insurance Research Database for this cohort study. The SCI group comprised 22,197 patients with a diagnosis of SCI. Case and control patients were based on risk-set sampling in a 1:4 ratio, and we excluded patients with a prior diagnosis of AMI. Comorbidities were categorized as the proportion of prior illnesses in the SCI and non-SCI groups. We used the Cox proportion model to explore adjusted hazard ratio (aHR) for developing AMI between case and control patients.

RESULTS

Patients with SCI were significantly more likely to exhibit pre-existing illnesses associated with AMI than patients without SCI. Patients with a diagnosis of SCI exhibited significantly higher aHRs for developing AMI than patients without SCI (aHR=1.17; P<0.05). Patients with SCI, compared with patients without SCI, were associated with a subsequent AMI risk (aHR=1.17; P<0.05). Several comorbidities, such as cardiovascular disease (aHR=1.29; P<0.05), chronic obstructive pulmonary disease (aHR=1.51; P<0.05), hypertension (aHR=1.34; P<0.01), and renal disease (aHR=1.76; P<0.05), were associated with an increased AMI risk. Furthermore, T-spine SCI was significantly associated with an AMI risk (aHR=1.38; P<0.05).

CONCLUSION

Patients with as diagnosis of SCI exhibited an increased risk of AMI compared with patients without SCI. These findings have broad implications for surveillance among patients with SCI, and future studies should evaluate whether risk factor modification can decrease AMI risk among patients with SCI.

LEVEL OF EVIDENCE

3.

Spinal cord injury increases the reactivity of rat tail artery to angiotensin II

Studies in individuals with spinal cord injury (SCI) suggest the vasculature is hyperreactive to angiotensin II (Ang II). In the present study, the effects of SCI on the reactivity of the rat tail and mesenteric arteries to Ang II have been investigated. In addition, the effects of SCI on the facilitatory action of Ang II on nerve-evoked contractions of these vessels were determined. Isometric contractions of artery segments from T11 (tail artery) or T4 (mesenteric arteries) spinal cord-transected rats and sham-operated rats were compared 6–7 weeks postoperatively. In both tail and mesenteric arteries, SCI increased nerve-evoked contractions. In tail arteries, SCI also greatly increased Ang II-evoked contractions and the facilitatory effect of Ang II on nerve-evoked contractions. By contrast, SCI did not detectably change the responses of mesenteric arteries to Ang II. These findings provide the first direct evidence that SCI increases the reactivity of arterial vessels to Ang II. In addition, in tail artery, the findings indicate that Ang II may contribute to modifying their responses following SCI.

Sexual dysfunction in patients with spinal cord lesions

Many aspects of sexuality can be disrupted following a spinal cord lesion (SCL). It can alter an individual's self-esteem and body image, interfere with positioning and mobility, introduce unexpected problems with incontinence and spasticity, decrease pleasure, and delay orgasm. Sexual concerns in men can involve erectile function, essential for intercourse, ejaculation function, necessary for fertility, and the ability to reach orgasm. In women they can involve concerns with vaginal lubrication, genital congestion, and vaginal infections, which can all go unnoticed, and orgasm, which may be lost. All of these concerns must be addressed during rehabilitation as individuals with SCL continue to live an active sexual life, and consider sexuality among their top priority for quality of life. This chapter describes the impact of SCL on various phases of men's and women's sexual responses and on various aspects of sexuality. Treatments are described in terms of what is currently available and what is specific to the SCL population. New approaches in particular for women are described, along with tips from sexual counseling which consider an overall approach, taking into account the primary, secondary, and tertiary consequences of the SCL on the individual's sexuality. Throughout the chapter, attempts are made to integrate neurophysiologic knowledge, findings from the literature on SCL, and clinical experience in sexual rehabilitation.

Heart rate response during underwater treadmill training in adults with incomplete spinal cord injury

BACKGROUND

Walking on a submerged treadmill can improve mobility in persons displaying lower limb muscle weakness and balance deficits. Little is known, however, regarding the effect of water treadmill exercise on cardiac performance in persons with incomplete spinal cord injury (iSCI).

OBJECTIVE

To assess heart rate response during underwater treadmill training (UTT) in adults with iSCI.

METHODS

Seven males and 4 females with iSCI (age = 48 ± 13 years; 5 ± 8 years after injury) completed 8 weeks of UTT (3 sessions per week; 3 walks per session) incorporating individually determined walking speeds, personalized levels of body weight unloading, and gradual, alternating increases in speed and duration. Heart rate was monitored during the last 15 seconds of the final 2 minutes of each walk.

RESULTS

Over the course of 3 biweekly periods in which walking speed remained constant, heart rate fell by 7% (7 ± 1 b•min(-1); P < .001) in weeks 2 and 3, 14% (17 ± 6 b•min(-1); P < .001) in weeks 4 and 5, and 17% (21 ± 11 b•min(-1); P < .001) in weeks 6 and 7.

CONCLUSION

In adults with iSCI, progressively greater absolute and relative reductions in submaximal exercise heart rate occurred after 2 months of UTT featuring a systematic increase in training volume.

Clinical treatment of orthostatic hypotension after spinal cord injury with training based on electric uprise bed coupled with remote ECG and BP monitor

BACKGROUND

The treatment for orthostatic hypotension (OH) after spinal cord injury (SCI) is an important part of rehabilitation in late-stage SCI. Electric uprise bed training is a relatively commonly used method in treating OH, and how to carry out uprise bed training safely and effectively is an urgent problem. In the early stage of SCI, we used a remote monitoring system to monitor the whole process of uprise bed training, and we explored a safe and efficient method of electric uprise bed training.

MATERIAL AND METHODS

The experimental group consisted of 36 patients diagnosed with orthostatic hypotension (OH) after SCI and who received training with an electric uprise bed coupled with remote monitoring system, and the control group of 18 subjects who used a traditional training method.

RESULTS

There were no differences in baseline data between the 2 groups. There were no severe symptoms during training in the experimental group, but 3 patients had severe symptoms in the control group. Among the 32 enrolled subjects reaching upright training status within 30 days (17 subjects in the experimental group and 15 subjects in the control group), time interval of training from horizontal position to erect position in the experimental group was 18.00±3.12 days and 21.40±4.95 days in the control group. Time interval in the experimental group was significantly less than in the control group. However, among all 36 subjects, by combining results of follow-up, there was no significant difference of time interval of training from horizontal position to erect position between the experimental group and the control group. In the experimental group 90.52% of patients finished training compared to 78.19% in the control group (P<0.01). After training, values of OCs and OCd of the experimental group were lower than in the control group. There was no significant difference between groups in number of re-diagnosed OH.

CONCLUSIONS

Implementation of training with electric uprise bed coupled with remote monitoring system is generally safe for patients with OH after SCI. For patients who could reach standing training status within 30 days, implementation can improve efficiency of training by shortening time interval of training from horizontal position to erect position. It can increase orthostatic blood pressure change during position change.

Perioperative implications of the patient with autonomic dysfunction

PURPOSE OF REVIEW

The autonomic nervous system functions to control heart rate, blood pressure, respiratory rate, gastrointestinal motility, hormone release, and body temperature on a second-to-second basis. Here we summarize some of the latest literature on autonomic dysfunction, focusing primarily on the perioperative implications.

RECENT FINDINGS

The variety of autonomic dysfunction now extends to a large number of clinical conditions in which the cause or effect of the autonomic component is blurred. Methods for detecting dysautonomia can be as simple as performing a history and physical examination that includes orthostatic vital signs measured in both recumbent and vertical positions; however, specialized laboratories are required for definitive diagnosis. Heart rate variability monitoring is becoming more commonplace in the assessment and understanding of autonomic instability. Degenerative diseases of the autonomic nervous system include Parkinson's disease and multiple system atrophy, with the most serious manifestations being postural hypotension and paradoxical supine hypertension. Other conditions occur in which the autonomic dysfunction is only part of a larger disease process, such as diabetic autonomic neuropathy, traumatic brain injury, and spinal cord injury.

SUMMARY

Patients with dysautonomia often have unpredictable and paradoxical physiological responses to various perioperative stimuli. Knowledge of the underlying pathophysiology of their condition is required in order to reduce symptom exacerbation and limit morbidity and mortality during the perioperative period.

Right-sided infective endocarditis as a potentially fatal complication in patients with long-term refractory severe bradyarrhythmia after cervical spinal cord injury: A case report

Bradyarrhythmia is usually a spontaneously subsiding complication of cervical spinal cord injury. However, in severe cases, it can lead to cardiac arrest. We report a case of cervical spinal cord injury, complicated by right-sided infective endocarditis after the placement of a temporary pacing catheter in the right ventricle for severe bradyarrhythmia that led to cardiac arrest. Although the patient׳s condition was successfully treated by pacing catheter removal and pharmacological therapy, right-sided infective endocarditis would be a fatal complication in cases of cervical spinal cord injury where cardiac pacing is required for long-term refractory severe bradyarrhythmia.

Selective alpha adrenergic antagonist reduces severity of transient hypertension during sexual stimulation after spinal cord injury

On a daily basis, the majority of those with high-level spinal cord injury have autonomic dysreflexia, which describes a life-threatening episode of transient extreme hypertension (i.e., as high as 300 mm Hg) as many as 90% of people living with this condition. Unfortunately, ejaculation is a major initiating factor for autonomic dysreflexia, which discourages sexual activity. In order to obtain a sperm specimen, or for initial assessment of fertility, penile vibrostimulation is clinically performed. Nifedipine, a selective calcium channel blocker, is the most commonly prescribed pharmaceutical for a priori management of autonomic dysreflexia secondary to ejaculation or other causes; however, it is limited because of its potential exacerbation of low resting pressure, which also affects this population. The present study examined the effect of a short-acting selective α1 antagonist (prazosin) on autonomic dysreflexia severity using a randomized placebo trial during medically supervised penile vibrostimulation in six males with cervical spinal cord injury. Beat-by-beat blood pressure and heart rate were recorded throughout penile vibrostimulation during placebo and prazosin-treated days. The increase in systolic blood pressure was mitigated during vibrostimulation in subjects administered prazosin as compared with those administered placebo (+140±19 mm Hg vs. +96±14 mmHg; p<0.05). On average, the peak in systolic blood pressure was 46 mm Hg lower during penile vibrostimulation when patients were administered prazosin (p<0.05), whereas resting blood pressure was not affected. Prazosin appears to be effective at reducing the severity of autonomic dysreflexia during sexual stimulation in patients with spinal cord injury, without exacerbating resting hypotension in high-level spinal cord injury.

Immune dysfunction and chronic inflammation following spinal cord injury

STUDY DESIGN

Review article.

OBJECTIVES

The objective of this study is to provide an overview of the many factors that contribute to the chronic inflammatory state typically observed following spinal cord injury (SCI).

METHODS

Literature review.

RESULTS

Not applicable.

CONCLUSION

SCI is typically characterized by a low-grade inflammatory state due to a number of factors. As bidirectional communication exists between the nervous, endocrine and immune systems, damage to the spinal cord may translate into both endocrinal and immune impairment. Damage to the autonomic nervous system may induce immune dysfunction directly, through the loss of neural innervation of lymphoid organs, or indirectly by inducing endocrinal impairment. In addition, damage to the somatic nervous system and the corresponding loss of motor and sensory function increases the likelihood of developing a number of secondary health complications and metabolic disorders associated with a state of inflammation. Lastly, numerous related disorders associated with a state of chronic inflammation have been found to be at a substantially higher prevalence following SCI. Together, such factors help explain the chronic inflammatory state and immune impairment typically observed following SCI. An understanding of the interactions between systems, both in health and disease, and the many causes of chronic inflammation may aid in the effective future treatment of immune dysfunction and related disorders following SCI.

Catabolic signaling and muscle wasting after acute ischemic stroke in mice: indication for a stroke-specific sarcopenia

BACKGROUND AND PURPOSE

Muscle wasting is a common complication accompanying stroke. Although it is known to impair poststroke recovery, the mechanisms of subacute catabolism after stroke have not been investigated in detail. The aim of this study is to investigate mechanisms of local and systemic catabolism and muscle wasting (sarcopenia) in a model of ischemic stroke systematically.

METHODS

Changes in body composition and catabolic activation in muscle tissue were studied in a mouse model of acute cerebral ischemia (temporal occlusion of the middle cerebral artery). Tissue wasting (nuclear magnetic resonance spectroscopy), tissue catabolism (caspases-3 and -6, myostatin), and proteasome activity were assessed. Food intake, activity levels, and energy expenditure were assessed, and putative mechanisms of postischemic wasting were tested with appropriate interventions.

RESULTS

Severe weight loss in stroke animals (day 3: weight loss, -21.7%) encompassed wasting of muscle (-12%; skeletal and myocardium) and fat tissue (-27%). Catabolic signaling and proteasome activity were higher in stroke animals in the contralateral and in the ipsilateral leg. Cerebral infarct severity correlated with catabolic activity only in the contralateral leg but not in the ipsilateral leg. Lower energy expenditure in stroke animals together with normal food intake and activity levels suggests compensatory mechanisms to regain weight. Interventions (high caloric feeding, β-receptor blockade, and antibiotic treatment) failed to prevent proteolytic activation and muscle wasting.

CONCLUSIONS

Catabolic pathways of muscle tissue are activated after stroke. Impaired feeding, sympathetic overactivation, or infection cannot fully explain this catabolic activation. Wasting of the target muscle of the disrupted innervation correlated to severity of brain injury. Our data indicate the presence of a stroke-specific sarcopenia.

Reprint of "Drawing breath without the command of effectors: the control of respiration following spinal cord injury"

The maintenance of blood gas and pH homeostasis is essential to life. As such breathing, and the mechanisms which control ventilation, must be tightly regulated yet highly plastic and dynamic. However, injury to the spinal cord prevents the medullary areas which control respiration from connecting to respiratory effectors and feedback mechanisms below the level of the lesion. This trauma typically leads to severe and permanent functional deficits in the respiratory motor system. However, endogenous mechanisms of plasticity occur following spinal cord injury to facilitate respiration and help recover pulmonary ventilation. These mechanisms include the activation of spared or latent pathways, endogenous sprouting or synaptogenesis, and the possible formation of new respiratory control centres. Acting in combination, these processes provide a means to facilitate respiratory support following spinal cord trauma. However, they are by no means sufficient to return pulmonary function to pre-injury levels. A major challenge in the study of spinal cord injury is to understand and enhance the systems of endogenous plasticity which arise to facilitate respiration to mediate effective treatments for pulmonary dysfunction.

Autonomic cardiovascular control in Paralympic athletes with spinal cord injury

INTRODUCTION

Disruption of autonomic control after spinal cord injury (SCI) results in life-threatening cardiovascular dysfunctions and impaired endurance performance; hence, an improved ability to recognize those at risk of autonomic disturbances is of critical clinical and sporting importance.

PURPOSE

The objective of this study is to assess the effect of neurological level, along with motor, sensory, and autonomic completeness of injury, on cardiovascular control in Paralympic athletes with SCI.

METHODS

Fifty-two highly trained male Paralympic athletes (age, 34.8 ± 7.1 yr) from 14 countries with chronic SCI (C2-L2) completed three experimental trials. During trial 1, motor and sensory functions were assessed according to the American Spinal Injury Association Impairment Scale. During trial 2, autonomic function was assessed via sympathetic skin responses (SSR). During trial 3, cardiovascular control was assessed via the beat-by-beat blood pressure response to orthostatic challenge.

RESULTS

Athletes with cervical SCI exhibited the lowest seated blood pressure and the most severe orthostatic hypotension (P < 0.025). There were no differences in cardiovascular function between athletes with different American Spinal Injury Association Impairment Scale grades (P > 0.96). Conversely, those with the lowest SSR scores exhibited the lowest seated blood pressure and the most severe orthostatic hypotension (P < 0.002). Linear regression demonstrated that the combined model of neurological level and autonomic completeness of SCI explained the most variance in all blood pressure indices.

CONCLUSION

We demonstrate for the first time that neurological level and SSR score provide the optimal combination of assessments to identify those at risk of abnormal cardiovascular control. We advocate the use of autonomic testing in the clinical and sporting classification of SCI athletes.

The "ABCs of AD": A pilot test of an online educational module to increase use of the autonomic dysreflexia clinical practice guidelines among paramedic and nurse trainees

CONTEXT/OBJECTIVE

Despite availability of clinical practice guidelines (CPGs), gaps in autonomic dysreflexia (AD) knowledge and practice persist. A free, online educational module, the "ABCs of AD", was developed to improve knowledge of the AD-CPGs among emergency healthcare personnel. We examine short-term changes in paramedic and nurse trainees' knowledge of, and social cognitions towards using, the AD-CPGs following module completion.

DESIGN

Pre-post.

METHODS

Thirty-four paramedic and nurse trainees from two training programs in Canada completed measures immediately before and after viewing the online "ABCs of AD" module.

OUTCOME MEASURES

AD knowledge test; Theory of Planned Behavior social cognition questionnaire; module feedback survey.

RESULTS

Paired samples t-tests revealed significant increases in participants' AD knowledge test scores (M ± SDpre = 9.00 ± 2.46, M ± SDpost = 12.03 ± 4.07, P < 0.001; d = 0.84). Prior to viewing the module, participants reported positive social cognitions for using the AD-CPGs (all Ms ≥ 4.84 out of 7). From pre- to post-module, no significant changes were seen in participants' social cognitions for using the AD-CPGs. Participants' average module viewing time was 36.73 ± 24.17 minutes (range 8-90 minutes). There was a decline in viewing from the first to the last module sections, with only half of participants viewing all six sections.

CONCLUSION

Knowledge alone is insufficient for clinical behavior change; as such, social cognitive determinants of behavior should be explicitly targeted in future iterations of the module to increase the likelihood of increased use of the AD-CPGs. To engage viewers across all module sections, the "ABCs of AD" module should include supplementary learning strategies, such as interactive quizzes and peer-to-peer interaction.