Transcutaneous spinal cord stimulation and its impact on cardiovascular autonomic regulation after spinal cord injury.

Individuals with spinal cord injury (SCI) have significant dysfunction in cardiovascular autonomic regulation. Although recent findings postulate that spinal cord stimulation improves autonomic regulation, limited scope of past methods have tested only above level sympathetic activation, leaving significant uncertainty. To identify whether transcutaneous spinal cord stimulation improves cardiovascular autonomic regulation, two pairs of well-matched individuals with and without high thoracic, complete SCI were recruited. Baseline autonomic regulation was characterized with multiple tests of sympathoinhibition and above/below injury level sympathoexcitation. At three subsequent visits, testing was repeated with the addition submotor threshold transcutaneous spinal cord stimulation at three previously advocated frequencies. Uninjured controls demonstrated no autonomic deficits at baseline and had no changes with any frequency of stimulation. 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 with 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 cardiovascular autonomic regulation. Collectively, transcutaneous spinal cord stimulation demonstrates no improvements in autonomic regulation after SCI, and instead likely generates tonic sympathoexcitation which may lower the threshold for dangerous autonomic dysreflexia.NEW & NOTEWORTHY Spinal cord stimulation increases blood pressure after spinal cord injury, though it is unclear if this restores natural autonomic regulation or induces a potentially dangerous pathological reflex. We performed comprehensive autonomic testing batteries, with and without transcutaneous spinal cord stimulation at multiple frequencies. Across 96 independent tests, stimulation did not change uninjured control responses, though all frequencies facilitated pathological reflexes without improved autonomic regulation for those with spinal cord injuries.

Autonomic dysreflexia in spinal cord injury.

Autonomic dysreflexia is a relatively common condition in people who have a spinal cord injury above the level of T6. It is a potentially life-threatening; without timely and effective treatment, it can have deleterious cardiophysiological and systemic consequences. It is therefore imperative for medical professionals to have a clear understanding of its acute management, and be prepared to provide support and education to those caring for at-risk patients. In this paper we provide practical guidance and supporting evidence regarding the management of autonomic dysreflexia in adults with spinal cord injury.

[Autonomic hyperreflexia after spinal cord injury : perioperative management]. / L'hyperréflexie autonome après lésion médullaire : prise en charge en période périopératoire.

Spinal cord injury can have widespread consequences beyond the disruption of sensory and motor functions. Injury at or above the sixth thoracic spinal cord segment frequently leads to dysregulation of the autonomic nervous system, which results in a syndrome called autonomic hyperreflexia or dysreflexia. It is a hypertensive crisis triggered by visceral or somatic stimuli below the level of the injury and caused by sympathetic spinal reflexes not modulated by regulatory centers in the brain. Patients with spinal cord injuries frequently undergo surgery for multiple reasons. Because of the potentially lethal complications of autonomic hyperreflexia, physicians, and in particular anaesthesiologists, must be aware of the underlying pathophysiological mechanisms and adequate perioperative management.

Les lésions de la moelle épinière peuvent avoir de nombreuses conséquences autres que la perturbation des fonctions sensitives et motrices. Une lésion d'un niveau médullaire supérieur ou égal au sixième segment thoracique (T6) entraîne, fréquemment, une dysrégulation du système nerveux autonome et le développement d'un syndrome appelé hyperréflexie ou dysréflexie autonome. Il s'agit d'une crise hypertensive déclenchée par des stimuli viscéraux ou somatiques sous le niveau de la lésion et causée par des réflexes sympathiques médullaires non modulés par les centres régulateurs encéphaliques. Les patients porteurs de lésions médullaires bénéficient, régulièrement, d'interventions chirurgicales pour des raisons multiples. Les complications potentiellement létales de l'hyperréflexie autonome exigent des médecins et, en particulier, des anesthésistes-réanimateurs une connaissance des mécanismes physiopathologiques sous-jacents et une prise en charge péri-interventionnelle adéquate.

The Blood Pressure Pendulum following Spinal Cord Injury: Implications for Vascular Cognitive Impairment.

Cognitive impairment following spinal cord injury (SCI) has received considerable attention in recent years. Among the various systemic effects of SCI that contribute towards cognitive decline in this population, cardiovascular dysfunction is arguably one of the most significant. The majority of individuals with a cervical or upper-thoracic SCI commonly experience conditions called orthostatic hypotension and autonomic dysreflexia, which are characterized by dangerous fluctuations in systemic blood pressure (BP). Herein, we review the potential impact of extreme BP lability on vascular cognitive impairment (VCI) in individuals with SCI. Albeit preliminary in the SCI population, there is convincing evidence that chronic hypotension and hypertension in able-bodied individuals results in devastating impairments in cerebrovascular health, leading to VCI. We discuss the pertinent literature, and while drawing mechanistic comparisons between able-bodied cohorts and individuals with SCI, we emphasize the need for additional research to elucidate the mechanisms of cognitive impairment specific to the SCI population. Lastly, we highlight the current and potential future therapies to manage and treat BP instability, thereby possibly mitigating VCI in the SCI population.

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).

[AUTONOMIC DYSREFLEXIA].

Autonomic dysreflexia (AD) is a syndrome that occurs in patients with high spinal cord lesion. It is caused by activation of sympathetic nervous system by a noxious stimulus below the level of injury, usually consisting of distention and/or irritation of the bladder or constipation. Sympathetic system activation leads to blood pressure elevation because compensatory mechanisms cannot properly regulate blood pressure due to the spinal cord lesions. The most important manifestation of AD is arterial hypertension because of the possible cerebrovascular and cardiovascular complications, including death. Initial treatment consists of recognition of the symptoms and resolution of the cause. In patients with high blood pressure antihypertensive therapy is initiated (with nifedipine, captopril and nitroglycerin). Prevention is also a very important task, with the goal of influencing all possible triggers of this condition, specially micturition and colon disorders. One of the most important tasks is educating patients, their caregivers and health professionals about AD.

[Anesthesiological approach for patients with spinal cord injuries]. / Anästhesiologisches Vorgehen bei Patienten mit spinalem Querschnitt.

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.

Motherhood after Spinal Cord Injury: Breastfeeding, Autonomic Dysreflexia, and Psychosocial Health: Clinical Practice Guidelines.

The World Health Organization (WHO) recommends that children be breastfed exclusively for the first 6 months of age. This recommendation may prove challenging for women with spinal cord injury (SCI) who face unique challenges and barriers to breastfeeding due to the impact of SCI on mobility and physiology. Tailored provision of care from health care professionals (HCPs) is important in helping women navigate these potential barriers. Yet, HCPs often lack the confidence and SCI-specific knowledge to meet the needs of mothers with SCI. An international panel of clinicians, researchers, consultants, and women with lived experience was formed to create an accessible resource that can address this gap. A comprehensive survey on breastfeeding complications, challenges, resources, and quality of life of mothers with SCI was conducted, along with an environmental scan to evaluate existing postpartum guidelines and assess their relevance and usability as recommendations for breastfeeding after SCI. Building on this work, this article provides evidence-based recommendations for HCPs, including but not limited to general practitioners, obstetricians, pediatricians, physiatrists, lactation consultants, nurses, midwives, occupational therapists, and physiotherapists who work with prospective and current mothers with SCI.

Advancing spinal cord injury care through non-invasive autonomic dysreflexia detection with AI.

This paper presents an AI-powered solution for detecting and monitoring Autonomic Dysreflexia (AD) in individuals with spinal cord injuries. Current AD detection methods are limited, lacking non-invasive monitoring systems. We propose a model that combines skin nerve activity (SKNA) signals with a deep neural network (DNN) architecture to overcome this limitation. The DNN is trained on a meticulously curated dataset obtained through controlled colorectal distension, inducing AD events in rats with spinal cord surgery above the T6 level. The proposed system achieves an impressive average classification accuracy of 93.9% ± 2.5%, ensuring accurate AD identification with high precision (95.2% ± 2.1%). It demonstrates a balanced performance with an average F1 score of 94.4% ± 1.8%, indicating a harmonious balance between precision and recall. Additionally, the system exhibits a low average false-negative rate of 4.8% ± 1.6%, minimizing the misclassification of non-AD cases. The robustness and generalizability of the system are validated on unseen data, maintaining high accuracy, F1 score, and a low false-negative rate. This AI-powered solution represents a significant advancement in non-invasive, real-time AD monitoring, with the potential to improve patient outcomes and enhance AD management in individuals with spinal cord injuries. This research contributes a promising solution to the critical healthcare challenge of AD detection and monitoring.

Symptomatic Treatment of Myelopathy.

OBJECTIVE: This article discusses the effects of myelopathy on multiple organ systems and reviews the treatment and management of some of these effects. LATEST DEVELOPMENTS: Recent advances in functional electrical stimulation, epidural spinal cord stimulation, robotics, and surgical techniques such as nerve transfer show promise in improving function in patients with myelopathy. Ongoing research in stem cell therapy and neurotherapeutic drugs may provide further therapeutic avenues in the future. ESSENTIAL POINTS: Treatment for symptoms of spinal cord injury should be targeted toward patient goals. If nerve transfer for upper extremity function is considered, the patient should be evaluated at around 6 months from injury to assess for lower motor neuron involvement and possible time limitations of surgery. A patient with injury at or above the T6 level is at risk for autonomic dysreflexia, a life-threatening condition that presents with elevated blood pressure and can lead to emergent hypertensive crisis. Baclofen withdrawal due to baclofen pump failure or programming errors may also be life-threatening. Proper management of symptoms may help avoid complications such as autonomic dysreflexia, renal failure, heterotopic ossification, and fractures.

Impact of annual urodynamic evaluations on guiding bladder management in individuals with spinal cord injuries.

STUDY DESIGN: A single-center institutional review board-approved prospective cross-sectional observational study. CONTEXT: Urodynamic studies are essential to accurately direct bladder management following spinal cord injury (SCI). There is no consensus on how often testing should be performed. OBJECTIVE: To determine the impact of annual urodynamic studies on guiding bladder management following SCI. METHODS: Individuals with traumatic SCI undergoing annual urological evaluations were enrolled in this study. They had to be injured for at least 2 years so that urodynamic changes could be compared with their previous annual urodynamic evaluation. Changes in the urodynamic parameters and autonomic dysreflexia were determined by comparing this study with the previous year's study. All studies were done with the same physician and nursing staff. Demographic data, bladder management, urodynamic parameters, and the need and type of interventions based on the urodynamic study were obtained. The main outcome measure was whether or not there was a need for an intervention based on the urodynamics. Interventions were classified as urological intervention, non-urological intervention, or a combination of urological and non-urological intervention. The impact of the type of bladder management, length of injury, and level of injury was also evaluated. RESULTS: Ninety-six consecutive individuals with SCI undergoing annual urodynamic evaluations were enrolled over a 5-month period. Overall, 47.9% of individuals required at least one type of intervention based on urodynamic studies: 82.6% were urological interventions (medication changes were most common, comprising 54.3% of urological interventions); 13.0% were non-urological interventions; and 4.3% were a combination of non-urological and urological interventions. The need for interventions did not appear to be influenced by the type of bladder management, the length of time post-injury or level of injury. CONCLUSION: Annual urodynamic evaluation plays an important role in guiding bladder management following SCI.

Sexual function and autonomic dysreflexia in men with spinal cord injuries: how should we treat?

STUDY DESIGN: Systematic review. OBJECTIVES: Review the literature on the acute or prophylactic treatment of autonomic dysreflexia in the context of sexual activities. SETTING: International. METHODS: Medline search using AD and spinal cord injury and all years of publication. RESULTS: Thirty-seven papers on the specific treatment of AD showed that nifedipine, prazosin, captopril and clonidine are candidates in the context of sexual activities. Prazosin, however, has an initial hypotensive effect requiring to begin treatment 12 h before intercourse, which makes it less ideal for spontaneous sexual activities. Captopril has an initial hypotensive effect and was only studied in acute AD. Its usefulness in prophylaxis remains to be demonstrated. Clonidine has successfully been used clinically for decades, but never studied in randomized control trials. Nifedipine remains the most widely studied and significant treatment of AD whether in acute or prophylactic conditions. Recent concerns suggest increased cardiovascular risks with sublingual nifedipine in non-SCI populations, but negative long-term effects have not been reported in the SCI population. CONCLUSION: Sexual function is a priority for men with SCI. As sexual activities, in particular ejaculation, can be a source of AD, adequate treatments and prophylaxis must be considered in the context of sexual activities. Experts must meet and conclude on the thresholds, parameters and treatments that should be considered in the long-term management of AD in the context of sexual function in men with SCI.

Autonomic dysreflexia: recognizing a common serious condition in patients with spinal cord injury.

OBJECTIVE: To raise family physicians' awareness of autonomic dysreflexia (AD) in patients with spinal cord injury (SCI) and to provide some suggestions for intervention. SOURCES OF INFORMATION: MEDLINE was searched from 1970 to July 2011 using the terms autonomic dysreflexia and spinal cord injury with family medicine or primary care. Other relevant guidelines and resources were reviewed and used. MAIN MESSAGE: Family physicians often lack confidence in treating patients with SCI, see them as complex and time-consuming, and feel undertrained to meet their needs. Family physicians provide a vital component of the health care of such patients, and understanding of the unique medical conditions related to SCI is important. Autonomic dysreflexia is an important, common, and potentially serious condition with which many family physicians are unfamiliar. This article will review the signs and symptoms of AD and offer some acute management options and preventive strategies for family physicians. CONCLUSION: Family physicians should be aware of which patients with SCI are susceptible to AD and monitor those affected by it. Outlined is an approach to acute management. Family physicians play a pivotal role in prevention of AD through education (of the patient and other health care providers) and incorporation of strategies such as appropriate bladder, bowel, and skin care practices and warnings and management plans in the medical chart.

[Cardiac arrest in a 10-month-old boy with spinal cord injury]. / Hjertestans hos en ti måneder gammel gutt med ryggmargsskade.

A 10-month-old boy with a previous upper spinal cord injury was admitted to hospital with acute respiratory and circulatory distress. Shortly after admission the boy had severe bradycardia leading to asystolia and pulseless electrical activity. He was successfully resuscitated, and the investigation that followed excluded infection, congenital heart defect, arrhythmia and cerebral haemorrhage. Over the following days the patient had several episodes of isolated bradycardia and combined bradycardia and hypotension. It was concluded that the patient suffered from autonomic dysreflexia, triggered by a distended urinary bladder. He was treated with intermittent catheterization and a permanent pacemaker, and after 12 months there have not been any symptomatic episodes or registered arrhythmias. Autonomic dysreflexia is a common and well known complication of spinal cord injury above Th6, but the literature on paediatric patients is scarce. Our case report presents an infant with an atypical and severe episode of autonomic dysreflexia. Patients with spinal cord injury, their caregivers and health-care personal should be aware of this complication of spinal cord injury, in order to prevent and treat autonomic dysreflexia properly and avoid potentially fatal episodes.

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.

Remifentanil decreases sevoflurane requirements to block autonomic hyperreflexia during transurethral litholapaxy in patients with high complete spinal cord injury.

BACKGROUND: An inhaled anesthetic concentration required to block autonomic hyperreflexia (AHR) is high enough to cause severe hypotension in patients with high spinal cord injury (SCI). We determined the effects of remifentanil on the sevoflurane requirement to block AHR in SCI. METHODS: The study involved 96 patients with chronic, complete SCI scheduled to undergo transurethral litholapaxy during general anesthesia. Anesthesia was induced with thiopental, and sevoflurane concentrations in 50% nitrous oxide were adjusted to maintain a bispectral index of 40 to 50. Whether the patient develops an AHR [an increase of systolic blood pressure (SBP) >20 to 40 mm Hg] was first examined by distending the bladder with glycine solution (the first trial). Patients who developed AHR were then allocated to receive no remifentanil infusion (control, n = 31), a target-controlled plasma concentration of 1 ng/mL (n = 25), or 3 ng/mL remifentanil (n = 24). After baseline hemodynamics had recovered, the target sevoflurane and remifentanil concentrations were maintained for at least 20 minutes and the procedure was resumed (the second trial). Each target sevoflurane concentration was determined by the up-and-down method based on changes (15% increase or more) of SBP in response to the bladder distension. SBP, heart rate, and bispectral index were measured before and during the bladder distension during the trials, and plasma concentrations of catecholamines during the first trial. RESULTS: Eighty-two (85.4%) of 96 patients developed AHR during the first trial, in which 2 were excluded because of hypotension (mean arterial blood pressure <50 mm Hg) developed during target-controlled drug administration. During the second trial, the end-tidal concentrations of sevoflurane to prevent AHR were reduced to 2.6% (95% confidence interval 2.5% to 2.8%, P < 0.01) and 2.2% (2.1% to 2.4%, P < 0.0001) in the groups receiving 1 and 3 ng/mL remifentanil, respectively, in comparison with 3.1% (2.9% to 3.3%) in the control. When considering minimum anesthetic concentration (MAC) values and the contribution of 50% nitrous oxide (0.48 MAC), the combined MAC values, expressed as multiples of MAC, were 2.27, 1.98, and 1.75 in the control, 1 ng/mL remifentanil, and 3 ng/mL remifentanil groups, respectively. CONCLUSIONS: Target-controlled concentrations of 1 and 3 ng/mL remifentanil would reduce the requirement of sevoflurane combined with 50% nitrous oxide to block AHR by 16% and 29%, respectively, in SCI patients undergoing transurethral litholapaxy.

Safety and preliminary efficacy of functional electrical stimulation cycling in an individual with cervical cord injury, autonomic dysreflexia, and a pacemaker: Case report.

Context: Functional electric stimulation (FES) cycling is a commonly used therapeutic exercise modality after spinal cord injury (SCI); however, additional precautions must be taken in certain situations. The purpose of this study was to develop and apply a safety monitoring protocol for autonomic dysreflexia (AD) during FES cycling and to determine if an interval-FES cycling program can be safe and beneficial to an individual with cervical SCI, a history of AD, and a non-dependent cardiac pacemaker.The participant was a 36-year-old male with C6 AIS-C SCI sustained 9 years earlier, intermittent AD, and implanted cardiac pacemaker. Ten sessions of interval-FES cycling were performed twice weekly for 5 weeks. Rating of perceived exertion (RPE), blood pressure (BP), oxygen saturation (O2sat), and heart rate (HR) were monitored before, after, and every 5 min during cycling. ECG and cardiac pacemaker were evaluated by a cardiologist after ending the program.Findings: The participant reported self-limited chills 27 times over 10 sessions (19 "light", 3 "moderate", 5 "sharp"). Chills coincided with BP increases 59% of the time and their magnitudes moderately correlated (r = 0.32). The ECG was determined to be normal and the pacemaker fully functional at the end of the study, while blood glucose decreased (111-105 mg/dl), HbA1c levels increased (5.5-5.9%), and resting BP decreased (118/84-108/66 mmHg).Conclusion/Clinical Relevance: A person with cervical SCI, symptomatic AD, and a non-dependent pacemaker can safely participate and benefit from the interval-FES cycling program provided adequate monitoring of symptoms and vital signs.