Evaluation of captopril for the management of hypertension in autonomic dysreflexia: a pilot study

Autonomic Dysreflexia in Spinal Cord Injury: Mechanisms and Prospective Therapeutic Targets

High-level spinal cord injury (SCI) often results in cardiovascular dysfunction, especially the development of autonomic dysreflexia. This disorder, characterized as an episode of hypertension accompanied by bradycardia in response to visceral or somatic stimuli, causes substantial discomfort and potentially life-threatening symptoms. The neural mechanisms underlying this dysautonomia include a loss of supraspinal control to spinal sympathetic neurons, maladaptive plasticity of sensory inputs and propriospinal interneurons, and excessive discharge of sympathetic preganglionic neurons. While neural control of cardiovascular function is largely disrupted after SCI, the renin-angiotensin system (RAS), which mediates blood pressure through hormonal mechanisms, is up-regulated after injury. Whether the RAS engages in autonomic dysreflexia, however, is still controversial. Regarding therapeutics, transplantation of embryonic presympathetic neurons, collected from the brainstem or more specific raphe regions, into the injured spinal cord may reestablish supraspinal regulation of sympathetic activity for cardiovascular improvement. This treatment reduces the occurrence of spontaneous autonomic dysreflexia and the severity of artificially triggered dysreflexic responses in rodent SCI models. Though transplanting early-stage neurons improves neural regulation of blood pressure, hormonal regulation remains high and baroreflex dysfunction persists. Therefore, cell transplantation combined with selected RAS inhibition may enhance neuroendocrine homeostasis for cardiovascular recovery after SCI.

Autonomic dysreflexia associated with cervical spinal cord gliofibroma: case report

BACKGROUND

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

CASE PRESENTATION

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

CONCLUSIONS

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

Evaluation of the clinical outcome of captopril use for hypertensive urgency in Khartoum State's emergency centres

Background

Captopril is an important drug and is used to control hypertensive urgency world-wide. But there is very little data available regarding the evaluation of its outcomes in hypertensive urgency among African patients. This study aimed to evaluate the clinical outcomes of captopril use for hypertensive urgency at a selection of Sudanese emergency centres.

Methods

This was a cross-sectional study, conducted between 15 to 30 November 2015. A total of 50 patients, attending a selection of Khartoum State hospital emergency centres, with a clinical diagnosis of hypertensive urgency were approached by investigators for the study. Dose regimen, prognosis, and reduction in systolic and diastolic blood pressure were collected alongside a questionaire to patients regarding their care (compliance, etc.). Data were analysed using the Chi-square Test to compare the mean differences for various results. Differences were considered to be significant at P < 0.05.

Results

Around two-thirds (60%) of participants were female, and 28% were non-compliant with treatment. A 25mg dose of captopril was the most frequently used dose. Most of the patients (66%) did not have pre-existing disease. The majority of patients showed an improved blood pressure: both systolic and diastolic blood pressures were reduced by 16-25% and 5-15%, respectively.

Conclusion

The study concluded that the dose of 25 mg of captopril is effective in managing hypertensive urgency and controlling the blood pressure. We also recommend that patients receiving captopril must be observed in the emergency centre for further evaluation.

Distinct roles of angiotensin receptors in autonomic dysreflexia following high-level spinal cord injury in mice

Autonomic dysreflexia (AD), a syndrome caused by loss of supraspinal control over sympathetic activity and amplified vascular reflex upon sensory stimuli below injury level, is a major health problem in high-level spinal cord injury (SCI). After supraspinal sympathetic control of the vasculature below the lesion is lost, the renin-angiotensin system (RAS) is thought to be involved in AD by regulating blood pressure and vascular reactivity. In this study, we aimed to assess the role of different RAS receptors during AD following SCI. Therefore, we induced AD by colorectal distention (CRD) in wild-type mice and mice deficient in the RAS components angiotensin (Ang) II type 1a receptor (AT1a) (Agtr1a^-/-) and Ang-(1-7) receptor Mas (Mas^-/-) four weeks after complete transection of spinal cord at thoracic level 4 (T4). Systemic blood pressure measurements and wire myography technique were performed to assess hemodynamics and the reactivity of peripheral arteries, respectively. CRD increased mean arterial blood pressure (MAP) and decreased heart rate (HR) in all three animal groups. However, we found less increases in MAP in Mas^-/- mice compared to control mice after CRD, whereas AT1a deficiency did not affect the hemodynamic response. We found that the reactivity of wild-type and Mas^-/- mesenteric arteries, which are innervated from ganglia distal but close to thoracic level T4, was diminished in response to Ang II in AD after T4-SCI, but this difference was not observed in the absence of AT1a receptors. CRD did not influence the reactivity of femoral arteries which are innervated from ganglia more distal to thoracic level T4, in response to Ang II in AD. In conclusion, we identified a specific role of the Ang-(1-7) receptor Mas in regulating the systemic blood pressure increase in AD in T4-SCI mice. Furthermore, AT1a signaling is not involved in this hemodynamic response, but underlies increased vascular reactivity in mesenteric arteries in response to Ang II, where it may contribute to adaptive changes in regional blood flow.

Autonomic dysreflexia after spinal cord injury: Systemic pathophysiology and methods of management

Traumatic spinal cord injury (SCI) has widespread physiological effects beyond the disruption of sensory and motor function, notably the loss of normal autonomic and cardiovascular control. Injury at or above the sixth thoracic spinal cord segment segregates critical spinal sympathetic neurons from supraspinal modulation which can result in a syndrome known as autonomic dysreflexia (AD). AD is defined as episodic hypertension and concomitant baroreflex-mediated bradycardia initiated by unmodulated sympathetic reflexes in the decentralized cord. This condition is often triggered by noxious yet unperceived visceral or somatic stimuli below the injury level and if severe enough can require immediate medical attention. Herein, we review the pathophysiological mechanisms germane to the development of AD, including maladaptive plasticity of neural circuits mediating abnormal sympathetic reflexes and hypersensitization of peripheral vasculature that collectively contribute to abnormal hemodynamics after SCI. Further, we discuss the systemic effects of recurrent AD and pharmacological treatments used to manage such episodes. Contemporary research avenues are then presented to better understand the relative contributions of underlying mechanisms and to elucidate the effects of recurring AD on cardiovascular and immune functions for developing more targeted and effective treatments to attenuate the development of this insidious syndrome following high-level SCI.

A retrospective review of safety using a nursing driven protocol for autonomic dysreflexia in patients with spinal cord injuries

OBJECTIVE/BACKGROUND

Autonomic dysreflexia is a potentially life-threatening condition which afflicts a significant proportion of individuals with spinal cord injuries (SCI). To date, the safety and efficacy of several commonly used interventions for this condition have not been studied.

DESIGN

A retrospective chart review of the safety of a previously implemented nursing driven inpatient autonomic dysreflexia protocol.

METHODS

Seventy-eight male patients with SCI who experienced autonomic dysreflexia while inpatient at our Veterans Affairs SCI unit over a 3-1/2-year period were included. The safety of a nursing driven protocol utilizing conservative measures, nitroglycerin paste, and oral hydralazine was evaluated.

OUTCOME MEASURES

Occurrence of adverse events and relative hypotensive events during all episodes treated with the protocol, and efficacy of attaining target blood pressure for all episodes with protocol adherence and for initial episode experienced by each patient.

RESULTS

Four hundred forty-five episodes of autonomic dysreflexia were recorded in the study period, with 92% adherence to the protocol. When the protocol was followed, target blood pressure was achieved for 97.6% of all episodes. Twenty-three total adverse events occurred (5.2% of all episodes). All adverse events were due to hypotension and only 0.9% required interventions beyond clinical monitoring. Of each patient's initial autonomic dysreflexia episode, 97.3% resolved using the protocol without need for further escalation of care.

CONCLUSION

This inpatient nursing driven-protocol for treating autonomic dysreflexia utilizing conservative measures, nitroglycerin paste and oral hydralazine achieved target blood pressure with a high success rate and a low incidence of adverse events.

Prevention of recurrent autonomic dysreflexia: a survey of current practice

OBJECTIVE

There is a dearth of literature on the treatment of chronic recurrent autonomic dysreflexia (AD), a well-known complication of spinal cord injury that can have life-threatening implications. This study sought to identify clinical practices regarding the treatment of AD, both acute and recurrent, in patients with spinal cord injury (SCI).

METHODS

Online survey regarding AD management in SCI composed of 11 questions designed to obtain information on respondent characteristics, AD treatment options, and causes of AD.

SETTING

Veterans Administration health care system.

PARTICIPANTS

Veterans Health Administration National SCI Staff Physicians were sent an electronic email to participate in the anonymous web-based survey.

INTERVENTION

None applicable.

RESULTS

The response rate was 52%. The most commonly prescribed medications for minor and severe acute manifestations of AD were nitrates. For recurrent AD, clonidine was the most commonly prescribed medication.

INTERPRETATION

Anti-hypertensive medications continue to be the mainstay in the management of both acute and chronic recurrent AD. Current literature is lacking in prospective randomized controlled trials investigating the relative efficacy of AD interventions. Evidence-based practice guidelines are necessary to improve clinical care.

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.

Infertility in men with spinal cord injury: research and treatment

Spinal cord injury (SCI) occurs most often to young men. Following SCI, most men are infertile due to a combination of erectile dysfunction, ejaculatory dysfunction and semen abnormalities. Erectile dysfunction may be treated by the same therapies that are used in the general population. Similarly, the same treatments that are effective to assist conception in couples with non-SCI male factor patients are effective in assisting conception in SCI male-factor patients. The most apparent differences in male-factor symptoms between SCI and non-SCI patients are the high occurrences of anejaculation and atypical semen profiles in men with SCI. Methods available to assist ejaculation in men with SCI include penile vibratory stimulation and EEJ. Use of surgical sperm retrieval as the first line of treatment for anejaculation in men with SCI is controversial. Most men with SCI have a unique semen profile characterized by normal sperm concentration, but abnormally low sperm motility. Toxic substances in the semen contribute to this problem. Despite impaired sperm parameters, pregnancy outcomes using sperm from men with SCI are similar to pregnancy outcomes using sperm from non-SCI men. Future studies should focus on improving natural ejaculation and improving semen quality in these men.

Cardiovascular complications of spinal cord injury

BACKGROUND

The aim of this paper is to provide an overview of the autonomic innervation of the cardiovascular system and the cardiovascular sequelae of spinal cord injuries.

METHOD

A literature search was carried out in the PubMed database, with the search phrases "traumatic spinal cord injury"/"traumatic spinal cord injuries" together with "autonomic dysfunction", "autonomic dysreflexia" and "cardiovascular disease".

RESULTS

The most important cardiovascular complications in the acute phase are bradyarrhythmia, hypotension, enhanced vasovagal reflexes, supraventricular/ventricular ectopic beats, vasodilation and venous stasis. Important in the chronic phase are orthostatic hypotension and impaired regulation of blood pressure, blood volume and body temperature. Tetraplegia is frequently accompanied by autonomic dysreflexia, impaired transmission of cardial pain, loss of muscle mass in the left ventricle and pseudoinfarction. Patients with injuries above the sixth thoracic vertebra have a predisposition for autonomic dysreflexia. This is a condition characterised by sudden, uncontrolled sympathetic response accompanied by a rise in blood pressure. Autonomic dysreflexia usually leads to headaches and erythema on the upper chest. The condition may cause cerebral haemorrhage and is potentially life threatening. Patients with spinal cord injuries have an increased risk of atherosclerotic disease due to overweight, lipid disorders, metabolic syndrome and diabetes. They are predisposed to thrombotic emboli due to venous stasis and hypercoagulopathy, particularly immediately after the injury.

INTERPRETATION

Knowledge of cardiovascular sequelae after spinal cord injuries and assessment of these is important for correct diagnostics, planning of preventive measures and optimal treatment.

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.

Treatment of infertility in men with spinal cord injury

Most men with spinal cord injury (SCI) are infertile. Erectile dysfunction, ejaculatory dysfunction and semen abnormalities contribute to the problem. Treatments for erectile dysfunction include phosphodiesterase type 5 inhibitors, intracavernous injections of alprostadil, penile prostheses, and vacuum constriction devices. In anejaculatory patients who wish to father children, semen retrieval is necessary. Penile vibratory stimulation is recommended as the first line of treatment. Patients who fail penile vibratory stimulation can be referred for electroejaculation. If this approach is not possible, prostate massage is an alternative. Surgical sperm retrieval should be considered as a last resort when other methods fail. Most men with SCI have a unique semen profile characterized by normal sperm count but abnormally low sperm motility. Scientific investigations indicate that accessory gland dysfunction and abnormal semen constituents contribute to the problem. Despite abnormalities, sperm from men with SCI can successfully induce pregnancy. In selected couples, the simple method of intravaginal insemination is a viable option. Another option is intrauterine insemination. The efficacy of intrauterine insemination increases as the total motile sperm count inseminated increases. In vitro fertilization and intracytoplasmic sperm injection are options in cases of extremely low total motile sperm count. Reproductive outcomes for SCI male factor infertility are similar to outcomes for general male factor infertility.

A systematic review of the management of autonomic dysreflexia after spinal cord injury

OBJECTIVE

To review systematically the clinical evidence on strategies to prevent and manage autonomic dysreflexia (AD).

DATA SOURCES

A key word search of several databases (Medline, CINAHL, EMBASE, and PsycINFO), in addition to manual searches of retrieved articles, was undertaken to identify all English-language literature evaluating the efficacy of interventions for AD.

STUDY SELECTION

Studies selected for review included randomized controlled trials (RCTs), prospective cohort studies, and cross-sectional studies. Treatments reviewed included pharmacologic and nonpharmacologic interventions for the management of AD in subjects with spinal cord injury. Studies that failed to assess AD outcomes (eg, blood pressure) or symptoms (eg, headaches, sweating) were excluded.

DATA EXTRACTION

Studies were critically reviewed and assessed for their methodologic quality by 2 independent reviewers.

DATA SYNTHESIS

Thirty-one studies were assessed, including 6 RCTs. Preventative strategies to reduce the episodes of AD caused by common triggers (eg, urogenital system, surgery) primarily were supported by level 4 (pre-post studies) and level 5 (observational studies) evidence. The initial acute nonpharmacologic management of an episode of AD (ie, positioning the patient upright, loosening tight clothing, eliminating any precipitating stimulus) is supported by clinical consensus and physiologic data (level 5 evidence). The use of antihypertensive drugs in the presence of sustained elevated blood pressure is supported by level 1 (prazosin) and level 2 evidence (nifedipine and prostaglandin E(2)).

CONCLUSIONS

A variety of options are available to prevent AD (eg, surgical, pharmacologic) and manage the acute episode (elimination of triggers, pharmacologic); however, these options are predominantly supported by evidence from noncontrolled trials, and more rigorous trials are required.

Incidence of autonomic dysreflexia and silent autonomic dysreflexia in men with spinal cord injury undergoing sperm retrieval: implications for clinical practice

BACKGROUND/OBJECTIVE

To determine the incidence of symptomatic autonomic dysreflexia (AD) and asymptomatic autonomic dysreflexia (silent AD) in men with spinal cord injury (SCI) undergoing sperm retrieval procedures.

DESIGN

Descriptive study.

METHODS

Thirteen men underwent cardiovascular monitoring during vibrostimulation (or self-stimulation) to the point of ejaculation. Cardiovascular results were compared with objective and subjective signs of AD to determine the incidence of symptomatic and silent AD. Past history and knowledge of AD were correlated to participants' experience of AD in the clinical setting.

OUTCOME MEASURES

Change in diastolic and systolic blood pressure is the primary outcome data that will be compared to AD history and data from each participant's questionnaire.

RESULTS

Twelve of the 13 men experienced a rise in blood pressure consistent with AD (defined as an increase in blood pressure > 20 mmHg). Men with incomplete tetraplegia were able to identify symptoms associated with AD, and those with complete tetraplegia did not experience symptoms. Eleven of the 13 men knew that sexual activity could cause AD; however, only 2 of the 13 men acknowledged a history of AD with sexual activity and/or ejaculation.

CONCLUSIONS

Symptomatic and silent AD occur frequently during sperm retrieval in men with SCI above T6. Knowledge and past history of AD are not accurate indicators of who will experience AD with sexual activity and/or ejaculation.

Recognition and effective management of autonomic dysreflexia in spinal cord injuries

Autonomic dysreflexia is a potentially life-threatening hypertensive medical emergency that occurs most often in spinal cord-injured individuals with spinal lesions at or above the mid-thoracic spinal cord level. It is a condition that remains poorly recognised outside of spinal cord injury centres, which may result in adverse outcomes including mortality from potentially delayed diagnosis and treatment. Acute autonomic dysreflexia is characterised by severe paroxysmal hypertension associated with throbbing headaches, profuse sweating, nasal stuffiness, flushing of the skin above the level of the lesion, bradycardia, apprehension and anxiety, which is sometimes accompanied by cognitive impairment. The key to effective management is prevention of the condition, by recognition and avoidance of factors that initiate the condition. When it occurs, immediate recognition and reversal of trigger factors along with prompt administration of pharmacological treatment is of paramount importance in order to prevent complications, which include intracranial and retinal haemorrhage, convulsions, cardiac irregularities and death. Promising data from recent animal studies may hold the key to future treatment options.

Autonomic dysreflexia: a medical emergency

Autonomic dysreflexia is an important clinical diagnosis that requires prompt treatment to avoid devastating complications. The condition may present itself to all members of medical and surgical specialties, who may not be accustomed to treating it. It is the clinician's responsibility to have a basic understanding of the pathophysiology of the condition and the simple steps required to treat it.

Autonomic dysreflexia: a plastic surgery primer

Plastic surgeons are integral to the management team for patients with spinal cord injuries, with responsibilities including pressure sore management and upper extremity reconstruction. Injury to the spinal cord profoundly disrupts the body's ability to maintain homeostasis. In particular, the autonomic system can become unregulated, resulting in a massive sympathetic discharge called autonomic dysreflexia. Autonomic dysreflexia occurs in the majority of patients with injuries above the sixth thoracic vertebra and causes sudden, severe hypertension. If left untreated, autonomic dysreflexia can result in stroke or death. Because this syndrome causes morbidity and mortality, it is crucial for plastic surgeons to be able to recognize and treat autonomic dysreflexia. This article reviews the etiology, symptoms, and treatment of this syndrome.