The isolated sympathetic spinal cord: Cardiovascular and sudomotor assessment in spinal cord injury patients: A literature survey

Impact of Liver Sympathetic Nervous System on Liver Fibrosis and Regeneration After Bile Duct Ligation in Rats

The sympathetic nervous system (SNS) affects many functions of the body. SNS fibers regulate many aspects of liver function, repair, and regeneration. However, in the model of bile duct ligation (BDL) in rats, the kind of impact caused by the regulation of liver SNS on liver fibrosis and liver regeneration is unclear. The main research objective of this experiment is to examine the effect of SNS on liver fibrosis and liver regeneration. Twenty-four male Sprague-Dawley (SD) rats were assigned randomly to four groups. These groups included the sham surgery group (sham), model group (BDL), 6-hydroxydopamine group (BDL+6-OHDA), and spinal cord injury group (BDL+SCI). In the sham group, only exploratory laparotomy was performed without BDL. In the 6-OHDA group, 6-OHDA was used to remove sympathetic nerves after BDL. In the spinal cord injury group, rats underwent simultaneous BDL and spinal cord injury. After 3 weeks of feeding, four groups of rats were euthanized using high-dose anesthesia without pain. Moreover, liver tissue and blood were taken to detect liver fibrosis and regeneration indicators. After intraperitoneal injection of 6-OHDA into BDL rats, liver fibrosis indicators decreased. The administration of the injection effectively alleviated liver fibrosis and inhibited liver regeneration. However, after SCI surgery in BDL rats, liver fibrosis indicators increased. This resulted in exacerbating liver fibrosis and activating liver regeneration. The SNS plays a role in contributing to the liver injury process in the rat BDL model. Therefore, regulating the SNS may become a novel method for liver injury treatment.

Central versus peripheral mechanisms of cold-induced vasodilation: a study in the fingers and toes of people with paraplegia

PURPOSE

This study examined physiological and perceptual parameters related to cold-induced vasodilation (CIVD) in the fingers and toes of people with paraplegia and compared them with responses observed in able-bodied individuals.

METHODS

Seven participants with paraplegia and seven able-bodied individuals participated in a randomized matched-controlled study involving left-hand and -foot immersion in cold water (8 ± 1 °C) for 40 min during exposure to cool (16 ± 1 °C), thermoneutral (23 ± 1 °C), and hot (34 ± 1 °C) ambient conditions.

RESULTS

Similar CIVD occurrence was observed in the fingers in the two groups. In toes, three of the seven participants with paraplegia revealed CIVDs: one in cool, two in thermoneutral, and three in hot conditions. No able-bodied participants revealed CIVDs in cool and thermoneutral conditions, while four revealed CIVDs in hot conditions. The toe CIVDs of paraplegic participants were counterintuitive in several respects: they were more frequent in cool and thermoneutral conditions (compared to the able-bodied participants), emerged in these conditions despite lower core and skin temperatures of these participants, and were evident only in cases of thoracic level lesions (instead of lesions at lower spinal levels).

CONCLUSION

Our findings demonstrated considerable inter-individual variability in CIVD responses in both the paraplegic and able-bodied groups. While we observed vasodilatory responses in the toes of participants with paraplegia that technically fulfilled the criteria for CIVD, it is unlikely that they reflect the CIVD phenomenon observed in able-bodied individuals. Taken together, our findings favor the contribution of central over peripheral factors in relation to the origin and/or control of CIVD.

Quantitative gastrointestinal function and corresponding symptom profiles in autonomic neuropathy

Purpose

Peripheral neuropathies with autonomic nervous system involvement are a recognized cause of gastrointestinal dysmotility for a wide spectrum of diseases. Recent advances in wireless motility capsule testing allow improved sampling of regional and whole gut motility to aid in the diagnosis of gastrointestinal motility disorders and may provide additional insight into segment-specific enteric involvement of peripheral neuropathies affecting autonomic nervous system function.

Methods

We utilized standardized autonomic nervous system (ANS) reflex assessment and wireless motility capsule testing to evaluate 20 individuals with idiopathic autonomic neuropathy and unexplained gastrointestinal symptoms. Additionally, we examined the relationship between quantifiable autonomic neuropathy and gastrointestinal dysmotility at specific neuroanatomical levels. Symptom profiles were evaluated using the 31-item Composite Autonomic Symptom Score questionnaire (COMPASS-31) and compared to wireless motility capsule data.

Results

We found that transit times were predominately abnormal (delayed) in the foregut (10 of 20; 50%), while contractility abnormalities were far more prominent in the hindgut (17 of 20; 85%), and that motility and symptom patterns, as assessed by the COMPASS-31 GI domain items, generally corresponded. Finally, we also found that there was neuroanatomical overlap in the presence of autonomic reflex abnormalities and WMC-based transit and/or contractility abnormalities.

Conclusions

We found that transit times were predominately abnormal in the foregut and midgut, while contractility abnormalities were far more prominent in the hindgut in individuals with idiopathic autonomic neuropathy. There was a high rate of agreement in segmental wireless motility capsule data with neuroanatomically corresponding standardized ANS function measures (e.g., cardiovagal, sudomotor, adrenergic). Expanded sudomotor testing, including additional neuroanatomical segments, could provide additional indirect assessment of visceral involvement in ANS dysfunction.

Common carotid artery responses to the cold-pressor test are impaired in individuals with cervical spinal cord injury

Cervical spinal cord injury (SCI) leads to autonomic cardiovascular dysfunction that underlies the three- to fourfold elevated risk of cardiovascular disease in this population. Reduced common carotid artery (CCA) dilatory responsiveness during the cold-pressor test (CPT) is associated with greater cardiovascular disease risk and progression. The cardiovascular and CCA responses to the CPT may provide insight into cardiovascular autonomic dysfunction and cardiovascular disease risk in individuals with cervical SCI. Here, we used CPT to perturb the autonomic nervous system in 14 individuals with cervical SCI and 12 uninjured controls, while measuring cardiovascular responses and CCA diameter. The CCA diameter responses were 55% impaired in those with SCI compared with uninjured controls (P = 0.019). The CCA flow, velocity, and shear response to CPT were reduced in SCI by 100% (P < 0.001), 113% (P = 0.001), and 125% (P = 0.002), respectively. The association between mean arterial pressure and CCA dilation observed in uninjured individuals (r = 0.54, P = 0.004) was absent in the SCI group (r = 0.22, P = 0.217). Steady-state systolic blood pressure (P = 0.020), heart rate (P = 0.003), and cardiac contractility (P < 0.001) were reduced in those with cervical SCI, whereas total peripheral resistance was increased compared with uninjured controls (P = 0.042). Relative cerebral blood velocity responses to CPT were increased in the SCI group and reduced in controls (middle cerebral artery, P = 0.010; posterior cerebral artery, P = 0.026). The CCA and cardiovascular responsiveness to CPT are impaired in those with cervical SCI.NEW & NOTEWORTHY This is the first study demonstrating that CCA responses during CPT are suppressed in SCI. Specifically, CCA diameter, flow, velocity, and shear rate were reduced. The relationship between changes in MAP and CCA dilatation in response to CPT was absent in individuals with SCI, despite similar cardiovascular activation between SCI and uninjured controls. These findings support the notion of elevated cardiovascular disease risk in SCI and that the cardiovascular responses to environmental stimuli are impaired.

Adaptive Cycling: Injuries and Health Concerns

Para-cycling has high rates of acute injuries. The underlying medical conditions of para-athletes predispose these cyclists to injury patterns and sequelae different from those of their able-bodied counterparts. Such injuries include an increased incidence of upper-extremity and soft tissue injuries, along with predisposition for respiratory, skin, genitourinary, and heat-related illnesses. There are no validated sideline assessment tools or return-to-play protocols for sports-related concussion in wheelchair user para-athletes or those with balance deficits. Para-cyclists may be at increased risk for relative energy deficiency in sport due to competitive pressure to maintain certain weights and increased incidence of low bone mineral density.

Correlation of neurological level and sweating level of injury in persons with spinal cord injury

Objective: Thermoregulatory dysfunction after spinal cord injury (SCI) impairs quality of life and predisposes persons to life-threatening sequela of heat-related illness (HRI) in conditions of high ambient temperature. SCI clinicians currently have no objective way to predict which persons are at greatest risk of HRI. Evaporative cooling via sweating is the body's most efficient mechanism of heat dissipation. The relationship between the neurological level of injury (NLOI) and the degree of sudomotor dysfunction is not well defined. This study examines the relationship between the NLOI and sweating level of injury (SwLOI). This information can assist SCI clinicians in identifying individuals with SCI who have most impaired sudomotor function and thus highest risk of HRI.Design: Observational.Setting: Human physiology laboratory.Participants: 10 persons with tetraplegia (TP), 14 with paraplegia (PP) and 10 able-bodied (AB).Intervention: Passive heat stress (1°C rise in core temperature) with sweat responses (SR) quantified with the starch iodine test.Outcome measures: The most caudal dermatomal level in which sweating was visualized was recorded as the SwLOI, which was compared to the NLOI. Minimum, maximum and median differences between NLOI and SwLOI were calculated.Results: Persons with tetraplegia demonstrated no SR. Persons with paraplegia demonstrated SR at a median of 1 level below NLOI. Able-bodied controls demonstrated sweating on all skin surface areas.Conclusions: Persons with motor complete tetraplegia lack evaporative cooling capacity through SR during passive heat stress predisposing them to HRI. Meanwhile, persons with paraplegia sweat on average 1 dermatomal level below their NLOI.

Dartos reflex as autonomic assessment in persons with spinal cord injury

Study design

Prospective clinical series.

Objectives

The dartos reflex (DR) produces unilateral elevation of the testis with vermicular contraction of the scrotal skin and penile retraction. It is a somato-autonomic reflex that depends on the T11-L2 sympathetic segment. Its presence was analysed in men with various levels and severities of spinal cord injury (SCI).

Setting

France.

Methods

Male patients with SCI undergoing urodynamic or sexual assessment were included. DR of the scrotum and penis were systematically assessed in addition to the usual neurological examination that included assessment of the autonomic system, cremaster, and sacral reflexes. The DR was evoked by applying a small ice pack on the scrotum, separately to each side.

Results

Forty-six patients were assessed. DRs were always present when the T11-L2 segment was intact above the lesion (low paraplegia below L2) or below the lesion in an upper motor neuron (UMN) syndrome (spastic paraplegia above T10). They were more pronounced in the case of UMN syndrome. In the case of lower motor neuron (LMN) syndrome that included the T11-L2 segment, DRs disappeared in all but one patient. Patients with a LMN lesion were more prone to retrograde or absent ejaculation, loss of psychogenic erection, and open bladder neck.

Conclusions

The DR is a valuable test for the assessment of the integrity and excitability of the T11-L2 spinal segment. It is easy to perform and is predictive of some aspects of sexual and bladder neck function in men. DR should be considered as an addition to the autonomic standards.

Multi-Domain Assessment of Autonomic Function in Spinal Cord Injury Using a Modified Autonomic Reflex Screen

The aim of this study was to characterize autonomic lesions in participants with spinal cord injury (SCI; n = 10) using an autonomic reflex screen, incorporating sudomotor, cardiovagal, and sympathetic adrenergic tests, as well as hemodynamic responses to head-up tilt (HUT). Hemodynamic responses were compared to healthy controls (n = 20) and previously published normative cutoffs in order better identify autonomic impairments. Sympathetic skin responses (SSRs), heart rate response to deep breathing (HR_DB), and heart rate and beat-to-beat blood pressure responses to Valsalva maneuver (VM) and HUT were measured. SCI participants demonstrated impairment in at least one domain, with 7 of 10 demonstrating autonomic impairment across all domains. No single test was concordant with orthostatic hypotension on HUT, in all participants. Measures of cardiovagal function, including HR_DB (SCI = 7.7 ± 3.8 beats/min vs. controls = 17.6 ± 8.1 beats/min) and Valsalva ratio (SCI = 1.53 ± 0.29 vs. controls = 1.85 ± 0.37), were significantly reduced in SCI participants, compared to controls (p < 0.05). These findings suggest that an autonomic reflex screen, which includes standardized testing protocol and normative data for comparison, is useful for determining the autonomic domains affected by the neurological injury in SCI. We also demonstrated significant cardiovagal impairment in SCI participants compared to controls, which warrants further investigation to determine whether cardiovagal dysfunction is associated with the negative cardiovascular outcomes, which are known to occur in SCI.

[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.

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.

Olfactory ensheathing cell transplantation improves sympathetic skin responses in chronic spinal cord injury

Forty-three patients with chronic spinal cord injury for over 6 months were transplanted with bryonic olfactory ensheathing cells, 2-4 × 10(6), into multiple sites in the injured area under the surgical microscope. The sympathetic skin response in patients was measured with an electromyography/evoked potential instrument 1 day before transplantation and 3-8 weeks after transtion. Spinal nerve function of patients was assessed using the American Spinal Injury Association impairment scale. The sympathetic skin response was elicited in 32 cases before olfactory ensheathing cell transplantation, while it was observed in 34 cases after transplantation. tantly, sympathetic skin response latency decreased significantly and amplitude increased cantly after transplantation. Transplantation of olfactory ensheathing cells also improved American Spinal Injury Association scores for movement, pain and light touch. Our findings indicate that factory ensheathing cell transplantation improves motor, sensory and autonomic nerve functions in patients with chronic spinal cord injury.

Sympathetic skin responses and autonomic dysfunction in spinal cord injury

Sympathetic skin responses (SSRs), a measure of sympathetic cholinergic sudomotor function, have been used in the assessment of autonomic dysfunction in patients with spinal cord injury (SCI). This review highlights the basic mechanisms underlying SSRs as well as their application to the SCI population. We address the utility of SSRs in assessing autonomic function, the relationship between autonomic and sensorimotor impairment, and the association between SSRs and the sequelae of autonomic dysfunction in SCI, particularly autonomic dysreflexia and orthostatic hypotension. Overall, SSRs are a rapid, convenient and non-invasive method illustrating that the severity of autonomic impairment can be independent from sensorimotor impairment. We suggest that SSRs be used in conjunction with other validated autonomic tests in order to predict or document autonomic dysfunction in SCI.

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.

Quantitative testing in spinal cord injury: overview of reliability and predictive validity

Object

The objective of this study was to identify commonly used physiological outcome measures and summarize evidence on the reliability and predictive validity of quantitative measures used in monitoring persons with spinal cord injury (SCI).

Methods

A systematic search of PubMed through January 5, 2012, was conducted to identify publications using common outcome measures in persons with SCI and for studies that were specifically designed to evaluate the reliability and predictive validity of selected quantitative measures. Quantitative measures were defined as tests that quantify sensory and motor function, such as amount of force or torque, as well as thresholds, amplitudes, and latencies of evoked potentials that might be useful in studies and monitoring of patients with SCI. Reliability studies reporting interclass correlation coefficients (ICCs) or weighted κ coefficients were considered for inclusion. Studies explicitly evaluating correlation between measures and specific functional outcomes were considered for predictive validity.

Results

From a total of 121 potentially relevant citations, 6 studies of reliability and 4 studies of predictive validity for quantitative tests met the inclusion criteria. In persons with incomplete SCI, ICCs for both interrater and intrarater reliability of electrical perceptual threshold (EPT) were ≥ 0.7 above the sensory level of SCI but were less reliable below the sensory level. Interclass correlation coefficients for interrater and intrarater reliability of the Graded Redefined Assessment of Strength, Sensibility, and Prehension (GRASSP) components ranged from 0.84 to 0.98. For electromyography, the ICC was consistently high for within-day tests. The overall quality of reliability of the majority of studies was poor, due to the potential for selection bias and small sample sizes. No classic validation studies were found for the selected measures, and evidence regarding the predictive validity of the measures was limited. Somatosensory evoked potentials (SSEPs) may be correlated with ambulatory capacity, as well as the Barthel Index and motor index scores, but this correlation was limited for evaluation of bladder function recovery in 3 studies that assessed the correlation between baseline or initial SSEPs and a specific clinical outcome at a later follow-up time. All studies used convenience samples and the overall sample quality was low.

Conclusions

Evidence on the reliability and validity of the quantitative measures selected for this review is limited, and the overall quality of existing studies is poor. There is some evidence for the reliability of the EPT, dermatomal SSEPs, and the GRASSP to suggest that they may be useful in longitudinal studies of patients with SCI. There is a need for high quality studies of reliability, responsiveness, and validity for quantitative measures to monitor the level and degree of SCI.

Limb oxygenation during the cold pressor test in spinal cord-injured humans

OBJECTIVE

To investigate changes in tissue oxygenation in the arm and leg during the cold pressor test in humans with spinal cord injury (SCI).

METHODS

Subjects with SCI at cervical 6 (n=7) and subjects with SCI at thoracic 5 or thoracic 6 (n=5) experienced 3-min cold water immersion of the foot and subsequent 10-min recovery. Changes in tissue oxygenation and blood pressure were determined. Tissue oxygenation was assessed by hemoglobin/myoglobin concentration (Hb/MbO2) measured using near-infrared spectroscopy.

RESULTS

Mean arterial blood pressures increased significantly by 15±9 and 6±6 mmHg during cold water immersion in the cervical and thoracic SCI groups, respectively (P<0.001). Hb/MbO2 in the arm decreased significantly by 23±15 μM cm during cold water immersion only in the cervical SCI group (P<0.001), whereas Hb/MbO2 in the leg decreased significantly by 82±56 μM cm during cold water immersion only in the thoracic SCI group (P<0.001).

INTERPRETATION

Afferent activity coming from below the lesion due to cold stimuli would reflexively enhance sympathetic activity in both the arm and leg in individuals with cervical SCI but only in the leg in individuals with thoracic SCI. A decrease in tissue oxygenation might have been caused by sympathetic vasoconstriction. The reduction of tissue oxygenation in the arm was marked in individuals with cervical SCI, suggesting differential control of arm oxygenation and leg oxygenation in the region below SCI.