Management of acute spinal cord injury in the neurocritical care unit

Meglumine cyclic adenylate improves cardiovascular hemodynamics and motor-function in a rat model of acute T4 thoracic spinal cord injury

STUDY DESIGN

Animal experimental study.

OBJECTIVES

Spinal cord injury (SCI) at or above the T6 level causes cardiovascular dysfunction. Maintaining cAMP levels with cAMP analogs can facilitate neurological recovery. In the present study, the effects of meglumine cyclic adenylate (MCA), a cAMP analog and approved cardiovascular drug, on cardiovascular and neurological recovery in acute T4-SCI in rats were investigated.

SETTING

Hospital in Kunming, China.

METHODS

Eighty rats were randomly allocated to five groups, and groups A-D received SCI: (A) a group administered MCA at 2 mg/kg/d iv qd, (B) a group administered dopamine at 2.5 to 5 μg/kg/min iv to maintain mean arterial pressure above 85 mm Hg, (C) a group administered atropine at 1 mg/kg iv bid, (D) a group receiving an equal volume of saline iv qd for 3 weeks after SCI and (E) a group undergoing laminectomy only. The cardiovascular and behavioral parameters of the rats were examined, and spinal cord tissues were processed for hematoxylin and eosin staining, Nissl staining, electron microscopy, and analysis of cAMP levels.

RESULTS

Compared with dopamine or atropine, MCA significantly reversed the decrease in cAMP levels in both myocardial cells and the injured spinal cord; improved hypotension, bradycardia and behavioral parameters at 6 weeks; and improved spinal cord blood flow and histological structure at 7 days post-SCI. The regression analysis suggested spinal cord motor-function improved as decreased heart rate and mean arterial pressure were stopped post-SCI.

CONCLUSIONS

MCA may be an effective treatment for acute SCI by sustaining cAMP-dependent reparative processes and improving post-SCI cardiovascular dysfunction.

SPONSORSHIP

N/A.

Contemporary hemodynamic management of acute spinal cord injuries with intravenous and enteral vasoactive agents: A narrative review

DISCLAIMER

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

The pathophysiology and hemodynamic management of acute spinal cord injuries, including the use of intravenous and enteral vasoactive agents, are reviewed.

SUMMARY

Spinal cord injuries are devastating neurological insults that in the acute setting lead to significant hemodynamic disturbances, including hypotension and bradycardia, that are influenced by the level of injury. High thoracic (usually defined as at or above T6) and cervical injuries often manifest with hypotension and bradycardia due to destruction of sympathetic nervous system activity and unopposed vagal stimulation to the myocardium, whereas lower thoracic injuries tend to result in hypotension alone due to venous pooling. Initial management includes maintaining euvolemia with crystalloids and maintaining or augmenting mean arterial pressure with the use of intravenous vasoactive agents to improve neurological outcomes. Choice of vasopressor should be based on patient-specific factors, particularly level of injury and presenting hemodynamics. This review includes the most recent literature on intravenous vasopressors as well as the limited evidence supporting the use of enteral vasoactive agents. Enteral vasoactive agents may be considered, when clinically appropriate, as a strategy to wean patients off of intravenous agents and facilitate transfer outside of the intensive care unit.

CONCLUSION

The hemodynamic management of acute spinal cord injuries often requires the use of vasoactive agents to meet mean arterial pressure goals and improve neurological outcomes. Patient-specific factors must be considered when choosing intravenous and enteral vasoactive agents.

Current Concepts: Central Cord Syndrome

Central cord syndrome (CCS) represents a clinical phenomenon characterized by disproportionately greater motor impairment of the upper than of the lower extremities, bladder dysfunction. CSS is the most common form of incomplete traumatic spinal cord injury. The initial description of CSS was reported in 1887 secondary to cervical spinal trauma. However, recent literature describes a heterogenous injury patterns including high-energy and low-energy mechanisms and bimodal patient age distributions. Pathophysiology of clinical symptoms and neurological deficits often is affected by preexisting cervical spondylosis. Urgent clinical diagnosis is dependent on neurological examination and imaging studies. Treatment of CSS is dependent on injury mechanism and compressive lesions, neurological examination, preexisting cervical pathology, and patient-specific comorbidities. This article will review the current concepts in diagnosis, pathophysiology, and treatment of CSS with a highlighted case example.

Rural and Urban Living in Persons with Spinal Cord Injury and Comparing Environmental Barriers, Their Health, and Quality-of-Life Outcomes

There is worldwide geographic variation in the epidemiology of traumatic spinal cord injury (tSCI). The aim of this study was to determine whether environmental barriers, health status, and quality-of-life outcomes differ between patients with tSCI living in rural or urban settings, and whether patients move from rural to urban settings after tSCI. A cohort review of the Rick Hansen SCI Registry (RHSCIR) was undertaken from 2004 to 2012 for one province in Canada. Rural/urban setting was determined using postal codes. Outcomes data at 1 year in the community included the Short Form-36 Version 2 (SF36v2™), Life Satisfaction Questionnaire, Craig Hospital Inventory of Environmental Factors-Short Form (CHIEF-SF), Functional Independent Measure® Instrument, and SCI Health Questionnaire. Statistical methodologies used were t test, Mann-Whitney U test, and Fisher's exact or χ2 test. In the analysis, 338 RHSCIR participants were included; 65 lived in a rural setting and 273 in an urban setting. Of the original patients residing in a rural area at discharge,10 moved to an urban area by 1 year. Those who moved from a rural to urban area reported a lower SF-36v2™ Mental Component Score (MCS; p = 0.04) and a higher incidence of depression at 1 year (p = 0.04). Urban patients also reported a higher incidence of depression (p = 0.02) and a lower CHIEF-SF total score (p = 0.01) indicating fewer environmental barriers. No significant differences were found in other outcomes. Results suggest that although the patient outcomes are similar, some patients move from rural to urban settings after tSCI. Future efforts should target screening mental health problems early, especially in urban settings.

Higher Mean Arterial Pressure Values Correlate with Neurologic Improvement in Patients with Initially Complete Spinal Cord Injuries

BACKGROUND

Traumatic spinal cord injury (SCI) guidelines recommend to maintain mean arterial pressures (MAPs) above 85 mm Hg for 7 days following SCI to minimize spinal cord ischemia. Some physicians doubt that patients with initially complete injuries benefit.

OBJECTIVE

To assess the relationship between MAP augmentation and neurologic improvement in SCI patients stratified by initial American Spinal Injury Association Impairment Scale (AIS) score.

METHODS

High-frequency MAP values of acute SCI patients admitted over a 6-year period were recorded, and values were correlated with degree of neurologic recovery in an analysis stratified by postresuscitation AIS score.

RESULTS

Sixty-two patients with SCI were analyzed. Thirty-three patients were determined to have complete injuries, and of those 11 improved at least 1 AIS grade by discharge. The average MAP of initially AIS A patients who improved versus those who did not was significantly higher (96.6 ± 0.07 mm Hg vs. 94.4 ± 0.06 mm Hg, respectively; P < 0.001), and the proportion of MAP values <85 mm Hg was significantly lower (13.5% vs. 25.6%, respectively; P < 0.001). A positive correlation between MAP values and outcome was also observed in AIS B and C patients but was not observed in patients who were initially AIS D.

CONCLUSION

A positive correlation was observed between MAP values and neurologic recovery in AIS A, B, and C patients but not AIS D patients. These data raise the possibility that patients with an initially complete SCI may derive greater benefit from MAP augmentation than patients with initial AIS D injuries.

Mean Arterial Blood Pressure Correlates with Neurological Recovery after Human Spinal Cord Injury: Analysis of High Frequency Physiologic Data

Current guidelines for the care of patients with acute spinal cord injuries (SCIs) recommend maintaining mean arterial pressure (MAP) values of 85-90 mm Hg for 7 days after an acute SCI however, little evidence supports this recommendation. We sought to better inform the relationship between MAP values and neurological recovery. A computer system automatically collected and stored q1 min physiological data from intensive care unit monitors on patients with SCI over a 6-year period. Data for 100 patients with acute SCI were collected. 74 of these patients had American Spinal Injury Association Impairment Scale (AIS) grades determined by physical examination on admission and at time of hospital discharge. Average MAP values as well as the proportion of MAP values below thresholds were explored for values from 120 mm Hg to 40 mm Hg in 1 mm Hg increments; the relationship between these measures and outcome was explored at various time points up to 30 days from the time of injury. A total of 994,875 q1 min arterial line blood pressure measurements were recorded for the included patients amid 1,688,194 min of recorded intensive care observations. A large proportion of measures were below 85 mm Hg despite generally acceptable average MAP values. Higher average MAP values correlated with improved recovery in the first 2-3 days after SCI while the proportion of MAP values below the accepted threshold of 85 mm Hg seemed a stronger correlate, decreasing in strength over the first 5-7 days after injury. This study provides strong evidence supporting a correlation between MAP values and neurological recovery. It does not, however, provide evidence of a causal relationship. Duration of hypotension may be more important than average MAP. It provides support for the notion of MAP thresholds in SCI recovery, and the highest MAP values correlated with the greatest degree of neurological recovery. The results are concordant with current guidelines in suggesting that MAP thresholds >85 mm Hg may be appropriate after acute SCI.

Valproic Acid Arrests Proliferation but Promotes Neuronal Differentiation of Adult Spinal NSPCs from SCI Rats

Although the adult spinal cord contains a population of multipotent neural stem/precursor cells (NSPCs) exhibiting the potential to replace neurons, endogenous neurogenesis is very limited after spinal cord injury (SCI) because the activated NSPCs primarily differentiate into astrocytes rather than neurons. Valproic acid (VPA), a histone deacetylase inhibitor, exerts multiple pharmacological effects including fate regulation of stem cells. In this study, we cultured adult spinal NSPCs from chronic compressive SCI rats and treated with VPA. In spite of inhibiting the proliferation and arresting in the G0/G1 phase of NSPCs, VPA markedly promoted neuronal differentiation (β-tubulin III(+) cells) as well as decreased astrocytic differentiation (GFAP(+) cells). Cell cycle regulator p21(Cip/WAF1) and proneural genes Ngn2 and NeuroD1 were increased in the two processes respectively. In vivo, to minimize the possible inhibitory effects of VPA to the proliferation of NSPCs as well as avoid other neuroprotections of VPA in acute phase of SCI, we carried out a delayed intraperitoneal injection of VPA (150 mg/kg/12 h) to SCI rats from day 15 to day 22 after injury. Both of the newborn neuron marker doublecortin and the mature neuron marker neuron-specific nuclear protein were significantly enhanced after VPA treatment in the epicenter and adjacent segments of the injured spinal cord. Although the impaired corticospinal tracks had not significantly improved, Basso-Beattie-Bresnahan scores in VPA treatment group were better than control. Our study provide the first evidence that administration of VPA enhances the neurogenic potential of NSPCs after SCI and reveal the therapeutic value of delayed treatment of VPA to SCI.