A pharmacological analysis of the pathophysiological mechanisms of posttraumatic spinal cord ischemia

Using Nutraceuticals to Help Manage Traumatic Spinal Cord Injury

Traumatic spinal cord injury (TSCI) is a significant public health challenge that has an adverse impact on functional independence, quality of life, and life expectancy. Management of people's chronic conditions is a key aspect of contemporary medical practice. Our study was an open label, single arm, prospective pilot study to evaluate the feasibility of treating people with TSCI. The study intervention was treatment with oral selenium and vitamin E. Participants were 18 years or older and experienced a TSCI at least one year prior to enrollment. Daily doses of 50 mcg of selenium and 400 IU of vitamin E were administered. Participants had radiologic (MRI tractography) and clinical (ASIA) assessments prior to initiating treatment, and these assessments were repeated after one year of treatment. Four subjects completed the full twelve-month study. Adherence, based on pill counts, was approximately 75% in all subjects. There were no adverse events related to study medications. During the treatment period, subjects reported improvement in certain symptoms. There was no significant difference in ASIA scores before and after the intervention. Combination treatment with vitamin E and selenium has been demonstrated as safe for TSCI patients. It is possible to use DTI values to locate the epicenter of a lesion as well as gauge the extent of injury. MRI tractography may serve as a meaningful surrogate endpoint. The results of this study suggest that it is feasible to conduct a larger long-term clinical trial to evaluate the efficacy of combination treatment of TSCI.

Promising Advances in Pharmacotherapy for Patients with Spinal Cord Injury-A Review of Studies Performed In Vivo with Modern Drugs

Spinal cord injury (SCI) is a pathological neurological condition that leads to significant motor dysfunction. It is a condition that occurs as a result of tragic accidents, violent acts, or as a consequence of chronic diseases or degenerative changes. The current treatments for patients with SCI have moderate efficacy. They improve the quality of life of patients, but they are still doomed to long-term disability. In response to the modern directions of research on possible therapeutic methods that allow for the recovery of patients with SCI, a scientific review publication is needed to summarize the recent developments in this topic. The following review is focused on the available pharmacological treatments for SCIs and the problems that patients face depending on the location of the injury. In the following review, the research team describes problems related to spasticity and neuropathic pain; possible therapeutic pathways are also described for neuroprotection and the improvement of neurotransmission within the injured spinal cord, and the review focuses on issues related to oxidative stress.

Novel Methods of Necroptosis Inhibition for Spinal Cord Injury Using Translational Research to Limit Secondary Injury and Enhance Endogenous Repair and Regeneration

Spinal cord injuries (SCIs) pose an immense challenge from a clinical perspective as current treatments and interventions have been found to provide marginal improvements in clinical outcome (with varying degrees of success) particularly in areas of motor and autonomic function. In this review, the pathogenesis of SCI will be described, particularly as it relates to the necroptotic pathway which has been implicated in limiting recovery of SCI via its roles in neuronal cell death, glial scarring, inflammation, and axonal demyelination and degeneration. Major mediators of the necroptotic pathway including receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, and mixed-lineage kinase domain-like will be described in detail regarding their role in facilitating necroptosis. Additionally, due to the rapid accumulation of reactive oxygen species and inflammatory markers, the onset of necroptosis can begin within hours following SCI, thus developing therapeutics that readily cross the blood-brain barrier and inhibit necroptosis during these critical periods of inflammation are imperative in preventing irreversible damage. As such, current therapeutic interventions regarding SCI and targeting of the necroptotic pathway will be explored as will discussion of potential future therapeutics that show promise in minimizing long-term or permanent damage to the spinal cord following severe injury.

Extent of Spinal Cord Decompression in Motor Complete (American Spinal Injury Association Impairment Scale Grades A and B) Traumatic Spinal Cord Injury Patients: Post-Operative Magnetic Resonance Imaging Analysis of Standard Operative Approaches

Although decompressive surgery following traumatic spinal cord injury (TSCI) is recommended, adequate surgical decompression is rarely verified via imaging. We utilized magnetic resonance imaging (MRI) to analyze the rate of spinal cord decompression after surgery. Pre-operative (within 8 h of injury) and post-operative (within 48 h of injury) MRI images of 184 motor complete patients (American Spinal Injury Association Impairment Scale [AIS] grade A = 119, AIS grade B = 65) were reviewed to verify spinal cord decompression. Decompression was defined as the presence of a patent subarachnoid space around a swollen spinal cord. Of the 184 patients, 100 (54.3%) underwent anterior cervical discectomy and fusion (ACDF), and 53 of them also underwent laminectomy. Of the 184 patients, 55 (29.9%) underwent anterior cervical corpectomy and fusion (ACCF), with (26 patients) or without (29 patients) laminectomy. Twenty-nine patients (16%) underwent stand-alone laminectomy. Decompression was verified in 121 patients (66%). The rates of decompression in patients who underwent ACDF and ACCF without laminectomy were 46.8% and 58.6%, respectively. Among these patients, performing a laminectomy increased the rate of decompression (72% and 73.1% of patients, respectively). Twenty-five of 29 (86.2%) patients who underwent a stand-alone laminectomy were found to be successfully decompressed. The rates of decompression among patients who underwent laminectomy at one, two, three, four, or five levels were 58.3%, 68%, 78%, 80%, and 100%, respectively (p < 0.001). In multi-variate logistic regression analysis, only laminectomy was significantly associated with successful decompression (odds ratio 4.85; 95% confidence interval 2.2-10.6; p < 0.001). In motor complete TSCI patients, performing a laminectomy significantly increased the rate of successful spinal cord decompression, independent of whether anterior surgery was performed.

Dichotomous Locomotor Recoveries Are Predicted by Acute Changes in Segmental Blood Flow after Thoracic Spinal Contusion Injuries in Pigs

Neuroimaging facilitates the translation of animal pre-clinical research to human application. The large porcine spinal cord is useful for testing invasive interventions. Ideally, the safety and efficacy of a delayed intervention is tested in pigs that have recovered sufficiently after spinal cord injury (SCI) to allow either deterioration or improvement of function to be detected. We set out to create moderate severity T9 injuries in Yucatan minipigs by conducting a bridging study adapting methods previously developed in infant piglets. The injury severity was varied according to two pneumatic impactor parameters: the piston compression depth into tissue or the velocity. To stratify locomotor recovery, a 10-point scale used in prior piglet studies was redefined through longitudinal observations of spontaneous recovery. Using hindlimb body weight support to discriminate injury severity, we found that end-point recovery was strongly bimodal to either non-weight-bearing plegia with reciprocating leg movements (<5/10) or recovery of weight bearing that improved toward a ceiling effect (≥ 8/10). No intermediate recovery animals were observed at 2 months post-injury. The ability of intra-operative ultrasound and acute magnetic resonance imaging (MRI) to provide immediate predictive feedback regarding tissue and vascular changes following SCI was assessed. There was an inverse association between locomotor outcome and early gray matter hemorrhage on MRI and ultrasound. Epicenter blood flow following contusion predicted recovery or non-recovery of weight-bearing. The depth of the dorsal cerebrospinal fluid space, which varied between animals, influenced injury severity and confounded the results in this fixed-stroke paradigm.

Effects of Dietary Vitamin E Supplementation in Bladder Function and Spasticity during Spinal Cord Injury

Traumatic spinal cord injury (SCI) results in debilitating autonomic dysfunctions, paralysis and significant sensorimotor impairments. A key component of SCI is the generation of free radicals that contributes to the high levels of oxidative stress observed. This study investigates whether dietary supplementation with the antioxidant vitamin E (alpha-tocopherol) improves functional recovery after SCI. Female adult Sprague-Dawley rats were fed either with a normal diet or a dietary regiment supplemented with vitamin E (51 IU/g) for eight weeks. The rats were subsequently exposed either to a contusive SCI or sham operation, and evaluated using standard functional behavior analysis. We report that the rats that consumed the vitamin E-enriched diet showed an accelerated bladder recovery and significant improvements in locomotor function relative to controls, as determined by residual volumes and Basso, Beatie, and Bresnaham BBB scores, respectively. Interestingly, the prophylactic dietary intervention did not preserve neurons in the ventral horn of injured rats, but it significantly increased the numbers of oligodendrocytes. Vitamin E supplementation attenuated the depression of the H-reflex (a typical functional consequence of SCI) while increasing the levels of supraspinal serotonin immunoreactivity. Our findings support the potential complementary use of vitamin E to ameliorate sensory and autonomic dysfunctions associated with spinal cord injury, and identified promising new cellular and functional targets of its neuroprotective effects.

Discovery and Development of Calcium Channel Blockers

In the mid 1960s, experimental work on molecules under screening as coronary dilators allowed the discovery of the mechanism of calcium entry blockade by drugs later named calcium channel blockers. This paper summarizes scientific research on these small molecules interacting directly with L-type voltage-operated calcium channels. It also reports on experimental approaches translated into understanding of their therapeutic actions. The importance of calcium in muscle contraction was discovered by Sidney Ringer who reported this fact in 1883. Interest in the intracellular role of calcium arose 60 years later out of Kamada (Japan) and Heibrunn (USA) experiments in the early 1940s. Studies on pharmacology of calcium function were initiated in the mid 1960s and their therapeutic applications globally occurred in the the 1980s. The first part of this report deals with basic pharmacology in the cardiovascular system particularly in isolated arteries. In the section entitled from calcium antagonists to calcium channel blockers, it is recalled that drugs of a series of diphenylpiperazines screened in vivo on coronary bed precontracted by angiotensin were initially named calcium antagonists on the basis of their effect in depolarized arteries contracted by calcium. Studies on arteries contracted by catecholamines showed that the vasorelaxation resulted from blockade of calcium entry. Radiochemical and electrophysiological studies performed with dihydropyridines allowed their cellular targets to be identified with L-type voltage-operated calcium channels. The modulated receptor theory helped the understanding of their variation in affinity dependent on arterial cell membrane potential and promoted the terminology calcium channel blocker (CCB) of which the various chemical families are introduced in the paper. In the section entitled tissue selectivity of CCBs, it is shown that characteristics of the drug, properties of the tissue, and of the stimuli are important factors of their action. The high sensitivity of hypertensive animals is explained by the partial depolarization of their arteries. It is noted that they are arteriolar dilators and that they cannot be simply considered as vasodilators. The second part of this report provides key information about clinical usefulness of CCBs. A section is devoted to the controversy on their safety closed by the Allhat trial (2002). Sections are dedicated to their effect in cardiac ischemia, in cardiac arrhythmias, in atherosclerosis, in hypertension, and its complications. CCBs appear as the most commonly used for the treatment of cardiovascular diseases. As far as hypertension is concerned, globally the prevalence in adults aged 25 years and over was around 40% in 2008. Usefulness of CCBs is discussed on the basis of large clinical trials. At therapeutic dosage, they reduce the elevated blood pressure of hypertensive patients but don't change blood pressure of normotensive subjects, as was observed in animals. Those active on both L- and T-type channels are efficient in nephropathy. Alteration of cognitive function is a complication of hypertension recognized nowadays as eventually leading to dementia. This question is discussed together with the efficacy of CCBs in cognitive pathology. In the section entitled beyond the cardiovascular system, CCBs actions in migraine, neuropathic pain, and subarachnoid hemorrhage are reported. The final conclusions refer to long-term effects discovered in experimental animals that have not yet been clearly reported as being important in human pharmacotherapy.

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.

Effectiveness of minocycline and FK506 alone and in combination on enhanced behavioral and biochemical recovery from spinal cord injury in rats

Injury to the spinal cord results in immediate physical damage (primary injury) followed by a prolonged posttraumatic inflammatory disorder (secondary injury). The present study aimed to investigate the neuroprotective effects of minocycline and FK506 (Tacrolimus) individually and in combination on recovery from experimental spinal cord injury (SCI). Young adult male rats were subjected to experimental SCI by weight compression method. Minocycline (50mg/kg) and FK506 (1mg/kg) were administered orally in combination and individually to the SCI group daily for three weeks. During these three weeks, the recovery was measured using behavioral motor parameters (including BBB, Tarlov and other scorings) every other day for 29days after SCI. Thereafter, the animals were sacrificed and the segment of the spinal cord centered at the injury site was removed for the histopathological studies as well as for biochemical analysis of monoamines such as 5-hydroxytryptamine (5-HT) and 5-hydroxy-indolacetic acid (5-HIAA) and some oxidative stress indices, such as thiobarbituric acid-reactive substances (TBARS), total glutathione (GSH) and myeloperoxidase (MPO). All behavioral results indicated that both drugs induced significant recovery from SCI with respect to time. The biochemical and histopathological results supported the behavioral findings, revealing significant recovery in the regeneration of the injured spinal tissues, the monoamine levels, and the oxidative stress indices. Overall, the effects of the tested drugs for SCI recovery were as follows: FK506+minocycline>minocycline>FK506 in all studied parameters. Thus, minocycline and FK506 may prove to be a potential therapy cocktail to treat acute SCI. However, further studies are warranted.

Localized delivery of methylprednisolone sodium succinate with polymeric nanoparticles in experimental injured spinal cord model

With important social and economic consequences, spinal cord injuries (SCIs) still exist among major health problems. Although many therapeutic agents and methods investigated for the treatment of acute SCI, only high dose methylprednisolone (MP) is being used currently in practice. Due to the serious side effects, high dose systemic MP administration after SCI is a critical issue that is mostly considered controversial. In our study, it is aimed to develop a nanoparticle-gel combined drug delivery system for localization of MP on trauma site and eliminating dose-dependent side effects by lowering the administered dose. For this purpose, methyl prednisolone sodium succinate (MPSS) loaded polycaprolactone based nanoparticles were developed and embedded in an implantable fibrin gel. The effects of MPSS delivery system are evaluated on an acute SCI rat model, by quantification the levels of three inflammatory cytokines (interleukin-1β, interleukin-6 and caspase-3) and assessment of the damage on ultrastructural level by transmission electron microscopy. Developed NP-gel system showed very similar results with systemic high dose of MPSS. It is believed that developed system may be used as a tool for the safe and effective localized delivery of several other therapeutic molecules on injured spinal cord cases.

A preliminary evaluation of the reliability of a modified functional scoring system for assessing neurologic function in ambulatory thoracolumbar myelopathy dogs

BACKGROUND

The objective of this study was to develop and assess the reliability of a modified scoring system for evaluating the function of the two pelvic limbs separately, in ambulatory thoracolumbar myelopathy dogs. A previously established neurologic score scale for dogs with T3-L3 lesions was modified in order to provide a separate score for each pelvic limb.

RESULTS

Seventeen ambulatory dogs with thoracolumbar myelopathies were evaluated. Using the new scale, two observers independently performed 22 observational gait analyses (OGAs) in ten dogs without videotape. Another 18 OGAs were performed in seven dogs by watching videotapes of them ambulating. There was poor agreement (concordance correlation coefficient, 0.87) between the two observers for all 40 OGAs. When stratified, the agreement was moderate (concordance correlation coefficient, 0.90) in the OGAs without videotaping and poor (concordance correlation coefficient, 0.80) for the OGAs based on videotapes. For the decision regarding which pelvic limb was more severely affected, a fair agreement (kappa value, 0.30) between the two observers was noted. Without videotape there was only slight agreement (kappa value, 0.05), but with videotape there was moderate agreement (kappa value, 0.56).

CONCLUSIONS

The modified scoring system in this study provides moderate reliability in assessing the functional neurologic status of each pelvic limb, by OGA without videotape, in canine T3-L3 patients. Further development of this scoring system is required. However, imperfect agreement when visually quantifying neurological deficits is not unexpected.

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.

Therapeutic Hypothermia in Spinal Cord Injury: The Status of Its Use and Open Questions

Spinal cord injury (SCI) is a major health problem and is associated with a diversity of neurological symptoms. Pathophysiologically, dysfunction after SCI results from the culmination of tissue damage produced both by the primary insult and a range of secondary injury mechanisms. The application of hypothermia has been demonstrated to be neuroprotective after SCI in both experimental and human studies. The myriad of protective mechanisms of hypothermia include the slowing down of metabolism, decreasing free radical generation, inhibiting excitotoxicity and apoptosis, ameliorating inflammation, preserving the blood spinal cord barrier, inhibiting astrogliosis, promoting angiogenesis, as well as decreasing axonal damage and encouraging neurogenesis. Hypothermia has also been combined with other interventions, such as antioxidants, anesthetics, alkalinization and cell transplantation for additional benefit. Although a large body of work has reported on the effectiveness of hypothermia as a neuroprotective approach after SCI and its application has been translated to the clinic, a number of questions still remain regarding its use, including the identification of hypothermia's therapeutic window, optimal duration and the most appropriate rewarming rate. In addition, it is necessary to investigate the neuroprotective effect of combining therapeutic hypothermia with other treatment strategies for putative synergies, particularly those involving neurorepair.

Current and future medical therapeutic strategies for the functional repair of spinal cord injury

Spinal cord injury (SCI) leads to social and psychological problems in patients and requires costly treatment and care. In recent years, various pharmacological agents have been tested for acute SCI. Large scale, prospective, randomized, controlled clinical trials have failed to demonstrate marked neurological benefit in contrast to their success in the laboratory. Today, the most important problem is ineffectiveness of nonsurgical treatment choices in human SCI that showed neuroprotective effects in animal studies. Recently, attempted cellular therapy and transplantations are promising. A better understanding of the pathophysiology of SCI started in the early 1980s. Research had been looking at neuroprotection in the 1980s and the first half of 1990s and regeneration studies started in the second half of the 1990s. A number of studies on surgical timing suggest that early surgical intervention is safe and feasible, can improve clinical and neurological outcomes and reduce health care costs, and minimize the secondary damage caused by compression of the spinal cord after trauma. This article reviews current evidence for early surgical decompression and nonsurgical treatment options, including pharmacological and cellular therapy, as the treatment choices for SCI.

Oxidative stress and antioxidative parameters in patients with spinal cord injury: implications in the pathogenesis of disease

STUDY DESIGN

Oxygen-derived free radicals have been implicated in the pathogenesis of spinal cord injury (SCI) after trauma.

OBJECTIVE

In this review we will elucidate the importance of oxidative stress and antioxidants and its possible relationship with SCI.

METHODS

Literature analysis of oxidative stress, antioxidative parameters based on its implications in the pathogenesis along with devastating effect of oxidative stress parameters on SCI patients and its suggested proposed treatment by antioxidants have been performed.

RESULTS

SCI remains a major health problem despite advances in neurotechnology. Previous studies have reported oxidative stress in SCI patients, but the results were inconsistent. Furthermore, increased free radical levels are reported in SCI. Moreover, we have also mentioned in this review that oxidative stress is supposed to be increased in patients with SCI, which is related to the severity of SCI pain.

CONCLUSION

Oxidative stress was commonly seen in SCI patients, which may provide useful information to augment the understanding of pathophysiology of SCI patients. However, complete understanding of the biochemical events occurring at a cellular level that influence oxidative damage is required to guide future therapeutic advances. Furthermore, supplementation of antioxidants may also be considered in these patients.

Impact of aortic cross-clamping time on peripheral nerves: experimental model

PURPOSE

The present study investigated the correlation between extend aortic cross-clamping time and peripheral nerve injury on rats.

METHODS

24 male, Sprague Dawley rats were divided into 3 groups; (a) control group: abdomen was directly closed after reached aorta, and followed by 72 hours, (b) short-term ischaemia-reperfusion group: peripheral nerve ischemia was induced in rats by supraceliac aortic occlusion for 20 min followed by 72 h of reperfusion, (c) long-term ischaemia-reperfusion group: peripheral nerve ischemia was induced for 30 min followed by 72 h of reperfusion. Preoperative and postoperative, electromyography (EMG) recordings were done. End of 72 h, the sciatic nerves were harvested from each animal for histopathological and biochemical analysis.

RESULTS

The mean compound muscle action potential (CMAP) amplitude of long-term ischaemia-reperfusion group was statically significant reduced when compared to the control group (p <0.01). However, the mean distal latency value of long-term ischaemia-reperfusion group was statically significant increased (p <0.01). On the other hand, there were statically significant differences between the results of malondialdehyde, edema and ischemia fiber degeneration grades on control and long-term ischaemia-reperfusion group (p <0.001).

CONCLUSION

This study demonstrated that the extending cross clamping time directly harms the peripheral nerve of rats.

The dose-dependent neuroprotective effect of alpha-lipoic acid in experimental spinal cord injury

BACKGROUND AND PURPOSE

Free radical production after spinal cord injury (SCI) plays an important role in secondary damage. The aim of this study was to investigate neuroprotective effects of the powerful antioxidant alpha-lipoic acid (ALA) in a spinal cord clip compression injury model.

MATERIAL AND METHODS

Fifty-six Sprague-Dawley rats, weighing between 210 and 300 g, were randomly divided into seven groups. Spinal cord injury was performed by an aneurysm clip placed extradurally at the level of T9. Group 1 (sham) received laminectomy only. Group 2 (control) received SCI; Group 3 received 30 mg/kg of methylprednisolone sodium succinate (MPSS); Groups 4, 5, 6 and 7 received ALA at doses of 50, 100, 150, 200 mg/kg, respectively, via the intraperitoneal route immediately after SCI. The rats were neurologically tested 24 hours after trauma. Spinal cord samples from injury sites were harvested for measurement of lipid peroxidation products and histopathological evaluation.

RESULTS

Spinal cord malonyldialdehyde levels of rats in treatment groups decreased after administration of ALA. The difference between the trauma group and groups receiving MPSS-ALA was statistically significant. The difference between the ALA (50, 100, 150 mg/kg) and MPSS groups was insignificant. Group 7 (ALA 200 mg/kg) was excluded from the study because of the possible toxic effect. Alpha lipoic acid and MPSS had similar effects on spinal cord injury in terms of lipid peroxidation, neurological recovery and histopathological changes.

CONCLUSIONS

Alpha lipoic acid at a dose range of 50-150 mg/ kg is as effective as MPSS (30 mg/kg) in neuroprotection after SCI. Further, more detailed experimental studies are needed to determine the effects of ALA on the detrimental results of secondary SCI before its use in humans.

Updates in the management of the small animal patient with neurologic trauma

Neurologic trauma, encompassing traumatic brain injury (TBI) and acute spinal cord injury (SCI), is a cause of significant morbidity and mortality in veterinary patients. Acute SCIs occurring secondary to trauma are also common. Essential to the management of TBI and SCI is a thorough understanding of the pathophysiology of the primary and secondary injury that occurs following trauma. This article reviews the pathophysiology of this primary and secondary injury, as well as recommendations regarding clinical assessment, diagnostics, pharmacologic and nonpharmacologic therapy, and prognosis.

Mechanisms of injury and emergency care of acute spinal cord injury in dogs and cats

OBJECTIVES

To review the literature in regards to the pathophysiology of acute spinal cord injury, and to describe current concepts in regards to patient assessment, diagnostic, and therapeutic measures with a special emphasis on emergency and critical care considerations.

ETIOLOGY

Acute spinal cord injury occurs in 2 phases. The primary injury occurs at the time of initial injury and may include intervertebral disk herniation, vertebral fracture or luxation, penetrating injury, and vascular anomalies such as fibrocartilaginous embolic myelopathy. Secondary injury occurs following primary injury and is multifactorial encompassing numerous biochemical and vascular events that result in progression of injury.

DIAGNOSIS

The diagnosis is based on history and physical examination findings. A neurologic examination should be performed following initial patient assessment and stabilization. Further diagnostics to characterize acute spinal injury include radiographs and advanced imaging modalities such as myelography, computed tomography, or magnetic resonance imaging.

THERAPY

Initial treatment should focus on addressing the patient's cardiovascular and respiratory system. Supportive measures to support systemic perfusion are vital to minimizing secondary injury. Specific therapy toward minimizing secondary injury in veterinary medicine remains controversial, especially in regards to the utilization of methylprednisolone. Other therapies are either in need of additional research or have failed to document clinical difference.

PROGNOSIS

The prognosis for acute spinal injury is varied and is dependent upon the presence of concurrent trauma, location, and type of primary injury sustained, and extent of neurologic impairment at the time of initial presentation. The etiology of the underlying trauma is of great importance in determining prognosis and outcome. Loss of deep pain is generally accepted as a poor prognostic indicator; however, even these patients can recover depending on their response to treatment.

Limiting spinal cord injury by pharmacological intervention

The direct primary mechanical trauma to neurons, glia and blood vessels that occurs with spinal cord injury (SCI) is followed by a complex cascade of biochemical and cellular changes which serve to increase the size of the injury site and the extent of cellular and axonal loss. The aim of neuroprotective strategies in SCI is to limit the extent of this secondary cell loss by inhibiting key components of the evolving injury cascade. In this review we will briefly outline the pathophysiological events that occur in SCI, and then review the wide range of neuroprotective agents that have been evaluated in preclinical SCI models. Agents will be considered under the following categories: antioxidants, erythropoietin and derivatives, lipids, riluzole, opioid antagonists, hormones, anti-inflammatory agents, statins, calpain inhibitors, hypothermia, and emerging strategies. Several clinical trials of neuroprotective agents have already taken place and have generally had disappointing results. In attempting to identify promising new treatments, we will therefore highlight agents with (1) low known risks or established clinical use, (2) behavioral data gained in clinically relevant animal models, (3) efficacy when administered after the injury, and (4) robust effects seen in more than one laboratory and/or more than one model of SCI.

Antioxidant therapies in traumatic brain and spinal cord injury

Free radical formation and oxidative damage have been extensively investigated and validated as important contributors to the pathophysiology of acute central nervous system injury. The generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is an early event following injury occurring within minutes of mechanical impact. A key component in this event is peroxynitrite-induced lipid peroxidation. As discussed in this review, peroxynitrite formation and lipid peroxidation irreversibly damages neuronal membrane lipids and protein function, which results in subsequent disruptions in ion homeostasis, glutamate-mediated excitotoxicity, mitochondrial respiratory failure and microvascular damage. Antioxidant approaches include the inhibition and/or scavenging of superoxide, peroxynitrite, or carbonyl compounds, the inhibition of lipid peroxidation and the targeting of the endogenous antioxidant defense system. This review covers the preclinical and clinical literature supporting the role of ROS and RNS and their derived oxygen free radicals in the secondary injury response following acute traumatic brain injury (TBI) and spinal cord injury (SCI) and reviews the past and current trends in the development of antioxidant therapeutic strategies. Combinatorial treatment with the suggested mechanistically complementary antioxidants will also be discussed as a promising neuroprotective approach in TBI and SCI therapeutic research. This article is part of a Special Issue entitled: Antioxidants and antioxidant treatment in disease.

Targeting microvasculature for neuroprotection after SCI

Spinal cord injury (SCI) is characterized by secondary degeneration, which leads to tissue loss at the epicenter and subsequent functional deficits. This review provides insight into the pathophysiology of microvascular dysfunction and endothelial cell loss, which are among the earliest responses during the first postinjury day. The enigmatic role of the angiogenic response in the penumbra around the lost tissue, which occurs during the first 2 weeks, is also discussed. The importance of stabilizing and rescuing the injured vasculature is now well-recognized, and several pharmacological and genetic treatments have emerged in the past few years. We conclude with suggestions for future experimental research, including development of vascular-selective treatments and exploitation of genetic models. In summary, vascular dysfunction following SCI is an important contributor to neurological deficits, as proposed long ago. However, there now appears to be new and potentially powerful opportunities for treating acute SCI by targeting the vascular responses.

Antioxidant therapies for acute spinal cord injury

One of the most investigated molecular mechanisms involved in the secondary pathophysiology of acute spinal cord injury (SCI) is free radical-induced, iron-catalyzed lipid peroxidation (LP) and protein oxidative/nitrative damage to spinal neurons, glia, and microvascular cells. The reactive nitrogen species peroxynitrite and its highly reactive free radicals are key initiators of LP and protein nitration in the injured spinal cord, the biochemistry, and pathophysiology of which are first of all reviewed in this article. This is followed by a presentation of the antioxidant mechanistic approaches and pharmacological compounds that have been shown to have neuroprotective properties in preclinical SCI models. Two of these, which act by inhibition of LP, are high-dose treatment with the glucocorticoid steroid methylprednisolone (MP) and the nonglucocorticoid 21-aminosteroid tirilazad, have been demonstrated in the multicenter NASCIS clinical trials to produce at least a modest improvement in neurological recovery when administered within the first 8 hours after SCI. Although these results have provided considerable validation of oxidative damage as a clinically practical neuroprotective target, there is a need for the discovery of safer and more effective antioxidant compounds for acute SCI.

Rescuing vasculature with intravenous angiopoietin-1 and alpha v beta 3 integrin peptide is protective after spinal cord injury

Blood vessel loss and inflammation cause secondary degeneration following spinal cord injury. Angiopoietin-1 through the Tie2 receptor, and other ligands through alphavbeta3 integrin, promote endothelial cell survival during developmental or tumour angiogenesis. Here, daily intravenous injections with an alphavbeta3-binding peptide named C16 or an angiopoietin-1 mimetic following a spinal cord contusion at thoracic level 9 in mice rescued epicentre blood vessels, white matter and locomotor function, and reduced detrimental inflammation. Preserved vascularity and reduced inflammation correlated with improved outcomes. C16 and angiopoietin-1 reduced leukocyte transmigration in vitro. Growth factor receptors and integrins facilitate each others' function. Therefore, angiopoietin-1 and C16 were combined and the effects were additive, resulting in almost complete functional recovery. The treatment had lasting effects when started 4 h following injury and terminated after one week. These results identify alphavbeta3 integrin and the endothelial-selective angiopoietin-1 as vascular and inflammatory regulators that can be targeted in a clinically relevant manner for neuroprotection after central nervous system trauma.

Amitriptyline pharmacokinetics in experimental spinal cord injury in the rabbit

Previous studies have demonstrated that pharmacokinetic behavior of several drugs such as paracetamol, theophylline, and aminoglycosides are significantly altered in spinal cord injured patients. No pharmacokinetic study of amitriptyline has been performed in patients and experimental models of spinal cord injury. Pharmacokinetic parameters of amitriptyline in orally treated rabbits subjected to laminectomy and spinal cord injury compared with those underwent laminectomy alone. Among twenty four male rabbits were included in this study, nine of them subjected to spinal cord injury at the 8(th) thoracic level by knife severance method and six rabbits underwent laminectomy alone (sham group) and nine rabbits treated as control. All received a single oral dose of amitriptyline (20 mg/kg) 24 h after injury. Blood sampling were done at predetermined times to 36 h after drug administration. Amitriptyline concentration in serum samples was determined by high-performance liquid chromatography. Pharmacokinetic parameters including maximum concentration (C(max)), time to reach maximum concentration (T(max)), half life, and the area under the curve to last detectable concentration time point (AUC(0-t)) were directly determined from the concentration-time curve. Maximum concentration was observed at 6.5 h after administration in sham group with a concentration of 439.6 ng/ml, whereas in SCI group T(max) was at 2.7 h with a concentration of 2763.9 ng/ml. In control group it was 3.3 h and 396 ng/ml, respectively. In SCI group, AUC was 9465.6 ng.h/ml and half life was 6 h and for control group it was 2817.4 ng.h/ml and 6.4 h, respectively. Statistical analysis of data showed that SCI didn't induce significant changes in amitriptyline pharmacokinetic parameters.

Role of Prostacyclin in the Development of Compression Trauma-Induced Spinal Cord Injury in Rats

We investigated the role of prostacyclin (PGI(2)) in the development of compression trauma-induced spinal cord injury (SCI) in rats. When measured after induction of SCI, tissue levels of 6-keto-PGF(1), a stable PGI(2) metabolite, thromboxane B(2) (TXB(2)), a stable metabolite of thromboxane A(2), myeloperoxidase (MPO) activity, and tumor necrosis factor (TNF) in the injured spinal cord segment were significantly increased, peaking at 2, 3, and 4 h after induction of SCI, respectively. Subcutaneous administration of indomethacin (IM), a non-selective cyclooxygenase (COX) inhibitor, completely inhibited increases in tissue levels of 6-keto-PGF(1) and TXB(2), while administration of NS-398, a selective inhibitor of COX-2, did not affect these increases. Although pretreatment with IM enhanced increases in tissue levels of MPO, TNF, and TNF mRNA and exacerbated both motor disturbances and histological damage in the spinal cord of animals subjected to SCI, pretreatment with NS-398 had no effect on any of these findings. Both iloprost, a stable analog of PGI(2), and leukocyte depletion significantly reversed changes in various variables and exacerbation of motor disturbances induced by IM pretreatment in animals subjected to SCI. These observations strongly suggested that compression trauma-induced increase in PGI(2) production in spinal cord tissue might be mainly mediated by COX-1 and PGI(2) might play a critical role in reduction of motor disturbances following SCI by inhibiting neutrophil accumulation through inhibition of TNF production.

Intrathecal bupivacaine protects against extension of lesions in an acute contusive spinal cord injury model

BACKGROUND AND OBJECTIVE

We recently demonstrated that intrathecal bupivacaine before or after acute photochemical spinal injury improved functional outcome in rats. However, the closest model to spinal trauma is the contusive weight-drop method. The aim of this study was to evaluate functional, electrophysiological and anatomical consequences of a contusive spinal-cord lesion in rats with or without an intrathecal injection of bupivacaine.

METHODS

Fifteen minutes before a contusive spinal lesion, 18 rats received intrathecally either 0.5% bupivacaine (Group T) or saline (Group C). During an 18-days period, motor and sensory functions were evaluated, and bladder voiding dysfunction was noted. Somatosensory evoked potential testings were performed at day 18. Then, the intact spinal cord area at the epicentre of the lesion and the extent of the lesion were measured.

RESULTS

Motor deficit was less and inclined-plane stability was better in treated animals at all times, the scores were statistically different from day 7. There were no differences concerning the sensory test. Despite no significant difference, there were less spinal bladders in the T group from day 7. Somatosensory evoked potential latencies were longer in T group, but only the first negative component (N1) was statistically significant. Amplitudes were higher in T group, but were not statistically different. The spinal cord intact area at the epicentre of the lesion was higher in the T group (1.23 +/- 0.8 mm(2) vs. 0.81 +/- 0.39 mm(2); P < 0.05). The extent of the lesion was higher in the C group (9.4 +/- 2.9 mm vs. 6.4 +/- 3.4 mm; P < 0.05).

CONCLUSION

Intrathecal 0.5% bupivacaine provide a neuroprotective effect by decreasing functional, electrophysiological and anatomical consequences after a contusive spinal cord injury.

Dose-dependent neuroprotective effects of melatonin on experimental spinal cord injury in rats

BACKGROUND

This report examines the dose-dependent effects of melatonin on early lipid peroxidation levels, ultrastructural changes, and neurological function in experimental spinal cord injury (SCI) by comparing them with therapeutic levels of methylprednisone in rats.

METHODS

SCI was performed by an aneurysm clip placed extradurally at the level of T10. Rats were randomly divided into six groups of 10 rats each. Group 1 (sham) received only laminectomy; group 2 (control) received SCI; group 3 (placebo) received SCI and physiological saline; group 4 received methylprednisone (30 mg/kg); groups 5 and 6 received melatonin at doses of 50 or 100 mg/kg, respectively, after SCI. Rats were neurologically tested 24 hours after trauma. Spinal cord samples were harvested for both lipid peroxidation levels and ultrastructural histopathological evaluation.

RESULTS

Neurological scores of rats were not different in SCI groups. Lipid peroxidation levels are significantly restricted only in methylprednisone group at 24 hours. Melatonin-treated groups showed more ultrastructural improvement on electron microscope studies when compared with methylprednisone group. However, the therapeutic effects of melatonin were mainly observed on white matter of spinal cord in ultrastructural investigation. There was significant difference between melatonin dose groups increasing with dose.

CONCLUSIONS

Results showed that melatonin has no significant dose-dependent effects on early lipid peroxidation bur rather some neuroprotective effects on both axons and myelin sheaths of white matter in ultrastructural observations when compared with methylprednisone. These effects significantly augmented with dose increase.

Effectiveness of FK506 on lipid peroxidation in the spinal cord following experimental traumatic injury

STUDY DESIGN

An in vivo study in Wistar albino rats with injured spinal cord.

SETTING

Department of Neurosurgery, Biochemistry and Pathology, Gazi University, Ankara, Turkey.

OBJECTIVES

The aim of this study was to investigate and compare the effects of FK506 an immunosupressive agent with methylprednisolone (MP) on lipid peroxidation (LP) in injured spinal cord tissue.

METHOD

A total of 28 adult healthy Wistar albino rats were subjected to traumatic spinal cord injuries (SCI) by using an aneurysmal clip compression technique, and they were divided into four groups. The G1 group (n=8) received FK506 (1 mg/kg); the G2 group (n=8) received FK506 (1 mg/kg) and MP (30 mg/kg); the G3 group (n=6) received only MP (30 mg/kg); and the G4 group (n=6) received no medication. The injured spinal cord tissue was studied by means of lipid peroxides, malondialdehyde (MDA), with thiobarbituric acid reaction and additionally the FK506 (G1); the MP (G3) groups were studied for histopathologic alterations 72 h after SCI with eight separate animals.

RESULTS

Although LP values of G1, G2, G3 showed no statistical difference between intergroup analyses (P=0.547), a histopathological examination revealed that in the group that received MP, the oedema pattern was more significant than the group that received FK506. Another interesting finding was the presence of polymorphonuclear leucocytes in the MP group, whereas no infiltration was found in the FK506 group.

CONCLUSION

Analysis of the results indicated that FK506 is a valuable pharmacological agent that could be used to decrease the LP and polymorphonuclear leucocyte infiltration and inflamatory reactions in the injured spinal cord tissue.

Intrathecal bupivacaine protects against extension of lesions in an acute photochemical spinal cord injury model

PURPOSE

The photochemical spinal-cord injury model reproduces extensive secondary lesions that occur after spinal injury. We have evaluated in 27 rats the functional, electrophysiological and anatomical consequences of a photochemical spinal-cord lesion induced before or after intrathecal injection of bupivacaine.

METHODS

After randomization, nine rats received 20 micro L of intrathecal bupivacaine 0.5% 15 min before a photochemical spinal-cord lesion (Group I) and eight rats received 20 micro L intrathecal bupivacaine 15 min after such a lesion (Group II). Ten rats received 20 micro L of saline 15 min before the photochemical injury (control group). Paraplegia was tested on days one, three, five, seven, nine, 12, 15 and 18 using an evaluation of hindlimb movements and an inclined plane stability test. Sensory block was evaluated by the animal's response when each hindlimb was brought into contact with a hot plate. Sympathetic injury was evaluated in terms of bladder voiding dysfunction. On day 18, residual somatosensory evoked potentials (SEP) were measured and the area of the intact spinal cord was determined using a digitalized system.

RESULTS

Early paraplegia recovery was found in the two bupivacaine groups (P < 0.05). On day 12, motor recovery was complete in both bupivacaine groups whereas recovery was not complete on day 18 in the control group. Compared to the control group, inclined plane stability recovered earlier in Groups I and II, from day three to day 15. Sensory and sympathetic block scores were not different in the three groups. Nevertheless, SEP latencies were longer and amplitudes were lower in control group rats compared with the two bupivacaine groups on day 18. The intact spinal-cord cross-sectional area around the lesion was not different in the three groups.

CONCLUSION

Twenty microlitres of intrathecal bupivacaine before or after acute photochemical spinal injury improves hindlimb motor recovery and SEP parameters in rats.

Efficacy of DA-8159, a new PDE5 inhibitor, for inducing penile erection in rabbits with acute spinal cord injury

DA-8159 is a pyrazolopyrimidinone derivative which exhibits potent and selective phosphodiesterase type 5 (PDE5) inhibition. The aim of this study was to investigate the effects of DA-8159 on inducing a penile erection in rabbits with an acute spinal cord injury (ASCI). DA-8159 was given either orally (1, 3, or 10 mg/kg) or intravenously (0.1 or 0.3 mg/kg) to conscious male albino rabbits with a surgical transection of the spinal cord at the L2-L4 lumbar vertebra or ischemic-reperfusion SCI rabbits. Erection was evaluated in a time-course manner by measuring the length of the uncovered penile mucosa. DA-8159 induced a dose-dependent erection in both transection and ischemic-reperfusion ASCI rabbits. The efficacy of DA-8159 was potentiated by an intravenous injection of sodium nitroprusside, a nitric oxide donor. Potentiation of the effect by nitric oxide donor implies that DA-8159 can enhance the erectile activity during sexual arousal. These results suggest that DA-8159 may be useful for treating erectile dysfunction in patients with an SCI.

Magnesium sulfate treatment in experimental spinal cord injury: emphasis on vascular changes and early clinical results

Injury to the spinal cord results in disruption of neurons, cell membranes, axons, myelin, and endothelial cells. The aim of this study was to demonstrate the protective effect of magnesium sulfate on the blood-spinal cord barrier after acute spinal cord injury (SCI). This experiment was conducted in two parts. In the first, rats were injected intravenously with Evans blue 2 h after SCI. The laminectomy-only group had no trauma. Contusion injury (50 g-cm) was applied to the trauma and treatment groups. Magnesium sulfate (600 mg/kg) was given to the treatment group immediately after injury. For the second part, clinical evaluations were performed 24 h post surgery. Then, following Evans blue injection, spinal cord samples were obtained from the laminectomy-only, trauma, and treatment groups. For the control group, nontraumatized spinal cord samples were taken after Evans blue injection following clinical examination. Laminectomy did not affect the spinal cord Evans blue content in 2-h and 24-h groups. The trauma increased tissue Evans blue content, and 24-h samples showed more remarkable tissue Evans blue content, suggesting secondary injury. Application of 600 mg/kg of magnesium resulted in lower Evans blue content in the spinal cord than with injury. Remarkable clinical neuroprotection was observed in the treatment groups. Magnesium sulfate showed vaso- and neuroprotective properties after contusion injury to the rat spinal cord. The authors also demonstrated secondary injury of the blood-spinal cord barrier with the Evans blue clearance technique for the first time.

DA-8159, a new PDE5 Iihibitor, induces penile erection in conscious and acute spinal cord injured rabbits

OBJECTIVES

DA-8159 is a pyrazolopyrimidinone derivative showing potent and selective phosphodiesterase 5 (PDE5) inhibition. In the previous study, DA-8159 induced a dose-dependent increase in the intracavernous pressure (ICP) in anaesthetized dogs. The aim of this study was to investigate the effects of DA-8159 on penile erection in conscious and acute spinal cord injured (ASCI) rabbits.

METHODS

DA-8159 was given orally (0.3 to 10mg/kg) to normal rabbits and ASCI rabbits with a surgical transection of the spinal cord at the L2-L4 lumbar vertebra or ischemic-reperfusion. The erection was evaluated in a time-course manner by measuring the length of the uncovered penile mucosa in the absence or presence of intravenous sodium nitroprusside (SNP), a nitric oxide (NO) donor.

RESULTS

DA-8159 induced a dose-dependent penile erection in both the conscious and ASCI rabbits. The efficacy of DA-8159 was potentiated and the effective doses were significantly decreased by an intravenous injection of SNP. Potentiation of the effect by a nitric oxide donor implies that DA-8159 can enhance the erectile activity during sexual arousal.

CONCLUSION

These results demonstrate that DA-8159 may be a useful treatment option for erectile dysfunction in patients with or without a spinal cord injury, but further evaluation of the effects of DA-8159 on humans must be performed.

Effect of magnesium sulphate in experimental spinal cord injury: evaluation with ultrastructural findings and early clinical results

Excitotoxic mechanisms have been implicated in the pathophysiology of spinal cord injury (SCI). The authors have studied the protection against secondary damage to rat spinal cord with magnesium sulphate, a well-known N-methyl-D-aspartate antagonist. Rats were randomly allocated into 5 groups. Group 1 rats were controls and normal spinal cord samples were obtained after clinical examination. 50 g-cm contusion injury was introduced to Group 2. Group 3 was vehicle, 1 cc of physiologic saline was injected post-trauma. Group 4 and 5 were treatment groups and 100 mg/kg and 600 mg/kg of Magnesium sulphate was given immediately after trauma, intraperitoneally. Animals were evaluated with inclined plane, Tarlov motor scale and Basso-Beattie-Bresnahan scale 24h after SCI. Spinal cord samples for ultrastructural evaluations were obtained following clinical examinations. Magnesium treatment improved neurological outcome. Electron microscopic results showed obvious neuroprotection in the treatment groups. Application of 600 mg/kg of magnesium revealed better ultrastructural findings and clinical results than 100 mg/kg. These findings demonstrated that magnesium sulphate possesses neuroprotection on spinal cord ultrastructure and on functional scores after acute contusion injury to the rat spinal cord.

Effect of glutathione augmentation on lipid peroxidation after spinal cord injury

Lipid peroxidation (LPO) is considered a major factor in damage spread after spinal cord injury (SCI). Therapies that limit LPO after SCI have demonstrated some utility in clinical trials, but more effective treatments are needed. In the present study the effects of augmenting SC levels of the endogenous antioxidant glutathione (GSH) on LPO after SCI were studied in a rat contusion injury model. A significant decrease in GSH occurred 1h after SCI which was paralleled by increases of 123% in malondialdehyde (MDA) and >500% in the 4-hydroxyalkenals (4-HA's), two LPO products. SC irrigation with gamma-glutamylcysteine (GC) preserved GSH and reduced 4-HA's below naive levels but had no effect on MDA. By 24 h after SCI, MDA returned to naive levels but 4-HA's were still elevated. Once again, GC treatment reduced 4-HA's. 4-HA's are much more reactive than MDA and are considered among the most toxic LPO products. These results suggest that (1) conditions after SCI may favor particular branches of the LPO pathway leading to differential LPO product levels, (2) MDA measurement is not by itself an adequate test for the presence or magnitude of LPO after SCI, (3) binding of GSH to 4-HA's may be an important mechanism by which the GSH system confers protection against LPO after SCI, and (4) SC GSH can be augmented after trauma by local irrigation with GC. These results also suggest that GSH augmentation may be an effective strategy for curtailment of LPO-mediated damage in acute phase SCI.

Tetramethylpyrazine attenuates spinal cord ischemic injury due to aortic cross-clamping in rabbits

BACKGROUND

Lower limb paralysis occurs in 11% of patients after surgical procedure of thoracic or thoracoabdominal aneurysms and is an unpredictable and distressful complication. The aim of this study was to investigate the effects of tetramethylpyrazine (TMP), an intravenous drug made from traditional Chinese herbs, on the neurologic outcome and histopathology after transient spinal cord ischemia in rabbits.

METHODS

Forty-five male New Zealand white rabbits were anesthetized with isoflurane and spinal cord ischemia was induced for 20 min by infrarenal aortic occlusion. Animals were randomly allocated to one of five groups (n = 8 each). Group C received no pharmacologic intervention. Group P received intravenous infusion of 30 mg x kg(-1) TMP within 30 min before aortic occlusion. Group T1, Group T2 and Group T3 received intravenous infusion of 15, 30 and 60 mg x kg(-1) TMP respectively within 30 min after reperfusion. In the sham group (n = 5), the animals underwent the same procedures as the control group except infrarental aortic unocclusion. Neurologic status was scored by using the Tarlov criteria (in which 4 is normal and 0 is paraplegia) at 4 h, 8 h, 12 h, 24 h, and 48 h after reperfusion. All animals were sacrificed at 48 h after reperfusion and the spinal cords (L5) were removed immediately for histopathologic study.

RESULTS

All animals in the control group became paraplegic. Neurologic status and histopathology (48 h) in the Groups P, T2 and T3 were significantly better than those in the control group (P < 0.05). There was a strong correlation between the final neurologic scores and the number of normal neurons in the anterior spinal cord (r = 0.776, P < 0.01).

CONCLUSION

Tetramethylpyrazine significantly reduces neurologic injury related to spinal cord ischemia and reperfusion after aortic occlusion within a certain range of dose.

Management of acute spinal cord injuries in an intensive care unit or other monitored setting

STANDARDS

There is insufficient evidence to support treatment standards.

GUIDELINES

There is insufficient evidence to support treatment guidelines.

OPTIONS

Management of patients with acute spinal cord injury, particularly patients with severe cervical level injuries, in an intensive care unit or similar monitored setting is recommended. Use of cardiac, hemodynamic, and respiratory monitoring devices to detect cardiovascular dysfunction and respiratory insufficiency in patients after acute cervical spinal cord injury is recommended.

Blood pressure management after acute spinal cord injury

STANDARDS

There is insufficient evidence to support treatment standards.

GUIDELINES

There is insufficient evidence to support treatment guidelines.

OPTIONS

Hypotension (systolic blood pressure <90 mmHg) should be avoided if possible or corrected as soon as possible after acute spinal cord injury. Maintenance of mean arterial blood pressure at 85 to 90 mmHg for the first 7 days after acute spinal cord injury to improve spinal cord perfusion is recommended.

Development of a functional scoring system in dogs with acute spinal cord injuries

OBJECTIVES

To develop and compare the reliability of 2 methods of scoring pelvic limb gait in dogs recovering from thoracolumbar spinal cord injuries and to use this scoring system to determine the rate and level of functional recovery of dogs with acute thoracolumbar intervertebral disk herniations.

ANIMALS

46 dogs with spinal cord injuries resulting from intervertebral disk herniations.

PROCEDURE

Dogs' gaits were videotaped at different time intervals after injury. In phase 1 of the study, the stages of recovery of pelvic limb function were identified, and a numeric scoring system was devised to reflect that recovery. In phase 2, pelvic limb gait was scored by different observers, using a numeric and a visual analog scale. Intra- and interobserver coefficients of variability of both methods were compared. In phase 3, pelvic limb function was scored, using the numeric scale at various intervals after acute thoracolumbar disk herniations.

RESULTS

The numeric scale was significantly more reliable than the visual analog scale when both intra- and interobserver coefficients of variability were evaluated. Dogs that were paraplegic with no deep pain sensation recovered at different rates during the first 3 months, whereas dogs that were paraplegic with deep pain sensation typically recovered within 1 month of injury.

CONCLUSIONS

Pelvic limb gait of dogs recovering from thoracolumbar spinal cord injuries can be reliably quantified, using a numeric scale. This scale will facilitate the performance of clinical trials aimed at improving the outcome of acute spinal cord injuries.