The pathologic mechanisms underlying lumbar distraction spinal cord injury in rabbits

Delayed postoperative neurological deficits from scoliosis correction: a case series and systematic review on clinical characteristics, treatment, prognosis, and recovery

OBJECTIVE

This study was designed to investigate the clinical features, treatment modalities, and risk factors influencing neurological recovery in patients who underwent scoliosis correction with delayed postoperative neurological deficit (DPND).

METHODS

Three patients with DPND were identified from 2 central databases for descriptive analysis. Furthermore, all DPND cases were retrieved from the PubMed and Embase databases. Neurological function recovery was categorized into complete and incomplete recovery groups based on the American Spinal Injury Association (ASIA) impairment scale.

RESULTS

Two patients were classified as type 3, and one was classified as type 2 based on the MRI spinal cord classification. Intraoperative neurophysiological monitoring (IONM) was consistently negative throughout the corrective procedure, and intraoperative wake-up tests were normal. The average time to DPND development was 11.8 h (range, 4-18 h), and all three patients achieved complete recovery of neurological function after undergoing revision surgery. A total of 14 articles involving 31 patients were included in the literature review. The mean time to onset of DPND was found to be 25.2 h, and 85.3% (29/34) of patients experienced DPND within the first 48 h postoperatively, with the most common initial symptoms being decreased muscle strength and sensation (26 patients, 83.9%). Regarding neurological function recovery, 14 patients were able to reach ASIA grade E, while 14 patients were not able to reach ASIA grade E. Univariate analysis revealed that preoperative diagnosis (p = 0.004), operative duration (p = 0.017), intraoperative osteotomy method (p = 0.033), level of neurological deficit (p = 0.037) and deficit source (p = 0.0358) were significantly associated with neurological outcomes. Furthermore, multivariate regression analysis indicated a strong correlation between preoperative diagnosis (p = 0.003, OR, 68.633; 95% CI 4.299-1095.657) and neurological prognosis.

CONCLUSION

Our findings indicate that spinal cord ischemic injury was a significant factor for patients experiencing DPND and distraction after corrective surgery may be a predisposing factor for spinal cord ischemia. Additionally, it is important to consider the possibility of DPND when limb numbness and decreased muscle strength occur within 48 h after corrective scoliosis surgery. Moreover, emergency surgical intervention is highly recommended for DPND caused by mechanical compression factors with a promising prognosis for neurological function, emphasizing the importance of taking into account preoperative orthopedic diagnoses when evaluating the potential for neurological recovery.

Neurophysiological, histological, and behavioral characterization of animal models of distraction spinal cord injury: a systematic review

Distraction spinal cord injury is caused by some degree of distraction or longitudinal tension on the spinal cord and commonly occurs in patients who undergo corrective operation for severe spinal deformity. With the increased degree and duration of distraction, spinal cord injuries become more serious in terms of their neurophysiology, histology, and behavior. Very few studies have been published on the specific characteristics of distraction spinal cord injury. In this study, we systematically review 22 related studies involving animal models of distraction spinal cord injury, focusing particularly on the neurophysiological, histological, and behavioral characteristics of this disease. In addition, we summarize the mechanisms underlying primary and secondary injuries caused by distraction spinal cord injury and clarify the effects of different degrees and durations of distraction on the primary injuries associated with spinal cord injury. We provide new concepts for the establishment of a model of distraction spinal cord injury and related basic research, and provide reference guidelines for the clinical diagnosis and treatment of this disease.

The Associative Pattern Between Segmental Arterial Damage and Complete Neurological Disorder After Spinal Cord Injury: A Case-Control Study

INTRODUCTION

The prevalence of vascular trauma surrounding the thoracic spine following Spinal Cord Injury (SCI) is unknown. The potential for neurologic recovery is uncertain in many cases; in some cases, neurologic assessment is not possible, for example, in severe head injury or early intubation, and detection of segmental artery injury may help as a predictive factor.

OBJECTIVE

To assess the prevalence of segmental vessel disruption in two groups, with and without neurologic deficit.

MATERIAL AND METHODS

This is a retrospective cohort study, with a group SCI American Spinal Injury Association (ASIA) E and a group SCI ASIA A. All patients had a high-energy thoracic or thoracolumbar fracture from T1 to L1. Patients were matched 1:1 (one ASIA A matched with one ASIA E) according to the fracture type, age, and level. The primary variable was the assessment of the presence/disruption of the segmental arteries, bilaterally, around the fracture. Analysis was performed twice by two independent surgeons in a blinded fashion.

RESULTS

Both groups had 2 type A, 8 type B, and 4 type C fractures. The right segmental artery was detected in 14/14 (100%) of the patients with ASIA E and in 3/14 (21%) or 2/14 (14%) of the patients with ASIA A, according to the observers, p=0.001. The left segmental artery was detectable in 13/14 (93%) or 14/14 (100%) of the patients ASIA E and in 3/14 (21%) of the patients ASIA A for both observers. All in all, 13/14 of the patients with ASIA A had at least one segmental artery undetectable. The sensibility varied between 78%to 92%, and the specificity from 82% to 100%. The Kappa Score varied between 0.55 and 0.78.

CONCLUSION

Segmental arteries disruption was common in the group ASIA A. This may help to predict the neurological status of patients with no complete neurological assessment or potential for recovery post-injury.

Application of natural antioxidants from traditional Chinese medicine in the treatment of spinal cord injury

Spinal cord injury (SCI) is a devastating central nervous system disease, caused by physical traumas. With the characteristic of high disability rate, catastrophic dysfunction, and enormous burden on the patient’s family, SCI has become a tough neurological problem without efficient treatments. Contemporarily, the pathophysiology of SCI comprises complicated and underlying mechanisms, in which oxidative stress (OS) may play a critical role in contributing to a cascade of secondary injuries. OS substantively leads to ion imbalance, lipid peroxidation, inflammatory cell infiltration, mitochondrial disorder, and neuronal dysfunction. Hence, seeking the therapeutic intervention of alleviating OS and appropriate antioxidants is an essential clinical strategy. Previous studies have reported that traditional Chinese medicine (TCM) has antioxidant, anti-inflammatory, antiapoptotic and neuroprotective effects on alleviating SCI. Notably, the antioxidant effects of some metabolites and compounds of TCM have obtained numerous verifications, suggesting a potential therapeutic strategy for SCI. This review aims at investigating the mechanisms of OS in SCI and highlighting some TCM with antioxidant capacity used in the treatment of SCI.

Intraoperative Optical Monitoring of Spinal Cord Hemodynamics Using Multiwavelength Imaging System

The spinal cord is a major structure of the central nervous system allowing, among other things, the transmission of afferent sensory and efferent motor information. During spinal surgery, such as scoliosis correction, this structure can be damaged, resulting in major neurological damage to the patient. To date, there is no direct way to monitor the oxygenation of the spinal cord intraoperatively to reflect its vitality. This is essential information that would allow surgeons to adapt their procedure in case of ischemic suffering of the spinal cord. We report the development of a specific device to monitor the functional status of biological tissues with high resolution. The device, operating with multiple wavelengths, uses Near-InfraRed Spectroscopy (NIRS) in combination with other additional sensors, including ElectroNeuroGraphy (ENG). In this paper, we focused primarily on aspects of the PhotoPlethysmoGram (PPG), emanating from four different light sources to show in real time and record biological signals from the spinal cord in transmission and reflection modes. This multispectral system was successfully tested in in vivo experiments on the spinal cord of a pig for specific medical applications.

Mechanism Underlying Acupuncture Therapy in Spinal Cord Injury: A Narrative Overview of Preclinical Studies

Spinal cord injury (SCI) results from various pathogenic factors that destroy the normal structure and function of the spinal cord, subsequently causing sensory, motor, and autonomic nerve dysfunction. SCI is one of the most common causes of disability and death globally. It leads to severe physical and mental injury to patients and causes a substantial economic burden on families and the society. The pathological changes and underlying mechanisms within SCI involve oxidative stress, apoptosis, inflammation, etc. As a traditional therapy, acupuncture has a positive effect promoting the recovery of SCI. Acupuncture-induced neuroprotection includes several mechanisms such as reducing oxidative stress, inhibiting the inflammatory response and neuronal apoptosis, alleviating glial scar formation, promoting neural stem cell differentiation, and improving microcirculation within the injured area. Therefore, the recent studies exploring the mechanism of acupuncture therapy in SCI will help provide a theoretical basis for applying acupuncture and seeking a better treatment target and acupuncture approach for SCI patients.

Elucidating the Potential Mechanisms Underlying Distraction Spinal Cord Injury-Associated Neuroinflammation and Apoptosis

The incidence of distraction spinal cord injury (DSCI), which results from spinal cord ischemia due to vascular compromise and spinal cord tract disturbances, remains high. Furthermore, because no ideal animal model that mimics DSCI in clinical settings is available thus far, the related molecular mechanisms underlying DSCI remain unclear. Thus, this study aimed to establish a porcine model of DSCI and investigate the neuroinflammation and apoptosis mechanisms in these pigs. Before surgery, all pigs were randomly divided into three groups: sham group, osteotomy surgery only; the incomplete distraction spinal cord injury (IDSCI) and complete distraction spinal cord injury (CDSCI) group, osteotomy plus DSCI surgery with a motor-evoked potential (MEP) amplitude decreased by approximately 75% and 100%, respectively. After surgery, modified Tarlov scoring and MRC muscle strength scoring were used to evaluate neurologic function in each group. We observed the distracted spinal cord using MRI, and then all pigs were sacrificed. Inflammatory cytokine levels in the spinal cord and cerebrospinal fluid (CSF) were also analyzed. We used immunofluorescence staining to assess the neuronal and microglial structure and function and astrocyte hyperplasia in the central DSCI lesions (T15). Western blotting was used to determine the expression of apoptosis-related proteins. Results showed that the modified Tarlov scoring and muscle strength decreased significantly in the two DSCI groups. T2-MRI showed a relative enhancement at the center of the DSCI lesions. H&E and Lxol fast blue staining revealed that spinal cord distraction destroyed the normal structure of spinal cord tissues and nerve fiber tracts, exacerbating inflammatory cell infiltration, hyperemia, and edema. The IL-1β, IL-6, and TNF-α levels increased in the spinal cord and CSF following DSCI. Immunofluorescence staining results indicated the GFAP, Iba-1 expression increased following DSCI, whereas the NeuN expression reduced. Moreover, DSCI promoted the protein expression of P53, Bcl-2-associated X protein (Bax), and Caspase-3 in the spinal cord tissues, whereas it reduced the Bcl-2 expression. This study successfully established a porcine DSCI model that closely mimics DSCI in clinical settings, and clarified the mechanisms underlying DSCI-associated neuroinflammation and apoptosis; thus, our findings highlight potential DSCI-treatment strategies for further establishing suitable drug therapies.

Ginsenoside Rg1 inhibits oxidative stress and inflammation in rats with spinal cord injury via Nrf2/HO-1 signaling pathway

OBJECTIVES

In this study, our objective was to investigate the underlying mechanism of the neuroprotective role of ginsenoside Rg1 in attenuating spinal cord injury (SCI).

METHODS

A rat SCI model was established and treated with ginsenoside Rg1 and nuclear factor erythroid 2-related factor2(Nrf2) inhibitor all-trans retinoic acid (ATRA). The protective effects of ginsenoside Rg1 were evaluated by Basso, Beattie and Bresnahan (BBB) scale, hematoxylin/eosin staining, ELISA assay, western blotting and quantitative reverse transcription PCR (RT-qPCR).

RESULTS

Ginsenoside Rg1 alleviated neuronal edema and bleeding in the injured spinal cord, reduced inflammatory cell infiltration and cell necrosis, further repaired the injured spinal cord structure, improved BBB motor score in the SCI rat model and improved hind limb motor function. Meanwhile, ginsenoside Rg1 significantly increased the content of antioxidant enzymes superoxide dismutase and glutathione, and inhibited the production of oxidative marker malondialdehyde. In addition, ginsenoside Rg1also significantly inhibits the activities of the inflammatory factors tumor necrosis factor-α, interleukin-1β (IL-1β) and interleukin-6 (IL-6) to reduce the inflammatory response after trauma. Furthermore, western blot and RT-qPCR also suggested that ginsenoside Rg1 could activate the protein expression of Nrf2 and heme oxygenase-1 (HO-1) after SCI, and the inhibition of ATRA on these improvements further verified the neuroprotective effect of Nrf2 and HO-1 in ginsenoside Rg1 on SCI.

CONCLUSION

Ginsenoside Rg1 has a neuroprotective effect on SCI and can improve motor dysfunction caused by injury. The underlying mechanism may play antioxidative stress and anti-inflammatory effect by regulating the Nrf2/HO-1 signaling pathway.

Low-dose lipopolysaccharide protects nerve cells against spinal cord injury via regulating the PI3K-AKT-Nrf2 signaling pathway

This study explored the molecular mechanism behind the protective effects from low-dose lipopolysaccharide (LPS) on an in-vitro model of spinal cord injury (SCI). For this, PC12 cells were treated with different concentrations of LPS and the cell counting kit-8 assay was used to measure the toxicity of LPS to the cells. Next, we used immunofluorescence to measure nuclear translocation of Nrf2 in PC12 cells. PC12 cells were then treated with IGF-1 (PI3K agonist) and LY294002 (PI3K inhibitor). An in-vitro model of SCI was then established via oxygen-glucose deprivation/reoxygenation. Rates of apoptosis were measured using flow cytometry and the TUNEL assay. Low-dose LPS increased the expression levels of Nrf2, p-PI3K/PI3K, and p-AKT/AKT, and facilitated nuclear translocation of Nrf2. The activation of PI3K-AKT signaling by IGF-1 significantly increased the expression of Nrf2, whereas inhibition of PI3K-AKT signaling significantly decreased the expression of Nrf2. Low-dose LPS reduced the apoptotic ratio of PC12 cells, decreased the expression levels of caspase 3 and caspase 9, and increased the expression levels of HO-1, NQO1, and γ-GCS. Low-dose LPS also reduced the rate of apoptosis and oxidative stress by activating the PI3K-AKT-Nrf2 signaling pathway. Collectively, the results indicate that PI3K-AKT-Nrf2 signaling participates in the protective effects from low-dose LPS in an in-vitro PC12 cell model of SCI.

Multi-Site Optical Monitoring of Spinal Cord Ischemia during Spine Distraction

Optimal surgical management of spine trauma will restore blood flow to the ischemic spinal cord. However, spine stabilization may also further exacerbate injury by inducing ischemia. Current electrophysiological technology is not capable of detecting acute changes in spinal cord blood flow or localizing ischemia. Further, alerts are delayed and unreliable. We developed an epidural optical device capable of directly measuring and immediately detecting changes in spinal cord blood flow using diffuse correlation spectroscopy (DCS). Herein we test the hypothesis that our device can continuously monitor blood flow during spine distraction. Additionally, we demonstrate the ability of our device to monitor multiple sites along the spinal cord and axially resolve changes in spinal cord blood flow. DCS-measured blood flow in the spinal cord was monitored at up to three spatial locations (cranial to, at, and caudal to the distraction site) during surgical distraction in a sheep model. Distraction was halted at 50% of baseline blood flow at the distraction site. We were able to monitor blood flow with DCS in multiple regions of the spinal cord simultaneously at ∼1 Hz. The distraction site had a greater decrement in flow than sites cranial to the injury (median -40 vs. -7%,). This pilot study demonstrated high temporal resolution and the capacity to axially resolve changes in spinal cord blood flow at and remote from the site of distraction. These early results suggest that this technology may assist in the surgical management of spine trauma and in corrective surgery of the spine.

Engineering approaches to understanding mechanisms of spinal column injury leading to spinal cord injury

BACKGROUND

The mechanical interactions occurring between the spinal column and spinal cord during an injury event are complex and variable, and likely have implications for the clinical presentation and prognosis of the individual.

METHODS

The engineering approaches that have been developed to better understand spinal column and cord interactions during an injury event are discussed. These include injury models utilising human and animal cadaveric specimens, in vivo anaesthetised animals, finite element models, inanimate physical systems and combinations thereof.

FINDINGS

The paper describes the development of these modelling approaches, discusses the advantages and disadvantages of the various models, and the major outcomes that have had implications for spinal cord injury research and clinical practice.

INTERPRETATION

The contribution of these four engineering approaches to understanding the interaction between the biomechanics and biology of spinal cord injury is substantial; they have improved our understanding of the factors contributing to the spinal column disruption, the degree of spinal cord deformation or motion, and the resultant neurological deficit and imaging features. Models of the injury event are challenging to produce, but technological advances are likely to improve these models and, consequently, our understanding of the mechanical context in which the biological injury occurs.