Inflammation Level after Decompression Surgery for a Rat Model of Chronic Severe Spinal Cord Compression and Effects on Ischemia-Reperfusion Injury

Pramipexole has a neuroprotective effect in spinal cord injury and upregulates D2 receptor expression in the injured spinal cord tissue in rats

Spinal cord injury (SCI) has emerged as a prevalent condition with limited effective treatment options. The neuroprotective role of pramipexole (PPX) in inhibiting nerve cell apoptosis in central nervous system injuries is well established. Therefore, we investigated the effects of PPX in SCI. Adult Sprague-Dawley rats were divided into four groups (sham, SCI, PPX-0.25, and PPX-2.0 groups) according to the PPX therapy (n = 24). Then, SCI was induced using the modified Allen method, and PPX was intravenously administered into the tail at dosages of 0.25 or 2.0 mg/kg following the injury. Motor function was evaluated using the Rivlin-modified inclined plate apparatus and the Basso Beattie Bresnahan (BBB) workout scale. Western blotting assay was used to measure protein expression levels of DRD2, NeuN, Bax/Bcl-2, and caspase-3. Furthermore, immunohistochemistry assessed the effect of PPX on the quantity of NeuN-positive cells in the spinal cord tissue after SCI. Our findings revealed that the BBB and slanting board test scores of the PPX-treated model groups were considerably higher for the SCI group and significantly lower for the sham operation group (P < 0.001). Moreover, the PPX-2.0 group exhibited significantly higher NeuN expression levels than the SCI group (P < 0.01). Our findings indicate that PPX exerts a neuroprotective effect in secondary neuronal injury following SCI, facilitating the recovery of hind limb function by downregulating Bax/Bcl-2, caspase-3, and IL-1β.

A swift expanding trend of extracellular vesicles in spinal cord injury research: a bibliometric analysis

Extracellular vesicles (EVs) in the field of spinal cord injury (SCI) have garnered significant attention for their potential applications in diagnosis and therapy. However, no bibliometric assessment has been conducted to evaluate the scientific progress in this area. A search of articles in Web of Science (WoS) from January 1, 1991, to May 1, 2023, yielded 359 papers that were analyzed using various online analysis tools. These articles have been cited 10,842 times with 30.2 times per paper. The number of publications experienced explosive growth starting in 2015. China and the United States led this research initiative. Keywords were divided into 3 clusters, including "Pathophysiology of SCI", "Bioactive components of EVs", and "Therapeutic effects of EVs in SCI". By integrating the average appearing year (AAY) of keywords in VoSviewer with the time zone map of the Citation Explosion in CiteSpace, the focal point of research has undergone a transformative shift. The emphasis has moved away from pathophysiological factors such as "axon", "vesicle", and "glial cell" to more mechanistic and applied domains such as "activation", "pathways", "hydrogels" and "therapy". In conclusions, institutions are expected to allocate more resources towards EVs-loaded hydrogel therapy and the utilization of innovative materials for injury mitigation.

White Cord Syndrome: A Treatment Dilemma

Spinal cord reperfusion injury following decompressive surgery is extremely rare. This complication is known as white cord syndrome (WCS). A 61-year-old male presented with chronic neck stiffness associated with left C6/C7 radiculopathy and numbness. Magnetic resonance imaging (MRI) of the cervical spine reported a severely narrowed left C6/C7 neural exit canal. C6/C7 anterior cervical decompression and fusion (ACDF) was performed. There was no significant intraoperative injury. On postoperative day 6, the patient developed bilateral C8 numbness, which started post-operation. He was treated for surgical site inflammation and was prescribed prednisolone and amitriptyline. However, his condition progressively worsened. At postoperative six weeks, there was right hemisensory loss, right triceps atrophy, and positive right Lhermitte's and Hoffman's tests. This subsequently progressed to right C7 weakness and bilateral lower limb radiculopathy at postoperative eight weeks. Postoperative MRI of the cervical spine revealed a new focal gliosis/edema within the spinal cord at C6/C7. The patient was treated conservatively with pregabalin and was referred for rehabilitation. Early diagnosis and treatment initiation are crucial in the management of WCS. Surgeons should be aware of this potential complication and counsel patients on the risk prior to surgery. Magnetic resonance imaging (MRI) remains the gold standard in the diagnosis of WCS. The current mainstay of treatment is high-dose steroids, intraoperative neurophysiological monitoring, and early recognition of postoperative WCS.

White Cord Syndrome: A Reperfusion Injury Following Spinal Decompression Surgery

Reperfusion injury of the spinal cord has been scarcely reported. Herein, we present a case of white cord syndrome after spinal decompression. A 61-year-old male, who initially had ossification of the posterior longitudinal ligament at C3-6 level, was admitted to our hospital with a ruptured disc at the C6-7 level. The patient experienced radiating pain in both upper extremities. Anterior cervical discectomy and fusion was performed. However, the patient developed quadriplegia. Emergency magnetic resonance imaging revealed a new and enlarged signal change in the spinal cord at the C4-7 level. Additional posterior decompression surgery was performed. After intense rehabilitation, the patient’s motor function improved to grade 4. White cord syndrome is likely due to reperfusion injury following operative decompression of a compressed spinal cord segment. Although rare, spine surgeons should be aware of this complication and warn patients preoperatively.

Spinal Cord Parenchyma Vascular Redistribution Underlies Hemodynamic and Neurophysiological Changes at Dynamic Neck Positions in Cervical Spondylotic Myelopathy

Cervical spondylotic myelopathy (CSM) is a degenerative condition of the spine that caused by static and dynamic compression of the spinal cord. However, the mechanisms of motor and somatosensory conduction, as well as pathophysiological changes at dynamic neck positions remain unclear. This study aims to investigate the interplay between neurophysiological and hemodynamic responses at dynamic neck positions in the CSM condition, and the pathological basis behind. We first demonstrated that CSM patients had more severe dynamic motor evoked potentials (DMEPs) deteriorations upon neck flexion than upon extension, while their dynamic somatosensory evoked potentials (DSSEPs) deteriorated to a similar degree upon extension and flexion. We therefore generated a CSM rat model which developed similar neurophysiological characteristics within a 4-week compression period. At 4 weeks-post-injury, these rats presented decreased spinal cord blood flow (SCBF) and oxygen saturation (SO₂) at the compression site, especially upon cervical flexion. The dynamic change of DMEPs was significantly correlated with the change in SCBF from neutral to flexion, suggesting they were more sensitive to ischemia compared to DSSEPs. We further demonstrated significant vascular redistribution in the spinal cord parenchyma, caused by angiogenesis mainly concentrated in the anterior part of the compressed site. In addition, the comparative ratio of vascular densities at the anterior and posterior parts of the cord was significantly correlated with the perfusion decrease at neck flexion. This exploratory study revealed that the motor and somatosensory conductive functions of the cervical cord changed differently at dynamic neck positions in CSM conditions. Compared with somatosensory conduction, the motor conductive function of the cervical cord suffered more severe deteriorations upon cervical flexion, which could partly be attributed to its higher susceptibility to spinal cord ischemia. The uneven angiogenesis and vascular distribution in the spinal cord parenchyma might underlie the transient ischemia of the cord at flexion.

Pathophysiological Changes and the Role of Notch-1 Activation After Decompression in a Compressive Spinal Cord Injury Rat Model

Surgical decompression is the primary treatment for cervical spondylotic myelopathy (CSM) patients with compressive spinal cord injury (CSCI). However, the prognosis of patients with CSCI varies, and the pathophysiological changes following decompression remain poor. This study aimed to investigate the pathophysiological changes and the role of Notch-1 activation after decompression in a rat CSCI model. Surgical decompression was conducted at 1 week post-injury (wpi). DAPT was intraperitoneally injected to down-regulate Notch-1 expression. Basso, Beattie, and Bresnahan scores and an inclined plane test were used to evaluate the motor function recovery. Hematoxylin and eosin staining was performed to assess pathophysiological changes, while hypoxia-inducible factor 1 alpha, vascular endothelial growth factor (VEGF), von Willebrand factor (vWF), matrix metalloproteinase (MMP)-9, MMP-2, Notch-1, and Hes-1 expression in the spinal cord were examined by immunohistochemical analysis or quantitative PCR. The results show that early decompression can partially promote motor function recovery. Improvements in structural and cellular damage and hypoxic levels were also observed in the decompressed spinal cord. Moreover, decompression resulted in increased VEGF and vWF expression, but decreased MMP-9 and MMP-2 expression at 3 wpi. Expression levels of Notch-1 and its downstream gene Hes-1 were increased after decompression, and the inhibition of Notch-1 significantly reduced the decompression-induced motor function recovery. This exploratory study revealed preliminary pathophysiological changes in the compressed and decompressed rat spinal cord. Furthermore, we confirmed that early surgical decompression partially promotes motor function recovery may via activation of the Notch-1 signaling pathway after CSCI. These results could provide new insights for the development of drug therapy to enhance recovery following surgery.

'White cord syndrome', a rare but disastrous complication of transient paralysis after posterior cervical decompression for severe cervical spondylotic myelopathy and spinal stenosis: A case report

Transient paralysis following spinal decompression surgery is a rare but devastating postoperative complication. Spinal cord ischemia-reperfusion injury has been identified as one of the crucial pathogenic factors contributing to the sudden neurological deterioration associated with spinal decompression surgery. 'White cord syndrome' is a characteristic imaging manifestation of spinal cord ischemia-reperfusion injury, referring to high intramedullary signal changes in the sagittal T2-weighted MRI scan with unexplained neurological deficits following surgical decompression. The present study reported on the case of a 51-year old male patient who suffered from acute left limb hemiplegic paralysis following posterior cervical laminectomy decompression for severe cervical spondylotic myelopathy and spinal stenosis, which were caused by ossification of the posterior longitudinal ligament. The patient's neurological function gradually improved after the immediate administration of high-dose methylprednisolone therapy combined with mannitol and neurotrophic drugs. At the 2-month follow-up, the intensity of the spinal cord signal on MRI had almost returned to normal and the 'white cord syndrome' had disappeared. However, the patient complained of postoperative neck swelling pain caused by cerebrospinal fluid leakage; therefore, an additional cerebrospinal fluid leakage exploration and neoplasty were performed. At 2 weeks after the second surgery, the patient's neck swelling pain was relieved and the area of cerebrospinal fluid leakage was significantly reduced. Despite the low incidence rate, surgeons should be aware of this complication, particularly when treating chronic severe cervical spinal stenosis with anterior or posterior decompression. Once transient paralysis occurs, early diagnosis and interventions are essential to reverse the neurological deficit.

Time-Course Changes and Role of Autophagy in Primary Spinal Motor Neurons Subjected to Oxygen-Glucose Deprivation: Insights Into Autophagy Changes in a Cellular Model of Spinal Cord Ischemia

Spinal cord ischemia is a severe clinical complication induced by thoracoabdominal aortic surgery, severe trauma, or compression to the spinal column. As one of the most important functional cells in the spinal cord, spinal motor neurons (SMNs) suffer most during the process since they are vulnerable to ischemic injury due to high demands of energy. Previous researches have tried various animal models or organotypic tissue experiments to mimic the process and get to know the pathogenesis and mechanism. However, little work has been performed on the cellular model of spinal cord ischemia, which has been hampered by the inability to obtain a sufficient number of pure primary SMNs for in vitro study. By optimizing the isolation and culture of SMNs, our laboratory has developed an improved culture system of primary SMNs, which allows cellular models and thus mechanism studies. In the present study, by establishing an in vitro model of spinal cord ischemia, we intended to observe the dynamic time-course changes of SMNs and investigate the role of autophagy in SMNs during the process. It was found that oxygen-glucose deprivation (OGD) resulted in destruction of neural networks and decreased cell viability of primary SMNs, and the severity increased with the prolonging of the OGD time. The OGD treatment enhanced autophagy, which reached a peak at 5 h. Further investigation demonstrated that inhibition of autophagy exacerbated the injury, evidencing that autophagy plays a protective role during the process.

Spinal Cord Reperfusion Injury: Case Report, Review of the Literature, and Future Treatment Strategies

A rare complication of cervical spine decompression is acute paralysis following the procedure. This neurologic deficit is thought to be due to reperfusion injury of a chronically ischemic spinal cord and is referred to as "white cord syndrome" given the pathognomonic finding of hyperintensity on T2-weighted MRI. Three prior cases have been reported. We present a case of transient quadriplegia following posterior cervical decompression.

A 41-year-old male with cervical spondylotic myelopathy presented with bilateral progressive upper extremity weakness, hyperreflexia, and cervical spine MRI showing severe cord compression at C1 and partial hyperintense signal. Intraoperatively, after C1 bony decompression and without perceptible technical cause, the patient experienced a complete loss of both somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) with an eventual return to baseline prior to completing the operation.

The patient awoke from surgery with acute quadriplegia without perceptible technical cause (intraoperative compression or evident anatomic compromise). An immediate postoperative MRI revealed a more pronounced hyperintensity in the central cervical cord on T2-weighted sequences. Treatment with increased mean arterial pressure (MAP) therapy and dexamethasone resulted in the patient regaining some movement over a period of hours and full strength over a period of months.

The mechanism of acute weakness following cervical spine decompression in the absence of perceptible technical cause is not fully understood, but current theory suggests that a reperfusion injury is most likely the cause. It remains a diagnosis of exclusion. Familiarity with this potential postoperative complication can aid in appropriate postoperative therapy with early diagnosis and intervention leading to restored spinal cord function and excellent prognosis.

The effect of lithium chloride on the motor function of spinal cord injury–controlled rat and the relevant mechanism

The objective of this study is to discuss the effect and mechanism of lithium chloride on the rehabilitation of locomotion post spinal cord injury (SCI) by observing the effect of lithium chloride on the expression of the brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) pathway. In total, 36 Sprague-Dawley (SD) rats were randomly divided into the sham operation group (n = 12), model group (n = 12), and lithium chloride group (n = 12). The sham operation group underwent laminectomy, while for the model group and the lithium chloride group with the NYU spinal cord impactor the SCI model was established. Basso, Beattie, and Bresnahan (BBB) score was used to evaluate locomotion after administration for 1, 3, 5, and 7 days, and the tissues were gathered for Nissl staining, transmission electron microscopy, immunofluorescence, and Western blot. With a statistical difference ( P < 0.05) on the 3rd day and significant difference ( P < 0.01) on the 5th day post administration, a higher BBB score was observed in the lithium chloride group indicating that lithium chloride improved the locomotion function after SCI. A better structure and morphology of neuron were observed by Nissl staining in the lithium chloride group. Lithium chloride promoted BDNF secretion from neurons in the spinal cord anterior horn with a significant difference compared to the model group ( P < 0.01). Compared with the model group, lithium chloride significantly promoted the expression of BDNF protein and phosphorylated TrkB protein ( P < 0.05), but no difference in the expression of TrkB was detected. Lithium chloride can alleviate the locomotion function after SCI with a mechanism that it can promote BDNF secretion from neurons in the spinal cord anterior horn and phosphorylation of TrkB to upregulate the BDNF/TrkB pathway supporting survival of neurons and regeneration and remyelination of axons.

Progress in Intraoperative Neurophysiological Monitoring for the Surgical Treatment of Thoracic Spinal Stenosis

Thoracic spinal stenosis (TSS) is a group of clinical syndromes caused by thoracic spinal cord compression, which always results in severe clinical complications. The incidence of TSS is relatively low compared with lumbar spinal stenosis, while the incidence of spinal cord injury during thoracic decompression is relatively high. The reported incidence of neurological deficits after thoracic decompression reached 13.9%. Intraoperative neurophysiological monitoring (IONM) can timely provide information regarding the function status of the spinal cord, and help surgeons with appropriate performance during operation. This article illustrates the theoretical basis of applying IONM in thoracic decompression surgery, and elaborates on the relationship between signal changes in IONM and postoperative neurological function recovery of the spinal cord. It also introduces updated information in multimodality IONM, the factors influencing evoked potentials, and remedial measures to improve the prognosis.

What is the optimal sequence of decompression for multilevel noncontinuous spinal cord compression injuries in rabbits?

Background

In recent years, multilevel spinal cord injuries (SCIs) have gained a substantial amount of attention from clinicians and researchers. Multilevel noncontinuous SCI patients cannot undergo the multiple steps of a one-stage operation because of a poor general condition or a lack of proper surgical approaches. The surgeon subsequently faces the decision of whether to initially relieve the rostral or caudal compression. In this study, we established a spinal cord compression model involving two noncontinuous segments in rabbits to evaluate the effects of differences in decompression order on the functional recovery of the spinal cord.

Methods

A Fogarty catheter was inserted into the epidural space through a hole in T6-7 and advanced 3 cm rostrally or caudally. Following successful model establishment, which was demonstrated by an evaluation of evoked potentials, balloons of different volumes (40 μl or 50 μl) were inflated in the experimental groups, whereas no balloons were inflated in the control group. The experimental groups underwent the first decompression in the rostral or caudal area at 1 week post-injury; the second decompression was performed at 2 weeks post-injury. For 6 weeks post-injury, the animals were tested to determine behavioral scores, somatosensory evoked potentials (SEPs) and radiographic imaging changes; histological and apoptosis assay results were subsequently analyzed.

Results

The behavioral test results and onset latency of the SEPs indicated that there were significant differences between priority rostral decompression (PRD) and priority caudal decompression (PCD) in the 50-μl compression group at 6 weeks post-injury; however, there were no significant differences between the two procedures in the 40-μl group at the same time point. Moreover, there were no significant peak-to-peak amplitude differences between the two procedures in the 50-μl compression group.

Conclusions

The findings of this study suggested that preferential rostral decompression was more beneficial than priority caudal decompression with respect to facilitating spinal cord functional recovery in rabbits with severe paraplegia and may provide clinicians with a reference for the clinical treatment of multiple-segment spinal cord compression injuries.

Aldehyde dehydrogenase 2 overexpression inhibits neuronal apoptosis after spinal cord ischemia/reperfusion injury

Aldehyde dehydrogenase 2 (ALDH₂) is an important factor in inhibiting oxidative stress and has been shown to protect against renal ischemia/reperfusion injury. Therefore, we hypothesized that ALDH₂ could reduce spinal cord ischemia/reperfusion injury. Spinal cord ischemia/reperfusion injury was induced in rats using the modified Zivin's method of clamping the abdominal aorta. After successful model establishment, the agonist group was administered a daily consumption of 2.5% alcohol. At 7 days post-surgery, the Basso, Beattie, and Bresnahan score significantly increased in the agonist group compared with the spinal cord ischemia/reperfusion injury group. ALDH₂ expression also significantly increased and the number of apoptotic cells significantly decreased in the agonist group than in the spinal cord ischemia/reperfusion injury group. Correlation analysis revealed that ALDH₂ expression negatively correlated with the percentage of TUNEL-positive cells (r = −0.485, P < 0.01). In summary, increased ALDH₂ expression protected the rat spinal cord against ischemia/reperfusion injury by inhibiting apoptosis.

Differences in the time of onset of postoperative upper limb palsy among surgical procedures: a meta-analysis

BACKGROUND CONTEXT

The time of onset of postoperative upper limb palsy (ULP), also referred to as C5 palsy, varies among patients. Although some studies addressed the relationship between the time of onset of ULP and the potential etiologies, no meta-analysis has been conducted regarding the association between the time of onset of ULP and other factors such as surgical procedure type and treated diseases.

PURPOSE

This study aimed to elucidate differences in the time of onset of ULP among spinal surgical procedures and treated diseases to understand its etiology.

STUDY DESIGN

This is a meta-analysis.

OUTCOME MEASURES

The time of onset of ULP after cervical decompression surgery.

METHODS

We conducted a meta-analysis via searches of the PubMed, EMBASE, and Cochrane Library databases. Upper limb palsy within 2 days postoperatively or at 3 days or more postoperatively was defined as early- and late-onset, respectively. We calculated the pooled prevalence of early- and late-onset ULP with regard to surgical procedures and diseases using a random effects model. The proportion of early-onset ULP relative to all ULP was also determined. Surgical procedures were categorized into four procedures: (1) anterior cervical discectomy and fusion (ACDF); (2) anterior cervical corpectomy and fusion (ACCF); (3) laminoplasty or laminectomy (LPN); and (4) posterior spinal fusion with decompression (PSF). Treated diseases were classified as ossification of the posterior longitudinal ligament (OPLL) and non-OPLL.

RESULTS

The pooled prevalence of early-onset ULP was significantly stratified across three groups of surgical procedures (PSF [9.0%]>ACCF [3.7%] and LPN [2.5%]>ACDF [0.6%]). In the pooled analysis of late-onset ULP prevalence, three procedures (PSF [4.3%], ACCF [2.8%], and LPN [2.9%]) were similar, but ACDF (1.0%) was associated with a significantly lower prevalence than LPN. The prevalence of both early- and late-onset ULP was significantly higher with OPLL than without OPLL. However, the proportion of early-onset ULP relative to all ULP was similar between non-OPLL and OPLL (50.8% vs. 49.5%).

CONCLUSIONS

The high prevalence of early-onset ULP in PSF is attributable to a lag correction effect, which is triggered by posterior correction and fusion through comparison with LPN. The combination of our meta-analysis results and previous knowledge facilitates our understanding of the etiology of ULP.

Hydrogen sulfide protects against TNF-α induced neuronal cell apoptosis through miR-485-5p/TRADD signaling

BACKGROUND AND OBJECTIVE

Increasing studies suggest that miRNAs are served as responders and regulators for pathological change in human. miR-485-5p is such a miRNA that has been proved to be affected by spinal cord I/R injury. This study was to investigate the functional involvement and mechanism of miR-485-5p in sulfuretted hydrogen (H2S) protecting neural cell from injury.

METHODS

In this study, serum tumor necrosis factor (TNF-α) and miR-485-5p were detected in 20 patients with spinal cord ischemia/reperfusion (I/R) injury and in 20 healthy control. H2S was administered by GYY4137 treatment. Two TNF-α-stimulated neural human cell lines, AGE1.HN and SY-SH-5Y, were used for in vitro I/R experiments. Quantitative RT-PCR was performed to determine miR-485-5p expression. QRT-PCR and western blot were respectively performed to evaluate expression of tumor necrosis factor receptor type 1-associated DEATH domain protein (TRADD).

RESULTS

The result showed that serum TNF-α was significantly reduced in patients compared with healthy control. In vitro TNF-α treatment dose dependently caused GE1.HN and SY-SH-5Y apoptosis, whereas this promotion action was reversed by CYY4137. Moreover, we found that H2S protected neuronal cell against apoptosis via TRADD dependent. By luciferase reporting gene assay, western blot and qRT-PCR, we confirmed that TRADD expression was regulated by miR-485-5p. Such miR-485-5p/TRADD axis was proved to be involved in GE1.HN and SY-SH-5Y neural cell-protective process of H2S.

CONCLUSION

In summary, our data for the first time identifies miR-485-5p/TRADD axis in hydrogen sulfide protecting against TNF-α-induced neuronal cell apoptosis.