Effect of spinal cord compression on local vascular blood flow and perfusion capacity

Pre-operative spinal cord perfusion quantified by DSC MRI as a predictor of post-operative prognosis in patients with cervical spondylotic myelopathy

OBJECTIVE

This study aims to investigate the potential of preoperative blood supply condition measured by dynamic susceptibility contract (DSC) MRI in prediction of postoperative outcomes for patients with cervical spondylotic myelopathy (CSM).

MATERIALS AND METHOD

Thirty-nine patients (Age: 61 ± 7, male: 23, female: 16) with CSM who underwent laminoplasty were enrolled. All patients received DSC MRI before the operation. Five parameters include Enhance, rEnhance, full width at half maxima (FWHM), Slope1 and Slope2 in DSC MRI, were calculated at all the compressed spinal cord segments. Clinical outcomes were evaluated by modified Japanese Orthopaedic Association (mJOA) scores. Patients were divided into two groups based on mJOA recovery rate of 5 years: good recovery (> 50%) or poor recovery (≤ 50%). The difference between two groups were compared. The value of DSC MRI to CSM was evaluated by logistic and receiver operating characteristic (ROC) curve analysis.

RESULTS

There were 26 patients in good recovery group and 13 patients in poor recovery group. The baseline characteristics, including age, gender, preoperative mJOA score, and smoking status showed no significant difference between the two groups (all p > 0.05). The FWHM was significantly higher in the poor recovery group (9.77 ± 2.78) compared to the good recovery group (6.64 ± 1.65) (p = 0.002). Logistic regression analysis indicated that an increased FWHM was a significant risk factor for poor prognosis recovery (p = 0.013, OR = 0.392, 95%CI: 0.187-0.822). The AUC of FWHM for ROC was 0.843 (95% CI: 0.710-0.975) with a p value of 0.001. In addition, an FWHM greater than 5.87, with a sensitivity of 92.3% and specificity of 69.2%, was found to be an independent risk factor for poor postoperative recovery in patients with CSM.

CONCLUSION

In this study, we successfully quantified the spinal cord blood supply condition by DSC MRI technique. We found that an increase in FWHM was an independent risk factor for poor postoperative recovery in CSM patients. Specifically, patients with FWHM > 5.87 have a poor postoperative recovery.

Rodent Models of Spinal Cord Injury: From Pathology to Application

Spinal cord injury (SCI) often has devastating consequences for the patient's physical, mental and occupational health. At present, there is no effective treatment for SCI, and appropriate animal models are very important for studying the pathological manifestations, injury mechanisms, and corresponding treatment. However, the pathological changes in each injury model are different, which creates difficulties in selecting appropriate models for different research purposes. In this article, we analyze various SCI models and introduce their pathological features, including inflammation, glial scar formation, axon regeneration, ischemia-reperfusion injury, and oxidative stress, and evaluate the advantages and disadvantages of each model, which is convenient for selecting suitable models for different injury mechanisms to study therapeutic methods.

Neuroimmunological therapies for treating spinal cord injury: Evidence and future perspectives

Spinal cord injury (SCI) has a complex pathophysiology. Following the initial physical trauma to the spinal cord, which may cause vascular disruption, hemorrhage, mechanical injury to neural structures and necrosis, a series of biomolecular cascades is triggered to evoke secondary injury. Neuroinflammation plays a major role in the secondary injury after traumatic SCI. To date, the administration of systemic immunosuppressive medications, in particular methylprednisolone sodium succinate, has been the primary pharmacological treatment. This medication is given as a complement to surgical decompression of the spinal cord and maintenance of spinal cord perfusion through hemodynamic augmentation. However, the impact of neuroinflammation is complex with harmful and beneficial effects. The use of systemic immunosuppressants is further complicated by the natural onset of post-injury immunosuppression, which many patients with SCI develop. It has been hypothesized that immunomodulation to attenuate detrimental aspects of neuroinflammation after SCI, while avoiding systemic immunosuppression, may be a superior approach. To accomplish this, a detailed understanding of neuroinflammation and the systemic immune responses after SCI is required. Our review will strive to achieve this goal by first giving an overview of SCI from a clinical and basic science context. The role that neuroinflammation plays in the pathophysiology of SCI will be discussed. Next, the positive and negative attributes of the innate and adaptive immune systems in neuroinflammation after SCI will be described. With this background established, the currently existing immunosuppressive and immunomodulatory therapies for treating SCI will be explored. We will conclude with a summary of topics that can be explored by neuroimmunology research. These concepts will be complemented by points to be considered by neuroscientists developing therapies for SCI and other injuries to the central nervous system.

Biomechanical comparison of spinal cord compression types occurring in Degenerative Cervical Myelopathy

BACKGROUND

Degenerative Cervical Myelopathy results from spine degenerations narrowing the spinal canal and inducing cord compressions. Prognosis is challenging. This study aimed at simulating typical spinal cord compressions observed in patients with a realistic model to better understand pathogenesis for later prediction of patients' evolution.

METHODS

A 30% reduction in cord cross-sectional area at C5-C6 was defined as myelopathy threshold based on Degenerative Cervical Myelopathy features from literature and MRI measurements in 20 patients. Four main compression types were extracted from MRIs and simulated with a comprehensive three-dimensional finite element spine model. Median diffuse, median focal and lateral types were modelled as disk herniation while circumferential type additionally involved ligamentum flavum hypertrophy. All stresses were quantified along inferior-superior axis, compression development and across atlas-defined spinal cord regions.

FINDINGS

Anterior gray and white matter globally received the highest stress while lateral pathways were the least affected. Median diffuse compression induced the highest stresses. Circumferential type focused stresses in posterior gray matter. Along inferior-superior axis, those two types showed a peak of constraints at compression site while median focal and lateral types showed lower values but extending further.

INTERPRETATION

Median diffuse type would be the most detrimental based on stress amplitude. Anterior regions would be the most at risk, except for circumferential type where posterior regions would be equally affected. In addition to applying constraints, ischemia could be a significant component explaining the early demyelination reported in lateral pathways. Moving towards patient-specific simulations, biomechanical models could become strong predictors for degenerative changes.

SRμCT Reveals 3D Microstructural Alterations of the Vascular and Neuronal Network in a Rat Model of Chronic Compressive Thoracic Spinal Cord Injury

The complex pathology of chronic thoracic spinal cord compression involves vascular and neuroarchitectural repair processes that are still largely unknown. In this study, we used synchrotron radiation microtomography (SRμCT) to quantitatively characterize the 3D temporal-spatial changes in the vascular and neuronal network after chronic thoracic spinal cord compression in order to obtain further insights into the pathogenesis of this disease and to elucidate its underlying mechanisms. Direct 3D characterization of the spinal cord microvasculature and neural microstructure of the thoracic spinal cord was successfully reconstructed. The significant reduction in vasculature and degeneration of neurons in the thoracic spinal cord visualized via SRμCT after chronic compression were consistent with the changes detected by immunofluorescence staining. The 3D morphological measurements revealed significant reductions of neurovascular parameters in the thoracic spinal cord after 1 month of compression and became even worse after 6 months without relief of compression. In addition, the distinct 3D morphological twist and the decrease in branches of the central sulcal artery after chronic compression vividly displayed that these could be the potential triggers leading to blood flow reduction and neural deficits of the thoracic spinal cord. Our findings propose a novel methodology for the 3D analysis of neurovascular repair in chronic spinal cord compression, both qualitatively and quantitatively. The results indicated that compression simultaneously caused vascular dysfunction and neuronal network impairment, which should be acknowledged as concurrent events after chronic thoracic spinal cord injury. Combining neuroprotection with vasoprotection may provide promising therapeutic targets for chronic thoracic spinal cord compression.

Congenital deformation of the posterior arch of the atlas: Subluxation of the atlanto-axial joint with temporary quadriplegia

Instabilities of the craniocervical junction can be of rheumatic, traumatic, or congenital origin. The reported patient has a congenital malformation of the cervical spine, which is frequently observed in patients with Klippel–Feil syndrome. Her posterior arch of the atlas (C1) is hypoplastic and a chronic subluxation of the atlanto-axial joint would be possible. Although most common fusions in Klippel–Feil syndrome patients exist at C2/3, the majority of studies about Klippel–Feil syndrome deal with pediatric or adolescent individuals. Through extreme flexion of her neck, there was a compression of the spinal cord by the odontoid process. This led to a quadriplegia lasting about 10 min. Over the following weeks, all of her symptoms started to diminish. This situation turned out to be the third episode involving temporary neurological disorders in this 60-year-old female’s life.

F.E.M. Stress-Investigation of Scolios Apex

BACKGROUND

In scoliosis, kypholordos and wedge properties of the vertebrae should be involved in determining how stress is distributed in the vertebral column. The impact is logically expected to be maximal at the apex.

AIM

To introduce an algorithm for constructing artificial geometric models of the vertebral column from DICOM stacks, with the ultimate aim to obtain a formalized way to create simplistic models, which enhance and focus on wedge properties and relative tilting.

MATERIAL/METHODS

Our procedure requires parameter extraction from DICOM image-stacks (with PACS,IDS-7), mechanical FEM-modelling (with Matlab and Comsol). As a test implementation, models were constructed for five patients with thoracal idiopathic scoliosis with varying apex rotation. For a selection of load states, we calculated a response variable which is based upon distortion energy.

RESULTS

For the test implementation, pairwise t-tests show that our response variable is non-trivial and that it is chiefly sensitive to the transversal stresses (transversal stresses where of main interest to us, as opposed to the case of additional shear stresses, due to the lack of explicit surrounding tissue and ligaments in our model). Also, a pairwise t-test did not show a difference (n = 25, p-value≈0.084) between the cases of isotropic and orthotropic material modeling.

CONCLUSION

A step-by-step description is given for a procedure of constructing artificial geometric models from chest CT DICOM-stacks, such that the models are appropriate for semi-global stress-analysis, where the focus is on the wedge properties and relative tilting. The method is inappropriate for analyses where the local roughness and irregularities of surfaces are wanted features. A test application hints that one particular load state possibly has a high correlation to a certain response variable (based upon distortion energy distribution on a surface of the apex), however, the number of patients is too small to draw any statistical conclusions.

Immediate improvement of intraoperative monitoring signals following CSF release for cervical spine stenosis: Case report

Cervical spondylotic myelopathy (CSM) is a degenerative pathology characterized by partial or complete conduction block on intraoperative neuromonitoring. We describe a case treated using osseoligamentous decompression and durotomy for cerebrospinal fluid (CSF) release. Intraoperative monitoring demonstrated immediate signal improvement with CSF release, suggesting that clinical improvement in CSM may result from resolution of CSF flow anomalies.

Injectable Hydrogels for Spinal Cord Repair: A Focus on Swelling and Intraspinal Pressure

Spinal cord injury (SCI) is a devastating condition that leaves patients with limited motor and sensory function at and below the injury site, with little to no hope of a meaningful recovery. Because of their ability to mimic multiple features of central nervous system (CNS) tissues, injectable hydrogels are being developed that can participate as therapeutic agents in reducing secondary injury and in the regeneration of spinal cord tissue. Injectable biomaterials can provide a supportive substrate for tissue regeneration, deliver therapeutic factors, and regulate local tissue physiology. Recent reports of increasing intraspinal pressure after SCI suggest that this physiological change can contribute to injury expansion, also known as secondary injury. Hydrogels contain high water content similar to native tissue, and many hydrogels absorb water and swell after formation. In the case of injectable hydrogels for the spinal cord, this process often occurs in or around the spinal cord tissue, and thus may affect intraspinal pressure. In the future, predictable swelling properties of hydrogels may be leveraged to control intraspinal pressure after injury. Here, we review the physiology of SCI, with special attention to the current clinical and experimental literature, underscoring the importance of controlling intraspinal pressure after SCI. We then discuss how hydrogel fabrication, injection, and swelling can impact intraspinal pressure in the context of developing injectable biomaterials for SCI treatment.