Narrow Results

It is suggested that co-contraction of antagonist motor units perhaps due to abnormal disynaptic I_a reciprocal inhibition is responsible for Parkinsonian rigidity. A neural model of Parkinson's disease bradykinesia is extended to incorporate the effects of spindle feedback on key cortical cells and examine the effects of dopamine depletion on spinal activities. Simulation results show that although reciprocal inhibition is reduced in DA depleted case, it doesn't lead to co-contraction of antagonist motor neurons. Implications to Parkinsonian rigidity are discussed.

We investigated the anti-inflammatory effects of electroacupuncture (EA) on carrageenan-induced inflammatory model in association with peripheral and spinal COX-2 expression. EA with 2, 15 and 120 Hz, especially 2 Hz, had significant inhibitory effects on the developing of edema and hyperalgesia, which was measured in 30-min intervals after carrageenan injection. Therefore, we investigated whether the effect of 2 Hz EA on carrageenan-induced edema and hyperalgesia is associated with peripheral and spinal expression of inflammatory proteins. The expression of cyclooxygenase (COX)-1, COX-2, and inducible nitric oxide synthase (iNOS) was inhibited by 2 Hz EA in carrageenan-injected rat paws. Interestingly, we found that the mRNA of COX-1 and COX-2 expression in the spine was not induced by 2 Hz EA treatment after carrageenan-induced peripheral inflammation. In addition, synthesis of prostaglandin E₂ (PGE₂) was partially inhibited by 2 Hz EA treatment in both peripheral and spinal nociceptive regions. In conclusion, EA treatment might be a useful therapy for mitigation of inflammatory edema and hyperalgesia through regulation of COX-2 expression in both peripheral and central nociceptive sites.

A descending inhibitory mechanism from the periaqueductal gray (PAG) to the spinal cord through the nucleus raphe magnus (NRM) is strongly involved in endogenous analgesic system produced by acupuncture stimulation. In addition to the PAG to NRM system which descends in the medial pathway of the brain stem, the nucleus reticularis lateralis (NRL) situated in the lateral part of the brain stem is reported to play an important role in modulating centrifugal antinociceptive action. In the present study, to clarify the role of NRL in acupuncture analgesia, we investigated the response properties of NRL neurons to acupuncture stimulation. The majority of NRM-projecting NRL neurons were inhibited by electroacupuncture stimulation. This effect was antagonized by ionophoretic application of naloxone, indicating that endogenous opioids act directly onto these NRL neurons. By contrast, about half of spinal projecting NRL neurons were excited by electroacupuncture stimulation, suggesting that part of the NRL neurons may modulate pain transmission directly at the spinal level.

Through analysis of the morphology of dendritic arborisation of neurons from the substantia gelatinosa of dorsal horns from four different species, we have established that two types of cells (stalked and islet) are always present. The aim of the study was to perform the intra- and/or inter-species comparison of these two neuronal populations by fractal analysis, as well as to clarify the importance of the fractal dimension as an objective and usable morphological parameter. Fractal analysis was carried out adopting the box-counting method. We have shown that the mean fractal dimensions for the stalked cells are significantly different between species. The same is true for the mean fractal dimensions of the islet cells. Still, no significant differences were found for the fractal dimensions of the stalked and islet cells within a particular species. The human species has shown as the only exception where fractal dimensions of these two types of cells differ significantly. This study shows once more that the fractal dimension is a useful and sensitive morphological descriptor of neuronal structures and differences between them.

We report a rare case of intramedullary spinal cord abscess. The patient was operated on by surgical drainage and appropriate antibiotic therapy. Improvement was seen postoperatively. Significant changes in the presentation, management, and outcome in these more recent cases are emphasized.

There have been several pathologic descriptions of the spinal cord compressed chronically. Microglial changes, however, have been described scarcely. In the present study, microglial responses to the anterior unilateral compression were investigated by immunohistochemistry in the rabbit model. The cervical spinal cord was unilaterally compressed with a small screw at C5. The microglial response in the compressed and the contralateral halves of the spinal cord were investigated after 48 hours with the lectin RCA-1 immunostaining. Microglia were classified morphologically into resting and reactive microglia. Under mild compression, the mild proliferation of reactive microglia was observed in the anterior horn of the compressed half. A few reactive microglia were observed in the anterior horn of the contralateral half. The total number of resting and reactive microglia in each area of the gray and white matters did not differ between the sham and mild compression groups. Under severe compression, marked proliferation of reactive microglia was observed around the cavity in the gray matter of the compressed half. Moderate proliferation of reactive microglia was observed in gray matter of the contralateral half. These findings suggested that the resting microglia transformed into the reactive microglia, but not proliferated in the early stage of compression myelopathy.

Since their discovery in the late 19th century our conception of motoneurons has steadily evolved. Motoneurons share the same general function: they drive the contraction of muscle fibers and are the final common pathway, i.e., the seat of convergence of all the central and peripheral pathways involved in motricity. However, motoneurons innervate different types of muscular targets. Ordinary muscle fibers are subdivided into three main subtypes according to their structural and mechanical properties. Intrafusal muscle fibers located within spindles can elicit either a dynamic, or a static, action on the spindle sensory endings. No less than seven categories of motoneurons have thereby been identified on the basis of their innervation pattern. This functional diversity has hinted at a similar diversity in the inputs each motoneuron receives, as well as in the electrical, or cellular, properties of the motoneurons that match the properties of their muscle targets. The notion of the diverse properties of motoneurons has been well established by the work of many prominent neuroscientists. But in today's scientific literature, it tends to fade and motoneurons are often thought of as a homogenous group, which develop from a given population of precursor cells, and which express a common set of molecules. We first present here the historical milestones that led to the recognition of the functional diversity of motoneurons. We then review how the intrinsic electrical properties of motoneurons are precisely tuned in each category of motoneurons in order to produce an output that is adapted to the contractile properties of their specific targets.

Magnetic drug delivery is an effective method to decrease the side effects of traditional drug delivery methods. To enhance the efficiency of magnetic nanoparticle transport, a precise and cost-effective magnetic system is required. In this research, different arrangements of NdFeB magnets for drug delivery in human spinal cord were presented and then compared. Assummed magnetic nanoparticles are injected into the cerebrospinal fluid (CSF) and focused on the disease site with external magnets. The effects of these magnets on nanoparticles have been investigated. The results show that the arrangement of sharp magnets has a more accurate performance in delivering nanoparticles to the damage site than other arrangements. The designed magnetic system can improve the accuracy of drug delivery in the spinal cord compared to previous methods.

Interpreting the biochemical specificity of spinal cord tissue is the essential requirement for understanding the biochemical mechanisms during spinal-cord-related pathological course. In this work, a longitudinal study was implemented to reveal a precise linkage between the spectral features and the molecular composition in ex vivo mouse spinal cord tissue by microspectral Raman imaging. It was testified that lipid-rich white matter could be distinguished from gray matter not only by the lipid Raman peaks at 1064, 1300, 1445 and 1660cm${}^{-1}$, but also by protein (1250 and 1328cm${}^{-1})$ and saccharides (913 and 1137cm${}^{-1})$ distributions. $K$-means cluster analysis was further applied to visualize the morphological basis of spinal cord tissue by chemical components and their distribution patterns. Two-dimensional chemical images were then generated to visualize the contrast between two different tissue types by integrating the intensities of the featured Raman bands. All the obtained results illustrated the biochemical characteristics of spinal cord tissue, as well as some specific substance variances between different tissue types, which formed a solid basis for the molecular investigation of spinal cord pathological alterations.

Electrical stimulation has been integrated in recent decades into rehabilitation protocols following neuromuscular injuries. Existing literature supports the utilisation of prolonged or continuous stimulation generated by implantable or transcutaneous devices for chronic pain subsidence and muscle trophism maintenance, which improve outcomes following microsurgical interventions. Newer uses include brief electrical stimulation for peripheral nerve injury. Brief electrical stimulation has shown promise in expediting regeneration of both torn and crushed nerve axons in the murine model and has been incorporated into a limited number of clinical studies. Augmentation of the natural response of an injured peripheral nerve by electrical stimulation has the potential to accelerate regeneration, presumably leading to improved function and clinical outcomes. We review the existing literature on intraoperative utilisation of electrical stimulation to enhance regeneration, such as neural mechanisms of action and their microscopic effect in animal models, as well as results from initial human studies.

Level of Evidence: Level V (Therapeutic)

This paper presents the development of a magnetic resonance imaging (MRI)-conditional needle positioning robot designed for spinal cellular injection. High-accuracy targeting performance is achieved by the combination of a high precision, parallel-plane, needle-orientation mechanism utilizing linear piezoelectric actuators with an iterative super-resolution (SR) visual navigation algorithm using multi-planar MR imaging. In previous work, the authors have developed an MRI conditional robot with positioning performance exceeding the standard resolution of MRI, rendering the MRI resolution the limit for navigation. This paper further explores the application of SR to images for robot guidance, evaluating positioning performance through simulations and experimentally in benchtop and MRI experiments.

Lumbar disc diseases are the commonest complaint of Lower Back Pain (LBP). In this paper, a new method for automatic diagnosis of lumbar disc herniation is proposed which is based on clinical Magnetic Resonance Images (MRI) data. We use T2-W sagittal and myelograph images. Our method uses Otsu thresholding method to extract the spinal cord from MR images of Lumbar disc. In the next step, a third-order polynomial is aligned on the extracted spinal cords, and in the end of preprocessing step all the T2-W sagittal images are prepared for extracting disc boundary and labeling. After labeling and extracting a ROI for each disc, intensity and shape features are used for classification. The presented Method is applied on 30 clinical cases, each containing 7 discs (210 lumbar discs) for the herniation diagnosis. The results revealed 92.38% and 93.80% accuracy for Artificial Neural Network and Support Vector Machine (SVM) classifiers, respectively. The results indicate the superiority of the proposed method to those mentioned in similar studies.

Herniation in the lumbar area is one of the most common diseases which results in lower back pain (LBP) causing discomfort and inconvenience in the patients’ daily lives. A computer aided diagnosis (CAD) system can be of immense benefit as it generates diagnostic results within a short time while increasing precision of diagnosis and eliminating human errors. We have proposed a new method for automatic diagnosis of lumbar disc herniation based on clinical MRI data. We use T2-W sagittal and myelograph images. The presented method has been applied on 30 clinical cases, each containing 7 discs (210 lumbar discs) for the herniation diagnosis. We employ Otsu thresholding method to extract the spinal cord from MR images of lumbar disc. A third order polynomial is then aligned on the extracted spinal cords, and by the end of preprocessing stage, all the T2-W sagittal images will have been prepared for specifying disc boundary and labeling. Having extracted an ROI for each disc, we proceed to use intensity and shape features for classification. The extracted features have been selected by Local Subset Feature Selection. The results demonstrated 91.90%, 92.38% and 95.23% accuracy for artificial neural network, K-nearest neighbor and support vector machine (SVM) classifiers respectively, indicating the superiority of the proposed method to those mentioned in similar studies.

The vertebrate nervous system consists of a huge number of neurons and glial cells. These cell types are generated from neuroepithelial cells at precise positions during development. However, little is known about how kinetics of neuroepithelial cells is regulated, and how the balance of proliferation and differentiation are genetically coordinated. To elucidate cellular mechanisms underlying such complex cell behaviors in the neuroepithelium, we established time-lapse imaging system by applying confocal laser-scanning microscopy for the rat spinal cord slice culture. By electroporation the spinal cord with expression plasmids of fluorescent proteins, nuclear movement of neuroepithelial cells and morphological change on their radial fibers were clearly visualized. Four-dimensional (4-D) time-lapse analyses allowed us to investigate the spatiotemporal dynamics of neuroepithelial cells. These approaches make it possible to analyze functions of genes that regulate cell kinetics and cell morphology.

Accurate planning of radiation therapy entails the definition of treatment volumes and a clear delimitation of normal tissue of which unnecessary exposure should be prevented. The spinal cord is a radiosensitive organ, which should be precisely identified because an overexposure to radiation may lead to undesired complications for the patient such as neuronal dysfunction or paralysis. In this chapter, a knowledge-based approach to identifying the spinal cord in computer tomography images of the thorax is presented. The approach relies on a knowledge-base which consists of a so-called anatomical structures map (ASM) and a task-oriented architecture called the plan solver. The ASM contains a frame-like knowledge representation of the macro-anatomy in the human thorax. The plan solver is responsible for determining the position, orientation and size of the structures of interest to radiation therapy. The plan solver relies on a number of image processing operators. Some are so-called atomic (e.g. thresholding and snakes) whereas others are composite. The whole system has been implemented on a standard workstation. Experimental results performed on 23 patients show that the approach is reliable in spinal cord segmentation.

The anatomical structure of the cervical spine is presented in the following chapter in relation to disorders of the cervical spine. The uncus, Luschka's joint, spinal canal, and upper joint articulations are identified in particular, as they relate to spinal disorders. The intervertebral disc and the ligamentous structures are also assessed. The structure of the neural tissues are presented, and the various conditions that compress these structures are explained. Among these are disc herniation, osteophytes, ossification of the posterior longitudinal ligament, and the ligamentum flavum. A narrow spinal canal also plays an important role in the development of cervical spine disorders. The vertebral artery may also cave into the vertebral body. The radicular artery would be compressed prior to nerve root compression. To hold the head in its proper position, a continuous and delicate contraction-relaxation balance of the cervical muscles is essential.

The cervical spine supports the head, protects the spinal cord and nerve roots, and also allows for movement of the neck. Firm support and rapid movements seem to be contradicting demands but the structures of the cervical spine ingeniously meet them.