-
Neurosurgery Jul 1980The proceedings of the First International Symposium on Spinal Cord Reconstruction, held in Las Vegas, Nevada, on January 7 to 11, 1980, are reviewed and summarized.... (Review)
Review
The proceedings of the First International Symposium on Spinal Cord Reconstruction, held in Las Vegas, Nevada, on January 7 to 11, 1980, are reviewed and summarized. Major problems facing investigators of central nervous system regeneration are discussed.
Topics: Humans; Nerve Regeneration; Spinal Cord; Spinal Cord Injuries
PubMed: 6997772
DOI: 10.1227/00006123-198007000-00012 -
Developmental Neurobiology May 2008In this review, we discuss the use of imaging to visualize the spatiotemporal organization of network activity in the developing spinal cord of the chick embryo and the... (Review)
Review
In this review, we discuss the use of imaging to visualize the spatiotemporal organization of network activity in the developing spinal cord of the chick embryo and the neonatal mouse. We describe several different methods for loading ion- and voltage-sensitive dyes into spinal neurons and consider the advantages and limitations of each one. We review work in the chick embryo, suggesting that motoneurons play a critical role in the initiation of each cycle of spontaneous network activity and describe how imaging has been used to identify a class of spinal interneuron that appears to be the avian homolog of mammalian Renshaw cells or 1a-inhibitory interneurons. Imaging of locomotor-like activity in the neonatal mouse revealed a wave-like activation of motoneurons during each cycle of discharge. We discuss the significance of this finding and its implications for understanding how locomotor-like activity is coordinated across different segments of the cord. In the last part of the review, we discuss some of the exciting new prospects for the future.
Topics: Animals; Diagnostic Imaging; Neural Pathways; Neurons; Spinal Cord
PubMed: 18383543
DOI: 10.1002/dneu.20620 -
Neuromodulation : Journal of the... Jan 2020The electrically evoked compound action potential (ECAP) is a measure of the response from a population of fibers to an electrical stimulus. ECAPs can be assessed during...
INTRODUCTION
The electrically evoked compound action potential (ECAP) is a measure of the response from a population of fibers to an electrical stimulus. ECAPs can be assessed during spinal cord stimulation (SCS) to elucidate the relationship between stimulation, electrophysiological response, and neuromodulation. This has consequences for the design and programming of SCS devices.
METHODS
Sheep were implanted with linear epidural SCS leads. After a stimulating pulse, electrodes recorded ECAPs sequentially as they propagated orthodromically or antidromically. After filtering, amplification, and signal processing, ECAP amplitude and dispersion (width) was measured, and conduction velocity was calculated. Similar clinical data was also collected. A single-neuron computer model that simulated large-diameter sensory axons was used to explore and explain the observations.
RESULTS
ECAPs, both animal and human, have a triphasic structure, with P1, N1, and P2 peaks. Conduction velocity in sheep was 109 ms , which indicates that the underlying neural population includes fibers of up to 20 μm in diameter. For travel in both directions, propagation distance was associated with decrease in amplitude and increase in dispersion. Importantly, characteristics of these changes shifted abruptly at various positions along the cord.
DISCUSSION
ECAP dispersion increases with propagation distance due to the contribution of slow-conducting small-diameter fibers as the signal propagates away from the source. An analysis of the discontinuities in ECAP dispersion changes with propagation revealed that these are due to the termination of smaller-diameter, slower-conducting fibers at corresponding segmental levels. The implications regarding SCS lead placement, toward the goal of maximizing clinical benefit while minimizing side-effects, are discussed.
CONFLICT OF INTEREST
John Parker is the founder and CEO of Saluda Medical and holds stock options. Milan Obradovic, Nastaran Hesam Shariati, Dean M. Karantonis, Peter Single, James Laird-Wah, Robert Gorman and Mark Bickerstaff are employees of Saluda Medical with stock options. At the time the data was collected for the study, Prof. Cousins was a paid consultant for Saluda Medical. John Parker, Milan Obradovic, Dean Karantonis, James Laird-Wah, Robert Gorman and Peter Single are co-inventors in one or more patents related to the topics discussed in this work.
Topics: Action Potentials; Animals; Sheep; Spinal Cord; Spinal Cord Dorsal Horn
PubMed: 31215718
DOI: 10.1111/ner.12968 -
Child's Nervous System : ChNS :... Feb 2013Intramedullary spinal cord cavernous malformations are very uncommon in pediatric age, with only 26 cases reported within the available literature to date. The diagnosis... (Review)
Review
INTRODUCTION
Intramedullary spinal cord cavernous malformations are very uncommon in pediatric age, with only 26 cases reported within the available literature to date. The diagnosis of such lesions is often difficult and delayed because of their rarity and bizarre clinical presentation.
CASE REPORT
We report a case of intramedullary spinal cord cavernous malformation in a girl, in which sudden onset chest pain was the only presenting symptom, followed by appearance of neurological deficits after 5 days. We review the available literature discussing clinical features and principles of management of these lesions in children.
Topics: Chest Pain; Child; Female; Humans; Spinal Cord
PubMed: 23086011
DOI: 10.1007/s00381-012-1941-3 -
The Journal of Physiological Sciences :... May 2021Functional magnetic resonance imaging (fMRI) of the spinal cord relies on the integrity of neurovascular coupling (NVC) to infer neuronal activity from hemodynamic...
Functional magnetic resonance imaging (fMRI) of the spinal cord relies on the integrity of neurovascular coupling (NVC) to infer neuronal activity from hemodynamic changes. Astrocytes are a key component of cerebral NVC, but their role in spinal NVC is unclear. The objective of this study was to examine whether inhibition of astrocyte metabolism by fluorocitrate alters spinal NVC. In 14 rats, local field potential (LFP) and spinal cord blood flow (SCBF) were recorded simultaneously in the lumbosacral enlargement during noxious stimulation of the sciatic nerve before and after a local administration of fluorocitrate (N = 7) or saline (N = 7). Fluorocitrate significantly reduced SCBF responses (p < 0.001) but not LFP amplitude (p = 0.22) compared with saline. Accordingly, NVC was altered by fluorocitrate compared with saline (p < 0.01). These results support the role of astrocytes in spinal NVC and have implications for spinal cord imaging with fMRI for conditions in which astrocyte metabolism may be altered.
Topics: Animals; Astrocytes; Citrates; Electric Stimulation; Magnetic Resonance Imaging; Male; Neurovascular Coupling; Rats; Rats, Wistar; Regional Blood Flow; Sciatic Nerve; Spinal Cord
PubMed: 34049480
DOI: 10.1186/s12576-021-00800-6 -
Neuroscience and Biobehavioral Reviews 2007The final phase of spinal cord development follows the arrival of descending pathways which brings about a reorganisation that allows mature motor behaviours to emerge... (Review)
Review
The final phase of spinal cord development follows the arrival of descending pathways which brings about a reorganisation that allows mature motor behaviours to emerge under the control of higher brain centres. Observations made during typical human development have shown that low threshold stretch reflexes, including excitatory reflexes between agonist and antagonist muscle pairs are a feature of the newborn. However, perinatal lesions of the corticospinal tract can lead to abnormal development of spinal reflexes that includes retention and reinforcement of developmental features that do not emerge in adult stroke victims, even though they also suffer from spasticity. This review describes investigations in animal models into how corticospinal input may drive segmental maturation. It compares their findings with observations made in humans and discusses how therapeutic interventions in cerebral palsy might aim to correct imbalances between descending and segmental inputs, bearing in mind that descending activity may play the crucial role in development.
Topics: Animals; Cerebral Palsy; Disease Models, Animal; Humans; Pyramidal Tracts; Spinal Cord
PubMed: 17544509
DOI: 10.1016/j.neubiorev.2007.04.007 -
Pain Sep 2020
Topics: Posterior Horn Cells; Spinal Cord; Spinal Cord Dorsal Horn
PubMed: 33090745
DOI: 10.1097/j.pain.0000000000001980 -
Annals of the New York Academy of... Nov 1998The isolated lumbosacral cord of the chick embryo generates spontaneous episodes of rhythmic activity. Muscle nerve recordings show that the discharge of sartorius... (Review)
Review
The isolated lumbosacral cord of the chick embryo generates spontaneous episodes of rhythmic activity. Muscle nerve recordings show that the discharge of sartorius (flexor) and femorotibialis (extensor) motoneurons alternates even though the motoneurons are depolarized simultaneously during each cycle. The alternation occurs because sartorius motoneuron firing is shunted or voltage-clamped by its synaptic drive at the time of peak femorotibialis discharge. Ablation experiments have identified a region dorsomedial to the lateral motor column that may be required for the alternation of sartorius and femorotibialis motoneurons. This region overlaps the location of interneurons activated by ventral root stimulation. Wholecell recordings from interneurons receiving short latency ventral root input indicate that they fire at an appropriate time to contribute to the cyclical pause in firing of sartorius motoneurons. Spontaneous activity was modeled by the interaction of three variables: network activity and two activity-dependent forms of network depression. A "slow" depression which regulates the occurrence of episodes and a "fast" depression that controls cycling during an episode. The model successfully predicts several aspects of spinal network behavior including spontaneous rhythmic activity and the recovery of network activity following blockade of excitatory synaptic transmission.
Topics: Animals; Chick Embryo; Locomotion; Motor Neurons; Spinal Cord; Synaptic Transmission
PubMed: 9928307
DOI: 10.1111/j.1749-6632.1998.tb09044.x -
Bratislavske Lekarske Listy 2013The spinal cord is an integral part of central nervous system, therefore it can be expected that spinal cord has the same properties as the brain. Movement activity is...
The spinal cord is an integral part of central nervous system, therefore it can be expected that spinal cord has the same properties as the brain. Movement activity is realized by the activation of individual motoneurons of various spinal cord segments under the influence of analytical function of the spinal cord. When a hypothesis is accepted that the mentioned large volume of spinal cord white matter represents the entire length of neuronal network, an idea can be established that the activated motoneurons project through their reticular processes to this connecting network forming a synthetic picture of this movement and after fluent continuity the entire act of movement. Therefore, neuronal network plays the role of dynamic memory.The perspective of spinal cord stereotaxy in functional neurosurgery hypothetically enables a recognition and understanding of how brain and spinal cord communicate in movement performance (Fig. 2, Ref. 6).
Topics: Forecasting; Humans; Spinal Cord; Stereotaxic Techniques
PubMed: 23611055
DOI: 10.4149/bll_2013_062 -
NeuroImage Dec 2021Most of our knowledge about the human spinal ascending (sensory) and descending (motor) pathways comes from non-invasive electrophysiological investigations. However,... (Review)
Review
Most of our knowledge about the human spinal ascending (sensory) and descending (motor) pathways comes from non-invasive electrophysiological investigations. However, recent methodological advances in acquisition and analyses of functional magnetic resonance imaging (fMRI) data from the spinal cord, either alone or in combination with the brain, have allowed us to gain further insights into the organization of this structure. In the current review, we conducted a systematic search to produced somatotopic maps of the spinal fMRI activity observed through different somatosensory, motor and resting-state paradigms. By cross-referencing these human neuroimaging findings with knowledge acquired through neurophysiological recordings, our review demonstrates that spinal fMRI is a powerful tool for exploring, in vivo, the human spinal cord pathways. We report strong cross-validation between task-related and resting-state fMRI in accordance with well-known hemicord, postero-anterior and rostro-caudal organization of these pathways. We also highlight the specific advantages of using spinal fMRI in clinical settings to characterize better spinal-related impairments, predict disease progression, and guide the implementation of therapeutic interventions.
Topics: Humans; Magnetic Resonance Imaging; Spinal Cord
PubMed: 34732324
DOI: 10.1016/j.neuroimage.2021.118684