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Der Radiologe Mar 2021Spinal cord injuries are frequently associated with severe clinical-neurological deficits. These are evident with specific symptoms and syndromes. Hereby, a thorough... (Review)
Review
BACKGROUND
Spinal cord injuries are frequently associated with severe clinical-neurological deficits. These are evident with specific symptoms and syndromes. Hereby, a thorough knowledge of spinal neuroanatomy is essential.
METHODS
Spinal anatomy, examination procedures and classical spinal syndromes are presented.
RESULTS
Important spinal syndromes comprise the dorsal cord syndrome, spinothalamic tract syndrome, pyramidal tract syndrome, central cord syndrome, transversal and Brown-Séquard syndrome as well as combined syndromes.
CONCLUSION
Clinical examination allows assessment and anatomical classification of spinal syndromes and targeted examination of the spinal cord using additional diagnostic methods.
Topics: Brown-Sequard Syndrome; Humans; Spinal Cord; Spinal Cord Injuries; Spine
PubMed: 33590288
DOI: 10.1007/s00117-021-00817-3 -
Veterinary Pathology Jan 2023This report describes 2 events of degenerative myelopathy in 4- to 27-day-old piglets, with mortality rates reaching 40%. Sows were fed rations containing low levels of...
This report describes 2 events of degenerative myelopathy in 4- to 27-day-old piglets, with mortality rates reaching 40%. Sows were fed rations containing low levels of pantothenic acid. Piglets presented with severe depression, weakness, ataxia, and paresis, which were more pronounced in the pelvic limbs. No significant gross lesions were observed. Histologically, there were degeneration and necrosis of neurons in the spinal cord, primarily in the thoracic nucleus in the thoracic and lumbar segments, and motor neurons in nucleus IX of the ventral horn in the cervical and lumbar intumescence. Minimal-to-moderate axonal and myelin degeneration was observed in the dorsal funiculus of the spinal cord and in the dorsal and ventral nerve roots. Immunohistochemistry demonstrated depletion of acetylcholine neurotransmitters in motor neurons and accumulation of neurofilaments in the perikaryon of neurons in the thoracic nucleus and motor neurons. Ultrastructurally, the thoracic nucleus neurons and motor neurons showed dissolution of Nissl granulation. The topographical distribution of the lesions indicates damage to the second-order neurons of the spinocerebellar tract, first-order axon cuneocerebellar tract, and dorsal column-medial lemniscus pathway as the cause of the conscious and unconscious proprioceptive deficit, and damage to the alpha motor neuron as the cause of the motor deficit. Clinical signs reversed and no new cases occurred after pantothenic acid levels were corrected in the ration, and piglets received parenteral administration of pantothenic acid. This study highlights the important and practical use of detailed neuropathological analysis to refine differential diagnosis.
Topics: Animals; Swine; Female; Pantothenic Acid; Spinal Cord; Neurons; Medulla Oblongata; Spinal Cord Diseases; Swine Diseases
PubMed: 36250539
DOI: 10.1177/03009858221128920 -
The Journal of Neuroscience : the... Aug 2023Axon fasciculation is thought to be a critical step in neural circuit formation and function. Recent studies have revealed various molecular mechanisms that underlie...
Axon fasciculation is thought to be a critical step in neural circuit formation and function. Recent studies have revealed various molecular mechanisms that underlie axon fasciculation; however, the impacts of axon fasciculation, and its corollary, defasciculation, on neural circuit wiring remain unclear. Corticospinal (CS) neurons in the sensorimotor cortex project axons to the spinal cord to control skilled movements. In rodents, the axons remain tightly fasciculated in the brain and traverse the dorsal funiculus of the spinal cord. Here we show that plexinA1 (PlexA1) and plexinA3 (PlexA3) receptors are expressed by CS neurons, whereas their ligands, semaphorin-5A (Sema5A) and semaphorin-5B (Sema5B) are expressed in the medulla at the decussation site of CS axons to inhibit premature defasciculation of these axons. In the absence of Sema5A/5B-PlexA1/A3 signaling, some CS axons are prematurely defasciculated in the medulla of the brainstem, and those defasciculated CS axons aberrantly transverse in the spinal gray matter instead of the spinal dorsal funiculus. In the absence of Sema5A/Sema5B-PlexA1/A3 signaling, CS axons, which would normally innervate the lumbar spinal cord, are unbundled in the spinal gray matter, and prematurely innervate the cervical gray matter with reduced innervation of the lumbar gray matter. In both and mutant mice (both sexes), stimulation of the hindlimb motor cortex aberrantly evokes robust forelimb muscle activation. Finally, and mutant mice show deficits in skilled movements. These results suggest that proper fasciculation of CS axons is required for appropriate neural circuit wiring and ultimately affect the ability to perform skilled movements. Axon fasciculation is believed to be essential for neural circuit formation and function. However, whether and how defects in axon fasciculation affect the formation and function of neural circuits remain unclear. Here we examine whether the transmembrane proteins semaphorin-5A (Sema5A) and semaphorin-5B (Sema5B), and their receptors, plexinA1 (PlexA1) and plexinA3 (PlexA3) play roles in the development of corticospinal circuits. We find that Sema5A/Sema5B and PlexA1/A3 are required for proper axon fasciculation of corticospinal neurons. Furthermore, and mutant mice show marked deficits in skilled motor behaviors. Therefore, these results strongly suggest that proper corticospinal axon fasciculation is required for the appropriate formation and functioning of corticospinal circuits in mice.
Topics: Female; Male; Mice; Animals; Semaphorins; Axon Fasciculation; Neurons; Axons; Spinal Cord
PubMed: 37344234
DOI: 10.1523/JNEUROSCI.0073-22.2023 -
Current Topics in Developmental Biology 2021Commissural axons have been a key model system for identifying axon guidance signals in vertebrates. This review summarizes the current thinking about the molecular and... (Review)
Review
Commissural axons have been a key model system for identifying axon guidance signals in vertebrates. This review summarizes the current thinking about the molecular and cellular mechanisms that establish a specific commissural neural circuit: the dI1 neurons in the developing spinal cord. We assess the contribution of long- and short-range signaling while sequentially following the developmental timeline from the birth of dI1 neurons, to the extension of commissural axons first circumferentially and then contralaterally into the ventral funiculus.
Topics: Animals; Axon Guidance; Axons; Neurons; Spinal Cord
PubMed: 33706918
DOI: 10.1016/bs.ctdb.2020.10.009 -
International Journal of Molecular... Sep 2021This study aimed to reveal functional and morphological changes in the corticospinal tract, a pathway shown to be susceptible to diabetes. Type 1 diabetes was induced in...
This study aimed to reveal functional and morphological changes in the corticospinal tract, a pathway shown to be susceptible to diabetes. Type 1 diabetes was induced in 13-week-old male Wistar rats administered streptozotocin. Twenty-three weeks after streptozotocin injection, diabetic animals and age-matched control animals were used to demonstrate the conduction velocity of the corticospinal tract. Other animals were used for morphometric analyses of the base of the dorsal funiculus of the corticospinal tract in the spinal cord using both optical and electron microscopy. The conduction velocity of the corticospinal tract decreased in the lumbar spinal cord in the diabetic animal, although it did not decrease in the cervical spinal cord. Furthermore, atrophy of the fibers of the base of the dorsal funiculus was observed along their entire length, with an increase in the g-ratio in the lumbar spinal cord in the diabetic animal. This study indicates that the corticospinal tract fibers projecting to the lumbar spinal cord experience a decrease in conduction velocity at the lumbar spinal cord of these axons in diabetic animals, likely caused by a combination of axonal atrophy and an increased g-ratio due to thinning of the myelin sheath.
Topics: Action Potentials; Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Male; Motor Neurons; Neural Conduction; Pyramidal Tracts; Rats, Wistar; Spinal Cord; Streptozocin; Rats
PubMed: 34576288
DOI: 10.3390/ijms221810123 -
Pain Practice : the Official Journal of... Nov 2020Responses of spinal progenitors to spinal cord stimulation (SCS) following spinal cord injury (SCI) in rats were assessed to reveal their potential contribution to...
OBJECTIVES
Responses of spinal progenitors to spinal cord stimulation (SCS) following spinal cord injury (SCI) in rats were assessed to reveal their potential contribution to SCS-induced analgesia.
METHODS
Spinal epidural electrodes were implanted in rats at T12 rostral to a quadrant dorsal horn injury at T13. Further groups additionally received either a microlesion to the dorsolateral funiculus (DLF) or gabapentin (10 mg/kg). SCS was performed at 25 Hz for 10 minutes on day 4 (early SCS) and at 10 Hz for 10 minutes on day 8 (late SCS) after injury. Paw withdrawal threshold (PWT) was measured before injury, 30 minutes before or after SCS, and before cull on day 14, followed by immunostaining assessment.
RESULTS
Paw withdrawal thresholds in uninjured animals (51.0 ± 4.0 g) were markedly reduced after SCI (17.3 ± 2.2 g). This was significantly increased by early SCS (38.5 ± 5.2 g, P < 0.01) and further enhanced by late SCS (50.9 ± 1.9 g, P < 0.01) over 6 days. Numbers of neural progenitors expressing nestin, Sox2, and doublecortin (DCX) in the spinal dorsal horn were increased 6 days after SCS by 6-fold, 2-fold, and 2.5-fold, respectively (P < 0.05 to 0.01). The elevated PWT evoked by SCS was abolished by DLF microlesions (48.9 ± 2.6 g vs. 19.0 ± 3.9 g, P < 0.01) and the number of nestin-positive cells was reduced to the level without SCS (P < 0.05). Gabapentin enhanced late SCS-induced analgesia from 37.0 ± 3.9 g to 54.0 ± 0.8 g (P < 0.01) and increased gamma-aminobutyric acid (GABA)-ergic neuronal marker vesicular GABA transporter-positive newborn cells 2-fold (P < 0.01).
CONCLUSIONS
Spinal progenitor cells appear to be activated by SCS via descending pathways, which may be enhanced by gabapentin and potentially contributes to relief of SCI-induced neuropathic pain.
Topics: Analgesia; Animals; Doublecortin Protein; Hypesthesia; Male; Neural Stem Cells; Neuralgia; Pain Management; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; Spinal Cord Stimulation
PubMed: 32474998
DOI: 10.1111/papr.12921 -
Enhanced Network in Corticospinal Tracts after Infused Mesenchymal Stem Cells in Spinal Cord Injury.Journal of Neurotrauma Dec 2022Although limited spontaneous recovery occurs after spinal cord injury (SCI), current knowledge reveals that multiple forms of axon growth in spared axons can lead to...
Although limited spontaneous recovery occurs after spinal cord injury (SCI), current knowledge reveals that multiple forms of axon growth in spared axons can lead to circuit reorganization and a detour or relay pathways. This hypothesis has been derived mainly from studies of the corticospinal tract (CST), which is the primary descending motor pathway in mammals. The major CST is the dorsal CST (dCST), being the major projection from cortex to spinal cord. Two other components often called "minor" pathways are the ventral and the dorsal lateral CSTs, which may play an important role in spontaneous recovery. Intravenous infusion of mesenchymal stem cells (MSCs) provides functional improvement after SCI with an enhancement of axonal sprouting of CSTs. Detailed morphological changes of CST pathways, however, have not been fully elucidated. The primary objective was to evaluate detailed changes in descending CST projections in SCI after MSC infusion. The MSCs were infused intravenously one day after SCI. A combination of adeno-associated viral vector (AAV), which is an anterograde and non-transsynaptic axonal tracer, was injected 14 days after SCI induction. The AAV with advanced tissue clearing techniques were used to visualize the distribution pattern and high-resolution features of the individual axons coursing from above to below the lesion. The results demonstrated increased observable axonal connections between the dCST and axons in the lateral funiculus, both rostral and caudal to the lesion core, and an increase in observable axons in the dCST below the lesion. This increased axonal network could contribute to functional recovery by providing greater input to the spinal cord below the lesion.
Topics: Animals; Pyramidal Tracts; Spinal Cord Injuries; Recovery of Function; Axons; Spinal Cord; Mesenchymal Stem Cells; Nerve Regeneration; Mammals
PubMed: 35611987
DOI: 10.1089/neu.2022.0106 -
Temperature (Austin, Tex.) 2023Thermoregulatory behaviors are powerful effectors for core body temperature (T) regulation. We evaluated the involvement of afferent fibers ascending through the dorsal...
Selection of preferred thermal environment and cold-avoidance responses in rats rely on signals transduced by the dorsal portion of the lateral funiculus of the spinal cord.
Thermoregulatory behaviors are powerful effectors for core body temperature (T) regulation. We evaluated the involvement of afferent fibers ascending through the dorsal portion of the lateral funiculus (DLF) of the spinal cord in "spontaneous" thermal preference and thermoregulatory behaviors induced by thermal and pharmacological stimuli in a thermogradient apparatus. In adult Wistar rats, the DLF was surgically severed at the first cervical vertebra bilaterally. The functional effectiveness of funiculotomy was verified by the increased latency of tail-flick responses to noxious cold (-18°C) and heat (50°C). In the thermogradient apparatus, funiculotomized rats showed a higher variability of their preferred ambient temperature (T) and, consequently, increased T fluctuations, as compared to sham-operated rats. The cold-avoidance (warmth-seeking) response to moderate cold (whole-body exposure to ~17°C) or epidermal menthol (an agonist of the cold-sensitive TRPM8 channel) was attenuated in funiculotomized rats, as compared to sham-operated rats, and so was the T (hyperthermic) response to menthol. In contrast, the warmth-avoidance (cold-seeking) and T responses of funiculotomized rats to mild heat (exposure to ~28°C) or intravenous RN-1747 (an agonist of the warmth-sensitive TRPV4; 100 μg/kg) were unaffected. We conclude that DLF-mediated signals contribute to driving spontaneous thermal preference, and that attenuation of these signals is associated with decreased precision of T regulation. We further conclude that thermally and pharmacologically induced changes in thermal preference rely on neural, presumably afferent, signals that travel in the spinal cord within the DLF. Signals conveyed by the DLF are important for cold-avoidance behaviors but make little contribution to heat-avoidance responses.
PubMed: 37187830
DOI: 10.1080/23328940.2023.2191378 -
Journal of Orthopaedic Science :... Jul 2022A reference interval exists for posterior tibial nerve somatosensory evoked potentials (PTN-SEPs) in awake. However, the reference interval for intraoperative- PTN-SEPs...
BACKGROUND
A reference interval exists for posterior tibial nerve somatosensory evoked potentials (PTN-SEPs) in awake. However, the reference interval for intraoperative- PTN-SEPs (I-PTN-SEPs) remains unclear. As a substitute for PTN-SEPs in awake, we considered I-PTN-SEPs can provide functional information about the dorsal somatosensory system. No report evaluated the physiologic and analytical issues in the measurement of I-PTN-SEPs. We investigated the sources of variation and reference intervals for I-PTN-SEPs.
METHODS
We studied 143 patients with unilateral radiculopathy and without neurologic deficit who underwent surgery. Stimulation was delivered to the PTN at the ankle. The scalp recording electrode was placed at the Cz with a reference electrode located on the forehead at the Fz. SEPs were recorded from patients during electrical stimulation of the I-PTN.
RESULTS
P1 and N1 latencies showed significant positive linear correlations with age (P1 latency = 36.52 + 0.0814 × age, P = 0.00003; N1 latency = 46.21 + 0.081 × age, P = 0.00022), and body height (P1 latency = 16.94 + 14.91 × body height, P = 0.00000; N1 latency = 25.42 + 15.64 × body height, P = 0.00002). In contrast, I-PTN-SEPs amplitude showed no correlation with age or body height. The 95% confidence interval for I-PTN-SEPs amplitude, or the reference interval, was determined as 0.31-5.91 μV.
CONCLUSIONS
The lower normal limit value was 0.31 μV, and this reference interval may be useful to evaluate function of the posterior funiculus, such that as during surgery for patients with intramedullary tumor.
Topics: Body Height; Electric Stimulation; Evoked Potentials, Somatosensory; Humans; Reference Values; Tibial Nerve
PubMed: 34330609
DOI: 10.1016/j.jos.2021.05.004