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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 -
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 -
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 -
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 -
Neuroscience Insights 2020The highly interconnected somatosensory and motor systems are subjected to connectivity changes at close or remote locations following a central nervous system injury....
Cutaneous Inputs to Dorsal Column Nuclei in Adult Macaque Monkeys Subjected to Unilateral Lesion of the Primary Motor Cortex or of the Cervical Spinal Cord and Treatments Promoting Axonal Growth.
The highly interconnected somatosensory and motor systems are subjected to connectivity changes at close or remote locations following a central nervous system injury. What is the impact of unilateral injury of the primary motor cortex (hand area; MCI) or of the cervical cord (hemisection at C7-C8 level; SCI) on the primary somatosensory (cutaneous) inputs to the dorsal column nuclei (DCN) in adult macaque monkeys? The effects of treatments promoting axonal growth were assessed. In the SCI group (n = 4), 1 monkey received a control antibody and 3 monkeys a combination treatment of anti-Nogo-A antibody and brain-derived neurotrophic factor (BDNF). In the MCI group (n = 4), 2 monkeys were untreated and 2 were treated with the anti-Nogo-A antibody. Using trans-ganglionic transport of cholera toxin B subunit injected in the first 2 fingers and toes on both sides, the areas of axonal terminal fields in the cuneate and gracile nuclei were bilaterally compared. Unilateral SCI at C7-C8 level, encroaching partially on the dorsal funiculus, resulted in an ipsilesional lower extent of the inputs from the toes in the gracile nuclei, not modified by the combined treatment. SCI at C7-C8 level did not affect the bilateral balance of primary inputs to the cuneate nuclei, neither in absence nor in presence of the combined treatment. MCI targeted to the hand area did not impact on the primary inputs to the cuneate nuclei in 2 untreated monkeys. After MCI, the administration of anti-Nogo-A antibody resulted in a slight bilateral asymmetrical extent of cutaneous inputs to the cuneate nuclei, with a larger extent ipsilesionally. Overall, remote effects following MCI or SCI have not been observed at the DCN level, except possibly after MCI and anti-Nogo-A antibody treatment.
PubMed: 33283186
DOI: 10.1177/2633105520973991 -
BMC Neurology Nov 2020Persistent first intersegmental artery (PFIA) is a rare anatomical variation of vertebral arteries and is an asymptomatic finding in most cases. Here we report a rare...
BACKGROUND
Persistent first intersegmental artery (PFIA) is a rare anatomical variation of vertebral arteries and is an asymptomatic finding in most cases. Here we report a rare case of cervical myelopathy caused by spinal cord compression by the PFIA.
CASE PRESENTATION
The patient was a 52-year-old man who complained of numbness and burning sensation around the neck and left shoulder area, partial weakness in the left deltoid muscle, right side thermal hypoalgesia, and disturbance of deep sensation since the past 1 year, and the symptoms had gradually worsened. Magnetic resonance imaging (MRI) and computed tomography (CT) showed spinal cord compression by the left PFIA at the C1/C2 level. Because conservative treatment was ineffective, microvascular decompression (MVD) of the PFIA was performed. The left PFIA was laterally transposed using polytetrafluoroethylene (PTFE) bands and anchored to the dura mater using three PTFE bands. To achieve adequate transposition, the small blood vessels bridging the spinal cord and PFIA and the dorsal root nerve had to be sacrificed. Postoperative T2-weighted MRI showed a small hyperintense region in the lateral funiculus of the spinal cord, but no new neurological deficits were identified. In the early postoperative stage, the patient's deep sensory impairment and motor dysfunction were improved. His numbness and burning sensation almost disappeared, but slight thermal hypoalgesia remained in the lower limb.
CONCLUSION
MVD is an effective treatment for spinal cord compression caused by the PFIA, but further studies are necessary to help address technical difficulties and avoid complications.
Topics: Cervical Vertebrae; Humans; Magnetic Resonance Imaging; Male; Microvascular Decompression Surgery; Middle Aged; Spinal Cord Compression; Spinal Cord Diseases; Tomography, X-Ray Computed; Vertebral Artery
PubMed: 33143678
DOI: 10.1186/s12883-020-01976-x -
IBRO Reports Dec 2020Coordination between the urinary bladder (BL) and external urethral sphincter (EUS) is necessary for storage and elimination of urine. In rats interneuronal circuits at...
Coordination between the urinary bladder (BL) and external urethral sphincter (EUS) is necessary for storage and elimination of urine. In rats interneuronal circuits at two levels of the spinal cord (i.e., L6-S1 and L3-L4) play an important role in this coordination. In the present experiments retrograde trans-synaptic transport of pseudorabies virus (PRV) encoding fluorescent markers (GFP and RFP) was used to trace these circuits. To examine the relative localization of EUS-related and BL-related interneuronal populations we injected PRV-GFP into the EUS and PRV-RFP into the BL wall. The PRV infected populations of spinal interneurons were localized primarily in the dorsal commissure (DCM) of L6/S1 and in a hypothesized lumbar spinal coordinating center (LSCC) in L3/L4 above and lateral to central canal (CC). At both sites colocalization of markers occurred in a substantial number of labeled interneurons indicating concomitant involvement of these double-labelled neurons in the EUS- and BL-circuits and suggesting their role in EUS-BL coordination. Intense GFP or RFP fluorescent was detected in a subpopulation of cells at both sites suggesting that they were infected earlier and therefore likely to represent first order, primary interneurons that directly synapse with output neurons. Larger numbers of weakly fluorescent neurons that likely represent second order interneurons were also identified. Within the population of EUS-related first order interneurons only 3-8 % exhibited positive immunoreaction for an early transcription factor Pax2 specific to GABAergic and glycinergic inhibitory neurons suggesting that the majority of interneurons in DCM and LSCC projecting directly to the EUS motoneurons are excitatory.
PubMed: 32775758
DOI: 10.1016/j.ibror.2020.07.002 -
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 -
Brain, Behavior, and Immunity Jul 2020The pathways for peripheral-to-central immune communication (P → C I-comm) following sterile lung injury (SLI) are unknown. SLI evokes systemic and central...
The pathways for peripheral-to-central immune communication (P → C I-comm) following sterile lung injury (SLI) are unknown. SLI evokes systemic and central inflammation, which alters central respiratory control and viscerosensory transmission in the nucleus tractus solitarii (nTS). These functional changes coincide with increased interleukin-1 beta (IL-1β) in the area postrema, a sensory circumventricular organ that connects P → C I-comm to brainstem circuits that control homeostasis. We hypothesize that IL-1β and its downstream transcriptional target, cyclooxygenase-2 (COX-2), mediate P → C I-comm in the nTS. In a rodent model of SLI induced by intratracheal bleomycin (Bleo), the sigh frequency and duration of post-sigh apnea increased in Bleo- compared to saline- treated rats one week after injury. This SLI-dependent change in respiratory control occurred concurrently with augmented IL-1β and COX-2 immunoreactivity (IR) in the funiculus separans (FS), a barrier between the AP and the brainstem. At this barrier, increases in IL-1β and COX-2 IR were confined to processes that stained for glial fibrillary acidic protein (GFAP) and that projected basolaterally to the nTS. Further, FS radial-glia did not express TNF-α or IL-6 following SLI. To test our hypothesis, we blocked central COX-1/2 activity by intracerebroventricular (ICV) infusion of Indomethacin (Ind). Continuous ICV Ind treatment prevented Bleo-dependent increases in GFAP + and IL-1β + IR, and restored characteristics of sighs that reset the rhythm. These data indicate that changes in sighs following SLI depend partially on activation of a central COX-dependent P → C I-comm via radial-glia of the FS.
Topics: Animals; Area Postrema; Bleomycin; Communication; Lung Injury; Neuroglia; Rats; Rats, Sprague-Dawley
PubMed: 32097765
DOI: 10.1016/j.bbi.2020.02.006 -
Frontiers in Molecular Neuroscience 2019The corticospinal tract (CST) plays an important role in controlling voluntary movement. Because the CST has a long trajectory throughout the brain toward the spinal...
The corticospinal tract (CST) plays an important role in controlling voluntary movement. Because the CST has a long trajectory throughout the brain toward the spinal cord, many axon guidance molecules are required to navigate the axons correctly during development. Previously, we found that double-knockout (DKO) mouse embryos lacking the heparan sulfate endosulfatases, and , showed axon guidance defects of the CST owing to the abnormal accumulation of Slit2 protein on the brain surface. However, postnatal development of the CST, especially the pyramidal decussation and spinal cord projection, could not be assessed because DKO mice on a C57BL/6 background died soon after birth. We recently found that DKO mice on a mixed C57BL/6 and CD-1/ICR background can survive into adulthood and therefore investigated the anatomy and function of the CST in the adult DKO mice. In DKO mice, abnormal dorsal deviation of the CST fibers on the midbrain surface persisted after maturation of the CST. At the pyramidal decussation, some CST fibers located near the midline crossed the midline, whereas others located more laterally extended ipsilaterally. In the spinal cord, the crossed CST fibers descended in the dorsal funiculus on the contralateral side and entered the contralateral gray matter normally, whereas the uncrossed fibers descended in the lateral funiculus on the ipsilateral side and entered the ipsilateral gray matter. As a result, the CST fibers that originated from 1 side of the brain projected bilaterally in the DKO spinal cord. Consistently, microstimulation of 1 side of the motor cortex evoked electromyogram responses only in the contralateral forelimb muscles of the wild-type mice, whereas the same stimulation evoked bilateral responses in the DKO mice. The functional consequences of the CST defects in the DKO mice were examined using the grid-walking, staircase, and single pellet-reaching tests, which have been used to evaluate motor function in mice. Compared with the wild-type mice, the DKO mice showed impaired performance in these tests, indicating deficits in motor function. These findings suggest that disruption of genes leads to both anatomical and functional defects of the CST.
PubMed: 32038163
DOI: 10.3389/fnmol.2019.00333