Browsing by Subject "Spinal cord"

Now showing 1 - 8 of 8
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    Concomitant brain abscess and spinal cord abscess in an immunocompetent teenage male: illustrative case
    (American Association of Neurological Surgeons, 2023-01-23) Virtanen, Piiamaria S.; Jimenez, Med Jimson D.; Horak, V. Jane; Desai, Virendra R.; Manaloor, John J.; Raskin, Jeffrey S.; Neurological Surgery, School of Medicine
    Background: Multiple bilateral brain abscesses occur rarely in immunocompetent patients. Hematogenous spread to the central nervous system (CNS) allows suppuration and abscess formation in the privileged immune environment of the CNS; hematogenous spread to the spinal cord is extremely rare and the combination of multifocal brain abscesses and intramedullary abscesses has not been reported. This report presents a rare presentation and diagrams a treatment algorithm involving iterative minimal access surgeries and prolonged medical management. Observations: The authors present a case of an 18-year-old male with numerous multifocal and bilateral intraparenchymal abscesses and a medically resistant C5 intramedullary spinal cord abscess. The symptomatic patient had a left oculomotor palsy and left hemiparesis, ultimately undergoing ultrasound-guided aspiration of abscesses in the left frontal and left cerebral peduncle. Following transient motor improvement, he evolved tetraparesis prompting spinal cord imaging and emergent ultrasound-guided needle aspiration of an occult C5 intramedullary spinal cord abscess. The patient received appropriate medical therapy, completed inpatient rehabilitation, and made a full recovery. Lessons: Needle- and ultrasound-guided catheter drainage of CNS abscesses should be considered for symptomatic lesions. Following the neurological examination closely is extremely important; if the expected neurological improvement is delayed or regresses, then expanded imaging is warranted.
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    Correlation between Electrophysiological Properties, Morphological Maturation, and Olig Gene Changes during Postnatal Motor Tract Development
    (Wiley, 2013) Cai, Jun; Zhang, Yi Ping; Shields, Lisa B. E.; Zhang, Zoe Z.; Lui, Naiqui; Xu, Xiao-Ming; Feng, Shi-Qing; Shields, Christopher B.; Neurological Surgery, School of Medicine
    This study investigated electrophysiological and histological changes as well as alterations of myelin relevant proteins of descending motor tracts in rat pups. Motor-evoked potentials (MEPs) represent descending conducting responses following stimulation of the motor cortex to responses being elicited from the lower extremities. MEP responses were recorded biweekly from postnatal (PN) week 1 to week 9 (adult). MEP latencies in PN week 1 rats averaged 23.7 ms and became shorter during early maturation, stabilizing at 6.6 ms at PN week 4. During maturation, the conduction velocity (CV) increased from 2.8 ± 0.2 at PN week 1 to 35.2 ± 3.1 mm/ms at PN week 8. Histology of the spinal cord and sciatic nerves revealed progressive axonal myelination. Expression of the oligodendrocyte precursor markers PDGFRα and NG2 were downregulated in spinal cords, and myelin-relevant proteins such as GalC, CNP, and MBP increased during maturation. Oligodendrocyte-lineage markers Olig2 and MOG, expressed in myelinated oligodendrocytes, peaked at PN week 3 and were downregulated thereafter. A similar expression pattern was observed in neurofilament M/H subunits that were extensively phosphorylated in adult spinal cords but not in neonatal spinal cords, suggesting an increase in axon diameter and myelin formation. Ultrastructural morphology in the ventrolateral funiculus (VLF) showed axon myelination of the VLF axons (99.3%) at PN week 2, while 44.6% were sheathed at PN week 1. Increased axon diameter and myelin thickness in the VLF and sciatic nerves were highly correlated to the CV (rs > 0.95). This suggests that MEPs could be a predicator of morphological maturity of myelinated axons in descending motor tracts.
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    The Effect of Retinoids on the Regenerating Axolotl Spinal Cord
    (2014-04-11) Kirk, Maia P.; Chernoff, Ellen A.G.
    In order to further elucidate the mechanics of the retinoid pathway on Urodele spinal cord regeneration, we employed Antibody/Horseradish Peroxidase Staining of both intact and regenerating Axolotl spinal cord tissues obtained from adult and juvenile animals to determine expression of two retinoid pathway components: Cellular Retinoic Acid Binding Protein II (CRABP II) and Cellular Retinol Binding Protein I (CRBP I). Current results demonstrate that CRABP II is heavily expressed in the arachnoid mater meningeal layer; CRPB I, however, is expressed in the following locations: the pia mater meningeal layer, the nuclei and cytoplasm of gray matter neuroblasts, as well as processes derived from neuroblasts and ependyma. Moreover, the morphogenic nature of the retinoids may possess a significant role in the regeneration-permissive interaction of the meninges and ependyma of the Axolotl spinal cord.
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    Mathematical modeling and analysis of spinal circuits involved in locomotor pattern generation and frequency-dependent left-right coordination
    (Springer Nature, 2014-07-21) Molkov, Yaroslav I.; Bacak, Bartholomew J.; Rybak, Ilya A.; Mathematical Sciences, School of Science
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    Nerve Growth Factor Mediates a Switch in Intracellular Signaling for PGE2-Induced Sensitization of Sensory Neurons from Protein Kinase A to Epac
    (Public Library of Science, 2014-08-15) Vasko, Michael R.; Habashy Malty, Ramy; Guo, Chunlu; Duarte, Djane B.; Zhang, Yihong; Nicol, Grant D.; Pharmacology and Toxicology, School of Medicine
    We examined whether nerve growth factor (NGF), an inflammatory mediator that contributes to chronic hypersensitivity, alters the intracellular signaling that mediates the sensitizing actions of PGE2 from activation of protein kinase A (PKA) to exchange proteins directly activated by cAMP (Epacs). When isolated sensory neurons are grown in the absence of added NGF, but not in cultures grown with 30 ng/ml NGF, inhibiting protein kinase A (PKA) activity blocks the ability of PGE2 to augment capsaicin-evoked release of the neuropeptide CGRP and to increase the number of action potentials (APs) evoked by a ramp of current. Growing sensory neurons in culture in the presence of increasing concentrations of NGF increases the expression of Epac2, but not Epac1. An intradermal injection of complete Freund's adjuvant into the rat hindpaw also increases the expression of Epac2, but not Epac1 in the dorsal root ganglia and spinal cord: an effect blocked by intraplantar administration of NGF antibodies. Treating cultures grown in the presence of 30 ng/ml NGF with Epac1siRNA significantly reduced the expression of Epac1, but not Epac2, and did not block the ability of PGE2 to augment capsaicin-evoked release of CGRP from sensory neurons. Exposing neuronal cultures grown in NGF to Epac2siRNAreduced the expression of Epac2, but not Epac1 and prevented the PGE2-induced augmentation of capsaicin and potassium-evoked CGRP release in sensory neurons and the PGE2-induced increase in the number of APs generated by a ramp of current. In neurons grown with no added NGF, Epac siRNAs did not attenuate PGE2-induced sensitization. These results demonstrate that NGF, through increasing Epac2 expression, alters the signaling cascade that mediates PGE2-induced sensitization of sensory neurons, thus providing a novel mechanism for maintaining PGE2-induced hypersensitivity during inflammation.
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    Neuron-astrocyte metabolic coupling facilitates spinal plasticity and maintenance of inflammatory pain
    (Springer Nature, 2024) Marty-Lombardi, Sebastián; Lu, Shiying; Ambroziak, Wojciech; Schrenk-Siemens, Katrin; Wang, Jialin; DePaoli-Roach, Anna A.; Hagenston, Anna M.; Wende, Hagen; Tappe-Theodor, Anke; Simonetti, Manuela; Bading, Hilmar; Okun, Jürgen G.; Kuner, Rohini; Fleming, Thomas; Siemens, Jan; Biochemistry and Molecular Biology, School of Medicine
    Long-lasting pain stimuli can trigger maladaptive changes in the spinal cord, reminiscent of plasticity associated with memory formation. Metabolic coupling between astrocytes and neurons has been implicated in neuronal plasticity and memory formation in the central nervous system, but neither its involvement in pathological pain nor in spinal plasticity has been tested. Here we report a form of neuroglia signalling involving spinal astrocytic glycogen dynamics triggered by persistent noxious stimulation via upregulation of the Protein Targeting to Glycogen (PTG) in spinal astrocytes. PTG drove glycogen build-up in astrocytes, and blunting glycogen accumulation and turnover by Ptg gene deletion reduced pain-related behaviours and promoted faster recovery by shortening pain maintenance in mice. Furthermore, mechanistic analyses revealed that glycogen dynamics is a critically required process for maintenance of pain by facilitating neuronal plasticity in spinal lamina 1 neurons. In summary, our study describes a previously unappreciated mechanism of astrocyte-neuron metabolic communication through glycogen breakdown in the spinal cord that fuels spinal neuron hyperexcitability.
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    The role of retinoids in the regeneration of the axolotl spinal cord
    (2015-07-17) Kirk, Maia P.; Chernoff, Ellen A. G.; Belecky-Adams, Teri; Baucum II, A. J.
    Retinoids play an important role in tissue patterning during development as well as in epithelial formation and health. In the mammalian central nervous system, the meninges are a source of retinoids for brain tissue. Retinoid production has been described in juvenile Axolotl ependymal cells. Retinoid effects may possess a significant role in the regeneration-permissive interaction of the meninges and ependyma of the Axolotl spinal cord after penetrating injury. During spinal cord regeneration in urodele amphibians, the pattern of retinoid production changes as the meninges interact with the injury-reactive ependymal cells reconstructing the injured spinal cord. In order to determine which components of the retinoid metabolism and intracellular signaling pathway act in Urodele spinal cord regeneration, we employed antibody/horseradish peroxidase staining of both intact and regenerating Axolotl spinal cord tissues obtained from adult animals as well as cell culture techniques to determine expression of three retinoid pathway components: Cellular Retinoic Acid Binding Protein II (CRABP 2), Cellular Retinol Binding Protein I (CRBP 1), and Retinaldehyde Dehydrogenase II (RALDH 2). Current results demonstrate the following in the intact cord: 1) CRBP 1 is expressed in the pia and dura mater meningeal layers, in gray matter neurons (including their axonal processes), and the ependymal cell radial processes that produce the glia limitans, 2) CRABP 2 is expressed in the arachnoid and/or dura mater meningeal layers surrounding the spinal cord, and 3) RALDH 2 is expressed in the meninges as well as cytoplasm of grey matter neurons and some ependymal/sub-ependymal cells. In the regenerating cord, CRBP 1 is expressed in ependymal cells that are undergoing epithelial-to-mesenchymal transition (EMT), as is CRABP 2. RALDH 2 staining is very strong in the reactive meninges; in addition, expression is also upregulated in the cytoplasmic and perinuclear regions of reactive grey matter neurons, including motor neurons and in the apical region of ependymal. Preliminary studies culturing reactive meninges and ependymal cells together suggested that the meninges could drive re-epithelialization of the reactive ependymal cells. Experiments to characterize this interaction show an unusual proliferation pattern: Proliferating Cell Nuclear Antigen (PCNA) labeling is present in intact and regenerating cord ependymal cells. However, in culture, the presence of meninges results in no proliferation proximal to the explant, but extensive proliferation in leading cell outgrowth; also, the cultured meninges is positive for RALDH2. In summary, the intact adult cord shows meningeal production of RA, which is upregulated following injury; in addition, during this time, RA production is upregulated in the adult ependymal cells as well. In culture, the reactive meninges appears to modulate the behavior of reactive ependymal cells.
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    Supraclavicular Approach to the Brachial Plexus
    (Wolters Kluwer, 2023-01-23) Dawson, Steven E.; Gross, Jeffrey N.; Berns, Jessica M.; Weinzerl, Thomas; Adkinson, Joshua M.; Borschel, Gregory H.; Surgery, School of Medicine
    Background: The brachial plexus consists of an intricate array of nerves originating from the C5–T1 ventral rami of the spinal cord. Their course is complex and can be substantially distorted after injury. Thus, dissection of the brachial plexus can be difficult. Here, we present a practical approach to the supraclavicular dissection of the brachial plexus, with emphasis on relevant anatomy and surgical landmarks. Methods: This anatomical review was prepared using intraoperative surgical imaging. In addition, illustrations are used to display the images in schematic form. We present a stepwise surgical approach to the supraclavicular dissection of the brachial plexus. We highlight the differences between pre- and postganglionic nerve root injuries, and also relevant anatomical variants of the brachial plexus. Results: Eleven steps are recommended to facilitate the supraclavicular approach to the brachial plexus. Conclusion: The supraclavicular dissection of the brachial plexus is reliable with consistent landmarks and can be carried out in a stepwise fashion.