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Results for “SPINAL NERVES”

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At least 19 recordsLinked to original sources
PubMed2003

The role of uninjured nerve in spinal nerve ligated rats points to an improved animal model of neuropathic pain.

L5 and L6 spinal nerve ligation (SNL) in rats leads to behavioral signs of neuropathic pain including mechanical allodynia. The purposes of this study were to investigate the role of the intact L4 spinal nerve in the development of mechanical allodynia following L5 and L6 SNL and, as a result, to develop a modified model of neuropathic pain. As a first set of experiments, in addition to tight ligation of the left L5 and L6 spinal nerves, the intact L4 spinal nerve was manipulated either (1) by gentle repeated stretching of the L4 spinal nerve immediately after L5 and L6 SNL or (2) by intermittent mechanical stimulation to the ipsilateral paw during the first week after SNL. Tactile sensitivity was measured by determining the foot withdrawal threshold before and after SNL. Mild irritation of L4 spinal nerve and application of mechanical stimuli to the ipsilateral paw significantly increased the development of mechanical allodynia after SNL. In a second set of experiments, SNL was produced by tightly ligating only the left L5 spinal nerve with or without a loop of 5-0 chromic gut placed loosely around the L4 spinal nerve. This additional L4 loop significantly increased long-lasting tactile sensitivity compared to L5 SNL alone. These results suggest that afferent activity of the intact L4 spinal nerve aids in the development of mechanical allodynia in the SNL model of neuropathic pain. The addition of a chromic gut loop around the intact L4 spinal nerve can augment the development of mechanical allodynia following SNL of L5. We propose this latter as a useful and practical animal model of neuropathic pain.

Afferent Pathways↗
PubMed1995

Progress of myelination in the human fetal spinal nerve roots, spinal cord and brainstem with myelin basic protein immunohistochemistry.

The early progress of myelination was studied, by means of myelin basic protein (MBP) immunohistochemistry and luxol-fast-blue (LFB) staining, in the spinal cord, spinal nerve roots and brainstem of 66 fetuses and neonates. The degree of myelination was classified from 1 (slight) to 4 (mature). MBP immunoreactivity exhibited slight LFB positivity. Myelination first occurred in the medial longitudinal fasciculus at 20 weeks of age, reaching degree 4 at 34 weeks, but began at 23-24 weeks in the other sites. Myelination of spinal nerve roots progressed with gestation and attained degree 4 at 35-36 weeks. The cuneate fasciculus also reached degree 4 at 34-36 weeks, but corticospinal tracts and solitary tracts, which exhibited long myelinating phases, were slow and incomplete at 40 weeks. This normal development of MBP and LFB myelination can be used for the assessment of delayed myelination in fetal and neonatal diseases.

Brain Stem↗
PubMed2004

Nerve injury about the shoulder in athletes, part 2: long thoracic nerve, spinal accessory nerve, burners/stingers, thoracic outlet syndrome.

Nerve injuries about the shoulder in athletes are being recognized with increasing frequency. Prompt and correct diagnosis of these injuries is important to treat the patient and to understand the potential complications and natural history, so as to counsel our athletes appropriately. This 2-part article is a review and an overview of the current state of knowledge regarding some of the more common nerve injuries seen about the shoulder in athletes, including long thoracic nerve, spinal accessory nerve, burners and stingers, and thoracic outlet syndrome. Each of these clinical entities will be discussed independently, reviewing the anatomy, mechanism of injury, patient presentation (history and examination), the role of additional diagnostic studies, differential diagnosis, and management.

Accessory Nerve Injuries↗
PubMed1986

Potassium ion channel blockade restores conduction in heat-injured nerve and spinal nerve roots.

Compound action potentials were recorded in vitro from rat peroneal and sural nerves and from dorsal and ventral roots of the cauda equina before and after radiofrequency heating of 5-mm-length segments of these nerves to 41 to 45 degrees C. The heating was continued for intervals sufficient to reduce response amplitude by 50%. Inflection velocity, potential duration at 1/2 peak height, and the proportion of conducting A alpha fibers were also measured. The topical application of 4-aminopyridine (4-AP) and tetraethylammonium chloride (TEA) to the previously heated segments immediately following the radiofrequency injury completely or near-completely restored amplitude height to the preheat value in all experiments. A alpha sensory fibers were the most susceptible to the conduction block. Conduction in these fibers was also the most readily restored by the application of 4-AP or TEA. The effects of TEA, but not of 4-AP, could be reversed by saline or buffer washing. Topical application of verapamil and of magnesium or calcium ions had no discernible effect on heated nerves. We suggest that the mechanism of heat-induced conduction block may be similar to that from early demyelination or stretch injury. Further, motor and sensory A alpha fibers differ both in their vulnerability to heat and in their subsequent response to the application of potassium channel blockers.

4-Aminopyridine↗
PubMed2003

Distinct functional types of macrophage in dorsal root ganglia and spinal nerves proximal to sciatic and spinal nerve transections in the rat.

Inflammation proximal to a peripheral nerve injury may be responsible for ectopic discharge and/or death of sensory neurones, factors thought to contribute to the development and/or maintenance of neuropathic pain. Here, ED1+, ED2+ and major histocompatibility complex class II (MHC II)+ macrophages in dorsal root ganglia (DRGs) and spinal nerve roots have been compared quantitatively in adult rats following transection of one sciatic or one spinal nerve, using double labelling immunohistochemistry. In control DRGs, all ED2+ cells expressed ED1 and some also MHC II. One week after either lesion, the ED2+ cells changed negligibly, except that all expressed MHC II. ED1+ and MHC II+ cell density increased markedly, with cells expressing MHC II alone (the majority), ED1/MHC II or rarely ED1 alone. In the spinal roots, ED1+ and MHC II+ cell density increased less after sciatic than after spinal nerve transection when ED1+ foamy cells were prominent. All ED2- macrophages were aggregated with T lymphocytes around blood vessels at 1 week or around isolated somata at later stages. ED1+ cell density declined more rapidly than MHC II+ cell density. Within the DRG, the debris of retrogradely labelled neurones appeared in ED2+ cells and a small proportion of MHC II+ cells that contained ED1. The data suggest that (i) resident ED2+ macrophages do not proliferate but are phagocytic and (ii) of ED1+ and MHC+ monocytes invading from the blood, only ED1+/MHC II+ cells are phagocytic. Four functional subtypes of macrophage within the DRGs were distinct from ED1+ foamy cells that phagocytosed myelin after spinal nerve transection.

Animals↗
PubMed1994

Developmental expression of P0 mRNA and P0 protein in the sciatic nerve and the spinal nerve roots of the rat.

Expression of myelin P0 protein by myelinating Schwann cells in vivo is dependent on axonal influences. This report describes P0 gene expression during development of rat sciatic nerve and spinal nerve roots using Northern blotting, in situ hybridization and immunohistochemistry. We demonstrate that: (1) the appearance of P0 mRNA and P0 protein in Schwann cells during nerve development in the rat begins prenatally, at day 18 post-fertilization (E18); (2) P0 mRNA and P0 protein have essentially identical developmental profiles, and are expressed in Schwann cells that are many days prior to myelin formation; (3) initial P0 gene expression is greatest in Schwann cells at the periphery of nerve bundles and in Schwann cells in contact with motor axons; (4) the decline in P0 expression with nerve maturation is accompanied by a sharp decline in P0 message levels in most Schwann cells, but a small subpopulation of these cells continue to synthesize very high levels of P0 mRNA. This study provides data on myelin P0 protein gene expression and distribution during PNS development and adds further insights into the axonal influences controlling Schwann cell behaviour during myelination of the rat PNS.

Aging↗
PubMed1997

Study on the developmental changes in angulation of spinal nerves, the length of the dorsal roots and spinal nerves in sheep.

This study reports the angulation of spinal nerves, the length of dorsal roots, the length of spinal nerves and the transverse and vertical diameters of the spinal cord during pre- and postnatal life in sheep of the Mehraban breed in Iran. The spinal cord of these animals was divided into 4 regions with respect to the angulation of spinal nerves. The first region was from the first to fifth cervical and the second was from the sixth cervical to the eighth thoracic in fetuses and from the six cervical to fourth thoracic in adults. The third region was from the ninth thoracic to second lumbar in fetuses and from the fifth thoracic to second lumbar in adults, and the fourth region was from third lumbar to fourth sacral in the animals of all age groups. The length of dorsal roots from their point of emergence from the spinal cord to the dorsal root ganglia showed a direct correlation with the length of the spinal nerves. While angulation of the spinal nerves showed a converse correlation with the length of either spinal nerves or dorsal roots. The transverse diameters of the spinal cord were always longer than the vertical diameters. The greatest diameters (vertical-7.00 mm; transverse-10.00 mm) are recorded at C1, T1 and L6 in adult sheep.

Animals↗
PubMed1986

Differential effects of in vitro heating on rat sciatic nerve branches and spinal nerve roots.

Locally applied heat induces nerve conduction block. Conflicting observations have been made regarding the relation of fiber conduction velocity to heat sensitivity. This study utilized sciatic nerve branches and spinal nerve roots which were heated until a substantial conduction block occurred. The results indicated that sensory fibers conducting at greater than 40 m/s are more heat-sensitive than motor fibers of the same conduction velocity.

Action Potentials↗