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At least 469 records · Page 26Linked to original sources
PubMed1997

[Incarceration of spinal nerve roots].

The aim of this study is to evaluate the prognosis of motor function in patients that experience the combination of a sudden disappearance of radicular pain and severe motor paresis. Eight patients were identified over a ten year period. Operative decompression of the affected lumbar root with removal of a disc prolapse seems to have a good prognosis if the patient is not paralytic before surgery. Patients treated conservatively for radicular pain should be advised to call their doctor immediately if they experience progressive motor paresis and diminishing pain.

Adult↗
PubMed1980

Growth of a limb spinal nerve: an ultrastructural study.

A quantitative study of the delivery of nerve fibres to the developing limb has been made. Electron microscope (EM) sections of SN 9 in Xenopus were taken at close intervals between dorsal root ganglion and limb-bud. Numbers and types of axons in each section were counted. Counts declined steadily with distance from the ganglion towards the base of the limb. This is large due to some axons not having grown the full distance at the time of fixation. The slope corresponded with an outgrowth velocity of 0.5 mm a day, without branching. Distally, at stages 50 and 51, but not at stages 49 and 54, the decline was reversed, and a peak of axon number was found. This is strong evidence for axon branching in this region. Since this took place at least one stage before SN 9 bifurcated, and since the bifurcation was distal to the branching when it did appear, it is suggested that axon branching at a nerve bifurcation might be part of a trial-and-error mechanism for pathway selection. Observations were made on the sheath surrounding the nerve, and on its assembly. Initially, axons grow out naked and not parallel; Schwann cells migrate after the growing front. Processes of these cells collect individual axons, and transfer them inwards to form the primitive parallel fibre bundle, enclosed by a family of Schwann cells. Myelination later occurs in a similar manner: Schwann-cell processes extend into a bundle of naked axons and eventually encircle a single transitional axon, with one Schwann cell eventually containing many such axons. Finally comes the stage of promyelin, in which a single Schwann cell encircles a single axon. Myelin whorls are then formed from this complex.

Animals↗
PubMed1989

The intersegmental anastomoses between spinal nerve roots.

Frequency and morphological characteristics of the intersegmental anastomoses between the spinal roots were investigated in 100 adult spinal cords from the cervical to lumbar segments. The frequencies of dorsal root anastomoses were 61, 7, and 22% of the cervical, thoracic, and lumbar cords, respectively. On the other hand, the incidence of anastomosis between the ventral roots was significantly low in both the cervical (10%) and lumbar (5%) cords as compared with that between the dorsal roots in these regions (P less than .01). No anastomotic connections were found in the thoracic ventral roots. The anastomoses were classified into four types: types A and B; the borders between the spinal segments were cranially and caudally shifted, respectively; type C, anastomosis attached to the spinal cord at the border between the segments; and type D, anastomosis bridged between the adjacent rootlets and coursing parallel to the cord. The proportions of the four types at each spinal level disclosed that type A was most commonly observed compared with the other three types in the dorsal roots (P less than .01). In the lumbar cord, the proportion of type C anastomosis between the dorsal roots increases noticeably toward the sacral level, while a complementary decrease occurred in type A. In the cervical ventral roots, types C and D predominated over the other two types (P less than .01). The lumbar ventral roots contained types B and/or C. Type D anastomosis occurred exclusively in the cervical segments.

Humans↗
PubMed1975

Quality of spinal extradural anaesthesia: the influence of spinal nerve root diameter.

Profiles on the progress of spinal extradural anaesthesia were made in 246 patients using various concentrations of lignocaine, bupivacaine and etidocaine. The advance of analgesia through the different dermatomes showed a consistent and orderly spread on the upper lumbar and thoracic segments. This spread was irregular through the lower lumbar and upper sacral segments. The first sacral segment was especially difficult to block with an overall failure rate of 17.53% with presently available concentrations of various local anaesthetics. This failure was abolished with the use of etidocaine 1.5%. The presence of a delay or failure at the level of L5-S2 is probably related to the larger diameter of these nerve roots as ascertained from measurements in 11 cadavers.

Acetanilides↗
PubMed1984

Spinal cord contains neurotrophic activity for spinal nerve sensory neurons. Late developmental appearance of a survival factor distinct from nerve growth factor.

Several tissues of the developing chick embryo have been reported to contain neurotrophic activity which can sustain the survival of sensory neurons maintained in culture. In a previous study, however, we noted that such nerve growth promoting activity was exceptionally low, if not absent, from extracts of spinal cord from chick embryos of up to 16 days incubation. Since then the combined results from a number of tissue culture studies have suggested that the central nervous system may be the source of a neurotrophic growth factor essential during the late development of sensory neurons. We have therefore carried out an extended range study of the neurotrophic properties of avian spinal cord. Extracts of spinal cord tissue prepared from chicks at stages between the last wk of embryogenesis and 12 wks after hatching were tested for their ability to promote survival and neurite outgrowth from both explant and dissociated neuron-enriched cultures of dorsal root, trigeminal, nodose and paravertebral chain sympathetic ganglia from chick embryos between 8 and 16 days old. We conclude from our results that spinal cord is a potent source of neurotrophic activity for sensory neurons, although this activity appears relatively late in development of the spinal cord. The predominant ontogenic increase in spinal cord neurotrophic activity was seen to occur during the first week after hatching. Sensory neurons from both spinal and cranial nerve ganglia were sustained in culture by spinal cord extracts, whereas sympathetic neurons did not respond. Neurons from older sensory ganglia (12-16 day old embryos) were much more responsive than similar neurons from young embryos (8 day).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Selective cooling of the spinal cord and spinal nerve roots in patients with spastic and pain syndromes].

Selective cooling of the spinal cord and its roots was applied in 26 patients with a high degree of muscle spasticity of various genesis and in 12 of those with various pain syndromes. Hypothermia was conducted by the open and closed (puncture) methods. The subarachnoid space was cooled to 11--7.5 degrees C. Spasticity diminished to grade I--II in 15 patients and to grade III in 9; in 2 patients it did not change. In 3 of 12 patients the sensation of phantom and pain were completely relieved, marked improvement occurred in 6 patients, while in 3 patients the effect proved short-lived or doubtful.

Evoked Potentials↗
PubMed1975

Abnormalities in Schwann cell sheaths in spinal nerve roots of dystrophic mice.

Dorsal and ventral spinal roots at cervical, thoracic, lumbar and sacral levels in dystrophic, dy/dy, mice of both 129/ReJ and C57Bl/6J phenotypes showed a complete lack of Schwann cell sheaths of any sort around the majority of their nerve fibres. This condition, termed amyelination, is more extensive (up to 1-5 cm in length) in the longer lumbar and sacral roots than in the shorter roots or in the proximal regions of the sciatic nerve which are also affected to some extent. Amyelination does not appear to be a consequence of myelin or Schwann cell degeneration, as debris is uncommon. Heterozygous carriers are not affected in any obvious way. Myelinated fibres, with Schwann cells of peripheral origin, occur immediately adjacent to the spinal cord in both dorsal and ventral roots, while in dorsal roots unmyelinated fibres also occur, as in normal animals. Amyelinated fibres begin to appear a few internodal lengths away from the cord and are present until near, or within, the dorsal root ganglion, where they become myelinated again. The portion of an axon which has no myelin begins at a normal appearing paranodal region (termed a half node of Ranvier) at the end of a myelin internode. Resumption of myelination likewise begins at a half node. A few myelinated axons may be seen in any given cross section of a root, but as a rule a given myelinated fibre does not remain myelinated throughout the whole length of the root. It is suggested that the nerve lesions develop where the nerves are lengthening rapidly as the animal grows and changes its shape. How these nerve changes release to those in muscle is conjectural.

Animals↗