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At least 19 recordsLinked to original sources
PubMed1992

Effects of magnitude and duration of compression on spinal nerve root conduction.

Spinal nerve root compression occurs commonly in conditions such as herniated nucleus pulposus, spinal stenosis, and trauma. However, the pathophysiology of the symptoms and signs related to spinal nerve root compression is poorly understood. The purpose of the present study was to assess and compare effects of various pressures and durations of acute compression on spinal nerve root conduction in the pig cauda equina. Efferent conduction (compound motor action potentials) and afferent conduction (compound nerve action potentials) were monitored during compression for 2 or 4 hours with compression pressures of 0 (sham), 50, 100, or 200 mm Hg. Recovery from compression was monitored for 1.5 hours. No significant deficits in spinal nerve root conduction were observed with 0 or 50 mm Hg compression, compared to significant conduction deficits induced by 100 and 200 mm Hg compression. Three-way analysis of variance demonstrated significant effects of compression pressure and duration on conduction at the end of compression and recovery, with a significant difference between efferent and afferent conduction at the end of the recovery period. These observations suggest an interaction between biomechanical and microvascular mechanisms in the production of nerve root conduction deficits. Such information may relate to the motor and sensory dysfunction in clinical conditions associated with spinal nerve root compression.

Action Potentials↗
PubMedDate not supplied

Nerve roots and spinal nerves in degenerative disk disease.

After 43 years of investigating the intervertebral disk, the long term results of the management of patients from the standpoint of pain are not significantly different than they were prior to the identification of the herniated disk nor do they seem to be significantly different than no treatment at all. This should at least suggest that the phenomena of low back pain is far more complex than can be accounted for on the basis of a simple mechanical-pressure theory of disk derangement. There is a significant volume of literature that would point to the neural tissues themselves as the most logical structures for future research that attempts to interfere with the natural history of this disease from the standpoint of pain. It seems most appropriate to attack lumbar disk disease from this standpoint because except in uncommon cases, the pathological process is benign and self limiting. It also seems logical that major advancements in the management of "diskogenic" back pain will depend upon an appreciation of the importance of controlling neural inflammation in the early phases of the disease rather than developing new techniques of managing irreversible neural lesions and their iatrogenetic or psychiatric sequelae.

Acute Disease↗
PubMed1976

A light and electron microscope study of changes occurring at the cut ends following section of the dorsal roots of rat spinal nerves.

Rat dorsal spinal nerve roots were cut; 20 h later the axons in the vicinity of the cut were examined by light and electron microscopy. The changes in the cut tip distant from the ganglion were largely degenerative. On the ganglionic side of the cut a cap of free unmyelinated sprouts was formed. These sprouts contained clear and dense-core vesicles 40-150 nm in diameter, smooth endoplasmic reticulum and mitochondria. Some of the unmyelinated sprouts were extensions of myelinated axons, others arose from myelinated axons by lateral budding. In both myelinated and non-myelinated axons there was an accumulation of mitochondria, tubulo-vesicular smooth endoplasmic reticulum and large and small dense-core vesicles for a distance of approximately 500 mum behind the tip. Dense-core vesicles were more common in non-myelinated axons than in their myelinated counterparts. In areas of intense accumulation the non-myelinated fibres were grossly swollen and distorted. The myelinated axons and some of the sprouts contained an unusual type of mitochondrion. The similarity between these sprouts and pre-synaptic terminals is discussed.

Animals↗
PubMed1992

Intraforaminal repair of plexus spinal nerves by a posterior approach: an experimental study.

Many spinal nerve roots injured due to stretch or other types of lesions are not reparable. Some spinal nerves might be repaired if they could be exposed in their intraforaminal course. A posterior subscapular approach for a more lateral exposure of the brachial plexus was combined with a facetectomy to expose intraforaminal nerves in a series of Macaca rhesus monkeys. This approach exposed a 6- to 10-mm segment of spinal nerve not approachable by a more classic anterior operation. Sural grafts were placed from the dural exit of the spinal nerves to the cord level of the plexus. Nine surviving animals were followed for 36 to 54 months and observed for clinical evidence of return of function. In each animal at least one electromyogram (EMG) was performed. The plexus was then re-exposed and intraoperative nerve action potentials were recorded across graft sites. Evoked muscle action potential and cortical potentials were recorded in six animals. Despite the proximal level of repair, adequate regeneration was shown by clinical, electrical, and histological studies. Functional return was best to the supraspinatus and biceps muscles and to wrist and finger flexors. Clinical recovery was present, but less effective, for deltoid, wrist, and finger extensors and intrinsic muscles of the hand, despite evidence on EMG of reinnervation. Recovery of the infraspinatus muscle was poor. Nerve action potentials could be recorded across each graft site. Reinnervational activity was recorded by EMG and evoked muscle action potential studies in most of the muscles studied, despite the persistence of some denervational changes 3 years or more after injury and repair. Histological studies confirmed the presence of a large number of axons of moderate size and myelination even at the forearm level.

Action Potentials↗
PubMed1991

Benign spinal nerve sheath tumors: their occurrence sporadically and in neurofibromatosis types 1 and 2.

Benign spinal nerve sheath tumors (neurofibromas and schwannomas) often occur on dorsal nerve roots sporadically or in neurofibromatosis types 1 and 2. These are histologically benign tumors, and distinction between them is frequently not made by clinicians. To determine if there is a correlation between the histological pattern of benign spinal nerve sheath tumors and the type of neurofibromatosis, the clinical and pathological features of these tumors (86 surgical specimens and five autopsies) in 68 patients were reviewed. The patients were classified into one of four categories: neurofibromatosis type 1, neurofibromatosis type 2, uncertain, or sporadic. The diagnostic criteria used for neurofibromatosis types 1 and 2 were established by the National Institutes of Health. Patients who did not fulfill criteria for either neurofibromatosis type 1 or 2 but who had multiple nervous system tumors or other stigmata of neurofibromatosis were designated "uncertain." Spinal nerve sheath tumors were considered sporadic in 42 cases (40 schwannomas and two neurofibromas). In the 14 patients with neurofibromatosis type 1, all spinal nerve sheath tumors were neurofibromas. In six of the seven patients with neurofibromatosis type 2, all spinal nerve sheath tumors were schwannomas. One patient with neurofibromatosis type 2 had a spinal nerve sheath schwannoma and a tumor with features of both tumor types. The authors conclude that spinal nerve sheath tumors in patients with neurofibromatosis type 1 are neurofibromas. In contrast, spinal nerve sheath tumors occurring in neurofibromatosis type 2 or sporadically are most frequently schwannomas. The distinct histological features of these tumors may reflect different pathogenetic mechanisms even though they arise at identical sites in neurofibromatosis types 1 and 2.

Humans↗
PubMed1992

Proximal cervical spinal nerve: MR appearance.

An interradicular cleft and a segment of nerve containing fascicles have recently been described in the cervical spinal nerve. This study was performed to determine whether the fascicles and the interradicular cleft have a distinctive appearance on magnetic resonance (MR) images. The proximal spinal nerves and nerve roots of C-4 and C-8 were removed from cadavers, imaged with MR, sectioned, and stained. Cervical neural foramina were imaged with MR and then sectioned. The MR images demonstrated a division of the root sheaths into ventral and dorsal portions, separated by fat within the interradicular cleft and located proximal to the dorsal root ganglion. Distal to the dorsal root ganglion, the proximal portion of the cervical spinal nerve containing multiple fascicles gave the proximal portion of the spinal nerve an inhomogeneous appearance on the MR images. This study suggests an anatomic explanation for the variable appearance of the cervical spinal nerves with MR imaging.

Aged↗
PubMed1990

Anterograde transport of opioid receptors in rat vagus nerves and dorsal roots of spinal nerves: pharmacology and sensitivity to sodium and guanine nucleotides.

We have utilized the technique of in vitro autoradiography to ascertain that opioid receptors are transported in the rat vagus nerve and in the rat dorsal spinal root fibers. In the dorsal roots, opioid receptors accumulated on both sides of the ligatures. In the vagus nerve, a distal accumulation of binding sites was difficult to detect, however, proximal to the ligatures, vagal receptors accumulated in a linear fashion during the first 12 h of ligation. At longer periods after ligation, accumulation was less than expected and the receptors appeared to migrate retrogradely. The receptor transport could be blocked by intravagal colchicine injection and the receptor translocation could be elicited in isolated vagal nerve segments suggesting that the receptors move by fast transport. Sodium chloride, present in the incubation medium, inhibited [3H]dihydromorphine ([ 3H]DHM) binding to receptors adjacent to and far from the proximal aspect of the ligature with IC50's of 42 mM and 51 mM, respectively. The addition of GTP in the incubation medium also inhibited [3H]DHM binding to "proximal" and "far proximal" receptors with IC50's of 0.27 microM and 1.0 microM, respectively. The presence of GTP also inhibited [3H]naloxone ([3H]Nal) binding to "proximal" and "far proximal" receptors with IC50's of 0.34 microM and 0.66 microM, respectively. The transported vagal opioid receptors bound the ligands in a stereospecific manner. Using [3H]DHM, [3H]D-ala2-D-leu5-enkephalin [( 3H]DADL), and [3H]ethylketocyclazocine ([3H]EKC), we found that most of the transported vagal receptors have mu-pharmacology although kappa and delta receptors are present.

Animals↗
PubMed1978

Relationship of the patellar tendon reflex to the ventral branch of the fifth lumbar spinal nerve in the dog.

The lumbosacral plexuses of dogs were exposed, using a ventral abdominal approach. In 4 dogs, the ventral branches (VB) of the 4th, 5th, 6th, or 7th lumbar spinal nerves were severed bilaterally. In 4 other dogs, the VB of combinations of 3 of these lumbar spinal nerves were severed so that the branch of only 1 nerve was kept intact. Among many neurologic deficits seen, the reflex of the patellar tendon was absent if the VB of the 5th lumbar spinal nerve was severed and was present if the branch was left intact. This finding was confirmed in another 12 dogs in which the VG of the 5th lumbar spinal nerve was severed on 1 side and the VB of the 4th and 6th lumbar spinal nerves were severed on the opposite side. In 4 additional dogs, the dorsal and ventral roots of the 5th lumbar spinal cord segment were isolated by dorsal laminectomy. Severing the dorsal root caused loss of the patellar tendon reflex, whereas severing the ventral root resulted in hyporeflexia. These findings would suggest that the major afferent impulse elicited by tapping the patellar tendon reaches the spinal cord by way of the dorsal root of the 5th lumbar spinal nerve.

Animals↗
PubMed1979

Observations on the topographical relations of spinal nerve roots in the rat.

The spinal cord along with the ventral and dorsal roots (C1-S4) were dissected out in 10 male and 5 female CF rats. The vertebral levels of origin and exit of the spinal nerve roots and termination of the spinal cord were recorded. It was observed that from the mid-cervical to the sacral region, the roots arose increasingly at cranial levels compared to their levels of exit. This disparity was at its maximum in the lumbar and sacral segments. The spinal cord terminated between the third and fourth lumbar vertebrae. There was no sexual dimorphism either at the level of termination of the cord or at the levels of origin and exit of origin and exit of the various nerve roots.

Animals↗
PubMed1979

Studies of human and bovine spinal nerve roots and the outgrowth of CNS tissues into the nerve root entry zone.

The outpouching of CNS tissues into the entering spinal nerve roots was documented by light and electron microscopy of human and bovine tissues. Astrocytic processes containing large bundles of glial filaments were very prominent in the nerve entry zone and extended for short distances into the adjacent endoneurium of the spinal nerve roots. Antiserum raised to glial acidic fibrillary (GFA) protein stained these glial elements, thereby characterizing the dome-shaped evaginations of CNS tissues into the nerve root entry zones. Antisera to CNS basic protein showed enhanced staining in the nerve entry zone. Analyses of nerve proteins by SDS gel electrophoresis disclosed a prominent 49,000 MW protein in the bovine and human nerve root entry zone. This protein was also prominent in spinal cord white matter, but was not seen in nerve roots which were not admixed with glial tissues. This finding supported the view that a 49,000 MW protein is a glial filaments but is not a component of bovine or human neurofilaments.

Animals↗
PubMed1976

Spinal nerves and their bearing on salamander phylogeny.

Examination of the vertebral columns of representatives of all families of salamanders revealed that, in contrast to the condition found in most other vertebrates, salamander spinal nerves of often pass through foramina in the vertebrae. Two kinds of spinal nerve foramina were found: those in the anterior halves of vertebrae, and those in the posterior halves. In addition, many salamanders retain intervertebral nerves. However, within each family or, in a few cases, subfamily there is a characteristic pattern of spinal nerve-vertebral relationships. The first spinal nerve of all salamanders exits through a foramen in the anterior half of the atlas. All more posterior nerves are intervertebral in the families Cryptobranchidae, Hynobiidae and Proteidae. The posterior caudal nerves exit through the posterior halves of the caudal vertebrae in the family Amphiumidae, while in the subfamilies Dicamptodontinae and Rhyacotritoninae all post-sacral nerves exit through the posterior halves of the vertebrae. All but the first three nerves exit through posterior foramina in the family Plethodontidae and the subfamily Ambystomatinae, while all but the first two nerves pass through posterior foramina in the families Salamandridae and Sirenidae. Several fossil salamanders were also examined. These showed that the amphiumid and dicamptodontine-rhyacotritonine nerve patterns had evolved by the Late Cretaceous, and the sirenid pattern had probably evolved by that time. Other Cretaceous genera associated with the Ambystomatoidea still possessed the primitive intervertebral pattern. Using spinal nerve patterns and several other previously described morphological characters, a new hypothesis of the phylogeny of recent and fossil salamanders is presented and compared to earlier proposed phylogenies of the group. A new classification of salamander families is presented.

Animals↗
PubMed1992

An experimental model for peripheral neuropathy produced by segmental spinal nerve ligation in the rat.

We attempted to develop an experimental animal model for peripheral neuropathic pain. Under sodium pentobarbital anesthesia, both the L5 and L6 spinal nerves (group 1) or the L5 spinal nerve alone (group 2) of one side of the rat were tightly ligated. For comparison, a parallel study was conducted with another group of rats (group 3) which received a partial tight sciatic nerve ligation, a paradigm developed previously as a neuropathy model. Withdrawal latencies to application of radiant heat to the foot were tested for the next 16 weeks in all 3 groups. Sensitivity of the hind paw to mechanical stimulation was tested with von Frey filaments. The general behavior of each rat was noted during the entire test period. Results suggested that the surgical procedure in all 3 groups produced a long-lasting hyperalgesia to noxious heat (at least 5 weeks) and mechanical allodynia (at least 10 weeks) of the affected foot. In addition, there were behavioral signs of the presence of spontaneous pain in the affected foot. Therefore, we believe we have developed an experimental animal model for peripheral neuropathy using tight ligations of spinal nerves. The model manifests the symptoms of human patients with causalgia and is compatible with a previously developed neuropathy model. The present model has two unique features. First, the surgical procedure is stereotyped. Second, the levels of injured and intact spinal segments are completely separated, allowing independent experimental manipulations of the injured and intact spinal segments in future experiments to answer questions regarding mechanisms underlying causalgia.

Animals↗
PubMed1992

Proximal lumbar spinal nerves in axial MR imaging, CT, and anatomic sections.

The proximal lumbar spinal nerve is composed of a group of small fascicles interspersed with fat. These fascicles converge into the ventral ramus. The authors studied the appearance of this portion of the spinal nerve through analysis of magnetic resonance (MR) images, computed tomographic (CT) scans, and exactly corresponding anatomic sections in cadavers. The fascicles can be identified at MR imaging or CT as poorly defined structures surrounded by the fat lateral to the neural foramen. The ventral ramus appears as a pair of oval, contiguous, small homogeneous structures. The evaluation of nerve compression may be aided by identification of the fascicles and ventral rami on CT and MR images.

Adult↗
PubMed1976

A scanning electron microscope study of the development of free axonal sprouts at the cut ends of dorsal spinal nerve roots in the rat.

Rat dorsal spinal nerve roots were cut and the tip on the ganglionic side of the cut was examined by scanning electron microscopy at 0, 7, 20 and 48 h after operation. Seven hours after cutting, free axonal sprouts had started to protrude from the cut end of the nerve. After 20 h the free sprouts were more profuse than at 7 h but were smaller and had a rougher surface. At both 7 and 20 h many of the sprouts consisted of a stalk 2-7 mum in diameter with a bulbous end 5-20 mum in diameter. A few branching sprouts were seen. At 48 h the sprouts were shrunken with a deeply furrowed surface. The significance of the surface structure of the sprouts is discussed.

Animals↗
PubMedDate not supplied

[Schwannoma of the spinal nerve].

A years old woman with a spinal nerve schwannoma is reported. Treatment and main clinical and histopathologic features of this very unusual location are discussed.

Adult↗