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PubMed1994

Development of the spinal nerves in the mouse with special reference to innervation of the axial musculature.

Development of the mouse spinal nerves was studied. On E11 (11th day of gestation), the primitive spinal nerve fascicle extended ventrally in the anterior half of the sclerotome. Spinal nerves in the forelimb region united with each other to form the primitive brachial plexus. Their terminal segment was covered by a peculiar cell mass. On E12, five primary branches developed along the primitive spinal nerve trunk. The ramus dorsalis was originally a cutaneous nerve, supplying two series of branches to the skin of the back. The medial series was derived from the dorsal ramus of C2-C8, and the lateral series from C8 and the more caudal dorsal rami. Nerves of the former series took the presegmental course through the intermyotomic space, while those of the latter the postsegmental course. The ramus cutaneous lateralis was a nerve that took the presegmental course to become cutaneous. The ramus intercostalis externus was a muscle branch whose distribution was restricted within the segment. The ramus anterior was a muscle branch from the end of the primitive spinal nerve trunk. The ramus visceralis connected a thoracic nerve with the para-aortic sympathetic cell cord. On E13-16 the ramus anterior secondarily gave off a cutaneous branch (ramus cutaneous anterior). The ramus intercostalis externus extended ventrally deep to the intercostalis externus muscle, crossing just caudal to the ramus cutaneous lateralis that secondarily gave off branches to the obliquus externus abdominis muscle.

Abdomen↗
PubMed1987

Development of the spinal nerves in the lamprey: II. Outflows from the spinal cord.

During a series of studies on the development of spinal nerves in the tail of larval lampreys (13 mm, 26 days), Lampetra japonica, we observed outflows of cytoplasmic processes (cytoplasmic outflow) or whole cell bodies (cellular outflow) from the neural tube or from the cord. Three types were distinguished according to their site of exit from the surface of the neuraxis. The dorsal outflow (DO) is the cellular outflow seen on the midsagittal surface of the dorsal wall of the caudalmost region of the neural tube, just rostral or caudal to the opening in the dorsal tube wall. It is hypothesized that the cells from the dorsal neural tube become polymorphous cells scattered in the extramedullar space. The dorsolateral outflow (DLO) is the cytoplasmic outflow emerging from the dorsolateral aspect of the spinal cord at the intermyotome level. DLO fibers are non-myelinated fibers arising from the dorsolateral tract (DLT) and, after piercing the basal lamina and the glia limitans, run in the myosepta laterally to spread along the deep surface of the dermis. DLO fibers terminate in two different ways: those of one group pierce the dermis and the basal lamina to end as intraepidermal free endings that contain aggregates of clear vesicles, and those of the other group form varicosities that lie within depressions on the lateral cell surface of myotomes. DLO fibers in the extramedullary space characteristically lack any sheaths, including the basal lamina. The ventrolateral outflow (VLO) represents primitive ventral roots consisting of both the cytoplasmic and the cellular outflows: the former shows the axonal outgrowth from primitive somatomotor neurons, and the latter is represented by elongated cells derived from the glia limitans, extending along the axonal processes to form the Schwann cell sheath around the proximal portion of the ventral root axons. The basal lamina covering the cord does not extend along the VLO fibers. The developing ventral root contains axons at different stages of differentiation. Some axons end on the medial surface of the myotome at the midsegmental level to form neuromuscular junctions. However, axonal processes of primitive motoneurons form close contacts with muscle cells by means of small cytoplasmic projections that contain no synaptic vesicles and lack the basal lamina interposed between them. The proposed sequence of development, based on stages in caudal to rostral sections, is the DO, the DLO, and then the VLO.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Evaluation of the L2 spinal nerve root infiltration as a diagnostic tool for discogenic low back pain.

BACKGROUND: To assess whether unilateral L2 infiltration with local anesthetic can be used to identify patients who will have negative discograms and thus eliminate the need for the discogram. Discogenic low-back pain is considered to have afferent pathways in the sinuvertebral nerves, mainly originating from the ventral rami of the spinal nerves. There is evidence that pain arising from the lower lumbar intervertebral discs may be transmitted through the sympathetic afferent fibers contained in the L2 spinal nerve root. Provocative discography, within the context of other clinical data, is the current "gold standard" by which to diagnose discogenic low-back pain, but a far more invasive procedure than L2 infiltration. OBJECTIVE: To evaluate the correlation between unilateral second lumbar (L2) spinal nerve root infiltration with local anesthetic and provocative discography in patients with chronic low back pain. STUDY DESIGN: A prospective, observational study. METHODS: All patients scheduled for discography were asked to participate in having local anesthetic infiltration of the L2 spinal nerve root at least two weeks prior to discography, until forty subjects were enrolled. Discography was performed after the patient's pain level returned to baseline. RESULTS: Local anesthetic infiltration of the L2 spinal nerve root was predictive of provocative discography results in only 46.5% of the subjects (26% true positives, and 20.5% true negatives). In 53.5% of the subjects, L2 infiltration was not predictive of discography results (20.5% false positives, and 33% false negatives). CONCLUSIONS: The results showed that unilateral L2 infiltration is not predictive of discogenic low-back pain when compared to discography, the current "gold-standard" for diagnosis.

Journal Article↗
PubMed1990

Spinal nerve root origin of the median, ulnar and musculocutaneous nerves and their muscle nerve branches to the canine forelimb.

The contribution individual ventral spinal nerve roots made to the canine median nerve, ulnar nerve, musculocutaneous nerve, and their muscle nerve branches was determined electrophysiologically. Each spinal nerve root was sequentially stimulated. Utilizing quantitative signal averaging techniques, the evoked potential was measured at each tested peripheral nerve. Evoked potential to the median nerve originated from the seventh cervical spinal root (C7) through the second thoracic spinal root (T2) with most input from C8 and T1. The ulnar nerve received evoked potential from C7-T2. Although T1 provided the major input to both the median and ulnar nerves, the relative contribution of T1 was greater in the ulnar nerve. The musculocutaneous nerve received input from ventral spinal roots C6-T1 with C6 and C7 providing most of the evoked potential. The ventral spinal roots which supplied the bulk of the evoked potential to a particular muscle nerve were consistent between individual dogs. Variation of evoked potential input was greatest from spinal roots which supplied less than 10% of the total potential.

Animals↗
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↗
PubMed1998

[Treatment of insufficiency of the anal sphincter by sacral spinal nerve stimulation with implantable neurostimulators].

The feasibility of permanent electrostimulation of the sacral spinal nerves was studied in patients with fecal incontinence and no detectable morphological lesions and thus not amenable to conventional surgical management. Applying acute percutaneous stimulation with needle electrodes, the most relevant sacral spinal nerve for striated sphincter muscle function was identified (sacral spinal nerve S3 or S4). The therapeutic potential of stimulation was tested by subchronic stimulation with temporary wire electrodes and, if effective, permanent electrodes were implanted in four patients. Long-term sacral spinal nerve stimulation persistently improved anal continence and increased the function of the striated muscular anal sphincter.

Adult↗
PubMed2001

The changes in expression of three subtypes of TTX sensitive sodium channels in sensory neurons after spinal nerve ligation.

Our previous studies showed that the ectopic discharges in injured sensory neurons and mechanical allodynia that developed after spinal nerve ligation were significantly reduced by application of a low concentration of tetrodotoxin (TTX) to the corresponding dorsal root ganglion (DRG) of the ligated spinal nerve. Based on these data, we hypothesized that expression of TTX-sensitive sodium channels is up-regulated in the injured sensory neurons and that such up-regulation plays an important role in the generation of ectopic discharges and thus pain behaviors in spinal nerve ligated neuropathic rats. To test this hypothesis, the present study examined the changes in three subtypes of TTX-sensitive sodium channels in the DRG after spinal nerve ligation. The changes in the total amount of mRNA for alpha-subunits of sodium channel brain type I (type I), brain type II (type II) and brain type III (type III) were determined by RNase protection assays (RPA). The population of DRG neurons expressing type III sodium channel protein was examined by an immunohistochemical method with antibodies to type III sodium channels. In the normal DRG, the level of mRNA for the type I sodium channel is high while that for type II and type III is very low. After spinal nerve ligation, the expression of type III mRNA was significantly increased at 16-h postoperatively (PO), doubled by 3 days PO and then was maintained at this high level until the end of the experiment (7 days PO). By contrast, the amount of mRNA for type I and type II sodium channels started to decrease at 1 day PO and were reduced to 25-50% of the normal control levels by 7 days after nerve ligation. Neurons showing positive immunostaining for type III sodium channels were rare ( approximately 3.2% of total population) in the normal DRG but increased after nerve ligation to 21% and 15% of the total neuronal population by 1 day and 7 days PO, respectively. Type III immunoreactivity was found preferentially in medium to large sized neurons. Thus the majority of neurons with cell bodies having diameters > or =40 microm became type III-positive after nerve ligation. The data indicate that the increased expression of type III sodium channels in axotomized sensory neurons may be the critical factor for the TTX sensitivity of ectopic discharges in injured sensory neurons and thus the generation of ectopic discharges and neuropathic pain behaviors in spinal nerve ligated rats.

Animals↗
PubMedDate not supplied

[Methods of instrumental physiotherapy in the rehabilitative treatment of pareses caused by nerve compression of the extremities and spinal nerve root compression].

The controlled study of comparative effectiveness of magnetic stimulation, infrared pulsed laser therapy, niacin electrophoresis by sinusoidal modulated current and ultrasound was conducted for 109 patients with flaccid pareses caused by nerve or spinal root compression. The patients were randomly assigned to 4 treatment groups (control group was exposed to laser imitation). The results obtained favour magnetic stimulation and laser as analgetics and reducers of motor deficiency. The benefit from the use of niacin electrophoresis was not proved in this study.

Adult↗
PubMed1981

Congenital hypomyelination neuropathy: glial bundles in cranial and spinal nerve roots.

Autopsy examination of a 3 1/4-year-old child with a severe congenital hypomyelination neuropathy showed the anterior spinal nerve roots and motor cranial nerves to be almost devoid of myelin in their subarachnoid course. The posterior spinal nerve roots and peripheral nerves were less severely affected. Onion bulb formation was minimal and was present only in the sural nerve. There was extensive glial overgrowth in cranial nerves and spinal nerve roots adjacent to the brainstem and spinal cord. The extent and severity of glial overgrowth were similar to that described in Werdnig-Hoffmann disease and morphologically appeared as glial bundles. These glial bundles are most likely secondary to chronic myelin and axonal damage.

Axons↗
PubMed2006

Activity-dependent slowing of conduction velocity in uninjured L4 C fibers increases after an L5 spinal nerve injury in the rat.

Growing evidence suggests that uninjured afferents may play an important role in neuropathic pain following nerve injury. The excitability of nociceptive neurons in the L4 spinal nerve appears to be enhanced following an injury to the adjacent L5 spinal nerve. In this study, we investigated whether the action-potential conduction properties of unlesioned, unmyelinated fibers are also altered. A teased-fiber technique was used to record from single C fibers from the L4 spinal nerve of the rat in vitro. Repeated electrical stimulation of the tibial nerve was used to investigate activity-dependent slowing of conduction velocity. Twin pulse stimulation at a 50 ms interpulse interval allowed investigation of supranormal conduction velocity. Blinded experiments were performed 8-10 days after sham surgery and after an L5 spinal nerve ligation (L5 SNL). Activity-dependent slowing revealed two populations of C fibers, a "nociceptor" population with a large degree of activity-dependent slowing and a "non-nociceptor" population with a smaller degree of activity-dependent slowing. Both populations showed enhanced activity-dependent slowing of conduction velocity and enhanced supranormal conduction velocities in lesioned animals compared to sham animals. Activity-dependent slowing was also enhanced after an L5 SNL in the mouse. These alterations in conduction velocity may reflect changes in expression of ion channels responsible for the membrane excitability. These data provide additional evidence that a nerve injury leads to persistent alterations in the properties of adjacent uninjured, unmyelinated fibers.

Action Potentials↗
PubMed1988

Spinal nerve root origins of the cutaneous nerves of the canine pelvic limb.

The spinal nerve root origins of the cutaneous nerves innervating the canine pelvic limb were determined in 12 barbiturate-anesthetized, healthy dogs by stimulating the dorsal roots L1-S3 and recording the evoked-action potentials from each cutaneous nerve. The dogs were then euthanatized, identification of each dorsal root and cutaneous nerve was verified by dissection, and the type of lumbosacral plexus (prefixed, median fixed, or postfixed) was determined. With one exception, the dorsal cutaneous branches and lateral cutaneous branches of L1-L3 originated only from their corresponding spinal nerve roots. The genitofemoral nerve received afferent fibers predominantly from L3-L4 nerve roots. The lateral cutaneous femoral nerve originated from L3-L5 nerve roots, and the saphenous nerve from L4-L6 nerve roots. The proximal caudal cutaneous sural nerve originated from L6-S1. The lateral cutaneous sural nerve originated from L5-S1; the deep and superficial fibular nerves arose primarily from L6-L7. The distal caudal cutaneous sural nerve originated predominantly from L7-S1, and the medial cutaneous tarsal nerve originated from L6-S1. The medial plantar nerve originated predominantly from L6-S1 roots, whereas the lateral plantar nerve originated from L6-S2 roots. The middle clunial nerve received afferent fibers primarily from S1-S2; the caudal clunial nerve received fibers from S1-S3. The caudal cutaneous femoral nerve originated predominantly from L7-S2. The dorsal nerve of the penis originated predominantly from S1-S2, and the superficial perineal nerve originated from S1-S3. One dog had a prefixed plexus, 8 dogs had median-fixed plexuses, and 1 dog had a postfixed plexus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

The use of thoracodorsal nerve transfer in restoration of irreparable C5 and C6 spinal nerve lesions.

There are only a few reports on the use of thoracodorsal nerve (TDN) transfer to the musculocutaneous or axillary nerves in cases of directly irreparable brachial plexus injuries. In this study, we analysed outcome and time-course of recovery in correlation with recipient nerves and type of nerve transfer (isolated or in combination with other collateral branches) for 27 patients with transfer to the musculocutaneous or axillary nerves. Using this nerve as donor, we obtained useful functional recovery in all 12 cases for the musculocutaneous nerve, and in 14 (93.3%) of 15 nerve transfers for the axillary nerve. Although, we found no significant statistical difference between analysed patients according to the percentage of recoveries and mean values, we established a better quality and shorter time of recovery for the musculocutaneous nerve. According to obtained results, we consider that transfer may be a valuable method in reconstruction after directly irreparable C5 and C6 spinal nerve lesions.

Adolescent↗
PubMed1991

The spinal nerve root sleeve is not a preferred route for redistribution of drugs from the epidural space to the spinal cord.

It has been frequently suggested that the spinal nerve root sleeve is a preferred route for redistribution of drugs from the epidural space to the spinal cord. To determine if this supposition is true, the authors measured the rate at which morphine, fentanyl, and lidocaine diffuse through dog and monkey meningeal specimens with and without a root sleeve. Two meningeal specimens of intact dura-arachnoid-pia mater were removed from each animal and placed in separate temperature-controlled diffusion cells. One specimen included a spinal nerve root sleeve; the other did not. The permeability of the tissues to each drug was then determined by placing the study drug in one of the reservoirs of the diffusion cell and measuring the rate at which the drug diffused through the tissue and accumulated in the second reservoir. There was no difference in permeability between specimens with and without a nerve root sleeve for any drug in either species. Lidocaine was found to diffuse through the tissue significantly faster than fentanyl in both the dog and monkey even though fentanyl is nearly 48 times more lipid soluble than lidocaine. Morphine diffused through the tissue significantly slower than both lidocaine and fentanyl. The authors conclude that the spinal nerve root sleeve is not a preferred route of entry for drugs moving from the epidural space to the spinal cord. In addition, despite hypotheses to the contrary, lipid solubility does not appear to be the overriding determinant of meningeal permeability.

Animals↗
PubMed1994

Involvement of spinal nerves in neurofibromatosis.

Spinal tumors are a frequent form of manifestation of neurofibromatosis. Out of 171 patients, who have been operated on over a ten years period on spinal tumors, 7 patients had neurofibromatosis (4.1%). A total of 9 operations were performed, removing 20 spinal tumors. Three patients had multiple neurofibromas. Half of the neurofibromas had a dumbbell configuration with a larger extraspinal extension. In three patients a family history of neurofibromatosis and typical dermatological signs were evident. Two cases will be selected and the basic concept regarding treatment and the risks involved will be discussed.

Adolescent↗
PubMed2000

Mechanical hyperalgesia after an L5 spinal nerve lesion in the rat is not dependent on input from injured nerve fibers.

An injury to a peripheral nerve in animals often leads to signs of neuropathic pain including hyperalgesia to heat, cold and mechanical stimuli. The role of injured and intact nerve fibers in mechanical hyperalgesia was evaluated in rats subjected to an L5 spinal nerve ligation-and-cut ('modified SNL lesion'). To assess the contribution of injured afferents, an L5 dorsal rhizotomy was performed immediately before, or 7 days after the modified SNL lesion. To study the role of adjacent intact spinal nerves, an L4 dorsal rhizotomy was performed 7 days after the modified SNL lesion. The up-down method of Dixon (Dixon WJ, Annu Rev Pharmacol Toxicol 1980;20:441-462) was used to measure the paw withdrawal threshold to mechanical stimuli at three sites on the rat hindpaw corresponding to the L3, L4, and L5 dermatomes. We found that the modified SNL lesion produced a significant, lasting (20 days) decrease of the mechanical withdrawal threshold. The severity and duration of mechanical hyperalgesia varied across testing sites. The L5 and L4 dermatome test sites developed the most severe and lasting mechanical hyperalgesia. In contrast, the L3 testing site developed significantly less severe and shorter lasting mechanical hyperalgesia. L5 dorsal rhizotomy, by itself, produced a transient decrease in mechanical withdrawal thresholds. L5 dorsal rhizotomy performed before, or 7 days after, the modified SNL lesion did not prevent or resolve the observed decrease in mechanical withdrawal thresholds. L4 dorsal rhizotomy performed 7 days after the modified SNL lesion resulted in an immediate reversal of mechanical withdrawal thresholds back to baseline values. These results suggest that, after L5 spinal nerve ligation-and-cut, mechanical hyperalgesia develops and persists independent of input from injured afferents. We propose that the Wallerian degeneration that develops after a nerve injury leads to interactions between the degenerating fibers of the injured spinal nerve and the intact fibers of adjacent spinal nerves. This leads to changes in the intact fibers that play a critical role for both initiation and maintenance of mechanical hyperalgesia.

Animals↗
PubMed2000

Anatomic study of the cervicothoracic spinal nerves and their relation to the pedicles.

Twelve cadavers were dissected for the study of the cervicothoracic junction. The results showed that the mean heights and widths of the ganglia tend to decrease from the C-6 to T-4 nerve. The mean distances between the dura and the ganglion and the mean spinal nerve angles increased consistently from C-5 to T-4. The mean distances from the spinal nerves to the superior and inferior pedicles ranged 0.8-2.3 mm. It was noted that the mean value was significantly greater for the distance from the spinal nerve to the superior pedicle than that to the inferior pedicle for the spinal nerves C5-7 (P< or =.05). This information, in conjunction with imaging studies, may minimize spinal nerve injury during posterior pedicle screw fixation in the cervicothoracic spine.

Aged↗
PubMed1994

Blood flow in the sciatic nerve is regulated by vasoconstrictive and vasodilative nerve fibers originating from the ventral and dorsal roots of the spinal nerves.

Anesthetized rats were subjected to repetitive electrical stimulation of either the ventral or dorsal root of the spinal nerves between the 11th thoracic and 2nd sacral spinal segments. The response of nerve blood flow (NBF) in the sciatic nerve was examined using laser Doppler flowmetry. For all nerve fibers stimulation was for a 10-30-s period at a supramaximal intensity. (1) Stimulation of the T11-L1 ventral roots produced an increase in mean arterial pressure (MAP) and a biphasic NBF response was comprised of an initial increase and a subsequent decrease. The initial increase was a passive vasodilation due to the increase in MAP, while the following decrease in NBF resulted from active vasoconstriction of the vasa nervorum due to the activation of sympathetic nerves innervating the sciatic vasa nervorum. (2) Stimulation of the ventral root of the L6 segment produced an increase in NBF, even though MAP decreased. This increase in NBF was apparently mediated by activation of parasympathetic cholinergic vasodilators, because the response was abolished by i.v. injection of atropine, a muscarinic cholinergic receptor antagonist. (3) Stimulation of the dorsal roots between the L3 and S1 segments produced an increase in NBF, independent of changes in MAP. This increase in NBF appeared to be mediated by activation of a calcitonin gene-related peptide (CGRP) containing afferent fibers innervating the vasa nervorum, because the response was abolished by topical application of hCGRP (8-37), a CGRP receptor antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗