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PubMedDate not supplied

Peripheral nerve injuries in children with traumatic brain injury.

The relationship between traumatic brain injuries and associated peripheral nerve injuries has not been previously studied in children in the rehabilitation setting. One hundred and fifty-seven consecutive admissions of brain-injured children were included in this prospective study to determine the frequency and pattern of recovery of peripheral nerve injuries in such patients. Twelve patients met the clinical diagnostic criteria for peripheral nerve injury. Electrodiagnostic studies confirmed the clinical diagnosis in 11 (7%) patients. Grading of spontaneous activity and electrodiagnostic study of the contralateral limb were used to differentiate electromyographic abnormalities due to upper motor neuron lesion and nerve injury. Electrodiagnostic study was useful to confirm clinical diagnosis and predict prognosis of nerve injuries. Two patients developed preventable pressure neuropathy. Eight patients showed moderate or full recovery in 9-10 months post-injury. All children with severe brain injuries should be evaluated for concomitant peripheral nerve injuries.

Adolescent↗
PubMed2003

Peripheral nerve fascicles: anatomy and clinical relevance.

Within a peripheral nerve, the individual nerve fibers are grouped together in fascicles. Whether there is somatotopic organization within these fascicles has long been of interest, the subject of many investigations, and somewhat controversial. Evidence from diverse sources now points to important somatotopic clustering of nerve fibers within most of the length of the nerve. Information is lacking regarding proximal segments, particularly the plexus and spinal nerve root levels. As a result of this somatotopic arrangement, partial focal nerve lesions can produce restricted clinical deficits that defy the classic rules of localization. Examples of such restricted nerve lesions are provided in this review. Recognition of fascicle somatotopy is also important in the surgical approach to disorders of peripheral nerves.

Animals↗
PubMedDate not supplied

Malignant peripheral nerve sheath tumor of the maxilla.

The term malignant peripheral nerve sheath tumor (MPNST) refers to most spindle cell sarcomas arising from nerve or neurofibroma or showing nerve sheath differentiation and has been recently adopted by WHO. Malignant tumors of the peripheral nerve sheath are most commonly seen in association with the neurofibroma or at the site of irradiation and may also occur de novo. Its diagnosis has been called "one of the most difficult and elusive diagnosis in soft tissues diseases". We present a rare case of MPNST in a 12-year-old girl, who presented with a swelling of left cheek region of 2 months duration. Intraorally, the swelling extended buccally and palatally from premolar to tuberosity region. Swelling was fixed and firm to hard in consistency. A clinical diagnosis of odontogenic sarcoma was made. It was surgically excised and the histological features were suggestive of malignant peripheral nerve sheath tumor of the maxilla.

Child↗
PubMed2004

An eclectic history of peripheral nerve surgery.

It is hard to decide where history stops and contemporary development of peripheral nerve surgery begins. This article provides an eclectic view of the history of peripheral nerve surgery. In trying to keep the story moving, the publications of many authors have been omitted. For this, we are sorry. We have also stopped short of reporting the contemporary history of molecular biology as applied to peripheral nerve regeneration. The future of peripheral nerve repairs lies in our understanding of the molecular cascades that stimulate axon growth and guide the axon to its proper destination. We hope that this review shows the reader that researchers who got us where we are traveled a road filled with erroneous dogma, bad advice,and misleading data. We believe that the lessons learned from those who brought us back to the right path are applicable to many disciplines.

History, 19th Century↗
PubMed1988

Central vs peripheral nerve conduction. Before and after treatment of subacute combined degeneration.

Central and peripheral nerve conduction was studied in two patients with subacute combined degeneration by using the short-latency somatosensory evoked potentials and the peripheral nerve conduction study during treatment with cyanocobalamin. Before the treatment, somatosensory evoked potentials with median nerve stimulation were normal, but those with peroneal nerve stimulation revealed prolonged central conduction indicating dysfunction within the posterior column. Peripheral sensory and motor nerve action potentials were reduced with normal or slightly reduced conduction velocity. After treatment, marked shortening of the central conduction time (by 24% and 31%, respectively) was observed with mild or no recovery of peripheral nerve action potentials. These physiologic findings suggest that the main pathologic changes in the central nervous system may be demyelination in the posterior column in addition to axonal degeneration in the peripheral nerve. The former was responsive to treatment but the latter was poorly responsive to treatment. Sensory symptom in subacute combined degeneration appears to be, at least partially, attributed to the spinal cord lesion.

Adolescent↗
PubMed1978

Organization of peripheral nerves and spinal roots of the Atlantic stingray, Dasyatis sabina.

1. The sizes and numbers of axons in peripheral nerves and spinal roots were investigated in the stingray, Dasyatis sabina. 2. The axons of the dorsal and ventral roots do not mingle in peripheral nerves of this animal as they do in higher vertebrates. Thus, it was usually possible to split the peripheral nerve into two portions, one containing only dorsal root axons, the other containing only ventral root axons. This feature was useful for the analysis of certain aspects of spinal cord organization. 3. The fact that dorsal and ventral root axons were segregated in peripheral nerves enabled us to demonstrate, without experimental surgery, that the central processes of the dorsal root ganglion cells and the proximal ventral root axons were 10-20% narrower, on the average, than the distal processes of the same dorsal root ganglion cells or the distal parts of the same ventral root axons. 4. The stingray is remarkable in having very few unmyelinated axons in the dorsal roots, ventral roots, or peripheral nerves. This paucity of unmyelinated axons distinguishes the Atlantic stingrays from all other vertebrates whose roots and nerves have been examined for unmyelinated fibers. 5. Similar findings were obtained for one spotted eagle ray (Aetobatus narinari) and two cow-nose rays (Rhinoptera bonasus).

Animals↗
PubMed2002

Quantitative assessment of the innervation of epineurial arteries in the peripheral nerve by immunofluorescence: differences between controls and patients with peripheral arterial disease.

The peripheral nerve is supplied by the vasa nervorum. The epi- and perineurial vessels are innervated by an autonomic plexus, which plays a role in regulation of the endoneurial blood flow. This innervation is decreased in diabetes and alcohol polyneuropathy and seems to precede the development of diabetic polyneuropathy. A decreased innervation may therefore play a role in the development of polyneuropathy. In peripheral arterial disease (PAD) clinical and morphological features are present, related to severity of ischemia. To investigate the innervation of the vasa nervorum in severe ischemia, we performed immunofluorescence staining with the general neural marker protein gene product (PGP) 9.5 in whole mount preparations of epineurial vessels of nine sural nerves taken from patients with legs amputated because of severe PAD (59+/-15 years, mean +/- SD) and ten age-matched controls (61+/-24 years). In patients with PAD the nerve density of the perivascular plexus was decreased in comparison with controls (mean intercept density/mm +/- SD) 26.0+/-6.9 in PAD and 39.9+/-10.7 in controls, area% 6.0+/-1.6 in PAD and 9.9+/-2.6 in controls, both P<0.01, t-test). A decreased perivascular plexus may result in a diminished regulation of the endoneurial blood flow in patients with severe PAD.

Adult↗
PubMed2006

Volumetric magnetic resonance imaging of dorsal root ganglia for the objective quantitative assessment of neuron death after peripheral nerve injury.

Prevention of neuron death after peripheral nerve injury is vital to regaining adequate cutaneous innervation density and quality of sensation, and while experimentally proven neuroprotective therapies exist, there lacks suitable clinical outcome measures for translational research. Axotomized dorsal root ganglia (DRG) histologically exhibit volume reduction in proportion to the amount of neuronal death within them. Hence, this study evaluated the validity of using magnetic resonance imaging (MRI) to quantify DRG volume as a proxy measure of cell death. A high-resolution 3D MRI sequence was developed for volumetric quantification of the L4 DRG in the rat sciatic nerve model. An unoperated "control" group (n=4), and a "nerve transection" group (n=6), 4 weeks after axotomy, were scanned. Accuracy and validity of the technique were evaluated by comparison with morphological quantification of DRG volume and stereological counts of surviving neurons (optical fractionator). The technique was precise (coefficient of variation=4.3%), highly repeatable (9% variability), and sensitive (mean 15.0% volume reduction in axotomized ganglia detected with statistical significance: p<0.01). MRI showed strong and highly significant correlation with morphological measures of DRG volume loss (r=0.90, p<0.001), which in turn correlated well with neuron loss (r=0.75, p<0.05). MRI similarly exhibited direct correlation with neuron loss (r=0.67, p<0.05) with consistent agreement. MRI volumetric quantification of DRG is therefore a valid in vivo measure of neuron loss. As a non-invasive, objective measure of neuronal death after nerve trauma this technique has potential as a diagnostic modality and a quantitative tool for clinical studies of neuroprotective agents.

Animals↗
PubMed1999

[Stimulation and inhibition mechanisms in peripheral nerve regeneration].

To better analyse the early growth of peripheral nerve regeneration, we recently developed a film model. Following transection of a peripheral nerve, e.g. the common peroneal nerve in mice, both proximal and distal stumps of the transected nerve are sandwiched between two sheets of film, and kept in vivo for various timed intervals after axotomy. The regenerating neurites sprout not only from the nodes of Ranvier close to the transected nerve end but also from the terminal bulbs which are formed at the transected nerve end. All of the regenerating neurites consist of naked axons for at least 2 days after axotomy, and elongate on the film with a growth rate of 77 microns/day. On migrating from a parent nerve to the regenerating axons, Schwann cells promote the axons to grow with a 4 times higher speed. Thereafter, a distal nerve stump of the transected nerve release some stimulating factors toward the regenerating nerves, and the axonal growth rate is increased by approximately 1.5 fold. Some inhibitory factors, one of which is myelin-associated glycoprotein, are at the same time released from the distal nerve segment for a week from the 7th post-operative day, and keep new axons from sprouting and inhibit outgrowth of young naked axons in order to optimum regeneration and maturation of outgrowing pioneer axons. It means a so-called pruning phenomenon.

Animals↗
PubMed1980

Scar prevention in peripheral nerve surgery.

Constriction of a peripheral nerve may precipitate a primary problem of prevent recovery from a pre-existing one. Any surgical technique to minimize subsequent constrictive scar formation would be advantageous. In this study, using rat femoral nerves, various modes of protection were evaluated. Wrapping the nerve with free fat seemed to offer the best prophylaxis.

Adipose Tissue↗
PubMed1992

Strain, stress and stretch of peripheral nerve. Rabbit experiments in vitro and in vivo.

Mechanical stretching is known to cause morphologic and functional changes in peripheral nerve. The points at which these changes occur, however, are not clearly defined and reported data are conflicting. The studies presented in this paper provide a basic understanding of the biomechanical properties, stretch-injury patterns, and changes of conduction properties of peripheral nerves due to stretching. Our studies showed that peripheral nerves exhibited non-linear stress-strain characteristics when placed under tension. Initially, under tension, the nerve had a low modulus that increased gradually with increasing strain until reaching a maximal value. When the nerve failed under tension, the perineurium inside the nerve ruptured, but the exterior of the nerve remained intact. Our results also show that a peripheral nerve in situ was under significant strain, but minimal in situ stress (less than 0.05 MPa). The in situ strain might vary with limb position, but did not appear to exceed the limit beyond which substantial tension or stress would be developed in the nerve. The time-dependent viscoelastic behavior of peripheral nerves were also characterized. The maintenance of small in situ stresses suggests that sustained increases in tension could be adversely affecting the electrophysiologic properties of the nerve. Indeed, marked alteration of conduction properties resulted from even a small stretch of 6 percent beyond the in situ length of the nerve, or stress less than 10 percent of the ultimate strength of the nerve.

Animals↗
PubMed1995

Echotexture of peripheral nerves: correlation between US and histologic findings and criteria to differentiate tendons.

PURPOSE: To correlate the histologic structure and echotexture of peripheral nerves and verify if ultrasound (US) findings can be used to differentiate nerve from tendon. MATERIALS AND METHODS: In an in vitro study, the echotexture of normal peripheral nerves was correlated with the histologic findings. In an in vivo study, US was used to differentiate median nerve from flexor pollicis longus tendon in healthy volunteers (12 male and eight female subjects 7-68 years of age; mean age, 35 years). RESULTS: US examination of the peripheral nerve specimens showed hypoechoic areas separated by hyperechoic bands. The hypoechoic areas corresponded to neuronal fascicles at histologic examination. This fascicular pattern was clear in all median and ulnar nerves, 15 of 20 vagus nerves, and 19 of 20 sciatic nerves in the volunteers but not in recurrent laryngeal nerves. CONCLUSION: Peripheral nerves have a typical US pattern that correlates with histologic structure and facilitates differentiation between nerves and tendons.

Adolescent↗
PubMed2003

Brain lipid binding protein in axon-Schwann cell interactions and peripheral nerve tumorigenesis.

Loss of axonal contact characterizes Schwann cells in benign and malignant peripheral nerve sheath tumors (MPNST) from neurofibromatosis type 1 (NF1) patients. Tumor Schwann cells demonstrate NF1 mutations, elevated Ras activity, and aberrant epidermal growth factor receptor (EGFR) expression. Using cDNA microarrays, we found that brain lipid binding protein (BLBP) is elevated in an EGFR-positive subpopulation of Nf1 mutant mouse Schwann cells (Nf1(-/-) TXF) that grows away from axons; BLBP expression was not affected by farnesyltransferase inhibitor, an inhibitor of H-Ras. BLBP was also detected in EGFR-positive cell lines derived from Nf1:p53 double mutant mice and human MPNST. BLBP expression was induced in normal Schwann cells following transfection with EGFR but not H-Ras12V. Furthermore, EGFR-mediated BLBP expression was not inhibited by dominant-negative H-Ras, indicating that BLBP expression is downstream of Ras-independent EGFR signaling. BLBP-blocking antibodies enabled process outgrowth from Nf1(-/-) TXF cells and restored interaction with axons, without affecting cell proliferation or migration. Following injury, BLBP expression was induced in normal sciatic nerves when nonmyelinating Schwann cells remodeled their processes. These data suggest that BLBP, stimulated by Ras-independent pathways, regulates Schwann cell-axon interactions in normal peripheral nerve and peripheral nerve tumors.

Animals↗
PubMed1999

Changes in the stress relaxation properties of peripheral nerves after transection.

Changes in peripheral nerve stress relaxation after transection were measured weekly for 5 weeks in the distal stumps of sciatic nerves of 50 Sprague-Dawley rats. Each week after transection the distal stumps of the transected nerves showed decreased stress relaxation compared with the freshly transected contralateral nerves after undergoing a 10% elongation. The transected side always showed less stress relaxation at 30 minutes than the intact contralateral side (average, 24%; range, 15% to 32%). A statistically significant difference in mean stress relaxation between the cut nerves and the uncut sciatic nerves occurred for weeks 1 through 4. Week 5 demonstrated a decrease in mean stress relaxation of the experimental side compared with the contralateral control side but this was not statistically significant. Decreased stress relaxation of the distal stump results in increased tension at the suture line as the nerve gap is overcome when performing a delayed neurorrhaphy at 1 to 5 weeks after transection.

Animals↗
PubMed1998

Vascular endothelial cadherin is expressed by perineurial cells of peripheral nerve.

AIMS: To study the distribution of vascular endothelial (VE) cadherin in peripheral nerves. METHODS AND RESULTS: Using two monoclonal antibodies that detect VE-cadherin (TEA1.31 and 7B4) an immunohistochemical study of VE-cadherin expression in five common peroneal nerve biopsies and five skin specimens containing small peripheal nerves was performed. VE-cadherin was consistently expressed by the perineurium of nerves but not by other nerve elements such as Schwann cells or axons. CONCLUSION: This report indicates that VE-cadherin is not. as was previously thought, a specific marker of endothelial cells and further defines the phenotype of the perineurial cell. The established role of VE-cadherin in controlling the permeability of vascular endothelium suggests that this molecule may have a similar role in the perineurium. VE-cadherin may therefore be important in the maintenance of the blood-nerve barrier, the peripheral nerve equivalent of the blood-brain barrier.

Antibodies, Monoclonal↗
PubMed1989

Epithelial membrane antigen expression by the perineurial cell: further studies of peripheral nerve lesions.

We have previously shown that a range of anti-epithelial membrane antigen monoclonal antibodies show immunoreactivity with the perineurial fibroblast, both in normal nerves and within a range of common peripheral nerve tumours. We have extended these observations by studying a further collection of peripheral nerve lesions, including some which have previously been thought to have an origin from the perineurial cell. The results provide further evidence that these antibodies reliably stain perineurial cells and that in conjunction with antisera to S-100 protein and neurofilaments, the relative contributions of the perineurial fibroblast, Schwann cell and neurone can be assessed within a nerve-related tumour/lesion. The perineurial fibroblast is an important component of some peripheral nerve lesions.

Fibroblasts↗
PubMed1996

Biomechanical properties of peripheral nerves.

The biomechanical properties of peripheral nerves still are not completely understood or quantified. This is partly because of the nonhomogeneous nature of nerves and the variation in the proportions of the components of different nerves. The recognition and quantification of the in-situ stress and the viscoelastic behavior of nerves have been important stepping stones in understanding their mechanical behavior. The effects of stretch and compression on the vascular supply and conduction properties of normal animal nerves have been well studied. Similar studies in injured nerves will provide invaluable information for understanding the mechanics of nerve function and the prevention of stretch- and compression-related trauma.

Animals↗