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At least 37 records · Page 2Linked to original sources
PubMed1999

A canine peripheral nerve sheath tumor including peripheral nerve fibers.

Peripheral nerve sheath tumor was found in a 7-year-old male mongrel dog. The tumors were located in the right cheek subcutis and oral submucosa. Histologically, neoplastic cells were arranged in streaming bundles, occasionally interlacing bundles or whorls of elongated and spindle cells. Cellular atypia was poor and mitotic figures were rarely observed. Ultrastructurally, neoplastic cells had basement membrane, typical of Schwann cells. One bundle of normal peripheral nerve fibers and some myelinated axons were seen within the tumor tissues. Immunohistochemically, neoplastic cells reacted to vimentin, glial fibrillary acidic protein, S-100 protein and neuron specific enolase. In addition to the above immunoreactions, the included nerve fibers were positive for myelin basic protein and neurofilament protein. This paper also discusses immunohistochemical findings on differential diagnosis in comparison with those of canine hemangiopericytomas reported hitherto.

Animals↗
PubMed2005

Extended remission of a recurrent median nerve malignant peripheral nerve sheath tumor after multimodal treatment. Case report.

Malignant peripheral nerve sheath tumors (MPNSTs) are difficult to control despite aggressive treatment. In this report the authors describe the treatment and follow-up review of a patient with neurofibromatosis Type I who harbored a recurrent median nerve MPNST. The man underwent preoperative intraarterial and intravenous chemotherapy followed by additional surgery for gross-total removal and postoperative radiotherapy. Two courses of preoperative intraarterial cisplatin and intravenous Adriamycin produced significant tumor shrinkage. Gross-total removal of the remaining tumor without amputation of the arm was followed by fractionated radiotherapy (total minimum tumor dose 6485 cGy, maximal dose 6575 cGy). The patient is alive 9.5 years after treatment without evidence of tumor recurrence and with only focal median nerve functional deficits. A review of the patient's treatment is warranted to provide a description of a regimen that may be useful in the treatment of similar patients in the future.

Adult↗
PubMed1991

Cellular magnetic fields: fundamental and applied measurements on nerve axons, peripheral nerve bundles, and skeletal muscle.

We review the fundamental origins of biomagnetic fields in terms of ionic currents flowing at the cellular level. Mathematical models provide the link between the macroscopic fields and the microscopic electrophysiological sources. The single cell view is then expanded to include more complex systems such as nerve and muscle bundles. We provide an overview of the two most promising methods to measure the magnetic fields from these systems, we discuss the capabilities and limitations of the techniques based on comparisons with conventional electric methods, and we show that the direct measurement of action currents and the ability to scan along nonuniform samples are of prime importance. We present a number of interesting applications for basic research under laboratory conditions, including measurements of the time course of electrophysiological changes following a crush injury to a nerve and the spatial and temporal dependence of action currents as they propagate away from the motor endplate zone of a single motor unit in skeletal muscle. We conclude by discussing the potential applications in the clinic, including the intraoperative assessment of neuroma-in-continuity and the long-term monitoring of nerve regeneration and degenerative neuromuscular disorders.

Action Potentials↗
PubMed2003

[The blood-nerve barrier in peripheral nerves].

AIM: To study ultrastructural details of perineurium and endothelium samples from the endoneural vessels that form part of the blood-nerve barrier of peripheral nerves, with the intention of furthering our understanding of how these natural structures protect axons against foreign substances. METHODS: We obtained samples from the sciatic nerve at the superior angle of the popliteal fossa. The samples were first fixed in glutaraldehyde and then in osmium tetroxide; later they were dehydrated with acetone and soaked in resin epoxy (Epon 812). Ultra-thin sections were treated with uranyl acetate and lead citrate in solution. The slides were observed under a transmission electron microscope. RESULTS: The perineurium has a thickness of 10 to 25 microns and is composed of 8 to 15 continuous cell layers lying concentrically around each nerve fascicle. Each perineurial cell layer consists of a single layer of flat cells joined together by specialized junctions to provide a barrier against diffusion. Most of the endoneural vessels found near the axons were capillaries measuring 6 to 10 microns in diameter and composed of 6 to 8 endothelial cells with specialized junctions without fenestrations. CONCLUSIONS: The blood-nerve barrier is a cylindrical structure formed partly by membranes composed of tightly joined perineurial cell layers whose union is reinforced by specialized junctions that tend to isolate each fascicle. In addition, there is a cylindrical structure made up of endoneural endothelial cells also united by specialized junctures. These tend to keep blood away from axons and to impede the passage of circulating substances into the endoneural environment. Systemic diseases that alter and diminish the efficacy of the barrier in peripheral nerves may have implications for the creation of peripheral nerve blocks.

Aged↗
PubMed2000

Verification of the two-dimensional disector, a method for the unbiased estimation of density and number of myelinated nerve fibers in peripheral nerves.

Quantification of the number of myelinated fibers in peripheral nerves is a common requirement in quantitative morphology. This parameter provides important information on the consequences of various physiological, pathological and experimental conditions on the nerve structure and is one of the main indicators of success of peripheral nerve repair. In this paper, the theoretical rationale for the application of stereological principles to obtain unbiased estimates of the density and total number of myelinated fibers in peripheral nerves is discussed and a simple stereological method is described. The method is applied together with a systematic random sampling scheme, that was optimized for the purposes of the present study, and with sampling scheme analysis by calculating the coefficient of error (CE). The stereological method, which consists of a two-dimensional variation of the classical disector procedure (two-dimensional disector), and the sampling scheme are verified by comparing estimates with the true density and total number of myelinated fibers in peripheral nerve trunks where true values have been accurately determined by extensive counting. The verification of the 2-D disector method, both of normal and regenerated nerves, showed that estimates of density and total number of myelinated nerve fibers are unbiased. The method also proved to be efficient (time-saving): Estimation of density and total number of myelinated fibers in a single nerve takes about 2-3 hours.

Animals↗
PubMed1981

Effects of capsaicin applied locally to adult peripheral nerve. I. Physiology of peripheral nerve and spinal cord.

(1) Systemic capsaicin treatment of neonatal and adult rats is known to affect unmyelinated afferents. However, the systemic route of administration presents several disadvantages and in order to overcome these a method was explored where a single nerve in adult rats was locally treated. (2) Sciatic nerves were exposed and a 10 mm length was soaked for 15 min in 1.5% capsaicin in vehicle or in the vehicle alone (10% Tween 80, 10% ethyl alcohol in saline). (3) Both the capsaicin solution and the vehicle caused acute block of the C compound action potential while in contact with the nerve. Removal of the solutions, however, resulted in substantial recovery of C fibre conduction. The A fibre volley was totally unaffected. (4) 13-21 days after treatment, the size of the myelinated and unmyelinated volleys evoked by maximal stimulation of the capsaicin treated nerve were unchanged but there was a 20% decrease of conduction velocity in the C fibres. (5) The ability of the maximal C volley from the treated nerve to excite cells in the spinal cord was substantially decreased (by 50%) 13-21 days after local capsaicin.

Animals↗
PubMed2000

Use of nerve conduits in peripheral nerve repair.

Studies on nerve conduits for peripheral nerve regeneration have concentrated on the manipulation of various conduit materials to avoid sacrificing native nerve in the clinical situation. With the proliferation of available nerve growth-stimulating factors, the focus is shifting experimentally toward molecular biologic manipulation, with the addition of these materials as substrates within the conduit. The clinical use of conduits has concentrated on the use of autogenous tissue, with a few examples of polyglactin (PGA) mesh and silicone. Ultimately, as yet, conduit material does not seem to have a profound effect on outcome. Substrate manipulation has not yet had clinical application. An important problem that remains, both experimentally and clinically, is overriding the size of the maximal gap that can be bridged successfully, as well as obtaining good functional sensory and motor recovery, compared with the use of nerve grafts. Advances in molecular biology may reveal further details about the nerve growth phenomenon, the precise sequencing of the substrate materials that are effective in promoting nerve growth, and when they should be applied. Advances in chemical engineering may provide additional biologically stable materials that have the ability to integrate growth-enhancing agents or factors into the lumen of the conduit.

Animals↗
PubMed2000

The relationship between melanocytes and peripheral nerve sheath cells (Part II): blue nevus with peripheral nerve sheath differentiation.

Peripheral nerve sheath differentiation was studied in 120 specimens of blue nevi (112 specimens of "common" blue nevi and 8 specimens of "cellular" blue nevi). In 10 of 112 common blue nevi, fascicles of pigmented dendritic melanocytes or less pigmented spindle-shaped melanocytes with S-shaped nuclei were associated with wavy delicate collagen bundles. In 4 of these 10 specimens, the melanocytes showed a perifollicular arrangement. These nerve fascicle-like structures were seen in some cellular blue nevi (5 of 8 specimens). Structures closely resembling authentic nerve fascicles were not observed in common or cellular blue nevi. The fascicles with S-shaped nuclei and fibrillary collagenous tissue observed in blue nevi (which were well detected in the cellular type but rarely found in the common type) may be peripheral nerve sheath features and perhaps evidence that dermal dendritic melanocytes in the reticular dermis may have arisen within a peripheral nerve sheath milieu from primitive fibroblast-like precursors. Some of the examples presented here may be identical to those reported for "pilar neurocristic hamartoma" or "neurocristic hamartoma." I also speculate on the pathogenesis of blue nevi based on the observations made in this study.

Cell Differentiation↗
PubMed1997

In vitro frog sciatic nerve as a peripheral nerve model for studies of the mechanism of action of low energy lasers: Part one.

BACKGROUND AND OBJECTIVE: There have been numerous reports of modulation of peripheral nerve action potential characteristics through application of low energy laser irradiation (LELI), although no mechanism has yet been advanced to explain these observations. In order to investigate the mechanism of LELI effects in peripheral nerve tissue, a well-characterized, reliable, and robust peripheral nerve preparation is required. The objective of this study was to evaluate the in vitro frog sciatic nerve as a candidate model for future LELI mechanism studies. MATERIALS AND METHODS: Following 60-minute baseline recordings of compound action potential (CAP) amplitude, latency, depolarization rate, and repolarization rate, helium-neon (HeNe) laser irradiation (632 nm, 15 min, 1-7 J, 44-320 J/cm2) was delivered to one of two sites on the nerve. Laser-induced changes in CAP parameters were analyzed during irradiation and for 60 minutes post-irradiation using a repeated measures linear regression model. RESULTS: In the treatment group that received 7 J of HeNe energy over the recording electrode, CAP latency increased relative to nonirradiated controls during the postirradiation period. No other treatment group demonstrated laser-induced changes in CAP characteristics at any time during the experiment. CONCLUSION: HeNe irradiation demonstrated limited ability to alter the CAP under these conditions. As such, the in vitro frog sciatic nerve is an inappropriate model for mechanism of action studies.

Action Potentials↗
PubMed1980

Creatine kinase isoenzyme patterns in neoplasms of peripheral nerve.

Normal peripheral nerve and neoplastic lesions of peripheral nerve varied in their creatine kinase (CK; EC 2.7.3.2) isoenzyme pattern, as assessed both with electrophoresis and with column chromatography. All three isoenzymes were seen in normal peripheral nerve, but the peripheral nerve tumors, neurofibroma and neurilemmoma, demonstrated predominantly CK-1 isoenzyme activity, with a trace amount of CK-3. No CK-2 activity was demonstrated in these tumors. In contrast, malignant schwannoma tissue contained all three isoenzymes, but in a different proportion than in normal peripheral nerve.

Creatine Kinase↗
PubMed1981

Interfascicular nerve grafting of peripheral nerve lesions in childhood.

Interfascicular cable grafting with autologous sural nerve was carried out in 43 peripheral nerve lesions among 37 children aged 5--16 years. The follow-up study included neurophysiologically proved regeneration. The results seem superior to those obtained with the conventional technique. The technique is advocated for use in children with nerve gaps of more than 2--2.5 cm.

Adolescent↗
PubMed1994

Nerve grafting in peripheral nerve microsurgery of the upper extremity.

The use of microsurgical techniques is essential in peripheral nerve surgery, in which dissection at the fascicular level is required. Magnification with an operating microscope allows for an accurate evaluation of the severity of the trauma to the nerve tissue and permits atraumatic interfascicular dissection. Fascicular or interfascicular dissection and repair with the use of nerve grafts was carried out in 220 peripheral nerve lesions of the upper extremity. Our results of nerve-grafting in the upper extremity (median, ulnar, and radial-nerves) indicate an inverse association between the age of the patient and the delay between injury and grafting. In addition, we found that nerve grafting without tension produces superior results over simple neurorrhaphy under tension and permits better axonal growth and nerve recovery.

Adolescent↗
PubMed1993

[An experimental study of compound implants made of vein and nerve for repairing peripheral nerve gaps].

The effect of peripheral nerve regeneration in bridging short gaps of peripheral nerve with non-neural material is reliable, but rather disappointed in long gaps. In this study, we bridged a 3.0 cm long peroneal nerve defect in rabbits only with an autogenous vein. no nerve regeneration was found 22 weeks after operation. In the experimental group, we divided the vein into two parts, and a 0.3 cm long free nerve segment was sutured between them, which was then used to bridge a peroneal nerve gap with the same length as above definite nerve regeneration was demonstrated by electrophysiological, histological examination and HRP tracing. Therefore, the effect was improved significantly with the addition of a nerve segment to the vein implant. Possible reasons for the positive effects of isolated nerve segment in bridging nerve gaps are discussed.

Animals↗
PubMedDate not supplied

Percutaneous electrode guidance: a noninvasive technique for prelocation of peripheral nerves to facilitate peripheral plexus or nerve block.

BACKGROUND AND OBJECTIVES: Typically, peripheral nerve block is done by approximating nerve location, usually by use of anatomical landmarks. Precise nerve location has been done by needle exploration. A new method, percutaneous electrode guidance (PEG) of the block needle, was performed. A transcutaneous stimulating cylindrical electrode was used to indent the skin, locate the underlying nerve, and guide a block needle near it. METHODS: PEG was used to prelocate the desired nerve or neural plexus by use of a shielded cylindrical electrode with a 1-mm-diameter conductive area of skin contact at the distal end, the center of which contained a 22-gauge (1/2 mm) hole, which precisely matched a shielded conventional block needle. Transcutaneous stimulation began at less than 10 mA and was decreased to minimal amperage that elicited the desired motor response. Electrode position was fixed, and electrode current was discontinued. A shielded 22-gauge block needle was advanced through the electrode guide to near the underlying nerve. Initial needle current was only 0.5 mA. Local anesthetic was injected to block the targeted nerve or nerves. Standard sensory/motor testing was performed at 20 minutes. RESULTS: Nine upper or lower extremity blocks were performed on 7 patients. All were successful. Minimal stimulating currents were 1.3 to 8.2 mA for transcutaneous electrode stimulation and 0.20 to 0.70 for needle stimulation. Needle depth was 0.4 to 1.1 cm beyond the electrode tip and correlated with minimal electrode stimulating current. CONCLUSIONS: A smooth, metal-tipped electrically shielded skin electrode probe can be used to comfortably and accurately indent the skin over a desired nerve or plexus, define its anatomical course, and subsequently guide a block needle near it.

Adult↗
PubMed2005

Pleiotrophin cellular localization in nerve regeneration after peripheral nerve injury.

Pleiotrophin (PTN) is a member of the family of heparin-binding growth factors that displays mitogenic activities and promotes neurite outgrowth in vitro. In vivo, PTN is widely expressed along pathways of developing axons during the late embryonic and early postnatal period. Although the level of PTN gene expression is very low during adulthood, activation of the gene may occur during recovery from injury and seems to play an important role in tissue regeneration processes. In this study, we investigated whether PTN was involved in the regenerative process of injured peripheral nerves. To refer localization of the fluorescent markers to myelinated axons, we developed a specific computer tool for colocalization of fluorescence images with phase contrast images. Immunohistochemical analysis showed PTN in different types of nonneural cells in distal nerve segments, including Schwann cells, macrophages, and endothelial cells, but not in axons. Schwann cells exhibited PTN immunoreactivity as early as 2 days after injury, whereas PTN-positive macrophages were found 1 week later. Strong PTN immunoreactivity was noted in endothelial cells at all time points. These findings support the idea that PTN participates in the adaptive response to peripheral nerve injury. A better understanding of its contribution may suggest new strategies for enhancing peripheral nerve regeneration.

Animals↗