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PubMed2006

An in vivo study of tricalcium phosphate and glutaraldehyde crosslinking gelatin conduits in peripheral nerve repair.

In order to modulate the mechanical properties of gelatin, we previously developed a biodegradable composite composed by tricalcium phosphate and glutaraldehyde crosslinking gelatin (GTG) feasible for surgical manipulation. In this study, we evaluated the in vivo applications of GTG conduit for peripheral nerve repair. The effect of sciatic nerve reconstruction was compared between resorbable permeable GTG conduits and durable impermeable silicone tubes. Traditional methods of assessing nerve recovery following peripheral nerve repair including histomorphometric and electrophysiologic features were conducted in our study. In addition, autotomy score and sciatic function index (SFI) in walking tract analysis were used as additional parameters for assessing the return of nerve function. Twenty-four weeks after sciatic nerve repair, the GTG conduits were harvested. Microscopically, regeneration of nerves was observed in the cross-section at the mid portion of all implanted GTG conduits. The cross-sectional area of regenerated nerve of the GTG group was significant larger than that of the silicone group. In the compound muscle action potentials (CMAP), the mean recovery index of CMAP amplitude was 0.24 +/- 0.02 for the silicone group, 0.41 +/- 0.07 for the GTG group. The mean SFI increased with time in the GTG group during the evaluation period until 24 weeks. Walking tract analysis showed a higher SFI score in the GTG group at both 12 and 24 weeks. The difference reached a significant level at 24 weeks. Thus, the histomorphometric, electrophysiologic, and functional assessments demonstrate that GTG can be a candidate for peripheral nerve repair.

Action Potentials↗
PubMed1983

Astrogliosis limits the integration of peripheral nerve grafts into the spinal cord.

Segments of peripheral nerve were grafted into the site of a spinal cord transection in mice. To determine the relationship of spinal cord astrocytes to graft derived Schwann cells, graft sites were examined with immunohistochemical as well as conventional histological techniques. Myelin derived from Schwann cells, as identified by immunoreactivity to antibodies against its major protein PO, was strictly confined to the graft. Astrocytes and astrocytic filaments, identified by immunoreactivity to antibodies against glial fibrillary acidic protein (GFAP), predominated at the graft-spinal cord interface, bordering the most central penetration of Schwann cell myelin. Occasional GFAP-positive astrocytes were observed within the graft. It appears that astrocytes limit the penetration of Schwann cells from peripheral nerve grafts into the spinal cord.

Animals↗
PubMed2003

Peripheral nerve block for ambulatory surgery and postoperative analgesia.

PURPOSE OF REVIEW: With this article we intend to increase the awareness of the efficiency and efficacy of peripheral nerve block as a treatment option for outpatient surgical anesthesia and postoperative home-based analgesia. RECENT FINDINGS: Current investigations have demonstrated that peripheral nerve block is associated with a superior outcome (reduced pain, nausea and vomiting) and more efficient patient turnover than general anesthesia. Continuous peripheral nerve block and patient controlled peripheral nerve block lead to further improvement in postoperative analgesia and patient satisfaction. SUMMARY: The recent advances and techniques described indicate that peripheral nerve block is both a valid and frequently a preferred option for ambulatory surgery.

Journal Article↗
PubMedDate not supplied

[Microsurgical reconstructive-rehabilitative operations in traumatic lesions of the peripheral nerves].

Microsurgical reconstructive-restorative operations were conducted on the peripheral nerves of the limbs in 381 patients at the Kazakh centre of microsurgery from 1983. The patients were divided into 3 groups: group 1-60 patients who underwent emergency neurography during replantation of limbs and their segments; group 2-186 patients in whom neurovascular bundles of the limbs were restored (320 nerves were restored) in the late period after the trauma; group 3-135 patients who were subjected to operative interventions on the brachial plexus and the adjacent vessels. In sequelae of injury to the neurovascular bundles of the limbs and the trunks of the brachial plexus one-stage operations must be carried out on the peripheral nerves and the accompanying vessels. The result of the operation is determined by the lapse of time from the moment of the injury, the type of reconstruction, and the length of the graft used.

Adolescent↗
PubMed1981

The spontaneously diabetic BB Wistar rat. Morphologic and physiologic studies of peripheral nerve.

The spontaneously diabetic "BB" Wistar rat was examined for evidence of peripheral nerve abnormalities by a combined morphologic and physiologic approach. The studies were done on rats kept severely hyperglycemic and frequently ketotic. The peripheral nerves of the lower extremities, including the most distal nerves of the intrinsic foot muscles, revealed only minimal abnormalities by histologic and morphometric examination. Sciatic nerve conduction studies, however, measured over a 2-month period did not show a significant slowing in diabetics compared with age-matched controls, as well as between diabetics and weight-matched controls. In addition, fast anterograde axoplasmic transport studies were correlated with serum glucose results. Rats maintained severely hyperglycemic with or without ketosis had abnormal down flow rats of [3H]leucine compared to controls. Diabetic rats maintained with normal blood glucose levels showed no change in transport rates. These results suggested that persistent hyperglycemia in the "BB" Wistar rat produces significant physiologic but not significant structural abnormalities in the peripheral nerve.

Animals↗
PubMed1985

Facilitated transport of glucose from blood into peripheral nerve.

D-Glucose is the major substrate for energy metabolism in peripheral nerve. The mechanism of transfer of glucose across the blood-nerve barrier is unclarified. In this study an in situ perfusion technique was utilized, in anesthetized rats, to examine monosaccharide transport from blood into peripheral nerve. Unidirectional influxes of D-[14C]glucose, L-[14C]glucose, and [14C]3-O-methyl-D-glucose across capillaries of the tibial nerve were measured at different perfusate concentrations of unlabelled D-glucose. The permeability-surface area product (PA) for D-[14C]glucose and [14C]3-O-methyl-D-glucose decreased, whereas the PA for L-[14C]glucose remained constant, as the perfusate concentration of D-glucose was increased. In the presence of no added unlabelled D-glucose in the perfusate, the PA for L-[14C]glucose equaled one-fifth the PA for D-[14C]glucose. These results demonstrate self-saturation, competitive inhibition, and stereospecificity of glucose transfer, and for the first time show a unidirectional facilitated transport mechanism for D-monosaccharides at capillaries of mammalian peripheral nerve. The data were fit to a model for facilitated transport and passive diffusion. The half-saturation constant and maximal rate of transport for the saturable component of D-glucose influx equaled 23 +/- 11 mumol X ml-1 and 6.6 +/- 3.2 X 10(-3) mumol X s-1 X g-1, respectively. The constant of nonsaturable glucose influx equaled 0.5 +/- 0.1 X 10(-4) s-1. At normal plasma glucose concentrations, the saturable component comprises about 80% of total D-glucose influx into nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Immunohistochemical and molecular analysis of p53, MDM2, proliferating cell nuclear antigen and Ki67 in benign and malignant peripheral nerve sheath tumours.

A series of 26 malignant peripheral nerve sheath tumours (MPNST) and 24 benign peripheral nerve sheath tumours (BPNST) were analysed immunocytochemically for p53 expression and the cell proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67 (with MIB1). In 23/26 MPNST, 5%-65% of the tumour cell nuclei were immunoreactive for Ki67 with MIB1 while none of the 24 BPNST had nuclear staining exceeding 5%. Greater than 50% nuclear PCNA staining was detected in 25/26 MPNST compared with 8/24 BPNST; 17/26 MPNST showed 5-100% nuclear staining for p53 (13/26 > 20%), whereas none of the BPNST had nuclear staining exceeding 1%. The Ki67, PCNA and p53 immunostaining results correlated significantly with benign versus malignant (P < 0.001, P < 0.001 and P < 0.005, respectively) as well as mitotic rate (P < 0.001, P < 0.05 and P < 0.05). Ki67 immunostaining results correlated significantly with PCNA and p53, as did p53 and Ki67 and PCNA (P < 0.001 in both). Stepwise (logistic regression forward) multivariate analysis of the variable, benign versus malignant, revealed the strongest correlations with PCNA (P = 0.007) and Ki67 (P = 0.021). Direct confirmation of the presence of p53 protein was obtained by western blot analysis of 3 MPNST and 5 BPNST. Two MPNST, showing 90% and 30% immunoreactivity, were positive for p53, while one MPNST with 5% immunoreactivity and all 5 BPNST were negative. Southern blot analysis performed on the two MPNST with high p53 protein levels revealed no amplification of the MDM2 gene, suggesting that high p53 levels in MPNST are likely to be due to mutation. The results also indicate that PCNA and Ki67 are potentially useful in distinguishing BPNST from MPNST, particularly in problematic cases of cellular schwannoma versus MPNST. The detection of p53 in a large percentage of cells of a plexiform neurofibroma giving rise to MPNST and Ki67 in 5% and 25% of cells of two similar cases suggests that malignant transformation may be detected in some cases by p53 and proliferation markers prior to overt histological evidence of malignancy.

Cell Division↗
PubMed1998

Use of explant cultures of peripheral nerves of adult vertebrates to study axonal regeneration in vitro.

Explanted preparations of peripheral nerves with attached dorsal root ganglia of adult mammals and amphibia survive for several days in serum-free medium and can be used to study axonal regeneration in vitro. This review outlines the methods which we routinely use and how they may be applied to study different aspects of axonal regeneration. When the peripheral nerves are crushed in vitro, axons regenerate through the crush site into the distal stump within 1 day (mouse) or 3 days (frog). The outgrowth distance of the leading sensory axons can be determined with the use of a simple method based on axonal transport of labelled proteins. A compartmentalised system permits selective application of drugs and other agents to either ganglia or peripheral nerve containing the regenerating axons and has been used to study selected aspects of regeneration including influence of non-neuronal cells, retrograde signalling, axonal release of proteins during regeneration and the role of phospholipase A2 activity. Explanted preparations may also be cultured in a layer of extracellular matrix material (matrigel), in which spontaneous outgrowth of a large number of naked axons from the cut ends of nerves starts within 1 day and continues for several days. This provides an opportunity to study the direct effects of different agents on axonal elongation. Preparations cultured in collagen gels show sparse spontaneous axonal growth, but this can be increased by addition of certain growth factors. The phenotype of the regenerating axons can be studied using immunohistochemical methods.

Animals↗
PubMed1984

Prolonged inhibition of primate spinothalamic tract cells by peripheral nerve stimulation.

Inhibition of spinothalamic tract (STT) cells was produced by repetitive peripheral nerve conditioning stimulation with high intensity and low frequency pulses. Identified STT cells were recorded from the lumbosacral spinal cord of intact, anesthetized monkeys. In addition, presumed STT cells were recorded from both unanesthetized, decerebrated and decerebrated, spinalized monkeys. These cells were identified by antidromically activating them from the contralateral ventral lateral funiculus of the cervical spinal cord. Both C fiber activity evoked by electrical stimulation of the sural nerve and activity evoked by noxious heat were greatly inhibited by repetitive conditioning stimuli applied either to the common peroneal or tibial nerve with a strong enough intensity for activation of C fibers at 2 Hz for 15 min. The inhibition was maintained during the period of conditioning stimulation and often outlasted stimulation by 20-30 min. The inhibition of cells produced by peripheral nerve stimulation was observed in decerebrate and spinalized animals as well as in intact anesthetized monkeys, although the mean recovery time in the decerebrate group was faster. This indicates that anesthetics did not interfere with the inhibitory mechanism. Furthermore, the presence of inhibition in spinalized animals means the inhibition must depend in part on spinal cord neuronal circuitry. Intravenous injection of naloxone produced a significant but small reduction of the recovery phase of the inhibition. No pharmacological agent was found that substantially interfered with the powerful inhibition produced during peripheral conditioning stimuli. The experimental animal model used in these experiments seems appropriate for studying the mechanisms of analgesia produced by peripheral nerve stimulation.

Animals↗
PubMed2004

Presurgical ultrasound-assisted neuro-examination in the surgical repair of peripheral nerve injury.

In spite of electrodiagnostic examinations, the determination of the precise localization of the injured site along the involved peripheral nerve may remain obscure or uncertain. Before starting the operation, a surgeon should have knowledge about the type of injury, the position of the proximal and distal nerve stumps, and the presence or absence of a neuroma and excessive perilesional scar tissue formation for orientation and planning of the surgical intervention. We hypothesized that real-time ultrasound could be helpful in the determination of the type of injury, the localisation of proximal and distal nerve stumps, as well as for diagnosing a neuroma. Fourteen patients with traumatic peripheral nerve injuries that were verified by neurological examinations and electrodiagnostic tests underwent surgical repair, and were examined by ultrasound before and during the surgical intervention. Visualisation of the injured site, the type of the injury, the position of the nerve stumps and the diagnosis of the neuroma were reliably feasible in all the patients by using ultrasonography. Axonal swelling of a nerve was diagnosed in 4 (29 %) patients, a stump neuroma was diagnosed in 3 (21 %) patients, a total nerve interruption (neurotmesis in the Seddon classification) was diagnosed in 9 (64 %) patients, and surrounding scar tissue was diagnosed in 5 (35 %) patients. Presurgical and intraoperative ultrasound-assisted neuroexamination is a useful diagnostic method in the determination of the precise localisation of the injured site, the type of injury, the position of stumps, and the diagnosis of a neuroma. The use of preoperative and intraoperative ultrasound can enhance the orientation of the surgeon to the surgical field. The application of our method to our patients shows that presurgical ultrasonographic neuroexamination can be used in the surgical repair of peripheral nerve injury.

Adolescent↗
PubMed2000

Influence of glial growth factor and Schwann cells in a bioresorbable guidance channel on peripheral nerve regeneration.

Using an established rat peripheral nerve regeneration model, we investigated the role of glial growth factor (GGF) in nerve regeneration in combination with a novel bioresorbable poly(lactic-co-glycolic) acid (PLGA) guide in vivo. Schwann cells, established from a 1-cm segment of excised rat sciatic nerve, were isolated and seeded onto nerve guides with or without GGF (n = 24/group). Living nerve guides were re-established in these animals, and nerve regeneration was assessed over a period of 12 weeks. Histological studies revealed a reduction in the total axon count and the number of myelinated axons in the presence of exogenously added Schwann cells compared to saline controls. In contrast, the addition of GGF alone enhanced the total number of axons and significantly increased the number of blood vessels. Although combining GGF with Schwann cells negated the enhanced numbers of axons and blood vessels seen with GGF alone, this combination resulted in the highest myelination index and the fastest conduction velocities recorded. The PLGA guide material did not trigger any histologically detectable host response and was permissive for nerve regeneration in this animal model. The results from this study demonstrate the potential utility of this guide in vivo and establish a promotional role for GGF in nerve regeneration.

Animals↗
PubMed1996

Molecular specializations at nodes and paranodes in peripheral nerve.

In the peripheral nervous system, nodes of Ranvier are formed by interactions between myelinating Schwann cells and axons. Nodes have an intricate ultrastructure, and their molecular architecture is similarly complex. A growing list of molecules have been found that are selectively localized to different parts of the nodes. Neural cell adhesion molecule (N-CAM), L1/Ng-CAM, and tenascin/cytotactin are enriched in the nodal basal lamina; hyaluronic acid, versican/hyaluronectin, N-CAM, L1/Ng-CAM, tenascin/cytotactin, and the ganglioside GM1 are enriched in the nodal gap; myelin-associated glycorprotein, oligodendrocyte-myelin glycoprotein, connexin32, E-cadherin, actin, the gangliosides GQ1b and GD1b, the potassium channel KV1.5, and alkaline phosphatase are enriched in the paranodal region of the Schwann cell; voltage-dependent sodium channels and the cytoskeletal proteins spectrin and ankyrin are enriched in the nodal axolemma. Many of these molecules are probably essential for the proper functioning and stability of nodes.

Animals↗
PubMed1976

Electromyographic studies in peripheral nerve injuries.

In every aspect of management of peripheral nerve injury, needle electromyography and nerve conduction velocity studies can give the clinician valuable objective information to supplement clinical findings. Comprehensive EMG studies in the fourth week after injury are helpful in diagnosing nerve injury, in localizing the site of injury, and in estimating the extent of injury. (In medicolegal situations, the first EMG study should be done within the first five days.) To assess the need for surgical exploration in cases of severe nerve injury, another EMG evaluation should be done eight weeks after injury. If there is no clinical and electrophysiologic evidence of improvement, surgical exploration is recommended. At exploration, the simple study of nerve potential on the exposed nerve in continuity will help the surgeon decide between neurorrhaphy and neurolysis. To assess regeneration, EMG study eight weeks after repair is recommended. When objective evidence of clinical improvement is desirable, serial EMP studies at intervals of four months are in order. To assess the recovery or residual effects of a lesion, final EMG study is recommended 18 months after injury or repair.

Electromyography↗
PubMed2004

Extracellular voltage profile for reversing the recruitment order of peripheral nerve stimulation: a simulation study.

Electrical stimulation of peripheral nerve activates large-diameter fibers before small ones. A physiological recruitment order, from small to large-diameter axons, is desirable in many applications. Previous studies using computer simulations showed that selective activation of small fibers could be achieved by reshaping the extracellular voltage profile along the nerve using an array of nine electrodes. In this study, several electrode-array configurations were tested in order to minimize the number of contacts. Electrode arrays of 5, 7, 9, and 11 contacts with 0.75 mm contact separation were performed in computer simulations of dog sacral root (S2). Electrode arrays of 5 and 7 contacts recruited 40% of small axons (<10 microm) when recruiting only 10% of larger axons. Effectiveness of 9- and 11-contact arrays decreased with the presence of epineurium and perineurium. The effectiveness of electrode arrays was independent of stimulation pulsewidth. The biphasic-pulse stimulation with the amplitude of the second phase set as low as possible should be used to prevent the excitation of large axons during the second phase and to minimize the electrode corrosion. Arrays of 5 and 7 contacts also decreased the recruitment curve slope to 26% and 51% of the tripolar electrode, respectively. This modeling study predicts that reversing the recruitment order of peripheral nerve stimulation could be achieved by reshaping the extracellular voltage using electrode arrays of 5 or 7 contacts.

Action Potentials↗
PubMed1995

Pharmacological evidence for the involvement of endogenous alpha-MSH-like peptides in peripheral nerve regeneration.

The possible involvement of alpha-MSH-like peptides in the regenerative response of peripheral nerves was investigated with a competitive antagonist of alpha-MSH, the synthetic hexapeptide [D-Trp7,Ala8,D-Phe10)alpha-MSH(6-11)-amide. Subcutaneous administration of the alpha-MSH antagonist during the first 10 days following sciatic nerve crush significantly decreased functional recovery as measured by the foot flick withdrawal test and the walking pattern analysis. Hypophysectomy delayed both the initial sprouting response and the outgrowth rate after major caudal nerve crush. When hypophysectomized rats were treated with the alpha-MSH antagonist, a further delay in initial sprouting was observed, whereas the outgrowth rate of nerve fibers was not affected. These results suggest that 1) endogenous alpha-MSH-like peptides stimulate nerve outgrowth following peripheral nerve injury and 2) alpha-MSH-like peptides derived from a source other than the pituitary may contribute to the physiological stimulus leading to sprouting.

Animals↗
PubMed2002

Peripheral nerve compression associated with low-voltage electrical injury without associated significant cutaneous burn.

Although peripheral-nerve injury has been described as clearly related to electrical injury, that electrical injury is usually associated with third- and often fourth-degree burns. The report presented here describes three cases of low-voltage electrical injury with associated peripheral-nerve symptoms but without clinically significant cutaneous burns. The symptoms and clinical findings resembled peripheral-nerve compression. The presence of these symptoms and findings in the upper- and lower-extremities and the presence of bilateral involvement suggest a systemic electrical injury that resembles a peripheral neuropathy. Symptoms were relieved by the decompression of nerves at multiple sites in each extremity. Perineurial fibrosis was identified at the time of nerve decompression. It is proposed that the electrical injury causes maximal heat production at areas of minimal limb cross-sectional area. In these areas, the peripheral nerve is in close proximity to bone and fibrous tissue. This results in perineurial fibrosis and symptoms of a compressive peripheral neuropathy.

Adult↗
PubMed1988

Newer electrodiagnostic techniques in peripheral nerve injuries.

Careful attention to technique is essential for the accurate evaluation of peripheral nerve function using conventional EMG and nerve conduction studies. Numerous technical, anatomic, and physiologic pitfalls must be avoided. The amplitudes of the M wave and SNAP contain useful diagnostic information and should be evaluated carefully in addition to conduction velocity and distal latency. Newer techniques using the F wave, H reflex, SEP, dermatomal SEP, and quantitative EMG may be helpful in evaluation of selected peripheral nerve problems. Comparative nerve conduction studies using "inching" technique permit evaluation of short nerve segments. Comparisons with parallel nerves improve diagnostic sensitivity.

Diagnostic Errors↗