form with motor involvement in specific compression sites such as wrist me- dian nerve Schematic drawing – different clinical patterns of diabetic neuropathy. Diabetic neuropathy (DN) refers to symptoms and signs of neuropathy in a patient with Figure 1 Schematic diagram showing types of diabetic neuropathy. Core tip: Diabetic neuropathic pain is a common complication of diabetes and the most common form of neuropathic pain. In this review, we will.
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The ePub format uses eBook readers, which have several "ease of reading" features Diabetic peripheral neuropathy is a prevalent, disabling condition. Neuropathic pain is one of the major disabling symptoms of patients with DSP. . Ultimately, these different forms of cellular stress cause dysfunction and/or death of. Keywords: DiabetesPolyneuropathyNeuropathyDiagnosisTreatment forms and potential therapeutic approaches of diabetic neuropathy. Together they form the Foundations of Best Practice for Skin and Wound. Management, an online resource available for free download from the Wounds The negative cascade of diabetic foot complications persists despite the many treat- .. the presence of peripheral neuropathy, previous ulceration or.
Oxidative and nitrosative stress As already mentioned, the polyol pathway activation could be the primary cause of oxidative stress associated with diabetes. However, oxidative stress could be also initiated by autoxidation of glucose and their metabolites, increased intracellular formation of AGEs, increased expression of the receptor for AGEs and its activating ligands, altered mitochondrial function, activation of PKC isoforms and overactivity of the hexosamine pathway[ 21 - 23 ].
It seems that, in addition to oxidative stress, reactive nitrogen species, especially the peroxynitrite also play an important role in the development of diabetes and its complications[ 24 - 26 ].
Although it has been clearly demonstrated significant changes in oxidative status in animal models of diabetes[ 27 ], tissue concentrations of known carbonyl compounds are nearly negligible and plasma ET-1, nitric oxide, catalase and glutathione levels did not differ in neuropathic diabetic patients when compared to non-neuropathic diabetic ones[ 28 ].
In line with this observation, clinical results have been contradictory for antioxidants as alpha lipoic acid, ranging from little benefit[ 29 , 30 ] to interesting advantages[ 31 , 32 ]. Microvascular changes DNP is frequently associated with microvascular impairment[ 33 , 34 ].
In clinical and preclinical studies, it was found that peripheral perfusion is reduced, not only in the nervous tissue[ 35 , 36 ], but also in the skin[ 37 ], being an important physiological evidence of microvasculature alteration.
As a result, nerve ischemia occurs, caused by raise in wall thickness and hyalinization of the basal lamina of vessels that nurse peripheral nerves[ 38 , 39 ], together with luminal reduction[ 38 ].
These alterations are caused by plasma protein scape of capillary membrane to endoneurium, promoting swelling and augmented interstitial pressure in the nerves, accompanied by higher capillary pressure, deposition of fibrin and thrombus development[ 40 ]. Hyperglycemia per se can evoke nerve hypoxia, especially in sensory nerves, altering their electrical stability[ 41 ]. Apparently controversial data from clinical studies described that diabetic patients suffering from the DNP presented higher levels of intravascular oxygen and augmented blood flow in the lower limbs than painless patients.
Nevertheless, authors still consider a hypoxic state inside the endoneurium[ 42 ]. Alternatively, a potential sympathetic dysfunction can be the cause of higher blood flow[ 43 ]. As a result of nerve ischemia, both diabetic patients and animals have shown a progressive nerve loss in proximal and distal segments[ 44 , 45 ], resulting in reduction of intraepidermal nerve fiber density[ 12 ]. Consequently, axonal degeneration and regeneration also occurs, but more frequently in patients that do not experience pain.
Besides axonal retraction and regeneration, another structural modification related to hyperglycemia is myelin sheath alteration. The observed demyelinization can be related to Schwann cells altered capacity to support normal myelin sheath[ 46 ].
It is also important to point out that endothelial function in patients with DNP is also altered.
The vaso dilatation induced by acetylcholine i. In addition, vasoconstriction mediate by the sympathetic system i.
It is believed that one potential cause of the microvascular changes described above may be the oxidative stress, since the treatment with antioxidant agents can maintain regular perfusion, restoring sensory transmission in type 1 diabetes model[ 48 ]. Channels sprouting Damaged nerve endings are believed to contribute to pain in DNP[ 49 , 50 ]. The most accepted hypothesis states that disturbed action potentials can be produced by damaged nerve endings, being interpreted by central nervous system CNS as pain or dysesthesias[ 51 ].
Changes in ion channel expression in peripheral fibers are direct consequences of nerve injury, leading to hyperexcitability[ 52 ], that is far linked with neuropathic pain[ 53 ]. In this regard, up-regulation of voltage-gated sodium channels Nav has been widely demonstrated in neuropathic pain models[ 54 , 55 ]. These channels are involved in generation and transmission of action potential, and can be classified into sensitive TTX-S or resistant TTX-R to tetrodotoxin[ 56 ].
Intriguingly, DRGs of allodynic diabetic rats showed a reduction of Nav1. The same reduction was detected for Nav1. In addition, an increase of Nav1. In this way, Sun et al[ 65 ] showed that TTX-S and TTX-R sodium currents are increased in small neurons in the DRG of diabetic animals, being this related not only with sensory disturbances, but also with the rise of efficiency of conductance in polymodal C fibers, which in turn, facilitates nociceptive transmission.
A new concept proposed by Hoeijmakers et al[ 68 ], links the beginning of pancreatic beta cells failure and DNP with genetic disruptions on Nav1. Since both pancreatic beta cells and peripheral neurons express Nav1. According to these authors, this theory could explain why some patients have neuropathy before diabetes onset[ 68 ].
Another interesting finding related to sodium channels modulation is the increased levels of methylglyoxal in type 2 diabetes DNP patients, when compared with those painless[ 70 , 71 ], and in complication-free type 1 diabetic patients[ 72 ]. This glycolytic metabolite can activate nerve endings through transient receptor potential cation channel subfamily A member 1 activation in the DRG[ 73 ], and also change the Nav1.
In line with this clinical observation, in preclinical models methylglyoxal was found to reduce nerve conduction velocity, to elevate calcitonin gene-related peptide release from sensory nerves and to induce thermal and mechanical sensibility[ 70 ].
In addition, in diabetic states methylglyoxal is also involved in the formation of AGEs[ 74 ]. Calcium channels can also be misregulated in a diabetic condition, leading to an enhanced calcium influx in sensory neurons[ 75 ], what can deflagrate both substance P and glutamate release[ 76 ].
However, there was no translation of these results to patients in clinical trials[ 80 ]. A possible future target for pharmacological intervention over calcium channels has been proposed by Orestes and colleagues , which observed that glycosilation of Cav3. Interestingly, the deglycosylation treatment with neuraminidase inhibits native calcium currents in nociceptors and completely and selectively reverses hyperalgesia in a pre-clinical model of type 2 diabetes[ 80 ].
Regarding the currents generated by activation of these Kv channels in primary afferents there are two main types: rapidly inactivating A-type currents IA , and slowly inactivating currents IK [ 82 , 83 ]. So, this down regulation can increase neuronal excitability and peptide release[ 83 ], which might also participate in hyperexcitability of peripheral nerves of diabetic subjects.
Microglial activation It is becoming increasingly recognized that glial cells play an important role in the pathogenesis of many diseases of the nervous system, including chronic pain states[ 85 ]. Glia comprises both macroglia including astrocytes, radial cells and oligodendrocytes and microglia cells, which are mainly responsible for maintain homeostasis, form myelin, and provide support and protection for neurons from both central and peripheral nervous system[ 85 ].
Activation of microglia occurs right after peripheral nerve injury, lasting for less than 3 mo, and is responsible for a production of several inflammatory mediators as cytokines, chemokines, and cytotoxic substances such as nitric oxide and free radicals, prompting to a pro inflammatory milieu[ 83 ].
Diabetes has impact on all glial cells of the spinal cord since persistent microglial activation was observed in streptozotocin-induced diabetic rats lasting from 4 wk[ 87 , 88 ] to 6 or 8 mo[ 61 , 89 ].
This microglial activation has been associated with sensorial changes and up-regulation of Nav1. Conversely, diabetes is associated with a reduction in glial fibrillary acidic protein i. Considering the potential of microglial activation in driving spinal sensitization, in the near future, drugs that target these cells may become an important therapeutic alternative in chronic pain control.
Central sensitization As already demonstrated in different neuropathic pain states, DNP may be a consequence of both peripheral and CNS changes[ 93 , 94 ].
It was well described that during DNP, primary afferents are sensitized, inducing dorsal horn hyperactivity and neuroplastic changes in central sensory neurons[ 93 ]. Among the factors that can lead to the hyperactivity of spinal neurons in diabetic neuropathy is the increased glutamate release from primary afferents in the spinal cord[ 96 , 97 ].
Moreover, spinal N-Methyl-D-aspartate NMDA receptor expression is augmented in this condition[ 98 ], generating increased and more frequent excitatory post synaptic currents in the lamina II[ 97 ]. Thus, it is plausible that augmented NMDA expression and glutamate release might contribute to spinal cord hyperactivity. On the other hand, GABAB receptors seem to be downregulated in the spinal cord in diabetic neuropathy[ 98 ]. Considering the importance of central sensitization in the hypersensitivity associated with DNP, strategies that aim to control spinal neurons hyperexcitability are very useful in pain control in this condition, as will be discussed bellow.
Brain plasticity Functional changes in pain processing areas in the CNS, besides the spinal cord, have been ultimately linked with DNP[ ], in a tight relation to increased peripheral input[ 93 , ]. Among these areas, marked changes in the thalamus, cortex and rostroventromedial medulla RVM have been reported in DNP patients and or experimental models.
The ventral posterolateral nucleus VPL of the thalamus is the main receiving area of nociceptive stimuli that is processed in the spinal cord[ ]. Projection neurons reach the thalamus trough the spinothalamic tract STT , which represents a major ascending nociceptive pathway.
It has been demonstrated that in diabetic rats, these neurons present increased spontaneous activity, enlargement of the receptive field and augmented responses to mechanical noxious and innocuous stimuli. The hyperexcitability of STT neurons probably accounts to hypersensitivity to external stimuli and spontaneous pain[ 93 ], increased in primary afferents activity[ 93 , ] and to plastic changes in spinal neurons[ 93 ].
In addition, in studies that assessed brain imaging in diabetic rats it was reported increased activity not only at VPL, but also in different thalamic nuclei that control sensory-motor aspects[ ]. In diabetic patients, a recent study showed increased activation of diverse brain areas, including medial thalamus after application of noxious thermal stimuli in feet[ ].
Moreover, it has been described that DNP patients has a marked reduction in the levels of N-acetyl-aspartate NAA levels in the thalamus compared to painless diabetic individuals[ ]. It is important to point out that patients with brain disorders in which neuronal loss or dysfunction are involved have consistently decreases in brain NAA concentrations[ ]. Other clinical finding related to thalamus alterations in diabetic patients is that subjects with painful type 1 diabetic neuropathy presented increased thalamus blood flow, when compared with those without pain, which was considered to reflect higher neuronal activity[ ].
Likewise, in a model of type 1 diabetes, increased glutamate transmission was reported in the anterior cingulate cortex a brain area involved in the processing of the affective-motivational dimension of pain[ ]. The consequence of higher stimulation of this area by glutamate is suggested to be a sustained negative perception of affective component of pain[ ].
Changes in the endogenous pain control system have also been described in pre-clinical and clinical studies of DNP. The RVM is a structure that receives direct influences of periaqueductal gray matter, which is, in turn, affected by other structures, such as amygdala and hypothalamus[ ]. Three different populations of cells have been describe within the RVM: activation of ON cells act in a pronociceptive way, while activation of OFF cells has the opposite effect[ ] and neural cells which activation is still contradictory and remains to be better clarified[ , ].
In diabetic animals, there is evidence of a reduction on the OFF cells and increase on the ON cells population. In addition, basal activity is augmented in ON cells, and reduced in OFF cells, in a resultant misbalance between pain facilitatory and inhibitory descending modulation in diabetic animals[ ]. After noxious mechanical stimulation in the periphery, there was no difference between diabetic and control ON cells activity. Thus, the mechanical hyperalgesia detected in diabetic rats could be associated with OFF cells impairment and consequently reduction on descending inhibitory tone[ ].
Some studies have also addressed the levels of the main neurotransmitters of the endogenous pain control system in different areas of the CNS in diabetic rats, but they have shown discrepant results. While some researchers found reduced release of norepinephrine in the spinal cord in diabetic rats[ ], others have described opposite findings[ ].
There is also evidence of diminished norepinephrine levels in supra spinal areas, such as brainstem and thalamus, but higher concentration in the cortex of diabetic animals[ ]. Additionally, impaired spinal opioid-induced release of serotonin 5HT has been demonstrated in diabetic rats, and this finding may be related to opioid hyporesponsiveness in experimental DNP[ ].
Increased norepinephrine and 5HT levels in the spinal cord, as well as, augmented expression of norepinephrine and 5HT in RVM neurons was also demonstrated in diabetic rats[ ]. Considering the facilitatory role of serotoninergic and noradrenergic descending modulation during chronic pain, these changes may probably account for enhanced pain during diabetic neuropathy[ ].
There is also clinical evidence for misbalance between excitatory and inhibitory neurotransmitters in the CNS of diabetic patients with positive symptoms of neuropathy.
These changes may contribute to pain development in DNP, but further studies are necessary to determine their clinical significance. The pharmacological treatments, with exception to those targeted to the glycemic control, are symptomatic, not focused on the pathophysiological mechanisms, limited by side effects[ 3 , ] and by the development of tolerance[ ].
A wide variety of drugs, used alone or in combination, has been shown to significantly reduce neuropathic pain compared with placebo in randomized controlled trials, but pain relief remains inadequate for most patients[ ]. Thus, the management of this condition basically consists of excluding other causes of painful peripheral neuropathy, improving glycemic control as a prophylactic therapy and using medications to alleviate pain[ ].
Despite of multimodal and multidisciplinary approaches to the treatment, the primary pathway is pharmacologically based[ ]. Three different agents have regulatory approval in the United States for the treatment of DNP: pregabalin, duloxetine and tapentadol[ 11 , ].
However, as pain relief is still suboptimal and challenging for clinicians[ 95 ], drugs from various pharmacological classes have been used and some of them are included in this review. Anticonvulsants Pregabalin was the first anticonvulsant to receive approval from the Food and Drug Administration FDA for the treatment of postherpetic neuralgia, DNP[ , ] and neuropathic pain after spinal cord injury[ ].
Several clinical trials evaluating pregabalin in DNP showed efficacy in the management of this condition[ 3 , , ] with a number needed to treat NNT of 6. In addition to its analgesic effects, pregabalin presents anxiolytic activity[ , ] and it has a beneficial effect on sleep and quality of life[ ], contributing, therefore, to improve the general condition of the patients.
The side effects include dizziness, somnolence, peripheral edema, headache and weight gain[ 3 ]. Some guidelines have also recommended gabapentin to treat DNP[ ]. Besides pregabalin, gabapentin is the only other anticonvulsant drug that demonstrated efficacy in the treatment of this condition[ ] with an NNT of 5. Gabapentin and pregabalin have a similar mechanism of action and the first is licensed for neuropathic pain in the United Kingdom, but not in the United States[ ].
Some clinical trials have suggested that gabapentin and pregabalin present better analgesic efficacy than tricyclic antidepressants or opioids[ ] and other important aspects of these drugs include their tolerability and lack of serious toxicity[ ]. Antidepressants Antidepressants represent the first line drugs in DNP management.
Duloxetine, a serotonin and norepinephrine reuptake inhibitor, is rated level A for efficacy and is approved in the United States for the treatment of this condition. Additionally, some clinical trials have pointed out the effectiveness of duloxetine in other chronic pain conditions, such as fibromyalgia and chronic musculoskeletal pain[ , ].
Moreover, in a 2-wk open-label randomized trial in diabetic patients poorly responsive to gabapentin, duloxetine was able to reduce the pain score to levels similar to those achieved with pregabalin[ , ]. Furthermore, analgesic efficacy of duloxetine in the treatment of DNP is maintained over a 6-mo period[ ], reinforcing its importance as a treatment option for this condition. The NNT for duloxetine varies from 1. Venlafaxine is also a selective serotonin and noradrenaline reuptake inhibitor, that predominantly inhibits serotonin reuptake at low doses and noradrenaline at higher doses[ ].
Patients who achieve a gross total resection at the time of IORT have a markedly better prognosis than those with residual gross disease. The major IORT-related post-operative complications are leakage from anastomoses, deep Unconscious Proprioception Last Updated on Tue, 11 Jun Blood Pressure 3 comments The corticospinal tract and related motor pathways synapse in the spinal cord, just before leaving the cord.
This anatomic feature is important because motor neurons above the level of this synapse are upper motor neurons UMN , whereas the peripheral nerve cell bodies in the anterior horn of the cord, and their axonal extensions outside the cord are lower motor neurons LMN.
Upper and lower motor neuron injuries produce different clinical signs. Although lesions at either level result in weakness, the presentations differ. Potential of Nonregenerating Tissues Last Updated on Tue, 11 Jun Regenerative Medicine Second, regenerative responses have been induced or enhanced in a number of tissues of experimental animals. Biodegradable, cell-free artificial regeneration templates have been used to induce dermal regeneration in excisional skin wounds and improve regeneration across gaps in peripheral nerves, though the results have been far from perfect Yannas, A variety of neuroprotective agents, as well as agents that neutralize molecules inhibitory to axon regeneration, and enzymes that degrade glial scar , have been used to improve spinal cord regeneration and slow the loss of neurons in Parkinson 's disease and amyotrophic lateral sclerosis ALS.
Cell-free ceramic templates can induce bone regeneration across large gaps Constanz et al. Attempts to induce epimorphic limb regeneration from the non- or poorly regenerating limbs of adult frogs have also elicited or enhanced regenerative responses.
In contrast, more than two copies of a gene may also cause disease inherited in an autosomal dominant manner, as is seen with duplication of the PMP22 gene in Charcot-Marie-Tooth IA peripheral neuropathy Boerkel et al. Factors Influencing Nerve Regeneration Last Updated on Tue, 11 Jun Microsurgery 1 comment After its reconstruction the peripheral nerve must be kept in a soft and well-vascularized bed.
If the lesion is associated to skin problems or necrotic surrounding tissues, the best possible local conditions have to be created with the use of local or distant flaps The more proximal the lesion, the more difficult it will be to obtain a good functional result as fiber mixing increases at the proximal levels. The nerve becomes simpler distally as it leaves its collateral motor or sensory branches. Distally, the terminal branches organize to reach their final targets, so, the best results can be obtained at a distal level.
Therefore, from a prognostic point of view, we may divide the possible lesion sites into 4 groups with inferior results from proximal to distal plexus nerve trunks well defined peripheral nerves terminal branches.
Scar formation is another factor which has to be technically contrasted as already stated, tension must be avoided while reconstructing peripheral nerve Clinical Findings and Diagnosis Last Updated on Sun, 27 May Travel Medicine Leprosy is a chronic disease that affects not only the skin but particularly the peripheral nerves bilaterally.
The hands and feet are the anatomical sites where inflammation, characteristic skin lesions, and nerve damage occur in the course of leprosy. The commonest skin lesions are nodules, erythematous plaques, or hypopigmented patches. Symptoms like hypo- or dysaesthesia, together with motor sensory nerve abnormalities and obvious thickening of peripheral nerve branches, suggest the characteristic demyelinating neuropathy of leprosy. Advanced disease manifests with skin atrophy, pigmentary changes, and in severe cases chronic ulceration leading to mutilation and disability Figure 9.
Mutilating lesions of the hands and feet result from bone resorption, mechanical trauma, and secondary bacterial infection. These latest findings suggest that C to U RNA editing occurs in only a subset of peripheral nerve sheath tumors and was undetectable in tissues from unaffected subjects. In exploring the features that distinguish tumors, in which C to U RNA editing was demonstrated, two defining characteristics emerged.
This feature is considered particularly relevant since the underlying mechanism of NF1 RNA editing and its relationship, if any, to apoB RNA editing was previously unresolved. Secondly, alignment of Skeletal Muscle Dedifferentiation Produces Progenitor Cells for Limb Regeneration Last Updated on Sun, 11 Nov Muscle Cells 1 comment A major question since the beginning of regeneration research has been which tissues contribute cells to the blastema and by what mechanism.
Experiments tracing the origin of the blastema through transplantation of marked tissues showed that the blastema derives from multiple tissues, including dermis, peripheral nerve, bone and muscle.
Therefore the transplantation of tissue did not completely resolve the cellular origin and the mechanism by which the blastema was formed. Retinic photoreceptors, cones and rods, relay the signal for further processing to other retinic neurons bipolar cells, horizontal cells, amacrine cells, retinal ganglion cells, and interplexiform cells.
Axons from the ganglion cells form the optic nerve. The potentials generated are transmitted via the optic nerve to the lateral geniculate nucleus visual information , superior colliculus somatic reflexes , and pretectal areas autonomic reflexes. In mammals, visual information is relayed to the thalamic lateral geniculate body, from which optic information is directed to the primary visual cortex through the geniculo-striate projection, or optic radiation.
In humans, the cortical area surrounds both walls Traumatic Brachial Plexus Injuries in Adults Sun, 23 Apr Microsurgery Knowledge of the anatomy of the brachial plexus and of the pathological changes of peripheral nerve lesions allows better understanding of the clinical symptoms and the findings of paraclinical diagnostic examination. Classification of nerve injuries on the other hand, is essential for the therapeutic approach and for the evaluation of the results.
In the majority of cases, the injury is the result of motorcycle accidents involving young adults and the lesions are usually more severe.
Although a small number of patients spontaneously recover in the early months following trauma, the majority of cases with total palsies diagnosed in the emergency department, do not recover spontaneously. Exposure is via inhalation main source leaded petrol and ingestion water, old paint. Multi-organ toxicity occurs with kidneys, central and peripheral nervous system, testes, red cells, bones and gastrointestinal tract all damaged. After initial distribution into red blood cells it is eventually deposited in bone.
The main biochemical effect is interference with haem synthesis at several points. Kidney toxicity may be due to lead-protein complexes and inhibition of mitochondrial function. Damage to nerves leads to peripheral neuropathy.
Treatment involves use of chelating agents EDTA. Thu, 19 Oct Protein Design Transthyretin TTR , a homotetramer with amino acid residue in each chain, is synthesized in the liver and is found in blood plasma and cerebrospi-nal fluid TTR is able to form amyloid which accumulate in different peripheral nerves of patients affected by familial amyloid polyneuropathy or in the heart of people affected by familial amyloid cardiomyopathy It has been published that TTR is a major AP-binding protein in cerebrospinal fluid 59 , and further studies demonstrated that TTR is able to prevent formation of AP fibrils in vitro, sequestering AP from cerebrospinal fluid by a stable complex formation Fri, 05 Jan Regenerative Medicine To decrease the area that needs to be covered by epidermis and filled in by scar tissue.
Contraction is characterized by the sliding and stretching of perilesional skin over the defect and should not be confused with contracture, which is the shortening of scar tissue, leading to deformity and loss of function. Dermal contraction accounts for a much greater percentage of wound closure in rodents than in pigs or humans figure 2. In vivo, contraction accounts for up to 90 of wound closure in mice Yannas, In humans, less than 50 of excisional wound closure is due to contraction the majority is due to scar tissue formation.
In addition to dermis, contraction has been shown to help close wounds in peripheral nerve, ligaments, ureter, esophagus, and duodenum Yannas, J Exp Zool Bisby MA Regeneration of peripheral nervous system axons. The Axon Structure, Function and Pathophysiology. New York, Oxford University Press, pp Bunge R Tissue culture observations relevant to the study of axon-Schwann cell interactions during peripheral nerve development and repair. J Exp Biol Mol Neurobiol 14 Goodrum JF, Bouldin TW The cell biology of myelin degeneration and regeneration in the peripheral nervous system.
J Neuropath Exp Neurol 55 Sun, 23 Dec Protein Kinase However, one striking difference between knockout and wild-type mice has been characterized mice lacking protein kinase Cy display reduced responses to nonnoxious pain stimuli following painful stimulation such as resulting from nerve injury, reduction in a phenomenon referred to as neuropathic pain.
Studies with knockout mice in protein kinase Ce have also implicated this isozyme as a potential target for pain and, also, anxiety , for example, mice lacking this isozyme display less anxiety in response to threatening situations.
Targeted disruption of the gene encoding protein kinase CP results in mice with an impaired immune response , with analysis of B cells from these mice revealing that the P isozymes are involved in B-cell activation. However, the molecular basis for many of the physiological differences observed in knockout mice is largely unresolved. Nerve Lesions Last Updated on Tue, 24 Mar Microsurgery The surgical treatment of these lesions must take into consideration the various factors which condition nerve regeneration.
Therefore, the different techniques of nerve repair are described through the analysis of these factors together with the indications for the treatment of peripheral nerve injuries.
Nervous system Last Updated on Fri, 08 May Metabolic Activation The nervous system, both peripheral and central, is a common target for toxic compounds, and the cells which make up the system are particularly susceptible to changes in their environment. Thus, anoxia, lack of glucose and other essential metabolites, restriction of blood flow, and inhibition of intermediary metabolism, may all underlie damage to cells of the nervous system as well as direct, cytotoxic damage.
The nervous system is a highly complex network of specialized cells, and damage to parts of this system may have permanent and serious effects on the organism as there is little capacity to regenerate and little reserve functional capacity.
Peripheral neuropathy is a toxic response to a variety of foreign compounds such as organophosphorus compounds, methyl mercury and isoniazid for example.
The 'designer drug' contaminant, 1-methylphenyl-1, 2, 3, 6-tetrahydropyridine MPTP causes specific damage to the dopamine containing cells in the substantia nigra area of the brain In accordance with these findings, anti-TRPV1 antiserum was shown to ameliorate pain in a murine model of diabetic neuropathy In humans, the density of TRPV1-positive nerve fibres is increased in women with chronic breast pain and with vulvodynia Disruption of TRPV1 gene causes attenuation of bone cancer pain in mice Example Last Updated on Tue, 12 Apr Environmental Risk The nervous system consists of millions of nerve cells known as neurons, which are responsible for receiving and processing sensory information and then controlling muscles to respond to external stimuli.
It is divided into two primary components the central nervous system and the peripheral nervous system. Neurons Figure The junction between the axon terminus of one neuron and the dendrites of an adjacent neuron is termed the synapse or synaptic junction. Neurons are able to regulate the electrical potential across their cellular membrane as a part of normal cell function.
In the nervous system, such membranes are responsible for the transmission of electrical impulses along the cell. Electrical signals are transmitted along the axon by an ionic pump. In its resting state, the neuron has Example Last Updated on Tue, 11 Jun Environmental Risk Lead is toxic to a number of organs and organ systems, including the nervous system, the blood, and the kidneys.
Human exposure to lead has historically been high, due to the many industrial uses of lead, such as fabrication of corrosion-resistant water pipes, as a paint additive, and as an additive in gasoline. The chemical similarity of lead and calcium allows lead to mimic calcium, thereby disrupting a variety of calcium-mediated effects. Lead neurotoxicity seems to be associated with interference with the normal neurotransmitter functions of the nervous system, due to its ability to mimic calcium chemically as well as its ability to interfere with synaptic receptor-ligand interactions.
The peripheral nervous system effects of lead involve the degradation of motor nerve function due to damage to the myelin lamellae surrounding the axons. Depressive State Last Updated on Mon, 04 Jan Working Memory The rotarod is an established test for evaluating pharmacological actions of psychotropic agents such as skeletal muscle relaxants, anticonvulsants, and antidepressants in the central or peripheral nervous system Dunhan and Miya, Morimoto and Kito have shown that this test is useful to evaluate the antidepressive effects of serotonergic and adrenergic antidepressants.
As shown in Figure 5, chronic stress impaired the rotarod performance, concomitant with unchanged traction performance and locomotor activity, suggesting that the impaired rotarod performance is not due to muscle relaxation or motor dysfunction.
As antidepressants increase the riding time on the rotating rod in normal rats Morimoto and Kito, , the impaired rotarod performance suggests a depressive behavioral state. Axon Regeneration Last Updated on Tue, 11 Jun Regenerative Medicine A large body of evidence suggests that whether or not axons regenerate depends in large part on their associated glial cells Yannas, Differences in the ability of peripheral and central glial cell populations to support regeneration have been well documented by experiments in which the regeneration of central axons was promoted by peripheral nerve sheaths grafted into the central nervous system, whereas central nerve sheaths inhibit the regeneration of peripheral axons Aguayo, These differences appear to reside largely in the adhesion molecules and soluble signals synthesized by glial cells.
Glial cells that support regeneration provide most or all of the molecules that are The Couptf Family Last Updated on Wed, 22 Apr Protein Kinase The COUP-TFs are highly expressed in the developing nervous system indicating a possible involvement in neuronal development and differentiation.
Gene knockout studies demonstrate that mCOUP-TFI null animals die perinatally and mutant embryos show abnormal development of a subset of neurons in the peripheral nervous system.
However, suc guidelines for dosing should be followed as risk of side effects and or complications may increase with dosage increases. It may be administered by chewing 4 tablets daily two tablets twice daily.
There may be limited general availability. Af Last Updated on Thu, 04 Oct Plasticity Lesion-induced changes in cortical topography are furthermore accompanied by a rapid increase in the expression of neurotrophins, including BDNF and NT-3, and relevant receptors Obata et al.
Neurotrophins are important regulators of synaptic development and plasticity in both the central and peripheral nervous system. Neurotrophins can modulate synaptic transmission at the pre- and postsynaptic level in a target-specific fashion.
The observation that the elevation of the neurotrophin levels is sustained for up to two years after induction of retinal lesions may reflect the fact that even though visually driven activity restores in the cortical scotoma, the level of activity never fully returns to that of the surrounding cortex and some imbalance of activity persists Das and Gilbert, b. The proteolytic maturation of these precursor proteins has been the subject of intense research of many studies.