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Query: UMLS:C0423716 (Neuropathic pain)
 1,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuropathic pain following spinal cord injury (SCI) can be difficult to manage using currently available pain management techniques. We describe a case of chronic pain following SCI which failed to respond to a variety of approaches including intrathecal administration of morphine. Use of clonidine in addition to the morphine resulted in a marked decrease in pain. The use of intrathecal clonidine with or without opioids may present an effective alternative in the management of intractable SCI pain and other forms of neuropathic pain.
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PMID:Intrathecal morphine and clonidine in the management of spinal cord injury pain: a case report. 785 95

This series of studies has investigated the involvement of the NMDA receptor and the translocation of PKC in the seemingly unrelated phenomena of neuropathic pain and tolerance and dependence to narcotic analgesic drugs. This work has demonstrated that the NMDA receptor and PKC translocation are importantly involved in neuropathic pain and morphine tolerance or dependence and that these phenomena may be importantly interrelated. Neuropathic pain following nerve injury is a major chronic pain syndrome. Utilizing a rat model of painful peripheral mononeuropathy produced by CCI of the sciatic nerve, the authors have investigated central mechanisms of postinjury neuropathic pain. Behavioral and pharmacological studies indicate that thermal hyperalgesia and spontaneous pain behaviors observed in this model are attenuated by treatment with NMDA receptor antagonists. A consequence of NMDA receptor activation is calcium influx, which in turn can result in translocation of PKC from cytosol to membrane. Inhibitors of intracellular PKC translocation and activation block thermal hyperalgesia and spontaneous pain behaviors after CCI and also reduce the elevated spinal cord neural activity in CCI rats. Furthermore, spinal cord levels of membrane-bound PKC reliably increase in CCI rats as a result of translocation of PKC revealed by the [3H]PDBu autoradiographic assay. This increase in membrane-bound PKC is associated with postinjury neuropathic pain behaviors in CCI rats and both pain-related behaviors and membrane-bound PKC are reduced potently by GM1 ganglioside.
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PMID:The association of neuropathic pain, morphine tolerance and dependence, and the translocation of protein kinase C. 874 91

Chronic pain may result from hyperexcitability following activation of spinal NMDA receptors. A naturally-derived mammalian peptide, histogranin, may possess NMDA antagonist activity. This study explored the possibility that stable analog [Ser1]Histogranin (SHG) could reduce chronic pain. Neuropathic pain was induced using the chronic constriction injury model (CCI). Intrathecal injection of SHG markedly attenuated the hyperalgesia and allodynia resulting from CCI, nearly normalizing responses. These results suggest that the natural peptide histogranin may be a novel adjunct in neuropathic pain management.
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PMID:Suppression of neuropathic pain by a naturally-derived peptide with NMDA antagonist activity. 917 1

Neuropathic pain is a chronic pain state that develops a central component following acute nerve injury. However, the pathogenic mechanisms involved in the expression of this central component are not completely understood. We have investigated the role of brain-associated TNF in the evolution of hyperalgesia in the chronic constriction injury (CCI) model of neuropathic pain. Thermal nociceptive threshold has been assessed in rats (male, Sprague-Dawley) that have undergone loose, chromic gut ligature placement around the sciatic nerve. Total levels of TNF in regions of the brain, spinal cord and plasma have been assayed (WEHI-13VAR bioassay). Bioactive TNF levels are elevated in the hippocampus. During the period of injury, hippocampal noradrenergic neurotransmission demonstrates a decrease in stimulated norepinephrine (NE) release, concomitant with elevated hippocampal TNF levels. Continuous intracerebroventricular (i.c.v.) microinfusion of TNF-antibodies (Abs) starting at four days, but not six days, following ligature placement completely abolishes the hyperalgesic response characteristic of this model, as assessed by the 58 degrees C hot-plate test. Antibody infusion does not decrease spinal cord or plasma levels of TNF. Continuous i.c.v. microinfusion of rrTNF alpha exacerbates the hyperalgesic response by ligatured animals, and induces a hyperalgesic response in animals not receiving ligatures. Likewise, field-stimulated hippocampal adrenergic neurotransmission is decreased upon continuous i.c.v. microinfusion of TNF. These results indicate an important role of brain-derived TNF, both in the pathology of neuropathic pain, as well as in fundamental pain perception.
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PMID:Brain-derived TNFalpha mediates neuropathic pain. 1054 89

Neuropathic pain, a form of chronic pain caused by injury to or disease of the peripheral or central nervous system, is a formidable therapeutic challenge to clinicians because it does not respond well to traditional pain therapies. Our knowledge about the pathogenesis of neuropathic pain has grown significantly over last 2 decades. Basic research with animal and human models of neuropathic pain has shown that a number of pathophysiological and biochemical changes take place in the nervous system as a result of an insult. This property of the nervous system to adapt morphologically and functionally to external stimuli is known as neuroplasticity and plays a crucial role in the onset and maintenance of pain symptoms. Many similarities between the pathophysiological phenomena observed in some epilepsy models and in neuropathic pain models justify the rational for use of anticonvulsant drugs in the symptomatic management of neuropathic pain disorders. Carbamazepine, the first anticonvulsant studied in clinical trials, probably alleviates pain by decreasing conductance in Na+ channels and inhibiting ectopic discharges. Results from clinical trials have been positive in the treatment of trigeminal neuralgia, painful diabetic neuropathy and postherpetic neuralgia. The availability of newer anticonvulsants tested in higher quality clinical trials has marked a new era in the treatment of neuropathic pain. Gabapentin has the most clearly demonstrated analgesic effect for the treatment of neuropathic pain, specifically for treatment of painful diabetic neuropathy and postherpetic neuralgia. Based on the positive results of these studies and its favourable adverse effect profile, gabapentin should be considered the first choice of therapy for neuropathic pain. Evidence for the efficacy of phenytoin as an antinociceptive agent is, at best, weak to modest. Lamotrigine has good potential to modulate and control neuropathic pain, as shown in 2 controlled clinical trials, although another randomised trial showed no effect. There is potential for phenobarbital, clonazepam, valproic acid, topiramate, pregabalin and tiagabine to have antihyperalgesic and antinociceptive activities based on result in animal models of neuropathic pain, but the efficacy of these drugs in the treatment of human neuropathic pain has not yet been fully determined in clinical trials. The role of anticonvulsant drugs in the treatment of neuropathic pain is evolving and has been clearly demonstrated with gabapentin and carbamazepine. Further advances in our understanding of the mechanisms underlying neuropathic pain syndromes and well-designed clinical trials should further the opportunities to establish the role of anticonvulsants in the treatment of neuropathic pain.
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PMID:Anticonvulsants for neuropathic pain syndromes: mechanisms of action and place in therapy. 1112 21

Increased glutamate availability in the spinal cord and primary afferent nerves plays an important role in acute and chronic pain. Afferent ectopic discharges from the site of nerve injury constitute a source of abnormal sensory input to the spinal dorsal horn. The ectopic afferent activity is largely responsible for the development of hypersensitivity of dorsal horn neurons and neuropathic pain. Inhibition of glutamate carboxypeptidase II (GCP II) reduces glutamate release generated from N-acetyl-aspartyl-glutamate in nerve tissues and may have an analgesic effect on neuropathic pain. In the present study, we determined the effect of a GCP II inhibitor, 2-(phosphono-methyl)-pentanedioic acid (2-PMPA), on allodynia and ectopic afferent discharges in an animal model of neuropathic pain. Neuropathic pain was induced by partial ligation of the left sciatic nerve in rats. Tactile allodynia was assessed using von Frey filaments applied to the plantar surface of the injured hindpaw. Single-unit activity of ectopic discharges was recorded from the sciatic nerve proximal to the site of ligation. Intravenous injection of 50 to 100 mg/kg 2-PMPA significantly reduced allodynia in a dose-dependent manner. Furthermore, 2-PMPA dose-dependently attenuated the ectopic discharge activity of injured sciatic afferent nerves. At a dose of 100 mg/kg, 2-PMPA significantly inhibited the ectopic activity from 14.7 +/- 2.1 to 4.4 +/- 0.5 impulses/s without altering the conduction velocity of afferent nerves. Therefore, these data suggest that the antiallodynic effect of 2-PMPA may be mediated, at least in part, by inhibition of ectopic afferent discharges at the site of nerve injury.
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PMID:Effect of 2-(phosphono-methyl)-pentanedioic acid on allodynia and afferent ectopic discharges in a rat model of neuropathic pain. 1180 30

Neuropathic pain is induced by injury or disease of the nervous system. Studies aimed at understanding the molecular pathophysiology of neuropathic pain have so far focused on a few known molecules and signaling pathways in neurons. However, the pathophysiology of neuropathic pain appears to be very complex and remains poorly understood. A global understanding of the molecular mechanisms involved in neuropathic pain is needed for a better understanding of the pathophysiology and treatment of neuropathic pain. Towards this end, we examined global gene expression changes as well as the pathobiology at the cellular level in a spinal nerve ligation neuropathic pain model using DNA microarray, quantitative real-time PCR and immunohistochemistry. We found that the behavioral hypersensitivity that is manifested in the persistent pain state is accompanied by previously undescribed changes in gene expression. In the DRG, we found regulation of: (1) immediate early genes; (2) genes such as ion channels and signaling molecules that contribute to the excitability of neurons; and (3) genes that are indicative of secondary events such as neuroinflammation. In addition, we studied gene regulation in both injured and uninjured DRG by quantitative PCR, and observed differential gene regulation in these two populations of DRGs. Furthermore, we demonstrated unexpected co-regulation of many genes, especially the activation of neuroinflammation markers in both the PNS and CNS. The results of our study provide a new picture of the molecular mechanisms that underlie the complexity of neuropathic pain and suggest that chronic pain shares common pathobiology with progressive neurodegenerative disease.
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PMID:Chronic neuropathic pain is accompanied by global changes in gene expression and shares pathobiology with neurodegenerative diseases. 1222 May 57

Neuropathic pain, a persistent chronic pain resulting from damage to the central or peripheral pain signaling pathway, has become an area of intense research activity--largely because it represents a disorder with high unmet medical need. It is not a single disease entity, but rather includes a range of heterogeneous conditions that differ in etiology, location and initiating cause. Despite this diversity, the clinical presentation is frequently surprisingly similar, which suggests a common biological basis. Until recently, little was known of the mechanisms underlying the various neuropathic pain conditions, making the directed development of novel therapies almost impossible. However, the steady increase in our understanding of the anatomical, cellular and molecular basis of neuropathic pain, coupled with the advent of a number of experimental models of neuropathy, has permitted relatively rapid progress, and the prospects for the emergence of new, more effective therapies look very good. Gabapentin (Pfizer), which appears to act by blocking calcium channels, is the first drug to acquire widespread regulatory approval for the treatment of neuropathic pain. The Society for Medicines Research symposium held June 26, 2003, considered this treatment modality alongside other approaches to therapy, such as N-methyl-D-aspartate receptor antagonists and cannabinoid receptor agonists. The whole meeting provided an excellent description of the challenges facing neuropathic pain drug discovery--at both the research and the development phases of the value chain.
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PMID:Pharmacotherapy for neuropathic pain: progress and prospects. 1470 44

Neuropathic pain arises from a lesion or dysfunction within the nervous system; the specific mechanisms that elicit neuropathic pain symptoms are the subject of ongoing research. It is generally acknowledged that neuropathic pain is extremely difficult to treat, and a major factor impacting outcomes is the presence of comorbidities such as poor sleep, depressed mood, and anxiety. Patients who suffer from chronic pain experience difficulties in initiating and maintaining sleep. Sleep deprivation has been associated with a decreased pain threshold, muscle aches, and stiffness in normal volunteers. The interrelationship of these factors is complex: Many chronic pain patients are depressed and anxious; sleep deprivation can lead to anxiety; and depression can be both the cause and the result of sleep disturbances. Thus, physicians must evaluate all aspects of pain, sleep, and mood in chronic pain patients. Several instruments have been developed to aid physicians in gathering qualitative and quantitative information from chronic pain patients. This triad of chronic pain, sleep disturbances, and depression/anxiety must be fully addressed if the patient is to be restored to optimal functionality. A multidisciplinary team approach allows for treatment of the whole patient. Nonpharmacologic interventions include relaxation therapy, sleep restriction therapy, and cognitive therapy. Strategies for pharmacologic interventions should attempt to maximize outcomes by employing, where possible, agents that address both the pain and the comorbidities. In this way, functionality may be restored and the patient's quality of life improved.
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PMID:Comorbidities in chronic neuropathic pain. 1499 27

Morphine and other opioids have direct analgesic actions in the spinal cord and chronic spinal administration of opioid agonists is used clinically in patients suffering from severe, chronic pain. Neuropathic pain resulting from peripheral nerve injury is often less sensitive to opioid therapy than other forms of chronic pain in both humans and animal models. Changes in spinal mu-opioid receptor (MOR) expression have been demonstrated in animal models of neuropathic pain. However, these changes alone fail to account for the attenuation of opioid activity. Reduced expression of delta-opioid receptors (DOR) following peripheral nerve injury has been reported but most of these reports are limited to subjective observation. The magnitude and consistency of these changes is therefore unclear. In addition, previous studies did not evaluate the effects of nerve injury on behavioral measures to confirm induction of aberrant pain symptoms. We therefore performed quantitative image analysis to evaluate the effect of peripheral nerve injury on DOR-immunoreactivity in spinal cord sections from rats previously characterized for sensory responsiveness. We observed statistically significant decreases ipsilateral to nerve injury in all three models tested: sciatic nerve transection, chronic constriction injury of the sciatic nerve and L5/L6 spinal nerve ligation. These results suggest that decreases in the expression of DOR are a common feature of peripheral nerve injury.
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PMID:Effects of peripheral nerve injury on delta opioid receptor (DOR) immunoreactivity in the rat spinal cord. 1513 30


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