Articles: neuralgia.
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Neuropathic pain syndromes may be treated by intervention at the sympathetic nervous system. The pain in these syndromes is therefore called sympathetically maintained pain (SMP). Typical disorders with a SMP component are complex regional pain syndromes (reflex sympathetic dystrophy and causalgia), traumatic neuralgias and herpes zoster. ⋯ Open questions are how the efferent sympathetic nervous system is capable of influencing pain sensation and which mechanisms underly the autonomic dysregulation often observed in these syndromes.(1) Somatic afferents that project through the sympathetic trunk do not exist. Therefore, a pure sympathetic block does not block afferent information arising from the affected extremity. What alternatives are possible? Under pathophysiological conditions a functional interaction of efferent sympathetic fibers and afferent nociceptive fibers could be demonstrated in patients and animal studies. The intensity of this coupling varies considerably between individual patients and is not necessary for the diagnosis of the disorder. (2) Sympathetically maintained pain and signs of autonomic dysfunction are independent clinical and pathophysiological phenomena without any causal relation. However, it is possible to treat both the SMP and the autonomic dysfunction with sympathetic blocks.
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Randomized Controlled Trial Comparative Study Clinical Trial
Diabetic peripheral neuropathy. Effectiveness of electrotherapy and amitriptyline for symptomatic relief.
To evaluate the efficacy of combining electrotherapy with amitriptyline for the management of chronic painful peripheral neuropathy in patients with type 2 diabetes. ⋯ Our clinical observations suggest that transcutaneous electrotherapy is effective in reducing the pain associated with peripheral neuropathy. This form of therapy may be a useful adjunctive modality when it is combined with a pharmacological agent, such as amitriptyline, to augment symptomatic relief.
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J. Neurol. Neurosurg. Psychiatr. · Aug 1998
Clinical TrialReversal of hypoaesthesia by nerve block, or placebo: a psychologically mediated sign in chronic pseudoneuropathic pain patients.
To gain understanding of the mechanism and meaning of improvement of hypoaesthesia after a diagnostic intervention, and of the nature of the population that displays such a sign. ⋯ Such reversal of hypoaesthesia is due to a placebo effect, acting on a psychogenic symptom because: (a) 27 of 27 patients in which the sign occurred had absence of nerve disease behind the "neuropathic" symptoms, (b) In 26 of 27 patients the area of hypoaesthesia was non-anatomical, (c) 16 of 27 patients had other sensory-motor signs that could not be explained as a result of organic pathology (give way weakness and punctual denial of hypoaesthesia), and (d) the phenomenon was not found in patients with organic neuropathy.
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Experimental neurology · Aug 1998
Comparative StudyDifferences in sympathetic innervation of mouse DRG following proximal or distal nerve lesions.
Nerve injury leads to novel sympathetic innervation of the dorsal root ganglion (DRG). We have hypothesized previously that the degenerating nerve increases the sympathetic sprouting in the DRG and pain after chronic sciatic constriction injury (CCI) by virtue of its influence on sensory and sympathetic axons spared by the injury. However, L5 spinal nerve ligation and transection (SNL) results in the complete isolation of the L5 DRG from the degenerating stump, yet sympathetic axons invade the ganglion, and sympathetically dependent pain develops. ⋯ Observation of the origins of the invading sympathetic axons revealed that after CCI, sympathetics innervating blood vessels and dura (probably intact) sprouted into the ganglion, but after SNL sympathetics (probably axotomized) invaded from the injured spinal nerve. Based on these findings, we hypothesize that there are two mechanisms for sympathetic sprouting into DRG, differentially dependent on Wallerian degeneration. Analysis of pain behavior in these animals reveals that (i) mechanoallodynia and sympathetic innervation of the DRG tend to coincide and (ii) thermal allodynia and Wallerian degeneration, but not sympathetic innervation of the DRG tend to coincide.
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Sodium channel antagonists have been used in the management of neuropathic pain for several years. Recent evidence suggests that lamotrigine, which is active at glutaminergic excitatory synapses, is very effective in producing pain relief. ⋯ Our results suggest that this novel channel antagonist can be used to treat neuropathic pain. Double blind placebo control studies are therefore needed to substantiate these findings.