Articles: neuralgia.
-
Recent evidence indicates that neuropathic pain from partial peripheral nerve injury is maintained by electrophysiologically abnormal signals from injured sensory neurons. To gain an insight into the mechanisms underlying this electrophysiological abnormality, we examined the effects of S1 spinal nerve transection on the membrane properties of S1 dorsal root ganglion neurons one to two weeks after injury. This injury produced significant action potential broadening [40% (1 ms) in C-, 149% (1.5 ms) in A delta- and 84% (0.5 ms) in A alpha/beta-cells], which was primarily due to the enhancement of the "shoulder" appearing on the falling phase of the action potential in C- and A delta-cells and the emergence of a shoulder in A alpha/beta-cells, and significant cell-type specific changes in the time-course of the rising phase of the action potential; i.e. an increase in rise time (A delta: 35%, 0.15 ms; A alpha/beta: 13%, 0.04 ms) and a decrease in the maximal rate of rise (A delta: 17%, 77 V/s; A alpha/beta: 13%, 79 V/s). ⋯ The nerve injury-induced reduction of rheobase was not accompanied by related change in input resistance or threshold potential in any of the cell populations. The present results indicate that chronic peripheral axotomy of dorsal root ganglion neurons, which gives rise to neuropathic pain, produces profound changes in the action potential waveform of dorsal root ganglion neurons in a cell type-specific fashion. Furthermore, the results suggest that the axotomy increases the excitability of dorsal root ganglion neurons not by altering input resistance (i.e. leak conductance) or threshold potential, but by increasing apparent input resistance near the resting membrane potential in A-cells and decreasing the resting membrane potential in C-cells.
-
We investigated the effect of intravenous magnesium, a N-methyl-D-asparate (NMDA) receptor antagonist, in 8 patients suffering from neuropathic pain (post herpetic neuralgia or causalgia etc.). After the nerve block, magnesium sulphate (0.5 mol.l-1) 5 ml was administered intravenously by bolus infusion taking 5 min, followed by continuous infusion of the same dose for one hour. All patients were treated with this therapy once a week. ⋯ Some patients felt heat sensation immediately after the bolus infusion of Mg, and had a good sleep after this therapy. However, there were not any severe side effects and significant change in HR or BP. We conclude that this therapy with magnesium once a week is safe and effective for relieving neuropathic pain.
-
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.
-
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.
-
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.