Pain
-
Randomized Controlled Trial Comparative Study Clinical Trial
A double-blind randomised comparison of the effects of epidural clonidine, lignocaine and the combination of clonidine and lignocaine in patients with chronic pain.
Twenty patients with chronic pain who previously had obtained analgesia from epidural clonidine and lignocaine agreed to participate in a double-blind crossover study of lumbar epidural clonidine (150 micrograms), lignocaine (40 mg) and the combination of clonidine (150 microgram) and lignocaine (40 mg), all drugs were given in a volume of 3 ml. There were 11 women and 9 men with a mean age 53 years (range: 23-78 years); 9 patients had low back and leg pain, 9 had neuropathic pain, 1 had pelvic pain and 1 Wegner's granulomatosis. Pain intensity and pain relief, as well as sensory and motor blockade, were assessed for 3 h following each injection. ⋯ Overall there was no relationship between neurological blockade and analgesia. The reported side effects appeared to be related to clonidine. These data indicate that in these patients with chronic pain epidural clonidine had a supra-additive effect and behaved more like a co-analgesic than a pure analgesic.
-
Clinical Trial
Concerning the homology of painful experiences and pain descriptors: a multidimensional scaling analysis.
How is the sensory (or other) experience of pain related to the words used to describe such experiences? Answering this question would not only improve our general understanding of the relationship between the experience of pain and the report of pain, but also would allow one to quantify inaccuracies or idiosyncracies in this regard. A continuous multidimensional scaling model was used to examine the similarity between noxious electrocutaneous stimuli and the words used to describe them. If these two types of stimulus objects were homologous, one would expect that physical and verbal stimuli with the same meaning would be scaled with similar values along a single dimension; if not, the two types of stimuli would be scaled at opposite poles of a dimension which distinguished between them. ⋯ A single dimension in the group stimulus space scaled both physical and verbal stimulus objects from least to greatest intensity. Since this (or any higher) dimension failed to segregate verbal from physical stimuli, the words appear to be homologous with experience. While conclusions are limited to these specific stimuli, results suggest that the INDSCAL model offers a valuable method for exploring the relationship between pain report and pain experience.
-
Randomized Controlled Trial Clinical Trial
A new method of recording somatosensory evoked potentials by randomized electrical tooth stimulation with 6 levels of intensity.
Dental somatosensory evoked potentials (SEPs) corresponding to the stimulus intensity levels were recorded at 6 different levels of intensity presented in a randomized order. The relationships between the amplitude of the late SEP component with latency between 150 and 300 msec and each stimulus intensity level were also compared in conditions of randomized intensity and constant intensity. The amplitude of the late component increased significantly with the increased stimulus intensity both in the randomized and constant intensity stimulation. ⋯ The latency of the late positive component significantly increased with the randomized stimulation with a 3-sec ISI. This phenomenon might be attributable to the psychological contamination. SEP recording in the randomized dental stimulation with a 1-sec ISI may have applications in neuropharmacological research or physiological research on pain and evaluation of the effects of analgesics, anesthetics, acupuncture and transcutaneous electrical nerve stimulation (TENS).
-
Clinical Trial
Mechanisms of spontaneous tension-type headaches: an analysis of tenderness, pain thresholds and EMG.
Pericranial muscle tenderness, EMG levels and thermal and mechanical pain thresholds were studied in 28 patients with tension-type headache and in 30 healthy controls. Each patient was studied during as well as outside a spontaneous episode of tension-type headache. Outside of headache, muscle tenderness and EMG levels were significantly increased compared to values in controls subjects, while mechanical and thermal pain thresholds were largely normal. ⋯ EMG levels were unchanged during headache. It is concluded that one of the primary sources of pain in tension-type headache may be a local and reversible sensitization of nociceptors in the pericranial muscles. In addition, a segmental central sensitization may contribute to the pain in frequent sufferers of tension-type headache.
-
Nerve growth factor (NGF) is known to produce hyperalgesia as well as to stimulate synthesis of neuropeptides in dorsal root ganglia (DRG). In the present study, we wanted to determine the effects of local NGF administration and assess to which extent mast cell-dependent factors are mediating NGF responses. Rats received 1 daily unilateral intraplantar injection for 3 days. ⋯ We suggest therefore that NGF-induced local edema was caused by mast cell-derived vasoactive compounds which act together with afferent neuron-derived CGRP to increase vascular permeability. NGF-induced thermal hyperalgesia most likely was caused by an increased sensitivity of peripheral endings of capsaicin sensitive afferents. This effect of NGF was not mediated by products of the cyclooxygenase pathway, and was also observed in mast cell-depleted rats.