Pain
-
Painful peripheral neuropathies involve both axonal damage and an inflammation of the nerve. The role of the latter by itself was investigated by producing an experimental neuritis in the rat. The sciatic nerves were exposed at mid-thigh level and wrapped loosely in hemostatic oxidized cellulose (Oxycel) that on one side was saturated with an inflammatory stimulus, carrageenan (CARRA) or complete Freund's adjuvant (CFA), and on the other side saturated with saline. ⋯ The neuropathic pain is specific to inflammation of the nerve because it was absent in animals with the experimental myositis and in those receiving sham-treatment. These results suggest that an acute episode of neuritis-evoked neuropathic pain may contribute to the genesis of chronically painful peripheral neuropathies, and that a chronic (or chronically recurrent) focal neuritis might produce neuropathic pain in the absence of significant (or clinically detectable) structural damage to the nerve. The model that we describe is likely to be useful in the study of the neuroimmune factors that contribute to painful peripheral neuropathies.
-
Randomized Controlled Trial Multicenter Study Clinical Trial
N of 1 randomised controlled trials of oral ketamine in patients with chronic pain.
Anecdotal reports suggest that the general anaesthetic drug ketamine, taken orally in low doses, can give rise to some extra analgesia in patients with refractory neuropathic pain. This study was designed to determine the proportion of patients with chronic neuropathic pain responding to oral ketamine, and then to separate the true treatment effect from non-specific effects by means of an n of 1 randomised controlled trial. Twenty-one patients gave informed consent and completed daily pain diaries and continued on their usual treatments (drug and non-drug) for the duration of the study. ⋯ We conclude that oral ketamine only gave rise to an extra analgesic response in three out of 21 patients with chronic neuropathic pain (14%). Adverse effects limited the use of the drug in almost half of the patients. The n of 1 trial was useful in demonstrating no true therapeutic effect for the ketamine in two thirds of the patients progressing to that part of the trial.
-
Randomized Controlled Trial Clinical Trial
Percutaneous electrical nerve stimulation: an alternative to TENS in the management of sciatica.
Sciatica is a common pain problem and current pharmacologic therapies have proven inadequate for many patients. The objective of this sham-controlled investigation was to compare a novel non-pharmacologic technique, percutaneous electrical nerve stimulation (PENS), to transcutaneous electrical nerve stimulation (TENS) in the management of the radicular pain associated with sciatica. Sixty-four consenting patients with sciatica due to lumbar disc herniation were treated with PENS, TENS and sham-PENS according to a randomized, single-blinded, cross-over study. ⋯ In the overall assessment, 73% of the patients reported that PENS was the most desirable modality (versus 21% for TENS and 6% for sham-PENS). Finally, 71% of the patients stated that they would be willing to pay extra to receive PENS therapy compared to 22% and 3% for TENS and sham-PENS, respectively. In this sham-controlled study, we concluded that PENS was more effective than TENS when administered at a stimulation frequency of 4 Hz in providing short-term pain relief and improved functionality in patients with sciatica.
-
Multicenter Study
Complex regional pain syndrome: are the IASP diagnostic criteria valid and sufficiently comprehensive?
This is a multisite study examining the internal validity and comprehensiveness of the International Association for the Study of Pain (IASP) diagnostic criteria for Complex Regional Pain Syndrome (CRPS). A standardized sign/symptom checklist was used in patient evaluations to obtain data on CRPS-related signs and symptoms in a series of 123 patients meeting IASP criteria for CRPS. Principal components factor analysis (PCA) was used to detect statistical groupings of signs/symptoms (factors). ⋯ Results also indicate motor and trophic changes may be an important and distinct component of CRPS which is not currently incorporated in the IASP criteria. An experimental revision of CRPS diagnostic criteria for research purposes is proposed. Implications for diagnostic sensitivity and specificity are discussed.
-
Clinical Trial Controlled Clinical Trial
The kappa opioid nalbuphine produces gender- and dose-dependent analgesia and antianalgesia in patients with postoperative pain.
Nalbuphine, pentazocine, and butorphanol, mixed agonist/antagonist opioids that induce analgesia by acting predominantly at kappa opioid receptors, have recently been shown in single-dose studies to have greater analgesic efficacy in women than in men. In the current experiments, the first placebo controlled dose response study of opioid analgesic efficacy that examines for gender differences, nalbuphine (5, 10, or 20 mg) and placebo were evaluated in 62 men and 69 women for the treatment of moderate to severe postoperative pain following extraction of impacted wisdom teeth. In a randomized, open injection, double blind experimental design, pain intensity was recorded on a 10 cm visual analog scale (VAS) immediately prior to drug administration (baseline) and at 20 min intervals thereafter. ⋯ These results suggest that the optimal analgesic dose of nalbuphine for women is lower than the highest dose that can be safely administered. In contrast, the antianalgesic effect of nalbuphine suggests avoidance of its routine use for postoperative analgesia in men until further studies clarify this issue. Because gender differences in other mixed kappa agonists/antagonists (i.e. pentazocine and butorphanol) have previously been shown, these results may generally apply to this class of opioid analgesics.