Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental studies have shown that opioids could produce two types of effect on neuronal excitability. The first one, aspecific, is a local anesthetic action on the nerve fiber with a diminution of sodium and potassium conductance. The second is specific: the sodium conductance lowering is due to a linkage of the opioid with a receptor on the internal face of the membrane. Opioids could also migrate to the posterior horn of the spinal cord after linkage with axonal receptors. Clinical studies have proved that opioid injection in peripheral nervous trunks and specially in the brachial plexus produce a prolonged analgesia status in the post operative period but also and mostly in the chronic pain. The more liposoluble opioids like fentanyl and buprenorphine are the more effective.
 ...
PMID:[Mechanism of action and clinical use of opioids administered by the peripheral perineural route]. 167 79

Thirty-eight consecutive patients with neuralgia after peripheral nerve injury were treated with one or two series of peripheral local anesthetic blocks. All patients experienced an initial total relief of ongoing pain for 4-12 h. Evoked pain (hyperalgesia or allodynia), which occurred in 17 patients, was blocked simultaneously with the spontaneous pain. In 18 patients the analgesia outlasted the conduction block and there was a period of complete pain relief of 12-48 h in 13 patients and of 2-6 days in the other 5. In 8 patients there was a second phase of analgesia of 4 h to 6 days duration occurring within 12 h of pain recurrence. Thus, mono- or biphasic prolonged complete analgesia occurred in 25 out of 38 patients. A prolonged analgesia may be the result of a central action of the local anesthetic at the spinal level after intra-axonal incorporation and centripetal axoplasmic transport. To test this hypothesis, an experimental study with [3H]lidocaine was performed in 6 rats. The radioactive local anesthetic was injected into one hind limb foot with the other side serving as a control. Tissue samples from the peripheral nerve, nerve root and the lumbosacral spinal cord segment were analyzed for radioactivity using a scintillation counter technique at various time intervals after the [3H]lidocaine injection. There was a low grade of activity in all samples and no difference between the test side and the control side. Thus these experiments provided no evidence in support of this hypothesis. Various alternative peripheral and central mechanisms are discussed. Further studies specifically directed to these alternatives and with longitudinal controls are prompted.
 ...
PMID:Prolonged relief of neuralgia after regional anesthetic blocks. A call for further experimental and systematic clinical studies. 170 93

The anatomy and physiology of the epidural space and the mechanism of action, sites of action, and pharmacokinetics of analgesics administered by continuous epidural infusion are reviewed, and the efficacy, adverse effects, and postoperative indications for use of analgesics administered by this route are discussed. Narcotics selectively block pain conduction by occupying specific opiate receptors in the spinal cord. Local anesthetics provide analgesia by axonal membrane blockade; they also can produce nonselective sympathetic and somatic (sensory and motor) blockade in addition to analgesia. A narcotic-local anesthetic mixture should provide an additive analgesic effect, without an increase in the incidence of adverse effects. Comparative efficacy studies have shown that continuous epidural infusions of narcotics, local anesthetics, and narcotic-local anesthetic combinations, when used appropriately, may produce better analgesia than conventional bolus methods of pain relief. Continuous epidural infusions also offer a safety advantage over intermittent epidural injections because peak and trough levels of the analgesic agent are avoided. Adverse effects of epidurally administered narcotics include respiratory depression, pruritus, urinary retention, nausea and vomiting, and sedation. Adverse effects of epidurally administered local anesthetics include urinary retention, hypotension, numbness, motor weakness, tachyphylaxis, and, rarely, systemic toxicity. The cost of epidurally administered drugs is substantially higher than that for i.m. or i.v. narcotic analgesia, but this cost may be offset by other benefits such as a shorter hospital stay. Current studies suggest superior analgesia for the majority of surgical procedures with continuous epidural analgesia infusions compared with more traditional methods of providing analgesia.
 ...
PMID:Management of postoperative pain by continuous epidural infusion of analgesics. 174 61

The effect of helium-neon laser irradiation (632.5 nm) on A delta- and C-fiber sensory afferents was investigated in the rabbit cornea, to determine the physiologic basis for reports that low power (0.1-5 mW) helium-neon (He-Ne) lasers produce acute analgesia and alleviate chronic pain. Multiple and single unit extracellular recordings from nociceptive corneal afferent nerves (C-fiber cold, C-fiber chemical, A delta mechanical and A delta bimodal) were used to study the effects of He-Ne laser radiation upon the electrophysiologic responses to mechanical, thermal, chemical and electrical stimulation of the cornea. Action potentials were analyzed for latency, amplitude, rise time, duration and frequency. Exposure of the neural receptive field and/or nerve bundle to a 4-mm diameter He-Ne laser (0-5 mW; 0-1800 sec) did not alter spontaneous or evoked neural activity. In addition, single unit action potential parameters were not altered by laser irradiation. Modeling of thermal changes produced by He-Ne radiation on corneal nerves indicated that effects predicted for receptor and axonal depths in both skin and cornea were minimal (less than 0.15 degrees C) and unlikely to alter sensory transduction or transmission.
 ...
PMID:Electrophysiologic recording and thermodynamic modeling demonstrate that helium-neon laser irradiation does not affect peripheral Adelta- or C-fiber nociceptors. 176 21

Electron microscopy of rats ultrathin sections from dorsal and central raphe nucleus and spinal cord after 5,7-dihydroxytryptamine intracisternal microinjection (200 micrograms) has revealed neurones and axonal terminals distruction, which associated with tail-flick hypoalgesia and blood pressure nociceptive reactions diminished. In this condition the morphine (2 mg/kg) analgesia and drug depressive effect on pain hemodynamic manifestations increase significantly.
 ...
PMID:[Effect of 5,7-dihydroxytryptamine on pain sensitivity and analgesic activity of morphine]. 316 83

A double-label immunofluorescence technique was used to demonstrate that immunoreactivities for the functionally antagonistic neuropeptides enkephalin and cholecystokinin octapeptide (CCK) are co-localized within individual neurons and processes in discrete areas of rat midbrain and forebrain. Coexistence was most prominent within varicose pericellular axons extending from the periaqueductal gray matter to a field overlying the medial lemniscus, axons and terminal-like puncta in the central medial, paracentral, interanterodorsal and ventral anterior thalamic nuclei, and perikarya and proximal axonal fragments in layers II and III of neo- and allocortex, and in the anterior olfactory nucleus. The former two systems of axons lie in areas of spinothalamic tract termination. These data suggest that some of the antagonism of opioid analgesia by CCK occurs at the synaptic level in nociceptive areas of brain-stem and thalamus where CCK and enkephalin are co-localized and presumably co-released.
 ...
PMID:Co-localization of enkephalin and cholecystokinin in discrete areas of rat brain. 354 90

Although the midbrain periaqueductal gray (PAG) is thought to have a major role in an endorphin-mediated analgesia system, little is known about its neuroanatomical organization. To determine the microcircuitry within the PAG through which exogenous and endogenous opiates may act, we analyzed the synaptic organization of normal and immunoreactive enkephalin (ENK)-labeled profiles in the caudal PAG, a region of particular interest because of its effectiveness in generating analgesia. Examination of the normal fine structure of this region demonstrated that there is no characteristic synaptic morphology that distinguishes individual regions of the caudal PAG (ventromedial, ventrolateral and dorsolateral) from one another. In all 3 regions of the caudal PAG, axodendritic synapses are the predominant form of synaptic interaction making up 93-97% of all synapses counted. Axosomatic synapses are much less common, as are presumed axoaxonic and dendrodendritic synapses. In the caudal ventral PAG, the largest population of ENK-labeled axonal boutons are found presynaptic to unlabeled, centrally placed dendrites. Much less frequently, immunoreactive ENK-containing boutons are found presynaptic to neuronal perikarya or vesicle-containing profiles. Thus, these results suggest that the dendrites of neurons intrinsic to the PAG are the most probable site of opiate action in the caudal ventral PAG.
 ...
PMID:The fine structure of the caudal periaqueductal gray of the cat: morphology and synaptic organization of normal and immunoreactive enkephalin-labeled profiles. 636 75

A patient with an apical lung tumour invading the brachial plexus (Pancoast's tumour) suffered from unbearable pain unmodified by daily treatment with morphine 180 mg subcutaneously. An interscalene brachial plexus block was performed using a solution containing 5 mg morphine hydrochloride in 10 ml isotonic saline. Complete analgesia was obtained after 20 minutes, an effect which lasted for the next 36 hours. Neuro-axonal transport of morphine to the spinal cord may be the explanation of the effect, an hypothesis which ought to be subjected to controlled trials.
 ...
PMID:Neuronal blockade with morphine. A hypothesis. 647 16

Effective analgesia resulted from the injection of peridural meperidine in two groups of cancer patients, eight with postoperative pain and eight with intractable pain. Peridural meperidine HCl, 100 mg (n = 8), in 10 ml saline administered to patients following surgery was followed by a median duration of analgesia of 6 hours (range 4-20 hours) over periods ranging from 1-4 days. Peridural meperidine HCl, 30-100 mg (n = 8), in 10 ml saline administered to patients with intractable pain gave a median duration of analgesia of 8 hours (range 4-20 hours) over periods ranging from 1-9 days. There was no obvious tendency towards tolerance. In all patients, the onset of analgesia was within 5 min and was complete within 30 min. This analgesia paralleled the rise in CSF meperidine concentrations following peridural administration. Systemic absorption of peridurally administered meperidine occurred with a half-life of 15-30 min and produced blood concentrations high enough to contribute to analgesia after approximately 20 min in the majority of patients. There was no objective evidence in any neurological change nor sympathetic blockade after peridural meperidine. From this evidence the dorsal horn of the spinal cord may be the major site of action as distinct from the axonal blockade produced by local anesthetics, indicating 'selective' spinal analgesia.
 ...
PMID:Peridural meperidine in humans: analgesic response, pharmacokinetics, and transmission into CSF. 729 5

We reviewed the clinical features of 12 patients with neurologic complications following lumbar epidural anesthesia or analgesia. Eleven patients experienced lumbosacral radiculopathy or polyradiculopathy and, of these, 10 received epidural anesthesia or analgesia and one received subarachnoid injection of medication after intended epidural anesthesia. One patient suffered a moderately severe thoracic myelopathy in the setting of unintended spinal anesthesia. The two patients with more severe polyradiculopathy had severe lumbar spinal stenosis on MRI. The other patients experienced mild to moderate neurologic deficits most often involving the L-2 root, and MRIs, when performed, were unremarkable. EMG on three patients helped to localize the lesions to the lumbosacral roots and to quantify the extent of axonal loss. Ten patients were ambulatory upon discharge from the hospital and had good neurologic outcome. One patient with severe polyradiculopathy did not improve after 4 years and had severe motor axonal loss based upon electrodiagnostic studies. The patient with a thoracic myelopathy was ambulatory 4 months after onset. Although generally a safe procedure with low frequency of complications, lumbar epidural anesthesia or analgesia occasionally causes neurologic sequelae such as radiculopathy or myelopathy. Neurologic complications may be more severe in the presence of spinal stenosis or after inadvertent subarachnoid injection of anesthetic or analgesic agent.
 ...
PMID:Neurologic complications of lumbar epidural anesthesia and analgesia. 900 49


1 2 3 4 Next >>