Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of the present study was to investigate the role of primary afferent fibres with polymodal nociceptors in the various pain symptoms and signs associated with post-herpetic neuralgia (PHN). Forty-four patients with PHN affecting thoracic dermatomes were examined clinically for evidence of sensory disturbance to touch and pinprick and compared to 14 normal subjects and 9 subjects with evidence of past herpes zoster infection but no pain. The patients were then divided into 3 groups on the basis of their clinical symptoms and signs-those with steady burning discomfort only (n = 12), those with burning discomfort, allodynia and hyperalgesia to pinprick (n = 17), and those with burning discomfort, allodynia and hypalgesia to pinprick (n = 15). Indirect measurement of primary afferent fibre function was performed by measuring the neurogenic axon reflex flare to topical capsaicin using Doppler flowmetry in the 5 clinical groups. The 2 groups with allodynia had significantly decreased neurogenic flare responses compared to PHN subjects without allodynia and the 2 control groups. These results suggest that allodynia in patients with post-herpetic neuralgia may be a consequence of disrupted function of primary afferent fibres.
Pain 1995 Oct
PMID:Capsaicin-induced flare and vasodilatation in patients with post-herpetic neuralgia. 857 95

We have investigated the effect of chronic lithium (Li+) treatment on stress-induced hypoalgesia, a phenomenon known to be dependent on the activation and sensitization of the central opioid system. Adult female Wistar rats received either 20 mM LiCl in the drinking water (serum level of 0.5 mEq/l, N = 110) or tap water (controls, N = 113) for 28 days. The rats were divided into three subgroups and were trained either by receiving 60 inescapable 1-mA footshocks (IS) while yoked to an escapable (ES) group, or by confinement (NS) to the shock box. As a control for the activation of the opioid system, we included rats injected with 0.9% saline (N = 24) or morphine (4 mg/kg, sc, N = 20) before confinement. Twenty-four hours later, the rats (N = 187) were either submitted to five inescapable (1 s, 0.6 mA) footshocks (shock reexposure) or received no shocks over the same period (N = 80). The pain threshold was estimated using a tail-flick apparatus after the training session and immediately after the shock reexposure. ANOVA followed by Duncan's test indicated that hypoalgesia was produced soon after the training session in the morphine and shocked groups and persisted in the Li(+)-IS group for up to three days. Hypoalgesia was reinstated in the control IS and morphine groups by reexposure to the shocks, but was not modified in the Li(+)-IS groups. We conclude that Li+ treatment prolongs the hypoalgesia induced by inescapable shocks.
 ...
PMID:Lithium treatment prolongs shock-induced hypoalgesia. 858 Aug 72

A behavioral hypalgesia (increased response threshold to noxious stimuli) has been consistently, although not invariably, reported in spontaneous and experimental acute and chronic hypertension in the rat. Studies in human hypertension have also demonstrated a diminished perception of pain, assessed as pain thresholds or ratings. The sensitivity to painful stimuli correlated inversely with blood pressure levels, and this relationship extended into the normotensive range. Evidence in humans and rats points to a role of the baroreflex system in modulating nociception. In the rat, blood pressure-related antinociception may be due to attenuated transmission of noxious stimuli at the spinal level secondary to descending inhibitory influences that are projected from brain stem sites involved in cardiovascular regulation and that may depend on baroreceptor activation and/ or on a central "drive." Both endorphinergic and noradrenergic central neurons (the latter acting through postsynaptic alpha 2-receptors) have been shown to be involved, and other mediators probably also play a role. Functionally, blood pressure-related antinociception may represent an aspect of a more-complex coordinated adaptive response of the body to "stressful" situations. It is still uncertain whether in human essential hypertension hypalgesia is secondary to elevated blood pressure or whether both depend on some common mechanism. Studies on the effect of hypotensive treatment are too few to allow conclusions. According to one hypothesis, the reduction in pain perception caused by baroreceptor activation secondary to blood pressure elevation may represent a rewarding mechanism that may be reinforced with repeated stress and may be involved in the development of hypertension in some individuals. Hypertension-associated hypalgesia may have clinically relevant consequences, especially in silent myocardial ischemia and unrecognized myocardial infarction, both of which are more prevalent in hypertensive individuals.
 ...
PMID:Hypertension-associated hypalgesia. Evidence in experimental animals and humans, pathophysiological mechanisms, and potential clinical consequences. 879 39

In 6 patients with Wallenberg's syndrome who showed a dissociated loss of pain sense, we recorded pain-related somatosensory evoked potentials following CO2 laser stimulation of the hand dorsum (pain SEPs). Two components, N2 and P2, were recorded by stimulation of the unaffected hand, whereas on the affected side they were absent or decreased in proportion to the severity of hypalgesia which was evaluated by both needle test and CO2 laser stimulation. Latency of either component, if appeared, was longer in the affected hand stimulation than that in the unaffected one. In contrast, N20 of the conventional electrically-stimulated SEPs (electric SEPs) showed no difference between the two sides. It is concluded that, unlike other electrophysiological methods, pain SEPs following CO2 laser stimulation can quantitatively evaluate functional impairment of the spinothalamic tract in Wallenberg's syndrome.
 ...
PMID:Pain-related somatosensory evoked potentials can quantitatively evaluate hypalgesia in Wallenberg's syndrome. 889 Oct 59

We report a case of foramen magnum meningioma in which case enhanced three-dimensional CT scan was valuable for preoperative evaluation of the surgical approach. A 53-year-old woman had suffered from stiffness and pain in the left occipital region and numbness of the left side of the face for about 2 years before admission. She had also weakness and numbness of the left side of her body for about 2 months before admission, and dysphagia and pain in the occipital region and in the posterior region of the neck produced by straining for about 1 month before admission. Neurological examination revealed left hemiparesis, and hypalgesia and tactile hypesthesia of the left side of the body, including the face. Plain X-P was normal. Enhanced CT scan and gadolinium enhanced MRI revealed a well-enhanced mass attached to the left anterolateral part of the foramen magnum. The left occipital condyle was observed at the lateral side of the attachment part of this mass. Angiography revealed tumor feeders from the meningeal branches of the left vertebral artery and the left ascending pharyngeal artery. Enhanced three-dimensional CT scan clearly showed that the tumor was attached to the left anterolateral part of the foramen magnum, that the left occipital condyle was at the lateral side of the attachment part of this mass and that the jugular foramen and jugular tubercle were situated superolateral to the attachment part of this mass. Considering these factors, we decided that removal of the posterior part of the left occipital condyle was necessary, but removal of the left jugular tubercle was not necessary for a good operative view from the left posterior lateral direction. The tumor was totally removed successfully and good results were obtained by the transcondylar approach without removal of the jugular tubercle. Histology of the tumor revealed meningothelial meningioma. In this case, preoperative evaluation with enhanced three-dimensional CT scan was helpful for deciding the surgical approach. With enhanced three-dimensional CT scan, it is easy to judge whether removal of the posterior part of the occipital condyle and/or the jugular tubercle is necessary for a good operative view, and we can get good images revealing the relationships between the tumor and surrounding structures. Preoperative evaluation with enhanced three-dimensional CT scan is very useful especially in this kind of situation.
 ...
PMID:[A case of foramen magnum meningioma in which case enhanced three-dimensional CT scan was valuable for preoperative evaluation of the surgical approach]. 921 59

The influence of an evolving painful inflammatory lesion on the development of autotomy, a behavioural model of denervation pain, was studied in rats suffering sciatic and saphenous nerves transection 30 or 60 min, and 1, 3, 7 or 14 days after being injected with formalin (50 microl, 5%, s.c). Hindpaws pressure and heat nociceptive thresholds and volume of the injected paw were assessed, in non-operated rats, at the above time-points. The main effects on autotomy were: (1) a significant attenuation when formalin injection preceded the neurectomies by 1 day or more, a period characterized by hypalgesia of the injected paw to both mechanical (during the first week) and thermal (spanning up to the third day after formalin) stimuli and inflammation (lasting for 14 days); (2) a significantly earlier onset when formalin was injected 30 min before neurectomies. Possible mechanisms linking nociceptive responsiveness and inflammation to the development of autotomy are discussed.
 ...
PMID:Autotomy in rats following peripheral nerve transection is attenuated by preceding formalin injections into the same limb. 953 29

The cardiovascular system shares numerous anatomic and functional pathways with the antinociceptive network. The aim of this study was to investigate whether angiotensin-converting enzyme (ACE) inhibitor treatment could affect hypertension-related hypalgesia. Twenty-five untreated hypertensive patients, together with a control group of 14 normotensive subjects, underwent dental pain perception evaluation by means of a pulpar test (graded increase of test current applied to healthy teeth). After the evaluation of the dental pain threshold (occurrence of pulp sensation) and tolerance (time when the subjects asked for the test to be stopped), all the subjects underwent a 24-hour ambulatory blood pressure monitoring. The hypertensive group then was treated with 20 mg/d enalapril, whereas the normotensive subjects remained without any treatment. After a time interval of 6+/-2 months, the dental pain sensitivity was retested in all the subjects, and ambulatory blood pressure was recorded during treatment in the hypertensive patients. At the first assessment, hypertensive patients showed a higher pain threshold than normotensive subjects (P<.001). On retesting of pain sensitivity in hypertensive patients, a significant decrease of both pain threshold and tolerance, leading to their normalization, was observed during treatment (P<.001 and P<.005, respectively), in the presence of reduced 24-hour and office blood pressure values. A slight, though significant, correlation was observed between variations in pain tolerance and baseline blood pressure changes occurring during treatment. During follow-up, the normotensive subjects did not show any significant pain perception or office blood pressure changes. Hypertension-related hypalgesia was confirmed. Mechanisms acting both through lowering of blood pressure and specific pharmacodynamic properties may account for the normalization of pain sensitivity observed in hypertensive patients during treatment with ACE inhibitors.
 ...
PMID:Treatment with enalapril modifies the pain perception pattern in hypertensive patients. 957 27

We report a rare case of two-level thoracic disc herniation that occurred in a 48-year-old woman. She was referred with a 10-month history of pain on the right side of the thorax. On examination, she had hypoesthesia and hypalgesia in the right T6-T8 dermatomes. An MRI scan revealed a large herniated disc at the T7/8 level and a smaller herniated disc at the T6/7 level. At surgery, the unilateral transpedicular approach was used, and a large prolapse was removed at the T7/8 level. The T6/7 level was decompressed. The patient made an uneventful recovery. Six months after surgery her pain had disappeared, but she still had hypoesthesia in the right T6-T8 dermatomes.
 ...
PMID:Two-level thoracic disc herniation. 984 71

Laser pulses selectively excite mechano-thermal nociceptors and evoke brain potentials that may reveal small-fiber dysfunction. We applied CO2-laser pulses to the perioral and supraorbital regions and recorded the scalp laser-evoked potentials (LEPs) and reflex responses in the orbicularis oculi, masticatory, and neck muscles in 30 controls and 10 patients with facial sensory disturbances. Low-intensity pulses readily evoked scalp potentials consisting of a negative component with a latency of 165 ms followed by a positive component at 250 ms. In vertex recordings, the amplitude of LEPs exceeded 30 microV. Although only high-intensity pulses evoked reflex responses, some subjects showed--even to low-intensity pulses--an orbicularis oculi (blink-like) response that markedly contaminated the scalp recording. Scalp LEPs were abnormal in patients with hypalgesia and normal trigeminal reflexes and normal in patients with normal pain sensitivity and abnormal trigeminal reflexes. Possibly because of the high receptor density in this area and the short conduction distance, laser stimulation of the trigeminal territory yields low-threshold and large LEPs, which are useful for detecting dysfunction in peripheral and central pain pathways.
 ...
PMID:Assessment of trigeminal small-fiber function: brain and reflex responses evoked by CO2-laser stimulation. 1020 87

Capsaicin applied topically to human skin produces itching, pricking and burning sensations due to excitation of nociceptors. With repeated application, these positive sensory responses are followed by a prolonged period of hypalgesia that is usually referred to as desensitization, or nociceptor inactivation. Consequently, capsaicin has been recommended as a treatment for a variety of painful syndromes. The precise mechanisms that account for nociceptor desensitization and hypalgesia are unclear. The present study was performed to determine if morphological changes of intracutaneous nerve fibers contribute to desensitization and hypalgesia. Capsaicin (0.075%) was applied topically to the volar forearm four times daily for 3 weeks. At various time intervals tactile, cold, mechanical and heat pain sensations were assessed in the treated and in contralateral untreated areas. Skin blisters and skin biopsies were collected and immunostained for protein gene product (PGP) 9.5 to assess the morphology of cutaneous nerves and to quantify the number of epidermal nerve fibers (ENFs). Capsaicin resulted in reduced sensitivity to all cutaneous stimuli, particularly to noxious heat and mechanical stimuli. This hypalgesia was accompanied by degeneration of epidermal nerve fibers as evidenced by loss of PGP 9.5 immunoreactivity. As early as 3 days following capsaicin application, there was a 74% decrease in the number of nerve fibers in blister specimens. After 3 weeks of capsaicin treatment, the reduction was 79% in blisters and 82% in biopsies. Discontinuation of capsaicin was followed by reinnervation of the epidermis over a 6-week period with a return of all sensations, except cold, to normal levels. We conclude that degeneration of epidermal nerve fibers contributes to the analgesia accredited to capsaicin. Furthermore, our data demonstrate that ENFs contribute to the painful sensations evoked by noxious thermal and mechanical stimuli.
Pain 1999 May
PMID:Topical capsaicin in humans: parallel loss of epidermal nerve fibers and pain sensation. 1035 1


<< Previous 1 2 3 4 5 6 7 8 Next >>