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Query: UMLS:C0033774 (pruritus)
 14,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Topical capsaicin in humans: parallel loss of epidermal nerve fibers and pain sensation. 1035 1

Local anesthetics do not penetrate readily through human skin if applied in their salt form; however, if applied in their base form various effects may be observed, such as a decrease in pricking pain and a change in burning, itch, and thermal sensations. These effects occur after skin penetration and may be attributed to the action of the anesthetics on nociceptors and thermoreceptors, i.e., on C and Adelta nerve fiber respectively. As there is little known about the time course of the pharmacodynamic response of cutaneously applied local anesthetic bases, this study was conducted to characterize various local anesthetics pharmacodynamically by measuring thermal thresholds over time with a thermal sensory analyzer. The results show that the investigated local anesthetics affect thermal thresholds to a different extent, with tetracaine and lidocaine being most efficient. From the response versus time profiles of all eight study subjects various response parameters were obtained: only the cold sensation parameters proved suitable for characterization of the local anesthetics, possibly because cold receptors are located in the epidermis and can easily be reached. Lag times of onset are short and the maximum anesthetic effect is reached within 2-3 h. Cold sensation parameters correlate linearly with the solubility of the local anesthetic bases in medium chain triglycerides and with the drug flux of 50% saturation, indicating that medium chain triglycerides may have similar properties with regard to the local anesthetics solubility as the stratum corneum lipids.
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PMID:Percutaneous penetration of local anesthetic bases: pharmacodynamic measurements. 1046 25

Symptoms of allergic rhinitis are produced by inflammatory mediators that are released upon activation of mast cells by antigen-IgE interaction. These mediators target the end organs directly or indirectly. Stimulation of sensory nerves by histamine, for example, leads to sneezing, pruritus, rhinorrhea, and nasal congestion. The clinical presentation of allergic rhinitis is also characterized by the phenomenon of hyperresponsiveness to nonallergic stimuli, such as cold air and various irritants. This phenomenon is believed to result from the effect of allergic inflammation on the sensory nerves that supply the upper airway mucosa. Various nonallergic triggers have been shown to act on the nasal mucosa through sensorineural stimulation. In allergic rhinitis, responsiveness to these stimuli is increased compared with the healthy state. A similar phenomenon is observed against such products of the allergic reaction as his-tamine and bradykinin. Also, in allergic rhinitis, stimulation of sensory nerves per se can produce inflammatory changes, a phenomenon known as neurogenic inflammation. The mechanism behind the development of sensorineural hyperresponsiveness and of increased propensity for neurogenic inflammation is unknown. However, evidence exists that the neurotrophin nerve growth factor, which can induce all these changes on sensory nerves, is produced in the human nasal mucosa and found in higher quantities in nasal secretions of patients with perennial allergic rhinitis as compared with healthy control subjects. Also, nerve growth factor is acutely released into nasal fluids after allergen provocation of patients with allergic disease. In patients with asthma of atopic origin, allergic rhinitis is almost ubiquitous. Because the nose is the air conditioner of the respiratory system, its dysfunction may negatively affect the lower airways. In addition to the conditioning of inhaled air, the association between allergic rhinitis and asthma may involve various mechanisms. For example, allergen provocation in the nose of a patient with asthma can lead to reductions in pulmonary function and to increased lower airway responsiveness after several hours. Also, nasal inflammation may propagate through a systemic route to affect the lower airways.
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PMID:Unique mechanistic features of allergic rhinitis. 1085 64

Few studies evaluate the effect of topical corticosteroids on thermal sensation and in alleviation of itch produced by intradermal injection of histamine. We evaluated the antipruritic effect of hydrocortisone (1% and 2.5%) on histamine-induced itch and sensory effects by measuring itch magnitude, itch duration and thermal thresholds using a computerized thermal sensory analyzer (TSA). This was a double-blind, random, comparative, controlled, single-dose and single-center study. Itch was experimentally induced in both forearms by intracutaneous injection of histamine in 18 subjects. Hydrocortisone 1%, 2.5% and placebo were applied to test sites on both forearms. The thermal threshold for warmth sensation, cold sensation, cold and heat pain was measured with the TSA. Itch magnitude was measured each minute after histamine injection for 10 min with a visual analogue scale (VAS). Itch duration was also recorded. In comparison to placebo, 2.5% hydrocortisone significantly (p = 0.03) reduced itch duration from 12.6 +/- 11.0 min (mean +/- SD) to 8.6 +/- 8.2 min (the reducing rate was 32%) as well as itch magnitude (at minutes 3, 6, 7 and overall). Placebo, 1% and 2.5% hydrocortisone significantly altered (p <0.05) the cold sensation threshold. No treatment altered cold or heat pain thresholds. These data suggest that topical application of 2.5% hydrocortisone may be significantly beneficial for the treatment of histamine-induced itch. The correlation between thermal measurements and antipruritic effects warrants further study.
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PMID:Antipruritic and thermal sensation effects of hydrocortisone creams in human skin. 1109 77

Urticaria is a common disorder that adversely affects quality of life; work-related and recreational activities are restricted, while rest, sleep, and emotions are seriously disturbed in a significant proportion of patients. The pathogenic mechanisms vary, but cutaneous mast-cell activation with release of histamine and other vasoactive or proinflammatory mediators is thought to be the final common pathway for lesion induction in most cases. A subsequent, but incompletely understood, late-phase allergic reaction seems to prolong the inflammatory process, particularly in certain chronic forms of the disorder. Although histamine is considered an important mediator of urticaria, additional substances, including the cysteinyl leukotrienes (LTs), are putative mediators of the immediate urticarial responses and the inflammatory events that follow in some types of urticaria. A second-generation antihistamine, mizolastine, which exhibits dual activity with selective H1-receptor antagonism and, as shown in animal studies, anti-5-lipoxygenase activity, represents an advance in the treatment of urticaria. It has rapid, potent and sustained action. At the recommended 10-mg dose, mizolastine suppresses the histamine-induced wheal reaction as early as 1 h after oral administration. Compared to placebo, mizolastine significantly reduces overall patient discomfort and pruritus in patients with chronic idiopathic urticaria. Double-blind, placebo-controlled studies have also shown mizolastine to be at least as effective as other second-generation antihistamines. Furthermore, with long-term use of mizolastine over 1 year, a reduction in pruritus and the number of urticarial episodes was maintained with no evidence of tachyphylaxis or tolerance. Mizolastine has also been shown to be an effective treatment for cold-induced urticaria, causing significant delay in the whealing response to the ice-cube test and also reducing the wheal diameter.
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PMID:Clinical advantages of dual activity in urticaria. 1129 78

Predictive validity of each word from the McGill Pain Questionnaire (MPQ) has not been investigated in relation to pain etiology. The purpose of this study was to explore differences in the words used to describe nociceptive and neuropathic pain. Patients with lung cancer (N = 123) selected words from the 78 MPQ pain quality descriptors and indicated the corresponding pain site for each word. Using only the MPQ pain location, and the cancer and treatment data abstracted from medical records, each pain site was classified as nociceptive or neuropathic (etiology). Pain etiology and quality descriptors were tested for proportional differences with sensitivity, specificity, and predictive value calculated for statistically significant descriptors. Of the 457 pain sites, 343 were classified as nociceptive (75%), 114 as neuropathic (25%). Lacerating, stinging, heavy, and suffocating were selected for a significantly larger proportion of nociceptive sites whereas throbbing, aching, numb, tender, punishing, pulling, tugging, pricking, penetrating, punishing, miserable, and nagging were selected for a larger proportion of neuropathic sites. Ten words correctly predicted 78% of the sites with 81% sensitivity to nociceptive pain and 59% sensitivity to neuropathic pain. Interestingly, several pain quality descriptors (burning, shooting, flashing, tingling, itching, and cold) previously associated with neuropathic pain did not distinguish between neuropathic and nociceptive pain. Infrequent selection of many MPQ words and lack of neurological exam data in the medical records are possible explanations for inconsistency with previous literature. Prospective studies are needed to validate pain quality descriptors for nociceptive and neuropathic types of lung cancer pain.
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PMID:Nociceptive and neuropathic pain in patients with lung cancer: a comparison of pain quality descriptors. 1172 93

A multicenter, open labeled, randomized early Phase II study for CGS 20267 was conducted at the doses 0.5 mg once daily and 1.0 mg once daily in postmenopausal women with advanced breast cancer. Sixty-four patients were randomly assigned to the doses of either 0.5 mg once daily (n = 33) or 1.0 mg once daily (n = 31). Thirty-one patients were eligible for 0.5 mg group, and 29 for 1.0 mg group. A total of 57 patients (30 in the 0.5 mg group and 27 in the 1.0 mg group) were eligible for the evaluation of efficacy. There were 3 CR, 5 PR, 5 stable disease (SD: NC lasting over 24 weeks), 7 NC and 10 PD in the 0.5 mg group. The objective response rate (ORR) was 26.7%. There were 4 CR, 7 PR, 8 SD, 3 NC and 5 PD in the 1.0 mg group. The ORR was 40.7%. A total of 57 patients (29 in the 0.5 mg group and 28 in the 1.0 mg group) were eligible for safety evaluation. Adverse clinical events related to CGS 20267 in the 0.5 mg group were headache, nausea, cold sweat, sleepiness and muscle ache in the lower extremities (2 patients, incidence rate 6.9%) whereas those in the 1.0 mg group were generalized itching and generalized hot feeling (2 patients, incidence rate 7.1%). All of the adverse events were grade 1 except the generalized itching which was grade 2. CGS 20267-related abnormalities in the laboratory tests for the 0.5 mg group were a decrease in WBC, and increases in GOT, GPT, LDH and gamma-GTP (5 patients, 14.3%) whereas those in the 1.0 mg group were increases in GPT, gamma-GTP, alkaline phosphatase, and total bilirubin (1 patient, 3.6%). The increases in GOT and GPT were grade 2, but others were grade 1. The data show both CGS 20267 0.5 mg once daily and 1.0 mg once daily to be effective and tolerable in the treatment of postmenopausal women with advanced breast cancer.
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PMID:[CGS 20267 (Letrozole), a new aromatase inhibitor: early phase II study for postmenopausal women with advanced breast cancer]. 1197 39

Fifteen patients (10 women and 5 men; median age 46 years; range 28-55), with recurrent severe carpal tunnel syndrome, were operated on with re-exploration and cover of the median nerve with free or pedicled flaps (five pedicled ulnar flaps, one pedicled dorsal forearm flap (served by the posterior interosseus artery), one groin flap, three free scapular flaps, and five free lateral arm flaps). The patients were followed up by a self-administered questionnaire at 3 months-14 years (median 8.5 years) after operation and replies were obtained from 14 patients. There was a significant improvement in pain (p = 0.01) and percussion tenderness at the wrist (p = 0.02), but no significant improvement in allodynia and cold intolerance in the hand as evaluated by the use of a visual analogue scale (VAS). Three of the 14 patients had less numbness/paraesthesiae and four had subjectively improved sensory function in the hand and fingers since the procedure. Ten patients had problems from the donor site, including a cosmetically unacceptable scar, allodynia, and itching. Four patients had worked before the operation and nine patients returned to ordinary or light work afterwards. In conclusion, 10/14 patients considered themselves as somewhat better, better, or cured, while four felt that they were unchanged or worse. We conclude that cover with vascularised fat may be worthwhile in some patients with recurrent severe carpal tunnel syndrome, preferably with a simple pedicled ulnar flap.
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PMID:Coverage of the median nerve with free and pedicled flaps for the treatment of recurrent severe carpal tunnel syndrome. 1214 Dec 6

Dermatologists may commonly see skin lesions that reflect an underlying endocrine disorder. Identifying the endocrinopathy is very important, so that patients can receive corrective rather than symptomatic treatment. Skin diseases with underlying endocrine pathology include: thyrotoxicosis; hypothyroidism; Cushing syndrome; Addison disease; acromegaly; hyperandrogenism; hypopituitarism; primary hyperparathyroidism; hypoparathyroidism; pseudohypoparathyroidism and manifestations of diabetes mellitus. Thyrotoxicosis may lead to multiple cutaneous manifestations, including hair loss, pretibial myxedema, onycholysis and acropachy. In patients with hypothyroidism, there is hair loss, the skin is cold and pale, with myxedematous changes, mainly in the hands and in the periorbital region. The striking features of Cushing syndrome are centripetal obesity, moon facies, buffalo hump, supraclavicular fat pads, and abdominal striae. In Addison disease, the skin is hyperpigmented, mostly on the face, neck and back of the hands. Virtually all patients with acromegaly have acral and soft tissue overgrowth, with characteristic findings, like macrognathia and enlarged hands and feet. The skin is thickened, and facial features are coarser. Conditions leading to hyperandrogenism in females present as acne, hirsutism and signs of virilization (temporal balding, clitoromegaly).A prominent feature of hypopituitarism is a pallor of the skin with a yellowish tinge. The skin is also thinner, resulting in fine wrinkling around the eyes and mouth, making the patient look older. Primary hyperparathyroidism is rarely associated with pruritus and chronic urticaria. In hypoparathyroidism, the skin is dry, scaly and puffy. Nails become brittle and hair is coarse and sparse. Pseudohypoparathyroidism may have a special somatic phenotype known as Albright osteodystrophy. This consists of short stature, short neck, brachydactyly and subcutaneous calcifications. Some of the cutaneous manifestations of diabetes mellitus include necrobiosis lipoidica diabeticorum, diabetic dermopathy, scleredema adultorum and acanthosis nigricans.
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PMID:Cutaneous manifestations of endocrine disorders: a guide for dermatologists. 1268 37

The unpleasantness of itching is reduced by cooling. Although previous research suggests the presence of a central itch modulation system, there is little documentation about the modulation system in the brain. In the present study, we investigated the modulating system of the itching sensation in human brains using positron emission tomography and H(2) (15)O. The significant increases of regional cerebral blood flow caused by histamine stimuli using iontophoresis were observed in the anterior cingulate cortex (BA24), the thalamus, the parietal cortex (BA40 and BA7), the dorsolateral prefrontal cortex (BA46) and the premotor cortex (BA6). We did not observe any changes in the secondary somatosensory cortex (S2) during the itching stimulus, corresponding to the previous imaging studies concerning itching. Activation in these areas related to itching stimuli was decreased by a simultaneous stimulation of itching and cold pain (the dual stimuli), as compared to itching alone. Interestingly, the midbrain, including periaqueductal gray matter (PAG), was only activated during the dual stimuli. PAG is well known to be a modulating noxious stimulus. Here we hypothesize that the activation of PAG may also be related to the itch modulation. These findings indicate that the modified brain activities in the PAG, the cingulate, the frontal and the parietal cortex might be associated with the itch modulation in the central nervous system and that the S2 might not be primarily involved in processing the itching perception in the brain since the activity of S2 was not observed in any concentration of itching stimuli.
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PMID:Imaging of central itch modulation in the human brain using positron emission tomography. 1449 52


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