Understanding pruritus in systemic disease

Separate peripheral pathways for pruritus in man

Recent findings suggest that itch produced by intradermal insertion of cowhage spicules in human is histamine independent. Neuronal mechanisms underlying nonhistaminergic itch are poorly understood. To investigate which nerve fibers mediate cowhage induced itch in man, action potentials were recorded from cutaneous C-fibers of the peroneal nerve in healthy volunteers using microneurography. Mechano-responsive and -insensitive C-nociceptors were tested for their responsiveness to cowhage spicules, histamine, and capsaicin. Cowhage spicules induced itching and activated all tested mechano-responsive C-units (24/24), but no mechano-insensitive C-fibers (0/17). Histamine also induced itch, but in contrast to cowhage, it caused lasting activation only in mechano-insensitive units (8/12). In mechano-responsive C-units, histamine caused no or only short and weak responses unrelated to the time course of itching. Capsaicin injections activated four of six mechano-responsive fibers and three of four mechano-insensitive C-fibers. Cowhage and histamine activate distinctly different nonoverlapping populations of C-fibers while inducing similar sensations of itch. We hypothesize that cowhage activates a pathway for itch that originates peripherally from superficial mechano-responsive (polymodal) C-fibers and perhaps other afferent units. It is distinct from the pathway for histamine-mediated pruritus and does not involve the histamine-sensitive mechano-insensitive fibers.

Ondansetron treatment in a child presenting with chronic intractable pruritus

The case of a seven-year-old boy with chronic pruritus secondary to a giant congenital melanocytic nevus is presented. The pruritus did not respond to conventional antipruritic drug treatment, but responded to ondansetron, a selective antagonist of 5-hydroxytryptamine type 3 receptors.

Low-Dose Intrathecal Morphine for Postoperative Analgesia in Children

BACKGROUND

We evaluated the efficacy and safety profile of low-dose (4-5 mcg/kg) intrathecal morphine for postoperative pain management after various surgical procedures in children.

METHODS

We reviewed the pain management service database and the medical records of patients who received low-dose intrathecal morphine for postoperative analgesia at The Children's Hospital of Philadelphia between October 2003 and March 2006. Patients had been prospectively followed for 24-48 h after the intrathecal morphine administration.

RESULTS

The medical records of 187 patients were examined. The mean age was 5.6 +/- 5.1 yr (median 4.0, interquartile range [IQR] 1.0-10.0). The median maximum pain score during the first 24 h in patients evaluated by the FLACC score and in those evaluated by the numeric verbal rating scale, was 0 (IQR 0-3) and 0 (IQR 0-4), respectively. The mean time to first rescue opioid was 22.4 +/- 16.9 h (range: 0-48 h, 95% CI: 19.9-24.8 h). During the first 24 h after surgery, 70 patients (37%) did not receive any opioids (oral or IV). Of the 117 patients who received opioids, 59 (50%) were managed with oxycodone only. Pain was managed with ketorolac in 33% of patients, either alone (11%) or in combination with IV or oral opioids (22%). The incidence of nausea or vomiting, pruritus, and urinary retention was 32%, 37%, and 6% respectively. One patient had transient postdural puncture headache, while two patients received supplemental oxygen beyond the first 60 postoperative minutes to manage occasional episodes of hypoxemia. No severe respiratory depression requiring assisted ventilation or naloxone administration was observed.

CONCLUSION

We conclude that low-dose intrathecal morphine in the pediatric population can be a useful and safe adjunct for postoperative analgesia.

Prevalence and predictors of psychosocial morbidity in patients with chronic pruritic skin diseases

BACKGROUND

Itch is a major symptom of many skin diseases and causes patients considerable distress, adversely affecting quality of life. Feelings of helplessness and lack of control can influence the perceived itch and psychosocial complaints.

OBJECTIVES

To determine the prevalence of psychosocial morbidity among patients with pruritic skin diseases, and the influence of itch-related variables, coping strategies, and demographic variables on psychosocial morbidity.

PATIENTS AND METHODS

One hundred and sixty-eight patients with pruritic skin diseases from five hospitals in the Netherlands participated in the study. Skin-related psychosocial morbidity was measured with the Adjustment to Chronic Skin Diseases questionnaire (ACS); general psychosocial morbidity was measured with the Symptom Checklist-90 (SCL-90). The frequency and intensity of itching and scratching was recorded in diaries. Itch-related coping was measured with the Itching Cognitions Questionnaire (ICQ). Multiple regression analyses were used.

RESULTS

Patients with pruritic skin diseases had higher SCL-90 scores than a healthy Dutch population. All patients had psychosocial complaints as measured with the ACS. Thirty-nine per cent of the variance in skin-related psychosocial morbidity was explained by 'catastrophizing and helpless coping'; another 11% was explained by itching and scratching. Age and sex together explained another 10%. The frequency of itching and scratching (11%), 'catastrophizing and helpless coping' (19%) and skin-related psychosocial morbidity (10%) explained the variance in general psychosocial morbidity.

CONCLUSIONS

Patients with a pruritic skin disease have a high level of psychosocial morbidity. Catastrophizing and helpless coping are the most important predictors of psychosocial morbidity, with itching, scratching and demographic variables having a limited influence.

Extrahepatic manifestations of cholestatic liver diseases: pathogenesis and therapy

Pruritus, fatigue, and metabolic bone disease are frequent complications of cholestatic liver diseases, which can be quite distressing for the patient and can considerably reduce the quality of life. The molecular pathogenesis of these extrahepatic manifestations of cholestasis is poorly understood, and hypotheses to explain these symptoms are being discussed. This article provides treatment recommendations for the complications of cholestasis based on putative pathomechanisms and summarizes recent experimental and clinical data involving management options.

Extrahepatic manifestations of cholestatic liver diseases: pathogenesis and therapy

Pruritus, fatigue, and metabolic bone disease are frequent complications of cholestatic liver diseases, which can be quite distressing for the patient and can considerably reduce the quality of life. The molecular pathogenesis of these extrahepatic manifestations of cholestasis is poorly understood, and hypotheses to explain these symptoms are being discussed. This article provides treatment recommendations for the complications of cholestasis based on putative pathomechanisms and summarizes recent experimental and clinical data involving management options.

Antipruritic and antiemetic effect of epidural droperidol

BACKGROUND AND OBJECTIVES

This study was designed to investigate whether single epidural droperidol or continuous epidural droperidol inhibit pruritus and postoperative nausea and vomiting induced by postoperative continuous epidural fentanyl administration, and to identify the optimal method of administering epidural droperidol.

METHODS

120 ASA I-II patients undergoing subtotal gastrectomy with general anaesthesia combined with epidural anaesthesia were randomly allocated into three groups: control (no droperidol), single injection (droperidol 2.5 mg) and continuous group (droperidol 2.5 mg 2 day(-1)). Postoperatively the frequency and severity of pruritus and postoperative nausea and vomiting in all groups were compared during 48 h.

RESULTS

The frequency and severity of pruritus was significantly lower in both single injection and continuous groups than control group after epidural fentanyl administration (P < 0.05). The frequency and severity of postoperative nausea and vomiting was significantly lower in single injection group than control group after epidural fentanyl administration (P < 0.05).

CONCLUSION

Epidural continuous droperidol is effective for reducing pruritus, and single epidural droperidol injection is effective for reducing pruritus and postoperative nausea and vomiting induced by postoperative continuous epidural fentanyl analgesia.

The role of intrathecal drugs in the treatment of acute pain

Intrathecal opioids are widely used as useful adjuncts in the treatment of acute and chronic pain, and a number of non-opioid drugs show promise as analgesic drugs with spinal selectivity. In this review we examine the historical development and current use of intrathecal opioids and other drugs that show promise for treating pain in the perioperative period. The pharmacology and clinical use of intrathecal morphine and other opioids is reviewed in detail, including dosing guidelines for specific surgical procedures and the incidence and treatment of side effects associated with these drugs. Available data on the use of non-opioid drugs that have been tested intrathecally for use as analgesics are also reviewed. Evidence-based guidelines for dosing of intrathecal drugs for specific surgical procedures and for the treatment of the most common side effects associated with these drugs are presented.

Life-threatening blood loss from scratching provoked by pruritus in the bulky perineal nevocytoma variant of giant congenital melanocytic nevus in a child

We describe a 3-year-old girl with intractable, debilitating pruritus associated with a giant congenital melanocytic nevus, resulting in life-threatening anemia from extensive bleeding skin excoriations. Multiple conventional oral and topical antipruritic medications failed to provide relief, but the patient was successfully treated with the selective serotonin 5-hydroxytryptamine type 3 inhibitor ondansetron, suggesting a serotonin-related mechanism to her pruritus.

Pharmacologic advances in the systemic treatment of itch

Itch is propagated by complex mechanisms located both peripherally and within the central nervous system. For decades, novel treatments of itch have been slow to emerge, with the majority of focus on antagonism of histamine. Recently, with a new understanding of the pathophysiology of itch transmission, new treatment strategies have been elucidated. Opiate receptor antagonists, antidepressants, antiepileptics, and thalidomide are currently available therapeutic options that have benefited many patients with variegated sources of itch. In addition, research focused on the neuromediators of itch transmission has led to the development of novel targets for itch reduction and great potential for future therapies.

Some historical and epistemological remarks on itch and pruritus

Although very common, itch is very hard to describe. It can be considered as one of the most distressing physical sensations we experience. Going back historically, old Latin and Greek writers cited it in ancient papers. So, etymology is of central importance to investigation in the field of itch, regarding the formation of a word with antique origins and different meanings. Scientists, poets, and painters for centuries tried to describe and represent itch. The study of their work reveals the development of the itch's significance. Today, a clinically relevant distinction defines pruritus and itch as two different sensations. Moreover, some terms like hyperknesis, alloknesis, atmoknesis, protopathic itch, and epicritic itch are described to approaching the complexity of this sensation and are utilized in clinical practice.

A controlled trial of ondansetron in the pruritus of cholestasis

BACKGROUND

In patients with pruritus of cholestasis, response to conventional drug treatment may be unsatisfactory. Activation of 5-hydroxytryptamine receptors on dermal sensory nerve-endings plays a role in the perception of pruritus. The 5-hydroxytryptamine(3) receptor antagonist, ondansetron, has been used in the treatment of pruritus of cholestasis, but there are few controlled data.

AIM

To determine whether ondansetron is effective in treating the pruritus of cholestasis.

METHODS

A total of 19 patients with resistant pruritus were randomized, double blind, to receive either ondansetron 8 mg or placebo as a single intravenous bolus, followed by oral ondansetron 8 mg or placebo twice daily for 5 days. Patients' perception of pruritus was recorded hourly using a visual analogue scale, and scratching activity measured by means of a piezo-electric crystal attached to the fingernail.

RESULTS

Mean pruritus score using visual analogue scale and scratching activity were reduced on the first treatment day compared with baseline in both the ondansetron and placebo groups (P < 0.05), but there were no significant differences in mean pruritus perception or scratching activity between the two groups.

CONCLUSION

Ondansetron was of no benefit in this group of pruritic patients during short-term treatment.

Mirtazapine for reducing nocturnal itch in patients with chronic pruritus: a pilot study

Nocturnal pruritus is a significant problem for patients with inflammatory skin diseases and many systemic diseases. The oral therapies currently available have a limited effect. We present an open, uncontrolled pilot study of 3 patients with inflammatory skin diseases and severe nocturnal pruritus who underwent treatment with mirtazapine (Remeron), a noradrenergic and specific serotonergic antidepressant. Mirtazapine is a safe medication without serious side effects and may be an effective alternative for the treatment of nocturnal pruritus.

The Role of Central μ Opioid Receptors in Opioid-Induced Itch in Primates

Pruritus (itch sensation) is a significant clinical problem. The aim of this study was to elucidate the roles of opioid receptor types and the site of action in opioid-induced itch in monkeys. Observers who were blinded to the conditions counted scratching after administration of various drugs. Intravenous (i.v.) administration of mu opioid receptor (MOR) agonists (fentanyl, alfentanil, remifentanil, and morphine) evoked scratching in a dose- and time-dependent manner. However, the kappa opioid agonist U-50488H [trans-(+/-)-3,4-dichloro-N-methyl-N-(2-[1-pyrrolidinyl]-cyclohexyl)-benzeneacetamide] and delta opioid agonist SNC80 [(+)-4-[(alphaR)-alpha-[2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl]-3-methoxybenzyl]-N,N-diethylbenzamide] did not increase scratching. Intrathecal (i.t.) administration of peptidic MOR agonist [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAMGO, 0.00032-0.01 mg) evoked scratching, but i.v. DAMGO (0.01-1 mg/kg) did not increase scratching. A similar difference between i.t. and i.v. effectiveness was seen with morphine. Antagonist studies revealed that i.v. administration of an opioid receptor antagonist (naltrexone, 0.0032-0.1 mg/kg) dose dependently attenuated scratching induced by i.v. fentanyl (0.018 mg/kg) or morphine (1 mg/kg). However, a peripherally selective opioid antagonist (quaternary naltrexone, 0.0032-0.32 mg/kg) did not block i.v. fentanyl- or morphine-induced scratching. Moreover, a histamine antagonist (diphenhydramine, 0.1-10 mg/kg), failed to attenuate scratching induced by i.t. morphine (0.032 mg) or i.v. morphine (1 mg/kg). Pretreatment with a selective MOR antagonist (clocinnamox, 0.1 mg/kg), but not kappa or delta opioid antagonists (nor-binaltorphimine or naltrindole), blocked i.t. morphine-induced scratching. Together, these data suggest that MOR, not other opioid receptor types or histamine, mediates scratching evoked by opioid analgesics. More important, this study provides in vivo pharmacological evidence that activation of central MOR plays an important role in opioid-induced itch in primates.

c-fos expression in superficial dorsal horn of cervical spinal cord associated with spontaneous scratching in rats with dry skin

Using a dry skin model in rats, we assessed spontaneous itch-related scratching behavior and associated c-fos expression in the superficial dorsal horn of the spinal cord. The number of spontaneous bouts of hind limb scratching directed toward the nape of the neck was significantly higher after 5 days of topical application of acetone-diethylether-water (AEW) compared to pre-treatment levels or to control animals treated with water only. In AEW-treated animals, neurons expressing Fos-like immunoreactivity (FLI) were observed in superficial laminae of the dorsal horn at C3-C5 levels. There was a significant, positive correlation between the number of neurons in lamina I expressing FLI and the number and cumulative duration of spontaneous scratching bouts. These results suggest that this model may be useful to assess mechanisms of dry skin pruritus, and that lamina I neurons are activated as a consequence of itching and/or scratching in this model.

A comparison of dexamethasone, ondansetron, and dexamethasone plus ondansetron as prophylactic antiemetic and antipruritic therapy in patients receiving intrathecal morphine for major orthopedic surgery

In a prospective, double-blinded, randomized trial, we evaluated the efficacy of IV (a) dexamethasone 8 mg, (b) ondansetron 8 mg, and (c) dexamethasone 8 mg plus ondansetron 4 mg for the prevention of postoperative nausea, vomiting (PONV), and pruritus in 130 (ASA physical status I to III) patients undergoing elective major orthopedic surgery after spinal anesthesia with hyperbaric 0.5% bupivacaine and intrathecal morphine. After spinal anesthesia, patients were randomized to one of three groups. Failure of PONV prophylaxis in the 24-h postoperative period occurred more frequently in patients who received dexamethasone alone (29 of 40; 73%) compared with those who received either ondansetron alone (23 of 47; 49%) (P = 0.02) or dexamethasone plus ondansetron together (19 of 43; 44%)(P = 0.01). There was no difference in the incidence of failure of prophylaxis of pruritus (70%, 72%, and 70% in dexamethasone 8 mg, ondansetron 8 mg, and dexamethasone 8 mg plus ondansetron 4 mg, respectively) (P > 0.1) in the 24-h postoperative period. We conclude that the administration of dexamethasone 8 mg with ondansetron 4 mg has no added benefit compared with ondansetron 8 mg alone in the prophylaxis of PONV and pruritus.

IMPLICATIONS

Postoperative nausea and vomiting (PONV) and pruritus are common side effects after spinal opioid administration. In this study, dexamethasone 8 mg plus ondansetron 4 mg was as effective as ondansetron 8 mg. The administration of dexamethasone alone was associated with a frequent incidence of PONV, demonstrating a lack of efficacy. This has important cost implications.

Neuraxial opioid-induced pruritus: a review

When intrathecal and epidural opioids are administered, pruritus occurs as an unwanted and troublesome side effect. The reported incidence varies between 30% and 100%. The exact mechanisms of neuraxial opioid-induced pruritus remain unclear. Postulated mechanisms include the presence of an "itch center" in the central nervous system, medullary dorsal horn activation, and antagonism of inhibitory transmitters. The treatment of intrathecal opioid-induced pruritus remains a challenge. Many pharmacological therapies, including antihistamines, 5-HT(3)-receptor antagonists, opiate-antagonists, propofol, nonsteroid antiinflammatory drugs, and droperidol, have been studied. In this review, we will summarize pathophysiological and pharmacological advances that will improve understanding and ultimately the management of this troublesome problem.

Deletion of the preprotachykinin A gene in mice does not reduce scratching behavior elicited by intradermal serotonin

Itch is thought to be signaled by a sub-population of pruritogen-selective C-fiber primary afferents. To assess a possible role of the neuropeptide, substance P (SP), in the central neurotransmission of itch, we investigated itch-related scratching behavior elicited by intradermal injection of serotonin (5-HT; 0.03-0.3%) in normal mice (wildtype, WT) and knockout mice (KO) with deletion of the preprotachykinin A gene. Both KO and WT groups showed dose-related increases in the number of 5-HT-evoked scratching bouts over the 44 min observation period. There were no significant differences in the numbers or durations of scratching bouts between WT and KO groups, although KO mice exhibited numerically more spontaneous and 5-HT-evoked scratching. It is concluded that either SP is not involved in the central neurotransmission of itch-related scratching behavior in this strain of mouse, or that compensatory developmental changes in the KO mice allow itch-related signaling.

Mirtazapine for pruritus

Pruritus is a relatively rare but distressing symptom associated with cholestasis, renal failure, and malignancies. Medical management recently has included the use of ondansetron and paroxetine. We report four patients whose pruritus responded to mirtazapine.

Pruritus - Pathophysiologie, Klinik und Therapie - Eine Ubersicht. Pruritus - pathophysiology, clinical features and therapy - an overview

Pruritus is an unpleasant sensory perception of the skin associated with the desire to scratch. As a physiological nociception, pruritus leads to the removal of harmful agents such as parasites and plants from the skin surface. More often, pruritus occurs as a severe and therapy-refractory symptom of various underlying dermatological and systemic diseases. Comparable to chronic pain, chronic pruritus worsens the general condition and may lead to physical and psychological exhaustion. Until the 1990s, pruritus had been regarded as an incomplete pain sensation. Only recently, itch was defined as a separate, pain-independent sensation with its own mediators, spinal neurons and cortical areas. These observations led to the development of new therapeutic modalities. This paper gives an overview of itch pathophysiology, clinical types and therapies.

Extrahepatic manifestations of cholestasis

Pruritus, fatigue and metabolic bone disease represent three major extrahepatic manifestations of chronic cholestatic liver disease that considerably affect the patient's quality of life. The present article reviews pathogenetic aspects of and current therapeutic approaches to extrahepatic manifestations of cholestatic liver disease. Pathogenesis of pruritus of cholestasis remains poorly understood. The involvement of putative peripherally acting pruritogens, such as bile acids or endogenous opioids, is being discussed. More recently, central mechanisms, including an increased central opioidergic tone and pertubations in the serotonergic system have been proposed. Treatment of the underlying disease is beneficial also for the control of cholestasis-associated pruritus. Current therapeutic recommendations include ursodeoxycholic acid, cholestyramine, rifampicin and opioid antagonists. Liver transplantation may be indicated when severe pruritus is refractory to medical treatment. Fatigue is being recognized as the most frequent and one of the most disabling complaints in chronic cholestasis. Fatigue is presumably of central origin and its association with other neuropsychiatric disorders (e.g. depression, obsessive-compulsive disorders) is consistent with defective central neurotransmission. No specific therapies are currently available and a healthy lifestyle, regular sleep and avoidance of unnecessary stress and other precipiting factors are recommended. Antidepressant therapy may be warranted in selected patients. Osteopenia and osteoporosis are common in chronic cholestatic liver disease, whereas osteomalacia is rare. The pathophysiology of cholestasis-associated metabolic bone disease is regarded as multifactorial. Therapeutic recommendations include regular exercise, calcium and vitamin D supplementation in late stage disease, hormone replacement therapy in postmenopausal women and bisphosphonates.

Pruritus in systemic disease: mechanisms and management

Pruritus is the most common symptom of skin disease. Even in the absence of primary cutaneous findings, severe and extensive pruritus often is associated with systemic disease. This review considers briefly the physiology of pruritus and discusses the various systemic diseases often accompanied by this bothersome symptom. In addition to exploring the possible mechanisms and potential therapies of itching in selected disorders, this review presents general recommendations for evaluating patients with unexplained pruritus and management guidelines for alleviating their discomfort.

Pruritus in cancer patients

Pruritus is an uncommon symptom in cancer patients but can often be difficult to treat. The pathogenesis is complex and is not fully understood although there is evidence of involvement of a number of mediators from which treatment options are developing. In cancer patients pruritus may be directly related to the cancer, indirectly related (e.g. cholestasis) or associated with treatment. It is not always possible to treat the underlying cause of the pruritus in these patients, or desirable to stop treatments that may contribute and in these cases we must address the pruritus itself. The treatment of pruritus is a developing area, and helpful research is slowly emerging. The evidence base is not extensive but some high quality studies exist. This short paper briefly discusses the pathogenesis, causes, effects and treatment options for pruritus in cancer patients.