A molecule that binds to Substance P and is associate with many biological functions including itch. A molecule that binds to the neurotransmitter glutamate and is associated with many biological functions. A group of interventions in which pharmaceutical products are not their main active component e. A diverse group of ion channels characterised by their low discrimination between many essential elements and toxic cations function in the absorption of nutrients. A chronic sensory neuropathy, secondary to the involvement of the spinal nerves, is a characteristic symptom of asymmetric dorsal upper to mid back pruritus.
Other symptoms may include pain, hyperaesthesia, paraesthesia, and hyperpigmentation of the affected area.
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Excessive accumulation of fluid, mainly water, in superficial parts of the body. Oedema may be local, as at the site of an injury, or generalised. A molecule that blocks the receptor, preventing the body from having a response to drugs, such as heroin. They are used in opiate addiction.
Type of skin disease that is characterised by small 1 to 2 mm bumps and blisters, sometimes with background redness and scales, localised to the skin around the mouth and nostrils.
A group of interventions in which the main component is the use of pharmaceutical products e. Subfamily of proteins that are predominantly found in inflammatory cells and may play a role in the regulation of cellular immunity. Treatment of disease by exposure to light, especially by variously concentrated light rays or specific wavelengths. A condition in which there is pain in a region of the body, which occurs due to damage to a peripheral nerve, caused by the reactivation of the varicella zoster virus. A membranous sac located within the presynaptic membrane of an axon terminal and containing a neurotransmitter.
A class of fatty acids with an important function as mediators of inflammation and immune response. Itch that arises from a primary skin disease, as opposed to an itch that is triggered by a systemic or neurological cause. A name given to physical illnesses that are believed to arise from emotional or mental stressors, or from psychological or psychiatric disorders. A term that is restricted to those illnesses that do have a clear physical basis, but where it is believed that psychological and mental factors also play a role.
It results in redness, papules, and pustules, swelling, and small and superficial dilated blood vessels. A study of serum for the diagnostic identification of antibodies formed in response to an infection, other foreign proteins, or to one's own proteins. A monoamine neurotransmitter.
Who gets chronic pruritus of unknown origin?
Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, blood platelets, and the central nervous system CNS of animals, including humans. An itch disorder where psychological factors play an evident role in the triggering, intensity, aggravation, or persistence of the pruritus. An uncontrolled growth cancerous of abnormal cells, arising from the squamous cells in the epidermis.
Compounds that lower the surface tension or interfacial tension between two liquids, between a gas and a liquid, or between a liquid and a solid. Large family of peptides that function as neurotransmitters in the central and peripheral nervous systems. A type of T cell that plays an important role in the immune system against extracellular parasites.
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The use of electric current produced by a device to stimulate the nerves for therapeutic purposes. It is activated by cold temperature below 25 degrees celsius. Proteins that are found in the central nervous system and in the peripheral nervous system and are involved in the transmission and modulation of pain. A group of nerve fibre of sensory neurons that carries the tactile sensation. They are thickly myelinated.
A group of nerve fibre of sensory neurons that carries cold, pressure, and some pain signals. They are thinly myelinated. The main end product of the metabolism of proteins and amino acids, found abundantly in urine and fecal matter. A condition resulting from kidney disease in which there is retention in the bloodstream of urea, normally excreted in the urine.
A type of pruritus caused by the accumulation of organic waste products from the kidneys in the presence of kidney insufficiency. Causing or related to actions that alter the diameter of a blood vessel dilating or constraining it. A type of regular and rapid heart rate that arises from improper electrical activity in the ventricles of the heart. A class of transmembrane proteins that forms ion sodium channels that are activated by changes in the electrical membrane potential near the channel. Pruritus itching is the predominant symptom of many diseases, and can best be described as a sensation that leads to the desire to scratch Goldsmith When the origin of pruritus is known, its management is straightforward, as long as there is an effective treatment for the disease that causes it.
However, the treatment of pruritus of unknown cause PUC , which is the focus of this review, is particularly difficult.
Pruritus is a common and distressing symptom, which fluctuates in intensity over an often long period of time. Effective relief of chronic itching can be difficult to achieve Stander The prognosis of pruritus depends on the underlying diagnosis see 'Causes of pruritus'.
Pruritus may originate in the skin or in the central nervous system Yosipovitch It occurs in a diverse range of skin diseases, and may appear as a prominent feature of extracutaneous disorders, such as systemic, neurologic, and psychiatric diseases. Pruritus can be classified, according to its duration, as acute lasts less than six weeks or chronic, if it lasts longer than six weeks Stander Itch can be classified as generalised all over the body or localised e. However, to date, there is no standardised classification of chronic pruritus Stander The International Forum for the Study of Itch IFSI has proposed a classification system for chronic pruritus and suggested three groups of conditions:.
The classification of the IFSI also describes categories of underlying pruritogenic diseases, as follows:. Category I: Dermatological diseases. Chronic pruritus arising from diseases of the skin, such as psoriasis, atopic dermatitis, dry skin, scabies and urticaria. Chronic itch arising from diseases of the internal organs, such as the liver or kidney, or diseases of the blood. This category also includes metabolic diseases or side effects of drugs. Category III: Neurological. Pruritus arising from diseases or disorders of the central or peripheral nervous system, such as nerve damage, nerve compression, or nerve irritation.
Category VI: Other pruritus of undetermined origin, or pruritus of unknown cause Stander The initial clinical approach in people with pruritus includes a medical history and physical examination. Further investigations to identify the underlying causes of pruritus might include: a complete blood count, ferritin levels, a chest radiograph, measurements of hepatic, renal, and thyroid function, serology for sexually transmitted infections, and when appropriate, tests to identify endemic parasitic infections.
However, in some cases the underlying cause remains unclear, and is called pruritus of unknown cause PUC Stander ; Millington The pathophysiology of pruritus is only partially understood. The thick myelinated Type II sensory fibres transmit tactile sensation, whereas the thinly myelinated A delta and unmyelinated C polymodal fibres are mainly involved in conducting thermal, pain, and itch sensation Lawson These neurons appear to be located more superficially, and are more sensitive to pruritogenic substances than pain receptors.
Neurotransmitters for these nerves include histamine, calcitonin gene—related peptide, neuropeptide substance P, serotonin, bradykinin, proteases e. Impulses are transmitted from the dorsal root ganglion to the spinothalamic tract, and eventually to the thalamus Matterne Neurogenic and systemic itch usually affects organs other than skin; however, there is no current evidence showing any neuronal pathology, though itch could be transmitted via the central nervous system.
The cause or mechanism of psychogenic itch is unclear; however, it stems from psychogenic disorders. In contrast, neuropathic itch is due to damage of peripheral or central sensory neurons, as it leads to the activation of pruritic neurons without any cutaneous stimuli. Lastly, pruritoceptive itch may originate in diseases of the skin Garibyan There are other mediators and receptors possibly involved in the physiopathology of pruritus.
These include:. Substance P tachykinin : this is a neuropeptide released from mast cells.
Identification of Viruses Associated With Diseases of Unknown Cause
The NKR1 receptor has been implicated in the induction of itch in rats. TRPV1 is expressed on sensory neurons, keratinocytes, and endothelial and mast cells. The prevalence of chronic pruritus increases with age Rea ; it might not be found in children, although prevalence studies in this population are lacking Weisshaar The condition may be more common in women than in men Matterne ; Stander The prevalence of pruritus of unknown cause in individuals with generalised pruritus range from 3.
Chronic pruritus is a frequent symptom, often intractable, and is associated with a reduced quality of life, described as being as debilitating as chronic pain Kini Deranged sleep patterns and mood disturbances, including anxiety and depression, are common, and may exacerbate the itching Kopyciok ; Zachariae Management options for pruritus of unknown cause may include a wide variety of treatments.
Standard treatment may vary across different countries and settings; however, healthcare professionals usually recommend the use of emollient or cooling creams, and the avoidance of irritating products for the skin, along with the use of topical products e. Pruritus of unknown cause is a challenging condition to treat, due to its unidentified etiology. The course of PUC is variable in intensity and frequency of symptoms over time.
Indeed, no sign or symptom at its initial presentation could accurately serve as a predictor of pruritus with a systemic etiology Yosipovitch Since the course of pruritus of unknown cause is variable, most of the treatments are used in a variable regime as well. It is important to monitor interactions between interventions given simultaneously, acknowledging these might be more relevant with systemic pharmacological agents that affect the central nervous system, e.
Chronic Kidney Disease of Unknown Cause in Agricultural Communities.
Emollients, colloquially known as moisturising creams, are commonly used to prevent or treat xerosis dry skin , and may be used to treat associated pruritus Simpson Emollients should be applied several times a day, especially if xerosis is present. Topical urea has been shown to have effective emollient and keratolytic effects on xerosis, and interfere with the development of pruritus Pan Higher concentrations have keratolytic properties, which would not be desirable for pruritus.
As with most emollients, urea is relatively safe, but may cause contact dermatitis Yosipovitch Most emollients rarely result in any side effects; however, redness, burning, or irritation may occur Grundmann Neutral or mild pH soaps maintain the slightly acidic pH of the skin mantle.
Soaps are generally used to clean the area of dirt. They should be used once a day, in a sufficient amount to cover the entire body Baranda Any disruption of the stratum corneum or the skin pH predisposes the skin to environmental irritants.