#Causes of hells itch skin#
There is nothing wrong with the skin itself, at least until it's been scratched. Systemic diseases may cause generalised pruritus. Scratching a localised itch may lead to lichen simplex, prurigo or prurigo nodularis. Dermatomal: herpes zoster (shingles) during the recovery phase.Neuropathic causes of localised pruritus without primary rash ( cutaneous dysaesthesia) Genitals: vulvovaginal Candida albicans infection, lichen sclerosus.Hands: pompholyx, irritant and/or allergic contact dermatitis.Scalp: seborrhoeic dermatitis, head lice.Neuropathic itch is sometimes associated with reduced or absent sweating in the affected area of skin. Neuropathic pruritus is due to compression or degeneration of nerves in the skin, on route to the spine or in the spine itself. It can occur in association with a primary rash (eg dermatitis) or may occur because of hypersensitive nerves in the skin ( neuropathic pruritus). Localised pruritus is pruritus that is confined to a certain part of the body. What causes pruritus?Ĭauses of pruritus can be classified under 5 main headings.
The way scratching stops itching has been explained by an interaction with pain pathways within the dorsal horn of the spinal cord. Patients with chronic pruritus usually have both peripheral and central hypersensitisation (a heightened reaction) which means they tend to overreact to noxious stimuli which normally inhibit itch (such as heat and scratching) and also misinterpret non-noxious stimuli as an itch (eg, light touch).These areas overlap with those activated by pain. These connect with secondary neurons which cross the opposite side of the spinothalamic tract and ascend to parts of the brain involved in sensation, emotion, reward and memory.The itch signal is transmitted mainly through small, itch-selective C-fibres in the skin in addition to histamine-triggered and non-histaminergic neurons.Mechanisms underlying pruritus are complex. Itch, like pain, can originate anywhere along the neural itch pathway, from the central nervous system (brain and spinal cord) to the peripheral nervous system and the skin.
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