Brachioradial pruritus is a condition where itch, burning, stinging, tingling and/or changed sensation arise in the areas of skin on either or both arms. The most commonly affected area is the mid-arm, but forearms and upper arms can also be affected. People often apply ice packs to the affected areas in an attempt to gain relief from the unpleasant symptoms.
The affected skin may appear entirely normal. Visible changes may arise from rubbing and scratching the affected area. These include purpura and ecchymoses (bruises), hyperpigmentation (brown marks), hypopigmentation (white marks), lichen simplex (a type of eczema), prurigo and scarring. There may be changed sensation when this is tested for with pinprick, cotton wool or heat and cold. Reduced or absent sweating may be noted in the affected area.
Brachioradial pruritus occasionally expands to involve the lower legs or generalises to other sites.
Cause of brachioradial pruritus
Brachioradial pruritus is due to a neuropathy of the small C fibre nerves. As brachioradial pruritus appears to be more often reported in sunny climates than in cooler areas, long term sun exposure may cause damage to the nerve fibres within the skin
In many cases, brachioradial pruritus is clearly due to nerve damage or radiculopathy in the cervical spine (neck), when it may be due to:
- Cervical vertebral osteoarthritis
- Cervical rib
- Cervical spinal tumour
- Nerve compression or myelopathy for any other reason
Prolonged compression of spinal itch-transmitting neurones can activate central sensitisation processes, affecting the A fibres. These convey light touch and pinprick symptoms, and stimulation can result in sensitive or painful skin with exaggerated response to light touch or pinprick (hyperaesthesia, hyperalgesia).
When compressed nerves atrophy (shrink), C fibres in the skin can proliferate.
A localised neuropathic itch may also expand to involve other dermatomes.
Treatment of brachioradial pruritus
Treatment is not always successful. Effective measures include the following:
- Cooling lotions as required (camphor and menthol).
- Cervical spine manipulation. This must be done by an appropriately qualified health professional.
- Electrical cutaneous nerve field stimulation.
- Capsaicin cream – this depletes nerve endings of their chemical transmitters.
- Local anaesthetic creams.
- Amitriptyline or other oral tricyclic taken at night.
- Anticonvulsant agents including gabapentin and pregabalin.
- Topical ketamine and amitriptyline has been reported to provide rapid relief