Brachioradial pruritus

What is brachioradial pruritus?

Brachioradial pruritus describes a localised cutaneous dysaesthesia, with an itch, burning, stinging, tingling and changed sensation on either or both arms.

The presentation is usually an itch without a rash; however, scratching and rubbing can result in secondary changes.

What is the 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, it has been suggested that 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 an 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 or dysaesthesia may also expand to involve other dermatomes.

What are the clinical features of brachioradial pruritus?

The most commonly affected area in brachioradial pruritus 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 — it itches but there is no rash. Visible changes may arise from rubbing and scratching the affected area. These include:

• Purpura and ecchymoses
• Hyperpigmentation and hypopigmentation
• Lichen simplex (a type of localised eczema)
• Prurigo 
• 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 shoulders, neck, back, lower legs, and other sites.

What is the treatment of brachioradial pruritus?

Treatment of brachioradial pruritus is not always successful. Effective measures include the following:

• Cooling lotions as required (camphor and menthol)
• Physiotherapy and neck exercises
• Cervical spine manipulation 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 antidepressant medication at night
• An anticonvulsant agent such as gabapentin and pregabalin.
• Topical ketamine has been reported to provide rapid relief.