Patients with localized itching or paraesthesiae usually attribute their puzzling symptoms
to the skin. But sensory neuropathy may cause itch or contribute to itch in conditions
such as chronic renal failure.
Symptoms :
• Burning, tingling, stinging, hypoaesthesia, or hyperalgesia.
• Distribution: distal symmetrical (polyneuropathy), individual nerve territories
(mononeuritis multiplex, e.g. vasculitis), dermatomal (radiculopathy), or one side of the
body (central).
• Evidence of rubbing (lichen simplex) or scratching.
• Sensory loss—check light touch, vibration, proprioception, pain, and temperature (use a
cold tuning fork). Asteatotic eczema may develop in hypoaesthetic skin.
• Motor/autonomic dysfunction in the distribution of sensory disturbance.
Causes of generalized neuropathic itch/pain
• Small-fibre neuropathy (Aδ and C-fibres), e.g. diabetes, amyloidosis, SLE, HIV. Fabry
disease (Aδ fibres)—rare.
• Centrally driven neuropathic itch has been described in association with brain tumours,
strokes, spinal tumours, and multiple sclerosis.
Causes of localized neuropathic itch
• Peripheral nerve or root impingement may underlie puzzling conditions such as notalgia
paraesthetica and perhaps brachioradial pruritus.
• Herpes zoster may cause itch, as well as pain.
• Trigeminal trophic syndrome.
• Keloids may be associated with neuropathic itch, but the cause is uncertain. Pain fibres
may be trapped in proliferating collagen.