Chronic Pruritus in the Absence of Specific Skin Disease: An Update on Pathophysiology, Diagnosis, and Therapy

Nicoletta Cassano; Gianpaolo Tessari; Gino A. Vena; Giampiero Girolomoni

Disclosures

Am J Clin Dermatol. 2010;11(6):399-411. 

In This Article

Neuropathic Itch: Brachioradial Pruritus and Notalgia Paresthetica

Localized recalcitrant pruritus without skin changes can be secondary to neurologic causes. In particular, peripheral nerve damage is implicated in anogenital pruritus secondary to lumbosacral radiculopathy,[25] and may be involved in brachioradial pruritus,[26] and notalgia paresthetica.[27]

Brachioradial pruritus is usually localized on the dorsolateral aspect of the upper arm and/or forearm, often occurring in fair-skinned people living in the tropics or subtropics. The ice-pack sign (relief with the application of ice packs) is nearly pathognomonic for this condition.[28] The causative pathophysiologic basis may be neurologic damage from either the peripheral nerves (e.g. solar radiation, local injury) or from the central sensory pathways (e.g. cervical spine disease with spinal root or cord compression). The role of sunlight as a trigger in some patients, along with the involvement of photo-exposed areas of the forearm, especially in the summer, and the association with signs of actinic damage, have contributed to the concept of brachioradial pruritus as a possible photo-induced condition.[29]

Notalgia paresthetica is a sensory neuropathy involving the dorsal spinal nerves. Several factors responsible for notalgia paresthetica have been hypothesized: increased dermal innervation, viscerocutaneous reflex mechanism, chemical neurotoxicity, and spinal nerve injury caused by trauma or entrapment. Patients with notalgia paresthetica have a characteristic hyperpigmented patch on their back, usually in the interscapular region.[27,29,30] Meralgia paresthetica, an entrapment neuropathy of the lateral femoral cutaneous nerve, may present with prominent numbness, paresthesia, and pain, and more rarely with true itch, in the anterolateral thigh.[31]

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