Neurocutaneous disease: Cutaneous neuroanatomy and mechanisms of itch and pain.

Few sources of information exist regarding cutaneous innervation and how to apply this basic neurologic science to the clinical treatment of itch, as often performed on a daily basis by dermatologists. We address the types of nerve fibers that innervate the skin and their different components and discuss the similarities and differences between itch and pain. We hope that increased knowledge of this topic will improve the recognition and treatment of neuropathic itch.

Neurocutaneous disease: Neurocutaneous dysesthesias.

Dysesthesia is a generic term for a cutaneous symptom--such as pruritus, burning, tingling, stinging, anesthesia, hypoesthesia, tickling, crawling, cold sensation, or even pain--without a primary cutaneous condition in a well-defined location that is often caused by nerve trauma, impingement, or irritation. There are multiple types of dysesthesias depending on the body location and the nerves involved. While location, exact symptoms, and etiologies might vary, the underlying theme is that these conditions are of neurologic origin and have dermatologic consequences. For many of these conditions, the symptoms are localized to the skin, and patients frequently present to the dermatologist; it is important for dermatologists to be knowledgeable about these symptoms and their underlying causes. In part II of this continuing medical education review, the primary diagnoses associated with underlying cutaneous dysesthesias will be explored, including scalp dysesthesia, trigeminal trophic syndrome, meralgia paresthetica, notalgia paresthetica, and brachioradial pruritus. The typical demographics in terms of symptoms, location, and patient populations will be discussed in addition to the specific etiologies, workups, and possible treatment options.