Chronic itch afflicts millions of people, but little is known about the underlying mechanisms
For most people, itch is an occasional, short-lived annoyance, provoked by a run-in with bloodthirsty insects or poisonous plants. But for Mary Ellen Nilsen, itchiness became a life-altering experience. In 1998, at age 38, Nilsen had a shingles outbreak, a resurgence of the chickenpox virus. Antiviral drugs cleared up the painful shingles rash on her face and scalp, but a ferocious itch took its place. "It was relentless," Nilsen says. Over a 13-month period, Nilsen scratched and scratched, despite her best efforts not to and despite her horror at the growing lesions she saw in the mirror. At the time, Nilsen says, she had no idea that the damage she was doing to herself was more than skin deep, but she ended up in a Boston emergency room with brain tissue protruding through a hole she'd scratched in her skull."She gave herself frontal-lobe brain damage," says Anne Louise Oaklander, a neuroscientist and neurologist at Harvard Medical School in Boston, who treated Nilsen and described her case at a recent meeting* here. Oaklander blames the infuriating itch on severe nerve damage caused by the virus--damage that also left Nilsen unable to feel pain from her scratching-induced wounds. Although Nilsen's experience is extreme, to say the least, chronic itch is far from rare. Millions of people worldwide suffer from incessant and largely unexplained itchiness brought on by kidney or liver disease, HIV, or various other ailments. Chronic itch disrupts sleep, reduces the quality of life, and undermines the health of those who suffer from it--yet there is little doctors can do to help.
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