Monday, July 25, 2011

Diagnosing patients who itch

In a fascinating 2008 New Yorker article, "The Itch," Harvard surgeon Atul Gawande told the story of a patient who experienced a nearly fatal complication from treatment-resistant pruritis of her scalp following an episode of herpes zoster:

One morning, after she was awakened by her bedside alarm, she sat up and, she recalled, “this fluid came down my face, this greenish liquid.” She pressed a square of gauze to her head and went to see her doctor again. M. showed the doctor the fluid on the dressing. The doctor looked closely at the wound. She shined a light on it and in M.’s eyes. Then she walked out of the room and called an ambulance. Only in the Emergency Department at Massachusetts General Hospital, after the doctors started swarming, and one told her she needed surgery now, did M. learn what had happened. She had scratched through her skull during the night—and all the way into her brain.

Although this sort of complication is highly unusual, pruritis - far from being only a "nuisance" symptom - is often associated with underlying systemic conditions, Dr. Brian Reamy and colleagues observe in "A Diagnostic Approach to Pruritis" in the July 15th issue of AFP. Clinicians should consider evaluating patients who present with generalized, unexplained pruritis for thyroid disorders, lymphoma, kidney and liver diseases, and diabetes. Many dermatoses of pregnancy can cause intense pruritis. Also, some psychiatric disorders are associated with pruritic sensations, leading to "neurotic excorations." Certain historical findings, including recent travel, exposure to animals, and constitutional symptoms such as weight loss and fatigue, can help to narrow the extensive differential diagnosis of this common and troublesome symptom.