CHICAGO --- About 40,000 people in the U.S. have severe reactions that simulate allergic reactions but where no external cause is involved.
They show up in emergency rooms and doctors' offices with sneezing, itchy nose, rashes or hives and spasms in the bronchial tubes that make it difficult to breathe and swallow. Frequently, these symptoms are accompanied by gastrointestinal problems, skin flush of the whole body, a dramatic drop in blood pressure and even unconsciousness. Without immediate treatment with a combination of adrenaline, antihistamines and prednisone, many of these patients could die.
While these symptoms would generally indicate an allergic reaction to an external stimulus, such as being stung by a bee or eating shellfish, there are some patients in whom there is no external cause for the reaction. They have a condition known as idiopathic anaphylaxis. Because their episodes are unpredictable and often recurrent, these patients are especially at risk for death if not identified and treated appropriately.
"Although treatment at an emergency room or hospital may be life-saving, the patient's prognosis isn't improved unless preventive therapy is initiated," said Roy Patterson, M.D., of Northwestern University Medical School, a leading expert on idiopathic anaphylaxis whose medical team has treated over 500 patients with this condition, more than anyone in the world.
Patterson said it is critical that patients with a severe allergic reaction be diagnosed to exclude known allergies and other medical conditions. If the cause is unknown, the type of idiopathic anaphylaxis should be classified according to a system developed by Patterson and co-researchers, and the patient should be started on a drug regimen to prevent recurring episodes. The drugs that Northwestern researchers have found most effective include a combination of prednisone, hydroxyzine and albuterol.
Patterson, Ernest S. Bazley Professor of Medicine and chief of allergy-immunology at Northwestern University, and his colleagues initially identified idiopathic anaphylaxis in 1978. Their research has defined a clinical classification for the various types of these allergic reactions and designed various therapies to control the episodes.
In what Patterson estimates as more than 1,200 "patient years" of observation of patients with idiopathic anaphylaxis, including one who has been treated for 24 years, only one patient has died.
Patterson presented information on idiopathic anaphylaxis at an international meeting on allergy in late February. The Northwestern research group, which includes Leslie Grammer, M.D., Paul Greenberger, M.D., Anne Ditto, M.D., and C. Raymond Zeiss, M.D., has written over 30 publications on the subject, including a new book titled "Idiopathic Anaphylaxis," due out in April.
(Other medical news from Northwestern University can be found on the World Wide Web at: medical news: http://www.nwu.edu/univ-relations/media/newsreleases/*medical/mindex.html)