Luce J M
Hosp Pract (Off Ed). 1983 Jul;18(7):173-5, 178-80, 185-6 passim.
Under this umbrella are grouped a multitude of disorders--with broadly similar manifestations but widely differing etiologies--believed to affect more than 10 million people in the United States. Cases attributable to known causes are treatable. Most, however, are of uncertain etiology and respond poorly to treatment. An updated diagnostic and therapeutic approach is presented.