What exactly is de Quervain's tendonitis and why is it called that?
de Quervain's tenosynovitis isn't the same thing as tendonitis, but it's close. It's caused by the inflammation and irritation in the tendons on the thumb side of your wrist.
Unfortunately, researchers and doctors don't know what causes it, although they do know that women get it more than men, and the two most common age groups for it are those under 20 years and those 40 years and older.
It is called de Quervain's tenosynovitis because Dr. de Quervain is the one who noticed the problem and recognized it as something different from other wrist problems.