DeQuervain's syndrome
DeQuervain's Syndrome, named for Swiss surgeon Fritz De Quervain who first identified it in 1885 (also known as "washerwoman's sprain" or "De Quervain's Disease"), is an inflammation of the sheath or tunnel that surrounds two tendons that control movement of the thumb. It is caused by the repetitive motion of the thumb constantly being required to move up and down (usually associated with using a computer keyboard or typewriter).
Symptoms are pain and swelling over the thumb side of the wrist, possibly numbness on the back of the thumb, and difficulty gripping.
It can be included in a loose group of conditions called Repetitive Strain Injuries.
The general condition of progressive restriction of the sheath surrounding a tendon is called Stenosing Tenosynovitis. Another common diagnosis in this area is trigger finger.