De Quervain syndrome also known as BlackBerry thumb, gamer's thumb, washerwoman's sprain, radial styloid tenosynovitis, de Quervain disease, de Quervain's tenosynovitis, de Quervain's stenosing tenosynovitis, mother's wrist, or mommy thumb), is a tenosynovitis of the sheath or tunnel that surrounds two tendons that control movement of the thumb.
The cause of de Quervain's disease is not established. Evidence regarding a possible relation with occupational risk factors is debated. A systematic review of potential risk factors discussed in the literature did not find any evidence of a causal relationship with occupational factors. Proponents of the view that De Quervain syndrome is a repetitive strain injury consider postures where the thumb is held in abduction and extension to be predisposing factors. Workers who perform rapid repetitive activities involving pinching, grasping, pulling or pushing have been considered at increased risk. Specific activities that have been postulated as potential risk factors include intensive mouse/trackball use and typing, as well as some pastimes, including bowling, golf and fly-fishing, piano-playing, and sewing and knitting.
>Women are affected more often than men. The syndrome commonly occurs during and after pregnancy. Contributory factors may include hormonal changes, fluid retention and—more debatably—lifting.