Specific activities that have been postulated as potential risk factors include intensive computer mouse use, trackball use, and typing, as well as some pastimes, including bowling, golf, fly-fishing, piano-playing, sewing, and knitting.Women are diagnosed more often than men. The syndrome commonly occurs during and, even more so, after pregnancy. Contributory factors may include hormonal changes, fluid retention and—again, more debatably and potentially harmfully—increased housework and lifting. Pathophysiology
De Quervain syndrome involves noninflammatory thickening of the tendons and the synovial sheaths that the tendons run through. The two tendons concerned are those of the extensor pollicis brevis and abductor pollicis longus muscles. These two muscles run side by side and function to bring the thumb away from the hand; the extensor pollicis brevis brings the thumb outwards radially, and the abductor pollicis longus brings the thumb forward away from the palm. De Quervain tendinopathy affects the tendons of these muscles as they pass from the forearm into the hand via a fibro-osseous tunnel (the first dorsal compartment). Evaluation of histopathological specimens shows a thickening and myxoid degeneration consistent with a chronic degenerative process, as opposed to inflammation. The pathology is identical in de Quervain seen in new mothers. Diagnosis
De Quervain syndrome is diagnosed clinically, based on history and physical examination, though diagnostic imaging such as X-ray may be used to rule out fracture, arthritis, or other causes, based on the persons history and presentation. The modified Eichoff maneuver, commonly called the Finkelsteins test, is a physical exam maneuver used to diagnose de Quervain syndrome.
To perform the test, the examiner grasps and ulnar deviates the hand when the person has their thumb held within their fist. If sharp pain occurs along the distal radius (top of forearm, about an inch below the wrist), de Quervains syndrome is likely. While a positive Finkelsteins test is often considered pathognomonic for de Quervain syndrome, the maneuver can also cause pain in those with osteoarthritis at the base of the thumb. Differential diagnosis
Differential diagnoses include:

Osteoarthritis of the trapezio-metacarpal joint
Intersection syndrome—pain will be more towards the middle of the back of the forearm and about 2–3 inches below the wrist, usually with associated crepitus. Wartenbergs syndrome: The primary symptom is paresthesia (numbness/tingling). Treatment
As with many musculoskeletal conditions, the management of de Quervains disease is determined more by convention than scientific data. A systematic review and meta-analysis published in 2013 found that corticosteroid injection seems to be an effective form of conservative management of de Quervains syndrome in approximately 50% of patients, although more research is needed regarding the extent of any clinical benefits. Efficacy data are relatively sparse and it is not clear whether benefits affect the overall natural history of the illness. One of the most common causes of corticosteroid injection failure are subcompartments of the extensor pollicis brevis tendon.Most tendinoses are self-limiting and the same is likely to be true of de Quervains although further study is needed.Palliative treatments include a splint that immobilized the wrist and the thumb to the interphalangeal joint and anti-inflammatory medication or acetaminophen.