De Quervain's syndrome is a repetitive stress injury that affects the thumb. De Quervain's syndrome is a form of tendinitis, tenosynovitis or commonly a combination of the two. It is an inflammation of some of the tendons and/or the sheaths that cover them that control the motion of your thumb and can be quite painful. It may also be an inflammation in the tenosynium of the opening in the wrist that the tendons slide through. Often the welling from the inflammation in either the tendon or tenosynovitis causes irritation that leads to inflammation in the other after repetitive use.
In either individual case, or with the combination of both anatomical features inflamed, the inflammation puts pressure on the tendons and constricts their ability to slide within the sheath. The inflammation results in swelling and pain that can run from the tip of the thumb all the way down to the wrist and even the upper portion of the forearm.
With De Quervain's syndrome the pain is often felt when you turn or flex your wrist or when you contract your thumb inward like when you make a fist or grab something.
If you flatten your hand out with the back of your hand downward then your thumb can move in two ways. It can move up and back down. This moves your thumb out of the plane of your hand and is called palmar abduction. Your thumb can also move left to right staying within the plane of your hand. This type of movement is called radial abduction.
The tendons involved in De Quervain's syndrome are those attached to the extensor pollicis brevis and abductor pollicis longus muscles, or the muscles that move your thumb in radial abduction. The muscles run side by side on the back of your forearm towards your wrist and the tendons run along the thumb from the tip to your wrist through an opening in your wrist where they then attach to the muscles.
These tendons are housed within synovial sheaths through the wrist passage. Synovial sheaths are kind of like a stiffer, outer tube that can bend but does not kink. The result is that when the wrist is bent or twisted the tendons can still slide back and forth through the wrist passage without getting snagged.
In De Quervain's syndrome, irritation from repetitive stress causes the inflammation in the tendon or synovial sheath which leads to swelling and enlarges a portion of the tendon making it difficult for the tendon to pass through the opening in the wrist.
The tendons pass through an opening in the wrist on the thumb side. This opening is covered in a slippery membrane called tenosynovium. Constant friction against this surface by inflamed synovial sheaths can cause inflammation in the tenosynium as well. Inflammation of a tensynovium is called tenosynivitis and is why De Quervain's syndrome is also known as De Quervain's Tenosynovitis.
As De Quervain's syndrome worsens the repetitive inflammation and irritation of the tendon's synovial sheaths causes them to thicken and degenerate. Because of the degenerative nature of this repetitive stress injury, if De Quervain's syndrome is left untreated it can become debilitating and leave you with a limited range of motion permanently.
De Quervain's syndrome is named after a nineteenth century Swiss surgean named Fritz de Quervain. He first identified the syndrome in 1895. Fritz de Quervain also identified a form of thyroiditis thatnis named after him as well, De Quervain's Thyroiditis.
There are a lot of other names for De Quervain's syndrome and it may be better known as Mother's Wrist or Washerwoman's Sprain. You may even know it as Nintendo Thumb, Gamer's Thumb, or Texting Thumb in the modern age of electronics. De Quervain's syndrome may also be spelled as deQuervain, de Quervain, or DeQuervain.