De Quervain's tenosynovitis is an irritation of tendons that run from the wrist to the thumb. These tendons pass through a tunnel-like tissue, called a sheath, at the wrist. The tunnel area can cause additional pressure and irritation on thickened or swollen tendons, making normal movements very painful.

De Quervain's Tenosynovitis
si55550704_96472_1
Copyright © Nucleus Medical Media, Inc.

De Quervain’s is caused by pressure on already irritated tendons as they move through the sheath at the wrist. The irritation of the tendon may be caused by repetitive movements of the thumb and wrists or a direct blow to the area.