DeQuervain's tenosynovitis describes a condition of painful inflammation and swelling of the extensor tendons to the thumb within a small tunnel on the thumb-side of the wrist. Symptoms of DeQuervain's syndrome usually include pain or swelling near the base of the thumb. The condition can develop in anyone, but it is common in new mothers that have the new challenge of lifting a heavy infant from beneath the arms. Patient's often notice pain with grasping, pinching, or twisting motions of the wrist. The onset of symptoms may be gradual or sudden. Some patients notice a catching sensation or a squeaking sound as the tendons glide through an inflamed synovium (lining) within the extensor tendon tunnel on the side of the wrist. DeQuervain's tendonitis may be caused by trauma, overuse, or inflammatory arthritis. The diagnosis of DeQuervain's syndrome is made by physical exam, but may be supported by findings on ultrasound or MRI scan in difficult cases. The goal of treatment of DeQuervain's tenosynovitis is to relieve the pain and swelling that comes from irritation of the lining of the thumb extensor tendons. Nonoperative treatments include splinting to immobilize the base of the thumb and rest the tendons. Patients should also avoid repetitive thumb movements or activities that stress the tendons. Nonsteroidal anti-inflammatory medications may also be beneficial. Some patients will benefit from an injection of corticosteroid medication into the tendon sheath to help reduce inflammation. An occupational therapist can help identify and correct behaviors that may worsen symptoms. Patients that do not respond to conservative treatment may require surgery to open the extensor tendon tunnel at the base of the thumb to release pressure on the irritated tendons. A small incision on the thumb-side of the wrist provides in order to access and release the extensor sheath (tunnel) to relieve pressure and inflammation on the tendons (see figure). Surgery may involve removal of a portion of the inflamed lining of the thumb extensor tendons, but the tendons are left intact to preserve normal motion. After surgery, patients generally wear a wrist splint for a short period of time before returning to gradual use of the thumb to prevent stiffness.