First dorsal compartment tendonitis, more commonly known as De Quervain’s tendonitis or tenosynovitis, is a condition brought on by irritation or inflammation of the wrist tendons at the base of the thumb.

The inflammation causes the compartment (a tunnel or a sheath) around the tendon to swell and enlarge, making movement of the thumb and wrist painful. Making a fist, grasping or holding objects is made painful as a result of this condition.

Causes

De Quervain’s tendonitis is an irritation of the tendons at the base of the thumb, usually caused by taking up a new, repetitive activity. New mothers are especially prone to this type of tendonitis. Caring for an infant often involves new, awkward hand positioning; hormonal fluctuations associated with pregnancy and nursing further contribute to its occurrence. A wrist fracture can also predispose a patient to De Quervain’s tendonitis, because of increased stress across the tendons.

Symptoms

Pain over the thumb-side of the wrist is the main symptom of De Quervain’s tendonitis. This pain may appear gradually or suddenly, and it will be primarily located at the first dorsal compartment at the wrist. It may also radiate down the thumb or up the forearm. Hand and thumb motion increases this pain, especially with forceful grasping or twisting. Swelling over the base of the thumb may include a fluid-filled cyst in this region. There may be an occasional “catching” or “snapping” sensation when moving the thumb. Because of the pain and swelling, certain motions, one such being pinching, may be difficult. Irritation of the nerve lying on top of the tendon sheath may cause numbness on the back of the thumb and index finger.