Stenosing tenosynovitis translates to “tendon inflammation due to narrowing passageways.” It is entrapment and inflammation of the extensor pollicus longus tendon, the muscle that moves the thumb up in a “hitchhiker sign.” It is also known as DeQuervain’s Syndrome.
The passageway in question is a tunnel formed by ligaments that hold the extensor pollicus longus tendon to the distal radius (lateral wrist), one of the two bones of the forearm.
The onset is gradual over a few days. There is a very sharp, unrelenting pain at the radial styloid, the bony prominence at the lateral wrist right below the wrist crease. There is no loss of muscle strength in the thumb. Bending the affected thumb inward towards the palm while bending the wrist sideways towards the ulna (in direction away from the pain) makes the pain much worse.
Causation is believed to be related to overusing the thumbs, such as BlackBerry use, or frequent bending of the wrist while carrying weight, such as in cradling a baby several times a day. However, there are documented cases of stenosing tenosynovitis occurring with no apparent trigger (idiopathic causation).
What is known is that the synovial sheath that covers the portion of the tendon in the tunnel gets inflamed and undergoes degenerative changes. It triggers a chronic, localized inflammatory response. Pain comes from tiny nerve endings in the synovial sheath that are irritated by rubbing against the ligament holding it to the distal radius, and perhaps also by exposure to the products of inflammation.
The condition is known to be self limiting, running its course for a few months and then resolving as the body regenerates the synovial sheath. However, during its acute stage it is quite unpleasant, despite the fact that only about an inch of tendon is involved.
Wrist immobilization (wrist brace with thumb splint) to limit movement of the adductor pollicus longus is recommended for 1-3 weeks. Wear most of the day and night; remove every hour or so to do ice therapy.
Ice massage is helpful in temporarily reducing the pain by numbing the area and constricting blood vessels, which tends to suppress production of inflammatory chemicals. A wrist ice wrap can also be effective. Apply ice for 10-20 minutes directly onto the painful area.
Topical ointments may be helpful in reducing the severity of the pain. Narayan oil and products containing capsaicin (don’t use together) are worth trying. Rub into inflamed tendon gently.
Chinese herbal patches may be helpful in temporarily relieving the pain as well.
Cortisone injection into the tunnel can be effective in neutralizing the pain; however it still may take a few weeks to months for the pain to go entirely away.