The surgeon thinks I have a ganglion cyst, but it could be a trigger finger. What's the difference?
A ganglion is a small, harmless cyst, or sac of fluid, that sometimes develops in the wrist. Doctors don't know exactly what causes ganglions. Technically, a ganglion cyst causes a trigger finger. The ganglion is just one of many possible causes of trigger finger. Let's define some of these terms to help you understand this better.
Trigger finger is a catching or popping of the tendons as they move the fingers. Usually this problem occurs as the finger is moved toward the palm of the hand. This movement is called flexion. But in rare cases, trigger finger of the extensor tendons (the ones that straighten the fingers) is the problem.
The tendons that move the fingers are held in place on the bones by a series of ligaments called pulleys. These ligaments form an arch on the surface of the bone that creates a sort of tunnel for the tendon to run in along the bone.
To keep the tendons moving smoothly under the ligaments, the tendons are wrapped in a slippery coating called tenosynovium. The tenosynovium reduces the friction and allows the tendons to glide through the tunnel formed by the pulleys as the hand is opened to release objects.
Triggering is usually the result of a thickening in the tendon. Constant irritation from the tendon repeatedly sliding through the pulley causes the tendon to swell in this area. A nodule or knob forms. The pulley ligament may thicken as well. The nodule catches on the pulley causing the popping or catching sensation.
Ganglions are generally attached by a stalk of tissue to a nearby joint capsule, tendon, or tendon sheath (tissure covering the tendon). Ganglions have been seen in almost every joint in the hand and wrist. Most of them occur along the back of the wrist/hand.
The ganglion that attaches itself to a tendon or tendon sheath can cause tendon triggering. As the finger bends, the tendon slides and glides through the tendon sheath. If there's a ganglion attached to the tendon, the cyst can get stuck on a pulley or the edge of the retinaculum. The retinaculum is a band of fibrous tissue that goes across the wrist (front and back).
Tendon thickening on the palmar side of the hand can cause triggering when the nodule bumps up against the retinaculum. Ganglion cysts on the back of the wrist/hand cause triggering when the cyst cannot pass under the retinaculum. Regardless of the cause, the result is the same: there's a palpable click, pop, or catching response.
Michael Khazzam, MD, et al. Extensor Tendon Triggering by Impingement on the Extensor Retinaculum: A Report of 5 Cases. In The Journal of Hand Surgery. October 2008. Vol. 33-A. No. 8. Pp. 1397-1400.
*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.