A ganglion is a cyst filled with clear jelly-like material, related to a joint or tendon sheath. The commonest position for a ganglion is over the back of the wrist, but ganglia are also found on the front of the wrist close to the radial pulse, in the palm close to the base of the finger arising from the tendon sheath, and over the back of the finger at the end joint, where pressure often causes a groove to form in the nail.
It is not fully understood why a ganglion develops, but it is thought to start with a degenerative process or injury in the capsule or ligaments around the joint, or the fibrous sheath around a tendon. Usually a ganglion forms a smooth prominent lump which may fluctuate in size or even disappear completely, though it may come back again. Some ganglia are painful, especially small ones deep inside the wrist joint, which are difficult to feel.
The time-honoured method of treatment involving a whack with the family bible is painful and risky. It is possible to empty the contents with a needle, but the material is viscous and complete emptying impossible, and the majority refill anyway. It can be a useful
temporary measure and occasionally obviates the need for surgery. It is useful in deciding if excision is likely to relieve pain.
Surgical removal is the definitive treatment, and can usually be done under local anaesthesia (axillary block). The scar is usually acceptable, but may become red and thick especially on the front of the wrist. Removal of a ganglion close to the nail involves tracing it down to the joint and removing a small bone spike in most cases, and there is often a shortage of skin, best treated by advancing skin from further down the finger, a rotation flap.
Ganglia are known to recur on occasions, and this does not necessarily mean that they were incompletely removed, although incomplete removal may lead to recurrence. If a ganglion does recur it can be removed again, still with a good chance of success.
As with all operations on the hand, there is a small possibility of unexpected stiffness, swelling or pain requiring physiotherapy or other treatment. This is an exaggeration of the normal response to injury or surgery (see under Complex Regional Pain Syndrome).