A ganglion is a bag of fluid that commonly occurs in the wrist and creates a small bump or mass under the skin.  The lump is approximately the size of a pea.  Although a ganglion may occur anywhere in the body the wrist is the most common location.  They are commonly completely painless and unaffected by elbow, wrist or finger movements.  However they may irritate other structures within the wrist causing pain.

The cause of ganglions is unknown, however they’re thought to form where there is weakness in the lining of a joint or tendon causing it to balloon outward and filling with fluid from within the joint.  For this reason the size of the ganglion may change over the course of the day as the fluid leaks from the joint into the ganglion and back again.

Generally, if ganglions aren’t painful they can be left alone.  If ganglions become painful a physiotherapist can assess whether the pain is as a result of the effect of the ganglion on surrounding structures which may be treatable with joint mobilisations or manipulations. 

The painful ganglion which fails to respond to rest and physiotherapy may need to be treated by injection or aspiration.  A sports doctor may be able to drain the fluid from the ganglion by inserting a needle into it.  Alternatively, they may be able to inject the ganglion with anti-inflammatory allowing it to settle.  Occasionally, despite these interventions, the ganglion will reform.  If it’s persistently painful it may be removed surgically.  Luckily there are no long term consequences of having a ganglion.