The injection serves two purposes. First it provides an antiinflammatory to the area. This helps reduce any swelling that might be putting pressure on the nerve. With a small amount of anesthetic, painful symptoms can also be stopped.
Injecting the nerve or tendon can cause an immediate increase in painful symptoms and should be avoided. Let your doctor know right away if the injection is painful or causes numbness. He or she will pull the needle back out and redirect it to a better spot.
If the injection works, your symptoms will go away. This tells you that the nerve is impaired. The exact cause of the nerve disturbance isn't identified by using steroid injections. Other diagnostic tests may be needed to rule out conditions such as diabetes, tumors, or a thyroid condition.