Carpal tunnel syndrome can be a painful condition caused by compression of the median nerve inside the carpal tunnel. Compression occurs as a result of swollen tissue pressing on the nerve. Swelling can be reduced by cortisone injections into the area that diminish pressure on the median nerve and alleviate the subsequent symptoms it produces.
How Cortisone Works
Injectable cortisone is a synthetic steroid similar to the chemical naturally produced by the body's adrenal glands. It is injected directly into inflamed tissues. Cortisone has a powerful effect on reducing inflammatory chemicals which in turn minimizes damage to tissues. It also has a powerful effect on the body's immune system by mediating the response of white blood cells. When injected into the carpal tunnel, cortisone lessens the inflammatory cascade of events that lead to swelling, pain and heat; all of which are mediated by the immune system, according to Carpal-tunnel-symptoms.com.
Cortisone injections are indicated for patients with carpal tunnel syndrome where the pain and other symptoms of the condition cannot be managed by other nonsurgical therapies, including oral medications. Once administered, the effect of cortisone on pain usually is immediate, although some patients feel relief only after some delay. A smaller proportion of patients feel little no symptomatic relief after cortisone injection therapy, according to MayoClinic.com
Focal Side Effects
The most common side effect of cortisone injections is called steroid flare. This occurs when cortisone becomes crystallized at the injection site. The patient feels pain at the site, which can be substantial. However, the pain is most likely a temporary condition that clears up in one or two days and can be managed easily by applying ice to the area. Another common side effect of cortisone injections is discoloration around the skin where the injection was given. This is a harmless condition yet is of concern to patients with dark skin. A less common side effect is atrophy of the skin around the injection, which results in thinning of the skin. This also is relatively harmless. A rare yet potentially serious side effect of cortisone injection, or any injection, is infection where the needle penetrates tissues. Sterile technique and careful injections greatly minimize this, according to Sportsmedinfo.net.
Systemic Side Effects
Patients with diabetes should be aware that following a cortisone injection, blood glucose can spike temporarily. Thus, precautions should be taken by diabetics in the event this occurs. Likewise, patients with problems in controlling blood pressure, especially high blood pressure, should be aware that cortisone injections can cause alterations that can make control difficult. However, this usually is a modest and temporary reaction. An uncommon side effect is inadvertent injection of the steroid into a blood vessel. This can have serious consequences but can be prevented with careful technique. Finally, allergic side effects to the cortisone also are possible but rare. (ref 2,3,4)
Other Side Effects
If the cortisone is injected into a nearby tendon which already is compromised by inflammation or mechanical stress, it can cause the tendon to rupture. Also, while not specifically a side effect, failure of the injection to reduce inflammation and pain can occur. This can happen if the needle in not directed to the proper area inside the wrist, and can be avoided by using a skilled doctor, according to Carpal-tunnel-symptoms.com.
Injections of cortisone should be used with care. They should not be given more than three times in the same area within one year, as this can cause weakening of the tissues in and around the injection site. When excessive injections are administered, avascular necrosis may occur. This is a very serious outcome, resulting in bone damage, most commonly the hip, knee and shoulder. Adrenal suppression also is rare but may occur with excessive injections, according to Arthritis-treatment-and-relef.com