An epidural can help back pain. It is a temporary treatment, and cannot be expected to last more than two months. The benefit of an epidural lies in the improvement that occurs when you are able to use your back in a more normal way, once the pain is controlled. Exercise and physiotherapy can be more effective after an epidural.
Epidurals are sometimes used in the investigation and treatment of other pain affecting the lower part of the body and the legs.
The injection
A small needle is placed in one hand so that any faintness or fall in blood pressure caused by the epidural injection can be treated.
You will be asked to curl up, either sitting on the edge of the bed, or lying on your side on the bed. The site of the injection is cleaned with cold antiseptic. A small injection of local anaesthetic (lidocaine), which stings for a few seconds, is used to numb the skin in the middie of the back.
The epidural needle is then inserted. You will feel some pushing, which can be uncomfortable. When the needle reaches the epidural space a few patients experience a sharp pain, accompanied by tingling, if the needle is close to a nerve. It is essential that you try not to jump or wriggle, which can cause damage to the nerve.
Local anaesthetic in the injection will reduce the pain within a few minutes, and will work for several hours. There may be some weakness, a feeling of heaviness and sometimes a feeling of numbness in the legs that usually lasts for a few hours at most.
A steroid is often included in the injection to prolong the effects: the steroid is chosen to remain in the epidural space, and has little effect on the rest of the body. It takes more than a day to have an effect, and the pain may return as the local anaesthetic wears off before the steroid begins to work.
Because of the effects of the injection, you should not travel home alone, and someone should stay with you on the day of the injection. The strength and sensation in the legs should be normal by the next day.
Problems
The injection cannot be given to patients who are sensitive or allergic to the drugs used. We put a dressing over the injection, and you should tell us if you are allergic to plasters, tapes or dressings. It is too dangerous to perform the injection on patients with clotting problems, or are taking anticoagulants. It is also too dangerous to perform the injection when there is an infection of the skin of the back, or septicaemia.
The blood pressure can sometimes fall, causing fainting, after the epidural injection. A more serious problem is a severe headache that can occur if the needle is placed too deeply: a second injection can be needed to treat this. The problem is rare, happening to fewer than one in two-hundred patients, but it can mean having to stay in hospital overnight. The bladder is sometimeS affected for a short while, and it can become difficult to pass water. We suggest emptying the bladder before the epidural injection.
