From the Neurologychannel website:
Overview
Epidural injection is the administration of medication into the epidural space. It is used to treat swelling, pain, and inflammation associated with neurological conditions that affect nerve roots, such as a herniated disk and radiculopathy.

Epidural injections may be painful and produce uncertain results. Studies show that epidural injection may provide short-term pain relief for patients when conservative treatments have failed.

Anatomy
The brain is covered by three membranes (dura, arachnoid, and pia), called the meninges that extend through the base of the skull and surround the entire spinal cord. The spinal cord travels down the entire length of the spinal column through the spinal canal. The epidural space is located between the dura and the interior surface of the spinal canal and contains veins, arteries, and fat. Epidural injection is the injection of medication into the epidural space.

Procedure
Epidural injection is usually given in an outpatient setting. An anesthesiologist usually administers the injection, but some neurosurgeons, orthopedic surgeons, and neurologists are also qualified to perform this procedure.

Here in the US it seems most moms-to-be are having epidurals during childbirth. My first pain doctor gave me two with no results but didn't hurt. My current pain doctor perfers staying out of the spinal column and feels he gets as good results as epidurals injecting in the area but without injecting into the spinal column. Sometimes I get a few days relief, other times nothing. I think is a traditional procedure and millions are done every year. Lynnie "ONE MOMENT CAN CHANGE EVERYTHING!"



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A mild sedative and a local anesthetic may be given prior to the procedure to relax the patient and numb the injection site. Medications, usually an anesthetic such as bupivacaine (Marcaine®) or a muscle relaxant, and a corticosteroid such as methylprednisolone (Medrol®), are injected directly into the epidural space. (The injection is commonly called a cortisone shot.)

Effectiveness
Approximately 30% to 70% of people who receive an epidural injection benefit from it. Some patients notice improvement within hours of the injection; others improve over a number of days; and others experience no improvement with the treatment. In some cases, two or three injections are given over weeks or months.