Sometimes, the terms "regional anesthesia" and "local anesthesia" are used interchangeably. Typically, however, regional anesthesia describes anesthesia that is used on a wider region of the body. For example, local anesthesia might be used to numb a section of the leg. Regional anesthesia, conversely, can numb the entire leg. When the entire leg is anesthetized, it is known as peripheral regional anesthesia because a single nerve or specific bundle of nerves is blocked. Another type of regional anesthesia is central anesthesia. For this method, a medical professional usually places an injection into the cerebrospinal fluid, the epidural space just outside the spinal canal.
You might also hear regional anesthesia referred to as a nerve block. Local anesthesia and regional anesthesia use some of the same drugs – they are just used in larger dosages for a stronger effect on the central nervous system. Like local anesthesia, patients often can remain conscious for procedures under regional anesthesia. It depends on the procedure and the patient"s preference -- some patients would rather not be conscious.
Regional anesthetics can be given with a single injection. They can also be given continuously through a catheter or intravenously. One technique, a Bier block, uses a tourniquet to prevent blood from flowing through a limb. Then, the drug is injected into a vein. (This can be used only with a relatively short procedure, though.)
The central anesthetic technique known as an epidural is probably familiar to women who have given birth. In this procedure, anesthesiologists insert a catheter into the epidural space, usually in the lower back area. That way, the patient gets a continuous feed of drugs like lidocaine as well as fentanyl or clonidine which provide pain relief via a loss of sensation from the waist down.
Other procedures below the waist -- such as Cesarean sections or hernia surgery – might benefit from spinal blocks, which are injected into the cerebrospinal fluid. They tend to paralyze further than epidurals.
More risks are present during regional anesthesia than for local anesthesia. These risks, which could include seizures and heart attacks, come from the increased involvement of the central nervous system.