When pain is blocked from a part of the body using local anesthetics, it is generally referred to as regional anesthesia. There are many types of regional anesthesia either by injecting into the tissue itself, a vein that feeds the area or around a nerve trunk that supplies sensation to the area. The latter are called nerve blocks and are divided into peripheral or central nerve blocks.
The following are the types of regional anesthesia:
Infiltrative anesthesia: a small amount of local anesthetic is injected in a small area to stop any sensation (such as during the closure of a laceration, as a continuous infusion or “freezing” a tooth). The effect is almost immediate.
Peripheral nerve block: local anesthetic is injected near a nerve that provides sensation to particular portion of the body. There is significant variation in the speed of onset and duration of anesthesia depending on the potency of the drug (e.g. Mandibular block).
Intravenous regional anesthesia (also called a Bier block): dilute local anesthetic is infused to a limb through a vein with a tourniquet placed to prevent the drug from diffusing out of the limb.
Central nerve blockade: Local anesthetic is injected or infused in or around a portion of the central nervous system (discussed in more detail below in Spinal, epidural and caudal anesthesia).
Topical anesthesia: local anesthetics that are specially formulated to diffuse through the mucous membranes or skin to give a thin layer of analgesia to an area (e.g. EMLA patches).
Tumescent anesthesia: a large amount of very dilute local anesthetics are injected into the subcutaneous tissues during liposuction.
Systemic local anesthetics: local anesthetics are given systemically (orally or intravenous) to relieve neuropathic pain