Nerve blocks may involve local anesthesia, regional anesthesia or analgesia, or surgery; dentists routinely use them for traditional dental procedures. Nerve blocks can also be used to prevent or even diagnose pain.
In the case of a local nerve block, any one of a number of local anesthetics may be used; the names of these compounds, such as lidocaine or novocaine, usually have an aine ending. Regional blocks affect a larger area of the body. Nerve blocks may also take the form of what is commonly called an epidural, in which a drug is administered into the space between the spine's protective covering (the dura) and the spinal column. This procedure is most well known for its use during childbirth. Morphine and methadone are opioid narcotics (such drugs end in ine or one) that are sometimes used for regional analgesia and are administered as an injection.
Neurolytic blocks employ injection of chemical agents such as alcohol, phenol, or glycerol to block pain messages and are most often used to treat cancer pain or to block pain in the cranial nerves (see The Nervous Systems). In some cases, a drug called guanethidine is administered intravenously in order to accomplish the block.