Nerve block is a generic term for when a procedure is done that reduces or halts the transmission of impulses along a particular nerve. It can encompass individual nerve or extend to involve entire groups of nerve, such as the brachial plexus the controls function to the entire upper extremity.
Blocking a nerve serves a valuable diagnostic purpose in that if the nerve is blocked and pain diminishes, the source of the pain can very often be isolated. Nerve blocks can be therapeutic as well and when longer pain relief is desired, steroids are often combined with long acting local anesthetics to provide this effect.
Nerve blocks can also be accomplished by using alcohol or phenol when permanent nerve block is indicated. Often times, depending on the location, fluoroscopy will be used to locate and identify the nerve being blocked.