Local anesthesia is any technique to induce the absence of

sensation Sensation (psychology) refers to the processing of the senses by the sensory system. Sensation or sensations may also refer to: In arts and entertainment In literature * Sensation (fiction), a fiction writing mode * Sensation novel, a Briti ...

in a specific part of the body, generally for the aim of inducing local analgesia, that is, local insensitivity to

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

, although other local senses may be affected as well. It allows patients to undergo surgical and dental procedures with reduced pain and distress. In many situations, such as cesarean section, it is safer and therefore superior to

general anesthesia General anaesthesia (UK) or general anesthesia (US) is a medically induced loss of consciousness that renders the patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general ...

. The following terms are often used interchangeably: * ''Local anesthesia'', in a strict sense, is

anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), ...

of a small part of the body such as a tooth or an area of skin. * ''Regional anesthesia'' is aimed at anesthetizing a larger part of the body such as a leg or arm. * ''Conduction anesthesia'' encompasses a great variety of local and regional anesthetic techniques.

Medical

A local anesthetic is a

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhala ...

that causes reversible local anesthesia and a loss of

nociception Nociception (also nocioception, from Latin ''nocere'' 'to harm or hurt') is the Somatosensory system, sensory nervous system's process of encoding Noxious stimulus, noxious stimuli. It deals with a series of events and processes required for an org ...

. When it is used on specific nerve pathways ( nerve block), effects such as analgesia (loss of

sensation) and paralysis (loss of

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

power) can be achieved. Clinical local anesthetics belong to one of two classes: aminoamide and aminoester local anesthetics. Synthetic local anesthetics are structurally related to

cocaine Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...

. They differ from cocaine mainly in that they have no abuse potential and do not act on th
sympathoadrenergic system
i.e. they do not produce

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high b ...

or local

vasoconstriction Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vess ...

, with the exception of Ropivacaine and Mepivacaine that do produce weak vasoconstriction. Unlike other forms of anesthesia, a local can be used for a minor procedure in a surgeon's office as it does not put you into a state of unconsciousness. However, the physician should have a sterile environment available before doing a procedure in their office. Local anesthetics vary in their pharmacological properties and they are used in various techniques of local anesthesia such as: *

Topical anesthesia A topical anesthetic is a local anesthetic that is used to numb the surface of a body part. They can be used to numb any area of the skin as well as the front of the eyeball, the inside of the nose, ear or throat, the anus and the genital area. To ...

(surface) - Similar to topical gel numbing before getting injected with Lidocaine. *

Infiltration Infiltration may refer to: Science, medicine, and engineering *Infiltration (hydrology), downward movement of water into soil *Infiltration (HVAC), a heating, ventilation, and air conditioning term for air leakage into buildings *Infiltration (me ...

* Plexus block Adverse effects depend on the

local anesthetic A local anesthetic (LA) is a medication that causes absence of pain sensation. In the context of surgery, a local anesthetic creates an absence of pain in a specific location of the body without a loss of consciousness, as opposed to a general a ...

method and site of administration discussed in depth in the

sub-article, but overall, adverse effects can be: # localized prolonged

paresthesia Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias a ...

due to infection,

hematoma A hematoma, also spelled haematoma, or blood suffusion is a localized bleeding outside of blood vessels, due to either disease or trauma including injury or surgery and may involve blood continuing to seep from broken capillaries. A hematoma is ...

, excessive fluid pressure in a confined cavity, and severing of nerves & support tissue during injection. # systemic reactions such as depressed CNS syndrome, allergic reaction, vasovagal episode, and

cyanosis Cyanosis is the change of body tissue color to a bluish-purple hue as a result of having decreased amounts of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Body tissues that show cyanosis are usually in locations ...

due to local anesthetic toxicity. # lack of anesthetic effect due to infectious pus such as an

abscess An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends ...

Non-medical local anesthetic techniques

Local pain management that uses other techniques than

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

medication include: * Transcutaneous electrical nerve stimulation, which has been found to be ineffective for lower back pain, however, it might help with

diabetic neuropathy Diabetic neuropathy is various types of nerve damage associated with diabetes mellitus. Symptoms depend on the site of nerve damage and can include motor changes such as weakness; sensory symptoms such as numbness, tingling, or pain; or autonomic c ...

. * Pulsed radiofrequency, neuromodulation, direct introduction of medication and nerve

ablation Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft material for ...

may be used to target either the tissue structures and organ/systems responsible for persistent

or the

nociceptors A nociceptor ("pain receptor" from Latin ''nocere'' 'to harm or hurt') is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sens ...

from the structures implicated as the source of chronic pain.

References

External links

New York School of Regional Anesthesia

Anesthesia Books

General information and tutorials in peripheral regional anesthesia

worldanaesthesia.org
Free online manual of regional anaesthesia- John Hyndman
Clinical Use of Peripheral Nerve Stimulators and The Neuromuscular Junction

ESRA - The European Society for Regional Anaesthesia Congress
{{Authority control Anesthesia

Medical

Non-medical local anesthetic techniques

See also

References

External links