Nerve block or regional nerve blockade is any deliberate interruption of signals traveling along a nerve, often for the purpose of

pain relief Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professionals ...

. Local anesthetic nerve block (sometimes referred to as simply "nerve block") is a short-term block, usually lasting hours or days, involving the injection of an anesthetic, a

corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are in ...

, and other agents onto or near a nerve. Neurolytic block, the deliberate temporary degeneration of nerve fibers through the application of chemicals, heat, or freezing, produces a block that may persist for weeks, months, or indefinitely. Neurectomy, the cutting through or removal of a nerve or a section of a nerve, usually produces a permanent block. Because neurectomy of a

sensory nerve A sensory nerve, or afferent nerve, is a general anatomic term for a nerve which contains predominantly somatic afferent nerve fibers. Afferent nerve fibers in a sensory nerve carry sensory information toward the central nervous system (CNS) f ...

is often followed, months later, by the emergence of new, more intense pain, sensory nerve neurectomy is rarely performed. The concept of nerve block sometimes includes ''central nerve block'', which includes

epidural Epidural administration (from Ancient Greek ἐπί, , upon" + ''dura mater'') is a method of medication administration in which a medicine is injected into the epidural space around the spinal cord. The epidural route is used by physicians an ...

and

spinal anaesthesia Spinal anaesthesia (or spinal anesthesia), also called spinal block, subarachnoid block, intradural block and intrathecal block, is a form of neuraxial regional anaesthesia involving the injection of a local anaesthetic or opioid into the suba ...

Local anesthetic nerve block

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 an ...

is often combined with other drugs to potentiate or prolong the analgesia produced by the nerve block. These adjuvants may include

epinephrine Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...

corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are in ...

opioids Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid us ...

ketamine Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ...

, or alpha-adrenergic agonists. These blocks can be either single treatments, multiple injections over a period of time, or continuous infusions. A continuous peripheral nerve block can be introduced into a limb undergoing surgery – for example, a femoral nerve block to prevent pain in

knee replacement Knee replacement, also known as knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability, most commonly offered when joint pain is not diminished by conservative sources a ...

. Local anesthetic nerve blocks are sterile procedures that are usually performed in an

outpatient A patient is any recipient of health care services that are performed by healthcare professionals. The patient is most often ill or injured and in need of treatment by a physician, nurse, optometrist, dentist, veterinarian, or other health c ...

facility or hospital. The procedure can be performed with the help of

ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies fr ...

fluoroscopy Fluoroscopy () is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a physician to see the internal structure and functi ...

, or CT to guide the practitioner in the placement of the needle. A

probe positioning system {{One source, date=December 2021 A probe positioning system is a tool for the positioning of a (hand-held) measuring device, such as an ultrasound transducer in a fixed, predetermined place to the object, such as a patient. The operation of these s ...

can be used to hold the ultrasound transducer steady. Electrical stimulation can provide feedback on the proximity of the needle to the target nerve. Historically, nerve blocks were performed blind or with electrical stimulation alone, but in contemporary practice, ultrasound or ultrasound with electrical stimulation is most commonly used. It is unclear if the use of

in addition to lidocaine is safe for nerve blocks of fingers and toes due to insufficient evidence. Another 2015 review states that it is safe in those who are otherwise healthy. The addition of dexamethasone to a nerve block or if given intravenously for surgery can prolong the duration of an upper limb nerve block leading to reduction in postoperative opioid consumption. Complications of nerve blocks most commonly include infection, bleeding, and block failure. Nerve injury is a rare side effect occurring roughly 0.03-0.2% of the time. The most significant complication of nerve blocks is local anesthetic systemic toxicity (LAST) which can include neurologic and cardiovascular symptoms including cardiovascular collapse and death. Other side effects can result from the specific medications used; for example, transient tachycardia may result if epinephrine is administered in the block. It is important to note that despite these complications, procedures done under regional anesthesia (nerve block with or without intravenous sedation) carry a lower anesthetic risk than general anesthesia.

Neurolytic block

A neurolytic block is a form of nerve block involving the deliberate injury of a nerve by freezing or heating (" neurotomy") or the application of chemicals (" neurolysis"). These interventions cause degeneration of the nerve's fibers and temporary (a few months, usually) interference with the transmission of nerve signals. In these procedures, the thin protective layer around the nerve fiber, the

basal lamina The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, though it does constitute a portion of the basement membrane. The ba ...

, is preserved so that, as a damaged fiber regrows, it travels within its basal lamina tube and connects with the correct loose end, and function may be restored. Surgical cutting of a nerve ( neurectomy), severs these basal lamina tubes, and without them to channel the regrowing fibers to their lost connections, over time a painful

neuroma A neuroma (; plural: neuromata or neuromas) is a growth or tumor of nerve tissue. Neuromas tend to be benign (i.e. not cancerous); many nerve tumors, including those that are commonly malignant, are nowadays referred to by other terms. Neur ...

or deafferentation pain may develop. This is why the neurolytic is usually preferred over the surgical block. The neurolytic block is sometimes used to temporarily reduce or eliminate pain in part of the body. Targets include * the

celiac plexus The celiac plexus, also known as the solar plexus because of its radiating nerve fibers, is a complex network of nerves located in the abdomen, near where the celiac trunk, superior mesenteric artery, and renal arteries branch from the abdom ...

, most commonly for cancer of the gastrointestinal tract up to the transverse colon, and pancreatic cancer, but also for stomach cancer, gall bladder cancer, adrenal mass, common bile duct cancer, chronic pancreatitis and active intermittent

porphyria Porphyria is a group of liver disorders in which substances called porphyrins build up in the body, negatively affecting the skin or nervous system. The types that affect the nervous system are also known as acute porphyria, as symptoms are ra ...

* the splanchnic nerve, for retroperitoneal pain, and similar conditions to those addressed by the celiac plexus block but, because of its higher rate of complications, used only if the celiac plexus block is not producing adequate relief * the hypogastric plexus, for cancer affecting the descending colon, sigmoid colon and rectum, as well as cancers of the bladder, prostatic urethra, prostate, seminal vesicles, testicles, uterus, ovary and vaginal fundus * the ganglion impar, for the perinium, vulva, anus, distal rectum, distal urethra, and distal third of the vagina * the stellate ganglion, usually for head and neck cancer, or sympathetically mediated arm and hand pain * the triangle of auscultation for pain from rib fractures and post thoracotomy using a rhomboid intercostal block * the intercostal nerves, which serve the skin of the chest and abdomen * and a dorsal root ganglion may be treated by targeting the root inside the subarachnoid cavity, most effective for pain in the chest or abdominal wall, but also used for other areas including arm/hand or leg/foot pain.

Neurectomy

Neurectomy is a

surgical Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pa ...

procedure in which a

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

or section of a nerve is severed or removed. Cutting a sensory nerve severs its basal lamina tubes, and without them to channel the regrowing fibers to their lost connections, over time a painful

or deafferentation pain may develop. This is why the neurolytic is usually preferred over the surgical sensory nerve block. This surgery is performed in rare cases of severe

chronic pain Chronic pain is classified as pain that lasts longer than three to six months. In medicine, the distinction between acute and chronic pain is sometimes determined by the amount of time since onset. Two commonly used markers are pain that continues ...

where no other treatments have been successful, and for other conditions such as involuntary twitching and excessive blushing or sweating.McMahon, M. (2012, November 6). What is a Neurectomy? (O. Wallace, Ed.) Retrieved from wise GEEK: http://www.wisegeek.com/what-is-a-neurectomy.htm# A brief "rehearsal" local anesthetic nerve block is usually performed before the actual neurectomy to determine efficacy and detect side effects. The patient is typically under general anesthetic during the neurectomy, which is performed by a neurosurgeon.

References

External links

{{Authority control Regional anesthesia

Local anesthetic nerve block

Neurolytic block

Neurectomy

See also

References

External links