Nerve block

Nerve block
Intervention
Ultrasound guided femoral nerve block
ICD-9-CM	04.81
MeSH	D009407

Nerve block or regional nerve blockade is any deliberate interruption of signals traveling along a nerve, often for the purpose of pain relief. 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 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 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 include central nerve block, which includes epidural and spinal anaesthesia.^[1]

Local anesthetic nerve block

Main article: Local anesthetic nerve block

A combination of local anesthetic (such as lidocaine), epinephrine, a steroid (corticosteroid) and an opioid is often used. Epinephrine produces constriction of the blood vessels which delays the diffusion of the anesthetic. Steroids can help to reduce inflammation. Opioids are painkillers. 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.^[2]

Local anesthetic nerve blocks are sterile procedures that are usually performed in an outpatient facility or hospital. The procedure can be performed with the help of ultrasound, fluoroscopy (a live X-ray) or CT to guide the physician in the placement of the needle. A probe positioning system can be used to hold the ultrasound transducer steady. Electrical stimulation can provide feedback on the proximity of the needle to the target nerve.

It is unclear if the use of epinephrine in addition to lidocaine is safe for nerve blocks of fingers and toes due to insufficient evidence.^[3] Another 2015 review states that it is safe in those who are otherwise healthy.^[4]

Neurolytic block

Main article: Neurolytic block

A neurolytic block is a form of nerve block involving the deliberate injury of a nerve by the application of chemicals (in which case the procedure is called "neurolysis") or physical agents such as freezing or heating ("neurotomy").^[5] These interventions cause degeneration of the nerve's fibers and temporary interference with the transmission of pain signals. In these procedures, the thin protective layer around the nerve fiber, the basal lamina, 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.^[6]

Neurectomy

Main article: Neurectomy

Neurectomy is a surgical procedure in which a nerve 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 neuroma or deafferentation pain pain may develop. This is why the neurolytic is usually preferred over the surgical sensory nerve block.^[6] This surgery is performed in rare cases of severe chronic pain where no other treatments have been successful, and for other conditions such as involuntary twitching and excessive blushing or sweating.^[7]

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.^[7]

References

↑ Portable Pathophysiology. Lippincott Williams & Wilkins. 2006. p. 149. ISBN 9781582554556.
↑ UCSD. Regional anesthesia
↑ Prabhakar, H; Rath, S; Kalaivani, M; Bhanderi, N (19 March 2015). "Adrenaline with lidocaine for digital nerve blocks.". The Cochrane database of systematic reviews 3: CD010645. doi:10.1002/14651858.CD010645.pub2. PMID 25790261.
↑ Ilicki, J (4 August 2015). "Safety of Epinephrine in Digital Nerve Blocks: A Literature Review.". The Journal of emergency medicine 49: 799–809. doi:10.1016/j.jemermed.2015.05.038. PMID 26254284.
↑ Scott Fishman; Jane Ballantyne; James P. Rathmell (January 2010). Bonica's Management of Pain. Lippincott Williams & Wilkins. p. 1458. ISBN 978-0-7817-6827-6. Retrieved 15 August 2013.
1 2 Williams JE. Nerve blocks: Chemical and physical neurolytic agents. In: Sykes N, Bennett MI & Yuan C-S. Clinical pain management: Cancer pain. 2nd ed. London: Hodder Arnold; 2008. ISBN 978-0-340-94007-5. p. 225–35.
1 2 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#

External links

Anesthesia (outline)

Types	General Spinal Epidural Conduction anesthesia Local Topical Intercostal nerve block Sedation / Twilight anesthesia Dental (Inferior alveolar nerve) Neuroleptanalgesic anesthesia

Techniques	Airway management Anesthesia provision in the US Arterial catheter Bronchoscopy Capnography Dogliotti's principle Drug-induced amnesia Intraoperative neurophysiological monitoring Nerve block Penthrox inhaler Tracheal intubation

Scientific Principles	Blood–gas partition coefficient Concentration effect Fink effect Minimum alveolar concentration Second gas effect

Measurements	ASA physical status classification system Baricity Bispectral index Direct Fick method Entropy monitoring Fick principle Goldman index Guedel's classification Mallampati score Neuromuscular monitoring Thyromental distance

Instruments	Anaesthetic machine Anesthesia cart Boyle's machine Gas cylinder Laryngeal mask airway Laryngeal tube Medical monitor Odom's indicator Relative analgesia machine Vaporiser Double-lumen endotracheal tube Endobronchial blocker

Drugs	Benzodiazepine Etomidate General anaesthetic Inhalational anaesthetic Infiltration analgesia Ketamine Local anesthetic Methohexital Methoxyflurane Midazolam Neuraxial blockade Opiate Propofol Thiopental Thiopentone

Complications	Emergence delirium Allergic reactions Anesthesia awareness Local anesthetic toxicity Malignant hyperthermia Perioperative mortality Postanesthetic shivering Postoperative nausea and vomiting Postoperative residual curarization

Fields of study	Cardiothoracic Geriatric Oral sedation dentistry

Professions	Anesthesiologist Anesthesiologist assistant Nurse anesthetist Operating Department Practitioners Certified Anesthesia Technician Certified Anesthesia Technologist Anaesthetic technician

History	A.C.E. mixture Helsinki Declaration for Patient Safety in Anaesthesiology History of general anesthesia History of neuraxial anesthesia History of tracheal intubation

Organizations	American Association of Nurse Anesthetists American Society of Anesthesia Technologists & Technicians American Society of Anesthesiologists Anaesthesia Trauma and Critical Care Association of Anaesthetists of Great Britain and Ireland Association of Veterinary Anaesthetists Australian and New Zealand College of Anaesthetists Australian Society of Anaesthetists International Anesthesia Research Society

Authority control	NDL: 01095842

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