{{Short description|Form of neuraxial regional anaesthesia}} {{Infobox medical intervention | Name = Spinal anaesthesia | Image = Liquor bei Spinalanaesthesie.JPG | Caption = Backflow of [[cerebrospinal fluid]] through a 25 gauge spinal needle after puncture of the [[arachnoid mater]] during initiation of spinal anaesthesia | ICD10 = | ICD9 = | ICD9_mult = | MeshID = D000775 | OPS301 = | OtherCodes = }}
'''Spinal anaesthesia''' (or '''spinal anesthesia'''), also called '''spinal block''', '''subarachnoid block''', '''intradural block''' and '''intrathecal block''',<ref name="BryantKnights2011">{{cite book |author1=Bronwen Jean Bryant |author2=Kathleen Mary Knights |title=Pharmacology for Health Professionals |url=https://books.google.com/books?id=TQV6sLzYsOYC&pg=PA273 |year=2011|publisher=Elsevier Australia|isbn=978-0-7295-3929-6|pages=273–}}</ref> is a form of neuraxial [[regional anaesthesia]] involving the [[intrathecal administration|injection]] of a [[local anaesthetic]] with or without an [[opioid]] into the [[subarachnoid space]]. Usually a single-shot dose is administrered through a fine [[hypodermic needle|needle]], alternatively continuous spinal anaesthesia through a intrathecal catheter can be performed.<ref>{{Cite journal |last1=Hay |first1=R. |last2=Gupta |first2=A. |date=2022-08-01 |title=Continuous spinal anaesthesia |url=https://www.bjaed.org/article/S2058-5349(22)00062-2/fulltext |journal=BJA Education |language=English |volume=22 |issue=8 |pages=295–297 |doi=10.1016/j.bjae.2022.03.007 |issn=2058-5349|pmc=9463624 }}</ref> It is a safe and effective form of [[anesthesia]] usually performed by [[anesthesiologists]] that can be used as an alternative to [[General anaesthesia|general anesthesia]] commonly in [[Surgery|surgeries]] involving the [[Human leg|lower extremities]] and surgeries below the [[Navel|umbilicus]]. The local anesthetic with or without an opioid injected into the [[cerebrospinal fluid]] provides locoregional anaesthesia: true anaesthesia, motor, sensory and autonomic (sympathetic) blockade. Administering analgesics (opioid, alpha2-adrenoreceptor agonist) in the cerebrospinal fluid without a local anaesthetic produces locoregional analgesia: markedly reduced [[pain]] sensation (incomplete analgesia), some autonomic blockade (parasympathetic plexi), but no sensory or motor block. Locoregional analgesia, due to mainly the absence of motor and sympathetic block may be preferred over locoregional anaesthesia in some [[Surgery#Postoperative care|postoperative care]] settings. The tip of the spinal needle has a point or small [[bevel]]. Recently, pencil point needles have been made available (Whitacre, Sprotte, [[Gertie Marx]] and others).<ref>{{cite journal|last1=Serpell|first1=M. G.|last2=Fettes|first2=P. D. W.|last3=Wildsmith|first3=J. A. W.|title=Pencil point spinal needles and neurological damage |journal=British Journal of Anaesthesia|date=1 November 2002 |volume=89|issue=5|pages=800–801 |doi=10.1093/bja/89.5.800|pmid=12393791|doi-access=free}}</ref>
==Indications== Spinal anaesthesia is a commonly used technique, either on its own or in combination with [[sedation]] or [[general anaesthesia]]. It is most commonly used for surgeries below the umbilicus, however recently its uses have extended to some surgeries above the umbilicus as well as for postoperative analgesia. Procedures which use spinal anesthesia include:{{cn|date=February 2022}} * [[Orthopaedics|Orthopaedic]] surgery on the [[pelvis]], [[hip]], [[femur]], [[knee]], [[tibia]], and [[ankle]], including [[arthroplasty]] and [[joint replacement]] * [[Vascular surgery]] on the [[human leg|legs]] * [[Endovascular aneurysm repair|Endovascular aortic aneurysm repair]] * [[Hernias|Hernia]] ([[inguinal hernia|inguinal]] or [[epigastric hernia|epigastric]]) * [[Haemorrhoid#Surgery|Haemorrhoidectomy]] * [[Nephrectomy]] and [[cystectomy]] in combination with general anaesthesia * [[Transurethral resection of the prostate]] and transurethral resection of bladder tumours * [[Hysterectomy]] in different techniques used * [[Caesarean sections]] * [[Pain management during childbirth|Pain management during vaginal birth and delivery]] * Urology cases * Examinations under anaesthesia
Spinal anaesthesia is the technique of choice for Caesarean section as it avoids a general anaesthetic and the risk of failed intubation (which is probably a lot lower than the widely quoted 1 in 250 in pregnant women<ref name=Rucklidge2012>{{cite journal | author = Rucklidge M, Hinton C. | title = Difficult and failed intubation in obstetrics. | journal = Continuing Education in Anaesthesia, Critical Care & Pain | volume = 12 | issue = 2 | pages = 86–91 | year = 2012 | doi = 10.1093/bjaceaccp/mkr060 | s2cid = 6998842 | doi-access = free }}</ref>). It also means the mother is conscious and the partner is able to be present at the birth of the child. The post operative analgesia from intrathecal opioids in addition to non-steroidal anti-inflammatory drugs is also good.
Spinal anesthesia may be favored when the surgical site is amenable to spinal blockade for patients with severe respiratory disease such as [[chronic obstructive pulmonary disease|COPD]] as it avoids the potential respiratory consequences of intubation and ventilation. It may also be useful in patients where anatomical abnormalities may make [[tracheal intubation]] relatively difficult.
In pediatric patients, spinal anesthesia is particularly useful in children with difficult airways and those who are poor candidates for endotracheal anesthesia such as increased respiratory risks or presence of full stomach.<ref name=":1" />
This can also be used to effectively treat and prevent pain following surgery, particularly thoracic, abdominal pelvic, and lower extremity orthopedic procedures.<ref name=":0">{{cite journal|last=Cwik|first=Jason|date=2012|title=Postoperative Considerations of Neuraxial Anesthesia|journal=Anesthesiology Clinics|volume=30|issue=3|pages=433–443|doi=10.1016/j.anclin.2012.07.005|pmid=22989587}}</ref>
==Contraindications== Prior to receiving spinal anesthesia, it is important to provide a thorough medical evaluation to ensure there are no absolute contraindications and to minimize risks and complications. Although contraindications are rare, below are some of them:<ref name=":1">{{cite journal|last=Hannu|first=Kokki|date=September 2011|title=Spinal blocks|doi=10.1111/j.1460-9592.2011.03693.x|pmid=21899656|journal=Pediatric Anesthesia|volume=22|issue=1|pages=56–64|s2cid=25795865 }}</ref><ref name=":0" /> * Patient refusal * Local infection or sepsis at the site of injection * [[Bleeding disorders]], thrombocytopaenia, or systemic anticoagulation (secondary to an increased risk of a [[spinal epidural hematoma]]) * Severe aortic stenosis * Increased intracranial pressure * Space occupying lesions of the brain * Anatomical disorders of the spine such as scoliosis (although where pulmonary function is also impaired, spinal anaesthesia may be favored)<ref>{{Cite journal |last1=Sethna |first1=N. F. |last2=Berde |first2=C. B. |date=November 1991 |title=Continuous subarachnoid analgesia in two adolescents with severe scoliosis and impaired pulmonary function |journal=Regional Anesthesia |volume=16 |issue=6 |pages=333–336 |issn=0146-521X |pmid=1772818}}</ref> * Hypovolaemia e.g. following massive haemorrhage, including in obstetric patients * [[Allergy]]
Relative Contraindication * [[Ehlers–Danlos syndrome]], or other disorders causing resistance to local anesthesia
==Risks and complications== Complications of spinal anesthesia can result from the physiologic effects on the nervous system and can also be related to placement technique. Most of the common side effects are minor and are self-resolving or easily treatable while major complications can result in more serious and permanent neurological damage and rarely death. These symptoms can occur immediately after administration of the anesthetic or be delayed.<ref>{{Cite journal |last1=Pryle |first1=B. J. |last2=Carter |first2=J. A. |last3=Cadoux-Hudson |first3=T. |date=March 1996 |title=Delayed paraplegia following spinal anaesthesia: Spinal subdural haematoma following dural puncture with a 25 G pencil point needle at T 12 -L 1 in a patient taking aspirin |journal=Anaesthesia |language=en |volume=51 |issue=3 |pages=263–265 |doi=10.1111/j.1365-2044.1996.tb13644.x|pmid=8712327 |s2cid=34160007 |doi-access=free }}</ref>
Common and minor complications include:<ref name=":0" /> * Mild [[hypotension]] * [[Bradycardia]] * Nausea and vomiting<ref>{{cite journal|last1=Balki|first1=M.|last2=Carvalho|first2=J.C.A.|date=July 2005|title=Intraoperative nausea and vomiting during cesarean section under regional anesthesia|journal=International Journal of Obstetric Anesthesia|volume=14|issue=3|pages=230–241|doi=10.1016/j.ijoa.2004.12.004|pmid=15935649|issn=0959-289X}}</ref> * Transient neurological symptoms (lower back pain with pain in the legs) <ref>{{cite journal|last1=Liu|first1=Spencer|last2=McDonald|first2=Susan|date=May 2001|title=Current Issues in Spinal Anesthesia|url=http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1944910#81331938|journal=Anesthesiology|volume=94|issue=5|pages=888–906|pmid=11388543|doi=10.1097/00000542-200105000-00030|s2cid=15792383 |doi-access=free}}</ref> * [[Post-dural-puncture headache]] or post-spinal headache<ref name=":1" /> – Associated with the size and type of spinal needle used. A 2020 meta analysis recommended use of the 26G atraumatic [[spinal needle]] to lower the risk of PDPH – specifically, the Braun Atraucan 26G needle.<ref name="Maranhao Liu Palanisamy Monks p. ">{{cite journal | last1=Maranhao | first1=B. | last2=Liu | first2=M. | last3=Palanisamy | first3=A. | last4=Monks | first4=D. T. | last5=Singh | first5=P. M. | title=The association between post-dural puncture headache and needle type during spinal anaesthesia: a systematic review and network meta-analysis | journal=Anaesthesia | publisher=Wiley | date=2020-12-17 | volume=76 | issue=8 | pages=1098–1110 | issn=0003-2409 | pmid=33332606 | doi=10.1111/anae.15320 | doi-access= }}</ref>
Serious and permanent complications are rare but are usually related to physiologic effects on the cardiovascular system and neurological system or when the injection has been unintentionally at the wrong site.<ref name=":0" /> The following are some major complications: * Nerve injuries: [[Cauda equina]] syndrome, radiculopathy * [[Cardiac arrest]] * Severe hypotension * [[Spinal epidural hematoma]], with or without subsequent neurological [[sequelae]] due to compression of the spinal nerves. * Epidural abscess * Infection (e.g. meningitis)
==Technique== Regardless of the [[anaesthetic]] agent (drug) used, the desired effect is to block the transmission of afferent nerve signals from peripheral [[nociceptor]]s. Sensory signals from the site are blocked, thereby eliminating pain. The degree of neuronal blockade depends on the amount and concentration of local anaesthetic used and the properties of the [[axon]]. Thin unmyelinated [[group C nerve fiber|C-fibres]] associated with pain are blocked first, while thick, heavily myelinated A-alpha [[motor neuron]]s are blocked moderately. Heavily myelinated, small preganglionic sympathetic fibers are blocked last. The desired result is total numbness of the area. A pressure sensation is permissible and often occurs due to incomplete blockade of the thicker A-beta mechanoreceptors. This allows surgical procedures to be performed with no painful sensation to the person undergoing the procedure.{{cn|date=February 2022}}
Some [[sedation]] is sometimes provided to help the patient relax and pass the time during the procedure, but with a successful spinal anaesthetic the [[surgery]] can be performed with the patient wide awake.
=== Anatomy === In spinal anesthesia, the needle is placed past the dura mater in [[Meninges|subarachnoid space]] and between lumbar vertebrae. In order to reach this space, the needle must pierce through several layers of tissue and ligaments which include the supraspinous ligament, interspinous ligament, and ligamentum flavum. Because the spinal cord ([[conus medullaris]]) is typically at the L1 or L2 level of the spine, the needle should be inserted below this between L3 and L4 space or L4 and L5 space in order to avoid injury to the spinal cord.
=== Positioning === Patient positioning is essential to the success of the procedure and can affect how the anesthetic spreads following administration. There are three different positions which are used: sitting, lateral decubitus, and prone. The sitting and lateral decubitus positions are the most common.
Sitting – The patient sits upright at the edge of the exam table with their back facing the provider and their legs hanging off the end of the table and feet resting on a stool. Patients should roll their shoulders and upper back forward.
Lateral decubitus – In this position, the patient lies on their side with their back at the edge of the bed and facing the provider. The patient should curl their shoulder and legs and arch out their lower back.
Prone – The patient is positioned face down and their back facing upwards in a jackknife position.
=== Limitations === Spinal anaesthetics are typically limited to procedures involving most structures below the upper [[abdomen]]. To administer a spinal anaesthetic to higher levels may affect the ability to breathe by paralysing the intercostal respiratory muscles, or even the [[thoracic diaphragm|diaphragm]] in extreme cases (called a "high spinal", or a "total spinal", with which consciousness is lost), as well as the body's ability to control the [[heart rate]] via the cardiac accelerator fibres. Also, injection of spinal anaesthesia higher than the level of [[lumbar vertebra 1|L1]] can cause damage to the spinal cord, and is therefore usually not done.
===Differences with epidural anaesthesia=== [[File:Prinzip der Spinalanaesthesie.png|thumb|Schematic drawing showing the principles of spinal anaesthesia]] [[Epidural anaesthesia]] is a technique whereby a local anaesthetic drug is injected through a [[catheter]] placed into the [[epidural space]]. This technique is similar to spinal anaesthesia as both are [[neuraxial blockade|neuraxial]], and the two techniques may be easily confused with each other. Differences include: * A spinal anaesthetic delivers drug to the subarachnoid space and into the [[cerebrospinal fluid]] (CSF), allowing it to act on the spinal cord directly. An epidural delivers drugs outside the dura (outside CSF), and has its main effect on nerve roots leaving the dura at the level of the epidural, rather than on the spinal cord itself. * A spinal gives profound block of all motor and sensory function below the level of injection, whereas an epidural blocks a 'band' of nerve roots around the site of injection, with normal function above, and close-to-normal function below the levels blocked. * The injected dose for an epidural is larger, being about 10–20 mL compared to 1.5–3.5 mL in a spinal. * In an epidural, an indwelling catheter may be placed that allows for redosing injections, while a spinal is almost always a one-shot only. Therefore, spinal anaesthesia is more often used for shorter procedures relative to procedures which require epidural anaesthesia. * The onset of analgesia is approximately 25–30 minutes in an epidural, while it is approximately 5 minutes in a spinal. * An epidural often does not cause as significant a [[neuromuscular block]] as a spinal, unless specific local anaesthetics are also used which block motor fibres as readily as sensory nerve fibres. * An epidural may be given at a [[cervical vertebrae|cervical]], [[thoracic vertebrae|thoracic]], or [[lumbar vertebrae|lumbar]] site, while a spinal must be injected below [[lumbar vertebra 2|L2]] to avoid piercing the spinal cord.
===Injected substances=== [[Bupivacaine]] (Marcaine) is the local anaesthetic most commonly used, although [[lidocaine]] ([[lignocaine]]), [[tetracaine]], [[procaine]], [[ropivacaine]], [[levobupivicaine]], [[prilocaine]], or [[cinchocaine]] may also be used. Commonly [[opioids]] are added to improve the block and provide post-operative pain relief, examples include [[morphine]], [[fentanyl]], [[diamorphine]], and [[buprenorphine]]. Non-opioids like [[clonidine]] or [[epinephrine]] may also be added to prolong the duration of analgesia (although Clonidine may cause hypotension). In the [[United Kingdom]], since 2004 the [[National Institute for Health and Care Excellence]] recommends that spinal anaesthesia for Caesarean section is supplemented with intrathecal [[diamorphine]] and this combination is now the modal form of anaesthesia for this indication in that country. In the United States, morphine is used for cesareans for the same purpose since diamorphine (heroin) is not used in clinical practice in the US.
[[Baricity]] refers to the density of a substance compared to the density of human [[cerebrospinal fluid]]. Baricity is used in anaesthesia to determine the manner in which a particular drug will spread in the [[intrathecal]] space. Usually, the hyperbaric, (for example, hyperbaric bupivacaine) is chosen, as its spread can be effectively and predictably controlled by the Anaesthesiologist, by tilting the patient. Hyperbaric solutions are made more dense by adding [[glucose]] to the mixture.
[[Baricity]] is one factor that determines the spread of a spinal anaesthetic but the effect of adding a solute to a solvent, i.e. [[solvation]] or [[Dissolution (chemistry)|dissolution]], also has an effect on the spread of the spinal anaesthetic. In [[tetracaine]] spinal anaesthesia, it was discovered that the rate of onset of analgesia was faster and the maximum level of analgesia was higher with a 10% glucose solution than with a 5% glucose spinal anaesthetic solution. Also, the amount of [[ephedrine]] required was less in the patients who received the 5% glucose solution.<ref>{{Cite journal|url=https://doi.org/10.1007/BF02479865|title=Effect of glucose concentration on the subarachnoid spread of tetracaine in the parturient|first1=Yoshihiro|last1=Hirabayashi|first2=Reiju|last2=Shimizu|first3=Kazuhiko|last3=Saitoh|first4=Hirokazu|last4=Fukuda|date=September 1, 1995|journal=Journal of Anesthesia|volume=9|issue=3|pages=211–213|via=Springer Link|doi=10.1007/BF02479865|pmid=28921218 |s2cid=29567413 |url-access=subscription}}</ref> In another study this time with 0.5% [[bupivacaine]] the mean maximum extent of sensory block was significantly higher with 8% glucose (T3.6) than with 0.83% glucose (T7.2) or 0.33% glucose (T9.5). Also the rate of onset of sensory block to T12 was fastest with solutions containing 8% glucose.<ref>[https://archive.today/20130905084722/http://bja.oxfordjournals.org/content/64/2/232.short Effect of Glucose Concentration on the Intrathecal Spread of 0.5% Bupivacaine]</ref>
==History== {{Main|History of neuraxial anesthesia}}
The first spinal analgesia was administered in 1885 by [[James Leonard Corning]] (1855–1923), a neurologist in New York.<ref name="Corning">Corning J. L. N.Y. Med. J. 1885, '''42''', 483 (reprinted in 'Classical File', ''Survey of Anesthesiology'' 1960, 4, 332)</ref> He was experimenting with [[cocaine]] on the [[spinal nerves]] of a dog when he accidentally pierced the [[dura mater]].
The first planned spinal anaesthesia for surgery on a human was administered by [[August Bier]] (1861–1949) on 16 August 1898, in [[Kiel]], when he injected 3 ml of 0.5% cocaine solution into a 34-year-old labourer.<ref name="Bier">Bier A. Versuche über Cocainisirung des Rückenmarkes. ''Deutsch Zeitschrift für Chirurgie'' 1899;51:361. (translated and reprinted in 'Classical File', ''Survey of Anesthesiology'' 1962, 6, 352)</ref> After using it on six patients, he and his assistant each injected cocaine into the other's [[spinal canal|spine]]. They recommended it for surgeries of legs, but gave it up due to the toxicity of cocaine.
==See also== * [[Combined spinal and epidural anaesthesia]] * [[Epidural]] * [[Intrathecal administration]] * [[Lumbar puncture]]
==References== {{Reflist}}
==External links== * [http://vam.anest.ufl.edu/simulations/spinalanesthesia.php Transparent reality simulation of spinal anaesthesia] * [https://imd-inc.com/ Various diagrams of needles for Lumbar puncture, Epidural, Spinal Anesthesia, etc]
{{Anesthesia}} {{Authority control}}
{{DEFAULTSORT:Spinal Anaesthesia}} [[Category:Regional anesthesia]] [[Category:Routes of administration]]