Editing Brachial plexus (section)

==Clinical significance==

===Injury===
[[File:Brachial Plexus Injury during Motorcycle accident.jpg|thumb|This shows a simulated example of motorcyclist colliding with the floor at an angle, which may damage the brachial plexus nerves. The photo shows how head and shoulder are extremely separated, which may stretch or even tear the nerves in the between area. Protective gear can help prevent nerve damage by providing extra support on the opposite side of the head to prevent over-stretching the neck.]]
{{Main|Brachial plexus injury}}
[[File:Brachial Plexus.png|thumb|Brachial Plexus relation with the clavicle and the subclavian artery.]]
[[Brachial plexus injury|Injury to the brachial plexus]] may affect sensation or movement of different parts of the arm. Injury can be caused by the shoulder being pushed down and the head being pulled up, which stretches or tears the nerves. Injuries associated with malpositioning commonly affect the brachial plexus nerves, rather than other peripheral nerve groups.<ref name="Missingor">{{cite journal |pmid=3342585 |year=1988 |last1=Cooper |first1=DE |last2=Jenkins |first2=RS |last3=Bready |first3=L |last4=Rockwood Jr |first4=CA |title=The prevention of injuries of the brachial plexus secondary to malposition of the patient during surgery |issue=228 |pages=33–41 |journal=Clinical Orthopaedics and Related Research |volume=228 |doi=10.1097/00003086-198803000-00005}}</ref><ref>{{cite journal |doi=10.1302/0301-620X.95B1.29625 |title=Iatropathic brachial plexus injury: A complication of delayed fixation of clavicle fractures |year=2013 |last1=Jeyaseelan |first1=L. |last2=Singh |first2=V. K. |last3=Ghosh |first3=S. |last4=Sinisi |first4=M. |last5=Fox |first5=M. |journal=The Bone & Joint Journal |volume=95-B |issue=1 |pages=106–10 |pmid=23307682}}</ref> Due to the brachial plexus nerves being very sensitive to position, there are very limited ways of preventing such injuries. The most common victims of brachial plexus injuries consist of victims of motor vehicle accidents and newborns.<ref>{{cite journal |last1=Midha |first1=Rajiv |journal=Neurosurgery |title=Epidemiology of Brachial Plexus Injuries in a Multitrauma Population |pmid=9179891 |year=1997 |volume=40 |issue=6 |pages=1182–8; discussion 1188–9 |doi=10.1097/00006123-199706000-00014}}</ref>

<!--Causes-->Injuries can be caused by stretching, diseases, and wounds to the lateral cervical region (posterior triangle) of the neck or the axilla. Depending on the location of the injury, the signs and symptoms can range from complete paralysis to anesthesia. Testing the patient's ability to perform movements and comparing it to their normal side is a method to assess the degree of paralysis. A common brachial plexus injury is from a hard landing where the shoulder widely separates from the neck (such as in the case of motorcycle accidents or falling from a tree). These stretches can cause ruptures to the superior portions of the brachial plexus or avulse the roots from the spinal cord. Upper brachial plexus injuries are frequent in newborns when excessive stretching of the neck occurs during delivery. Studies have shown a relationship between a newborn's weight and brachial plexus injuries; however, the number of cesarean deliveries necessary to prevent a single injury is high at most birth weights.<ref name="DoiSMissing">{{cite journal |doi=10.1016/S0029-7844(97)00007-0 |title=Birth Weight as a Predictor of Brachial Plexus Injury |year=1997 |last1=Ecker |first1=Jeffrey L. |last2=Greenberg |first2=James A. |last3=Norwitz |first3=Errol R. |last4=Nadel |first4=Allan S. |last5=Repke |first5=John T. |journal=Obstetrics & Gynecology |volume=89 |issue=5 |pages=643–47 |pmid=9166293}}</ref> 

<!-- Symptoms-->For the upper brachial plexus injuries, paralysis occurs in those muscles supplied by C5 and C6 like the deltoid, biceps, brachialis, and brachioradialis. A loss of sensation in the lateral aspect of the upper limb is also common with such injuries. An inferior brachial plexus injury is far less common but can occur when a person grasps something to break a fall or a baby's upper limb is pulled excessively during delivery. In this case, the short muscles of the hand would be affected and cause the inability to form a full fist position.<ref>{{cite book |last=Moore |first=Keith |title=Clinically Oriented Anatomy |year=2006 |publisher=Lippincott Williams & Wilkins |location=Philadelphia |isbn=0-7817-3639-0 |pages=[https://archive.org/details/clinicallyorient00moor_1/page/778 778–81] |url-access=registration |url=https://archive.org/details/clinicallyorient00moor_1/page/778 }}</ref>

To differentiate between preganglionic and postganglionic injury, clinical examination requires that the physician keep the following points in mind. Preganglionic injuries cause loss of sensation above the level of the clavicle, pain in an otherwise insensate hand, ipsilateral Horner's syndrome, and loss of function of muscles supplied by branches arising directly from roots—i.e., long thoracic nerve palsy leading to winging of scapula and elevation of ipsilateral diaphragm due to phrenic nerve palsy.

Acute brachial plexus neuritis is a neurological disorder that is characterized by the onset of severe pain in the shoulder region. Additionally, the compression of cords can cause pain radiating down the arm, numbness, paresthesia, erythema, and weakness of the hands. This kind of injury is common for people who have prolonged hyperabduction of the arm when they are performing tasks above their head.

==== Sports injuries ====
One sports injury that is becoming prevalent in contact sports, particularly in the sport of American football, is called a "stinger."<ref>{{Cite journal |last=Dimberg |first=Elliot L. |last2=Burns |first2=Ted M. |date=July 2005  |title=Management of Common Neurologic Conditions in Sports |url=http://dx.doi.org/10.1016/j.csm.2005.04.002 |journal=Clinics in Sports Medicine |volume=24 |issue=3 |pages=637–662 |doi=10.1016/j.csm.2005.04.002 |issn=0278-5919|url-access=subscription }}</ref> An athlete can incur this injury in a collision that can cause cervical axial compression, flexion, or extension of nerve roots or terminal branches of the brachial plexus.<ref>{{cite journal|last1=Elias|first1=Ilan|title=Recurrent burner syndrome due to presumed cervical spine osteoblastoma in a collision sport athlete - a case report|journal=Journal of Brachial Plexus and Peripheral Nerve Injury|date=2014 |volume=02 |pages=e61–e65 |doi=10.1186/1749-7221-2-13 |doi-access=free |pmid=17553154|pmc=1904218}}</ref> In a study conducted on football players at United States Military Academy, researchers found that the most common mechanism of injury is, "the compression of the fixed brachial plexus between the shoulder pad and the superior medial scapula when the pad is pushed into the area of [[Erb's point (neurology)|Erb's point]], where the brachial plexus is most superficial.".<ref>{{cite journal|last1=Cunnane|first1=M|title=A retrospective study looking at the incidence of 'stinger' injuries in professional rugby union players|journal=British Journal of Sports Medicine|date=2011|url=http://bjsm.bmj.com/content/45/15/A19.1.abstract|access-date=2015-02-12|doi=10.1136/bjsports-2011-090606.60|volume=45|issue=15|pages=A19.1–A19|url-access=subscription}}</ref> The result of this is a "burning" or "stinging" pain that radiates from the region of the neck to the fingertips. Although this injury causes only a temporary sensation, in some cases it can cause chronic symptoms.

==== Penetrating wounds ====
Most penetration wounds require immediate treatment and are not as easy to repair. For example, a deep knife wound to the brachial plexus could damage and/or sever the nerve. According to where the cut was made, it could inhibit action potentials needed to innervate that nerve's specific muscle or muscles.

==== Injuries during birth ====
Brachial plexus injuries can occur during the delivery of newborns when after the delivery of the head, the anterior shoulder of the infant cannot pass below the pubic symphysis without manipulation. This manipulation can cause the baby's shoulder to stretch, which can damage the brachial plexus to varying degrees.<ref>{{Cite web|url=http://www.ninds.nih.gov/disorders/brachial_plexus/brachial_plexus.htm|title=Brachial Plexus Injuries Information Page: National Institute of Neurological Disorders and Stroke (NINDS)|website=www.ninds.nih.gov|access-date=2016-11-28|archive-date=2016-12-02|archive-url=https://web.archive.org/web/20161202230331/http://www.ninds.nih.gov/disorders/brachial_plexus/brachial_plexus.htm|url-status=dead}}</ref> This type of injury is referred to as [[shoulder dystocia]]. Shoulder dystocia can cause obstetric brachial plexus palsy (OBPP), which is the actual injury to the brachial plexus. The incidence of OBPP in the United States is 1.5 per 1000 births, while it is lower in the United Kingdom and the Republic of Ireland (0.42 per 1000 births).<ref>{{Cite journal|last1=Doumouchtsis|first1=Stergios K.|last2=Arulkumaran|first2=Sabaratnam|date=2009-09-01|title=Are all brachial plexus injuries caused by shoulder dystocia?|journal=Obstetrical & Gynecological Survey|volume=64|issue=9|pages=615–623|doi=10.1097/OGX.0b013e3181b27a3a|issn=1533-9866|pmid=19691859}}</ref> While there are no known risk factors for OBPP, if a newborn does have shoulder dystocia it increases their risk for OBPP 100-fold. Nerve damage has been connected to [[birth weight]] with larger [[newborns]] being more susceptible to the [[injury]] but it also has to do with the delivery methods. Although very hard to prevent during live [[birth]], doctors must be able to deliver a [[newborn]] with precise and gentle movements to decrease chances of injuring the child.

=== Tumors ===
Tumors that may occur in the brachial plexus are [[schwannoma]]s, [[neurofibroma]]s and [[malignant peripheral nerve sheath tumor]]s.

=== Imaging ===
Imaging of the Brachial Plexus can be done effectively by using a higher magnetic strength MRI Scanner like 1.5 T or more. It is impossible to evaluate the brachial plexuses with plain Xray, CT and ultrasound scanning can manage to view the plexuses to an extent; hence MRI is preferred in imaging brachial plexus over other imaging modalities due to its multiplanar capability and the tissue contrast difference between brachial plexus and adjacent vessels. The plexuses are best imaged in coronal and sagittal planes, but axial images give an idea about the nerve roots. Generally, T1 WI and T2 WI images are used in various planes for the imaging; but new sequences like MR Myelolography, Fiesta 3D and T2 cube are also used in addition to the basic sequences to gather more information to evaluate the anatomy more.

===In anaesthetics===
{{Main|Brachial plexus block}}