Brachial plexus injury

Brachial plexus injury
Classification and external resources
ICD-10 G54.0, P14.3, S14.3
ICD-9 353.0, 767.6, 953.4
DiseasesDB 31267
MeSH D020516

The brachial plexus is a network of nerves that conducts signals from the spinal cord, which is housed in the spinal canal of the vertebral column (or spine), to the shoulder, arm and hand. These nerves originate in the fifth, sixth, seventh and eighth cervical (C5-C8), and first thoracic (T1) spinal nerves, and innervate the muscles and skin of the chest, shoulder, arm and hand. Brachial plexus injuries, or lesions, are caused by damage to those nerves.[1][2][3]

Brachial plexus injuries, or lesions, can occur as a result of shoulder trauma, tumours, or inflammation. The rare Parsonage-Turner Syndrome causes brachial plexus inflammation without obvious injury, but with nevertheless disabling symptoms.[1][4] But in general, brachial plexus lesions can be classified as either traumatic or obstetric. Obstetric injuries may occur from mechanical injury involving shoulder dystocia during difficult childbirth.[5] Traumatic injury may arise from several causes. "The brachial plexus may be injured by falls from a height on to the side of the head and shoulder, whereby the nerves of the plexus are violently stretched....The brachial plexus may also be injured by direct violence or gunshot wounds, by violent traction on the arm, or by efforts at reducing a dislocation of the shoulder joint".[6]

Contents

Causes

In most cases the nerve roots are stretched or torn from their origin, since the meningeal covering of a nerve root is thinner than the sheath enclosing the nerve. The epineurium of the nerve is contiguous with the dura mater, providing extra support to the nerve.

Brachial plexus lesions typically result from excessive stretching; from rupture injury where the nerve is torn but not at the spinal cord; or from avulsion injuries, where the nerve is torn from its attachment at the spinal cord. A build-up of scar tissue around a brachial plexus injury site can also put pressure on the injured nerve, disrupting innervation of the muscles. Although injuries can occur at any time, many brachial plexus injuries happen during birth: the baby's shoulders may become impacted during the birth process causing the brachial plexus nerves to stretch or tear. Obstetric injuries may occur from mechanical injury involving shoulder dystocia during difficult childbirth, the most common of which result from injurious stretching of the child's brachial plexus during birth, mostly vaginal, but occasionally Caesarean section. The excessive stretch results in incomplete sensory and/or motor function of the injured nerve.[2][5]

Traumatic brachial plexus injuries may arise from several causes, including sports, high-velocity motor vehicle accidents, especially in motorcyclists, but also all-terrain-vehicle (ATV) accidents. Injury from a direct blow to the lateral side of the scapula is also possible. The severity of nerve injuries may vary from a mild stretch to the nerve root tearing away from the spinal cord (avulsion). "The brachial plexus may be injured by falls from a height on to the side of the head and shoulder, whereby the nerves of the plexus are violently stretched...The brachial plexus may also be injured by direct violence or gunshot wounds, by violent traction on the arm, or by efforts at reducing a dislocation of the shoulder joint".[6]

Brachial plexus lesions can be divided into three types:

  1. An upper brachial plexus lesion, which occurs from excessive lateral neck flexion away from the shoulder. Most commonly, forceps delivery or falling on the neck at an angle causes upper plexus lesions leading to Erb's palsy.[6] This type of injury produces a very characteristic sign called Waiter's tip deformity due to loss of the lateral rotators of the shoulder, arm flexors, and hand extensor muscles.[2][7]
  2. Less frequently, the whole brachial plexus lesion occurs;[8]
  3. most infrequently, sudden upward pulling on an abducted arm (as when someone breaks a fall by grasping a tree branch) produces a lower brachial plexus lesion, in which the eighth cervical (C8) and first thoracic (T1) nerves are injured "either before or after they have joined to form the lower trunk. The subsequent paralysis affects, principally, the intrinsic muscles of the hand and the flexors of the wrist and fingers".[6] This results in a form of paralysis known as Klumpke's paralysis.[6][9]

Injury Classification

The severity of brachial plexus injury is determined by the type of nerve damage.[1] There are several different classification systems for grading the severity of nerve and brachial plexus injuries. Most systems attempt to correlate the degree of injury with symptoms, pathology and prognosis. Seddon's classification, devised in 1943, continues to be used, and is based on three main types of nerve fiber injury, and whether there is continuity of the nerve.[10]

  1. Neurapraxia: The mildest form of nerve injury. It involves an interruption of the nerve conduction without loss of continuity of the axon. Recovery takes place without wallerian degeneration.[10][11]
  2. Axonotmesis: Involves axonal degeneration, with loss of the relative continuity of the axon and its covering of myelin, but preservation of the connective tissue framework of the nerve (the encapsulating tissue, the epineurium and perineurium, are preserved).[10][12]
  3. Neurotmesis: The most severe form of nerve injury, in which the nerve is completely disrupted by contusion, traction or laceration. Not only the axon, but the encapsulating connective tissue lose their continuity. The most extreme degree of neurotmesis is transsection, although most neurotmetic injuries do not produce gross loss of continuity of the nerve but rather, internal disruption of the nerve architecture sufficient to involve perineurium and endoneurium as well as axons and their covering. It requires surgery, with unpredictable recovery.[10][13]

A more recent and commonly used system described by the late Sir Sydney Sunderland,[14] divides nerve injuries into five degrees: first degree or neurapraxia, following on from Seddon, in which the insulation around the nerve called myelin is damaged but the nerve itself is spared, and second through fifth degree, which denotes increasing severity of injury. With fifth degree injuries, the nerve is completely divided.[10]

Presentation (Signs and Symptoms)

Signs and Symptoms may include a limp or paralyzed arm, lack of muscle control in the arm, hand, or wrist, and lack of feeling or sensation in the arm or hand. Although several mechanisms account for brachial plexus injuries, the most common is nerve compression or stretch. Infants, in particular, may suffer brachial plexus injuries during delivery and these present with typical patterns of weakness, depending on which portion of the brachial plexus is involved. The most severe form of injury is nerve root avulsion, which results in complete weakness in corresponding muscles. This usually accompanies high-velocity impacts that occurs during motor vehicle or bicycle accidents.[2]

The cardinal signs of brachial plexus injury then, are weakness in the arm, diminished reflexes, and corresponding sensory deficits.

  1. Erb's palsy. "The position of the limb, under such conditions, is characteristic: the arm hangs by the side and is rotated medially; the forearm is extended and pronated. The arm cannot be raised from the side; all power of flexion of the elbow is lost, as is also supination of the forearm".[6]
  2. In Klumpke's paralysis, a form of paralysis involving the muscles of the forearm and hand,[15] a characteristic sign is the clawed hand, due to loss of function of the ulnar nerve and the intrinsic muscles of the hand it supplies.[7]

Diagnosis

The diagnosis may be confirmed by an EMG examination in 5 to 7 days. The evidence of denervation will be evident. If there is no nerve conduction 72 hours after the injury, then avulsion is most likely..

Treatment

Treatment for brachial plexus injuries includes occupational or physical therapy and, in some cases, surgery. Some brachial plexus injuries may heal without treatment. Many infants improve or recover within 6 months, but those that do not have a very poor outlook and will need further surgery to try to compensate for the nerve deficits.[1][5] The ability to bend the elbow (biceps function) by the third month of life is considered an indicator of probable recovery, with additional upward movement of the wrist, as well as straightening of thumb and fingers an even stronger indicator of excellent spontaneous improvement. Gentle range of motion exercises performed by parents, accompanied by repeated examinations by a physician, may be all that is necessary for patients with strong indicators of recovery.[2]

To relieve symptoms associated with this type of injury, common drugs include Lyrica and Cesamet..

Prognosis

The site and type of brachial plexus injury determine the prognosis. Avulsion and rupture injuries require timely surgical intervention for any chance of recovery. For milder injuries involving build-up of scar tissue and for neurapraxia, the potential for improvement varies, but there is a fair prognosis for spontaneous recovery, with a 90 - 100% return of function.[1][2]

See also

References

  1. ^ a b c d e "NINDS Brachial Plexus Injuries: Information Page". National Institute of Neurological Disorders and Stroke. Last updated September 29, 2008 - see bottom of webpage). http://www.ninds.nih.gov/disorders/brachial_plexus/brachial_plexus.htm. Retrieved 2009-10-11. 
  2. ^ a b c d e f "Brachial Plexus Injury: Description & illustrations". Cincinnati Children's Hospital, health information website. (revision 9/09 - see bottom of webpage). http://www.cincinnatichildrens.org/health/info/neurology/diagnose/brachial-plexus.htm. Retrieved 2009-10-11. 
  3. ^ Glanze, W.D., Anderson, K.N., & Anderson, L.E, ed (1990). Mosby's Medical, Nursing, and Allied Health Dictionary (3rd ed.). St. Louis, Missouri: The C.V. Mosby Co.. ISBN 0-8016-3227-7.  p.165
  4. ^ "Parsonage-Turner Syndrome". Who Named It? (whonamedit.com). Date unclear. http://www.whonamedit.com/synd.cfm/1910.html. Retrieved 2009-10-11. 
  5. ^ a b c A.D.A.M Healthcare center
  6. ^ a b c d e f Warwick, R., & Williams, P.L, ed (1973). Gray’s Anatomy (35th ed.). London: Longman.  pp.1046
  7. ^ a b "Neurology notes". MrCPass.com. (modified 3-10-2009 - see bottom of webpage). http://www.mrcpass.com/Notes/Neurology%20Notes.pdf. Retrieved 2009-10-11. 
  8. ^ http://books.google.com/books?id=DlF3yl2HJFIC&lpg=PA366&ots=6upxnXa8pe&dq=%22entire%20brachial%20plexus%20lesion%22&hl=sl&pg=PA366#v=onepage&q=%22entire%20brachial%20plexus%20lesion%22&f=false
  9. ^ Bienstock, A., & Kim, J.Y.S. (Updated July 13 2009). "Brachial Plexus Surgery article, with overview of brachial plexus injury". Emedicine. http://www.emedicine.com/plastic/topic450.htm. Retrieved 2009-10-11. 
  10. ^ a b c d e Tavaris, Marcio Pessanha (Publication date unclear). "Classification of nerve injuries". MEDSTUDENTS - Neurosurgery. http://www.medstudents.com.br/neuroc/neuroc4.htm. Retrieved 2009-10-08. 
  11. ^ Glanze, W.D., Anderson, K.N., & Anderson, L.E (1990), p.805
  12. ^ Glanze, W.D., Anderson, K.N., & Anderson, L.E (1990), p.117
  13. ^ Glanze, W.D., Anderson, K.N., & Anderson, L.E (1990), p.810
  14. ^ Ryan, G.B. (August 1995). "Obituary: Professor Emeritus Sir Sydney Sunderland (1910-1993)". Journal of Anatomy 187(Pt1): 249–251. PMC 1167365. PMID 7591982. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1167365. Retrieved 2009-10-08. 
  15. ^ Glanze et al. (1990) p.667

External links

Traumatic brain injury
Spinal cord injury
PNS

M: CNS

anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp

noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr

proc, drug(N1A/2AB/C/3/4/7A/B/C/D)

M: PNS

anat(h/r/t/c/b/l/s/a)/phys(r)/devp/prot/nttr/nttm/ntrp

noco/auto/cong/tumr, sysi/epon, injr

proc, drug(N1B)