Brachial Plexus Injury: Description, Causes and Risk Factors:
Brachial Plexus Injury: Major nerve plexus formed of the ventral primary rami of the fifth cervical to first thoracic spinal nerves for innervation of the upper limb. The ventral primary rami entering into formation of the plexus constitute the roots of the plexus; the roots are located in the posterior triangle of the neck, converging to emerge from the scalenus anterior and medius muscles. As they emerge from the scalene hiatus, the C5 and C6 roots combine to form the superior trunk, C7 remains alone as the middle trunk, and the C8 and T1 roots combine to form the inferior trunk of the plexus. The trunks pass beneath the clavicle, passing from the neck into the axilla through the
cervicoaxillary canal. As they cross the first rib, all three trunks divide into anterior and posterior divisions of the plexus. Nerve fibers contained within anterior divisions are destined for the anterior aspect of the limb; those contained within the posterior divisions are destined for the posterior aspect of the limb. Within the axilla, the anterior divisions of the superior and middle trunks merge to form the lateral cord of the plexus; the anterior division of the inferior trunk becomes the medial cord of the plexus, and the posterior divisions of all three trunks become the posterior cord, the cords being named for their position in relation to the axillary artery, to which they run parallel and which they surround. The cords of the brachial plexus give rise to most of the named peripheral nerves that are the products of the plexus formation. The major nerves of the lateral cord are the musculocutaneous nerve and the lateral root of the median nerve. The medial cord gives rise to the ulnar and medial root of the median nerve. The lateral and medial roots of the median nerve merge to form the medial nerve. The posterior cord of the plexus gives rise to the radial and axillary nerves.
Brachial Plexus Injury is nothing but damage to the brachial plexus related to delivery; associated with excessive lateral stretching of the head, typically in cases of shoulder dystocia or breech deliveries.
Brachial Plexus Injury in newborns usually occur during a difficult delivery, such as with a large baby, a breech presentation, or a prolonged labor, when the person assisting the delivery must exert some force to pull the baby from the birth canal. One side of the baby's neck is stretched, which can damage the nerves by stretching or tearing them. If the upper nerves are affected, the condition is called Erb's palsy. The infant may not be able to move the arm, but may be able to move the fingers. Injuries that involve both the upper and lower nerves are more severe and result in a condition called global palsy.
There are four types of nerve injuries to Brachial Plexus Injury
Avulsion injuries. The nerve is torn from its attachment to the spinal cord. This is the most serious type of injury.
- Rupture injuries. The nerve is torn, but not at the spinal cord.
- Neuroma injuries. These injuries result from scar tissue that forms and puts pressure on the nerve.
- Stretch injuries. These injuries, known as neurapraxia (new-rah-PRAK-see-ah) are the most common. The
- Nerve is damaged but not torn. Normally, these injuries heal on their own, usually within three months.
Brachial Plexus Injury is less common now that delivery techniques have improved. Cesarean delivery is used more often when there are concerns about a difficult delivery. Although a c-section reduces the risk of injury it does not prevent it, and this delivery also has other risks.
Brachial Plexus Injury may be confused with a condition called pseudoparalysis (apparent paralysis due to voluntary inhibition of motion because of pain, incoordination, or other cause
, but without actual paralysis), in which the infant has a fracture and is not moving the arm because of pain, but there is no damage to the nerves.
Symptoms can be seen immediately or soon after birth, and may include:
Newborn is not moving the upper or lower arm or hand.
- Absent Moro reflex on the affected side.
- Arm flexed (bent) at elbow and held against body.
- Decreased grip on the affected side.
A physical exam usually shows that the infant is not moving the upper or lower arm or hand. The affected arm may flop when the infant is rolled from side to side.The Moro reflex is absent on the side with the brachial plexus or nerve injury.
A careful examination of the clavicle or collarbone will be done to look for a fracture. Sometimes, the infant will need to have an x-ray of this bone.
A newborn with Erb's palsy will have the arm straight down at the side and will not move it.Sometimes, the arm may be slightly turned, with a bent wrist and straight fingers. A droopy eyelid on theaffected side may indicate a more severe injury. The doctor may order an X-ray or magnetic resonanceimage (MRI) to see if there is any damage to the bones and joints of the neck and shoulder. The doctor may also use an electromyogram or EMG (A graphic representation of the electric currents associated with muscular action) or nerve conduction studies (NCS) to see if any nerve signals arepresent in the upper arm muscle.
Gentle massage of the arm and range-of-motion exercises are recommended for mild cases. More severe cases, or those that do not improve in the first few weeks of life may need to be evaluated by several specialists.
If there is no change over the first three months, nerve surgery may be helpful. However, nerve surgery will not restore normal function or help infants over one year old. After surgery, the infant will wear a splint for approximately three weeks. Because nerves grow at a rate of one inch per month, it may take several months, or even years, for nerves repaired at the neck to reach the muscles of the lower arm and hand.
Some children with Brachial Plexus Injury will continue to have weakness in the shoulder, arm or hand. They may find it difficult to raise the hand over the head, to turn the hand palm up, or to extend the wrist. In some of these cases, a surgical procedure called tendon transfer may be helpful. Tendons are the connective tissues between muscle and bone. The surgeon will separate the tendon from its normal attachment and reattach it in a different place. This is often helpful in improving shoulder and wrist motions as well as elbow position and hand grip.
Tendon transfers are generally performed when the child is old enough to follow instructions. After surgery, the child will have to wear a cast for about six weeks and a splint at night for up to six months. Physical therapy may continue for up to one year after surgery.
Your doctor will discuss the various treatment options with you and make a specific recommendation based on your child's individual situation. Do not hesitate to ask questions; there is much that parents can do to help ensure a good functional outcome.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.