Erb’s palsy is a kind of paralysis affecting sensation and motor control of muscles of the upper arm. Palsies are disabilities affecting sensation and motor control to various parts of the body caused by damage to the brain, spinal cord or nervous system, often presenting as paralysis. Erb’s palsy is caused by damage to the lower portion of the brachial plexus, a nerve system that originates at the spinal cord in the back of the neck and continues through the upper arm. The brachial plexus controls sensation and movement in the arm, forearm, hand, wrist and fingers. Damage to the main nerve of the arm along vertebrae C5 and C6 where the nerves converge (Erb’s point) causes the kind of symptoms seen in Erb’s palsy.
Erb’s palsy affects the biceps, the shoulder muscles and the muscle that permits bending the arm at the elbow. The characteristic presentation of Erb’s palsy is the arm is rotated toward the body and the wrist is bent. Paralysis of the deltoid muscle limits the ability to raise the arm to the side, and paralysis of the brachialis and bicep limits the ability to bend the arm at the elbow.
Injury to the nerves can result from a difficult birth if the fetus’s arm or head was tractioned or manipulated with too much force such that the nerves were hyperextended or torn during delivery, especially in cases of breech presentation or in the event of shoulder dystocia — when the fetus’s shoulder is impacted against the mother’s pubic bone. Brachial plexus nerve damage can also result from a tumor composed of nerve cells growing on the nerve, or spinal cord injury from infection or oxygen deprivation during fetal development (rare). Individuals involved in contact sports or activities, such as diving or skiing, that put the body at risk for high-impact injuries to the head, neck and shoulder may sustain brachial plexus nerve injury. Other trauma, such as from falling or from car, bicycle, boating or motorcycle accidents, can cause damage to the brachial plexus nerve. Fracture of the clavicle (collar bone) can also result in injury to the brachial plexus.
In the most severe injuries, the nerve is torn from its root at the spinal cord or somewhere along the nerve (avulsion and rupture). Nerves that have been damaged, either due to a tumor or from injury, and healed, leaving scar tissue that interferes with the proper functioning of the nerve is called neuroma. The least severe injury that can best heal without residual complications is called neuropraxia, when the nerve has only been hyperextended, and is the most frequently occurring severity of brachial plexus injury.
Because injury to the brachial plexus can vary in severity and location, individual cases may present with a different range of symptoms and complications. Imaging technology, such as an MRI, can help a physician find out where and to what extend the brachial plexus or other nerves were damaged. Exams using imaging technology and the testing of certain reflexes are important to rule out injury to the spinal cord and other causes of paralysis. If a bone fracture is suspected, a standard X-ray can be performed. Tests that measure the conductivity of the nerves and determine if the nerve has been completely or partially severed can aid in the decision whether to use surgery in the treatment plan.
As with other forms of palsies, the most frequent complication is joint stiffness and contractures, loss of muscle tone and sensation in the afflicted areas. Nerve damage can also cause severe and/or constant pain. Vertebral alignment problems, such as scoliosis, and reduced bone density can result after many years of unbalanced muscle tone and activity. Individuals born with Erb’s palsy may have abnormal bone development while growing due to the lack of ability to move the arm, or the arm may be shorter or underdeveloped. Circulatory problems as a result of abnormal development of the arm can become a problem for correct temperature regulation of the limb, and ability of the skin to heal quickly enough to prevent infection.
Prognosis And Treatment:
Most children born with an injury to the brachial plexus nerve system recover quickly and have no long-lasting effects; however, for those whose symptoms persist beyond the first few weeks of life, physical and occupational therapies are the most common and useful treatments. In the first few weeks of life, a child with a brachial plexus injury must be treated with extra care when moving the head, neck, arms and shoulders to prevent further damage to the nerves. Caregivers can learn how to massage, stretch, and assist with strengthening “range of motion” exercises for an infant with a brachial plexus injury to help the rehabilitation process of nerves and maintain muscle tone. Certain kinds of wrist and elbow splints or taping may be used at times to reduce development of joint contractures (severe stiffness in the joint such that complete extension is impossible). For the most severe cases, those of anoxia and rupture, surgical procedures that re-attach the nerves are required to restore sensation and motor control, if any.