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The brachial plexus is a bundle of nerves responsible for providing movement and sensation to the arms. It runs from the spinal cord, through the neck, and down each arm. Individual nerves within the brachial plexus affect different parts of the arm, from the shoulder to the fingers.
These nerves can become damaged, most often during childbirth as they are pulled and stretched. Brachial plexus injury may also be due to trauma in children and adults.
Brachial plexus injuries in newborns cause weakness and paralysis in the arms to varying degrees.  How severe the symptoms are and wherein the arm they occur depends on how severely the nerves are damaged and which nerves are damaged.
The Brachial Plexus
The bundle of nerves called the brachial plexus starts at the spinal cord near the neck. The nerves run through the bones of the neck, to the shoulder, and then some run further down the arm, all the way to the fingertips. The five main nerves that make up the brachial plexus connect to smaller nerves in the arm and provide sensation and the ability to move the arms.
Each of the five nerves in the brachial plexus can potentially be damaged in a brachial plexus injury. Because each one controls a different part of the arm, symptoms of damage vary by which part of the arm is affected. The extent to which one or more of the nerves is damaged will affect how severe the resulting symptoms are. 
Types of Injury
The type of damage caused to the brachial plexus nerves is categorized by severity. The least severe type of injury is stretching, also known as neurapraxia. As a child is pulled from the birth canal it’s head and shoulder may be pulled apart to a degree that causes the brachial plexus nerves to stretch. A little stretching may cause no damage, but more stretching can cause stress to the nerves.
More severe damage is called a rupture. When the nerves are pulled to the extent that they tear, they are considered ruptured. The most severe type of brachial plexus injury is an avulsion. This occurs when the nerves are pulled so forcefully that they are completely torn away from the spinal cord. Avulsions are difficult to treat and are most likely to cause permanent symptoms.
Causes of Brachial Plexus Injuries
These nerve injuries are ultimately caused by stretching of the nerves to an unnatural degree. In adults and children, some type of forceful accident may cause an injury. This could include penetration wounds, gunshot wounds, and falls. Although these injuries are possible in adults and children, the most common timing of a brachial plexus injury in childbirth.
Childbirth damage to the brachial plexus can occur in a number of ways. When a baby is being born and its head and shoulder get stretched apart, for whatever reason, the brachial plexus may become damaged. Risk factors include large fetus size, long and difficult labor, and breech birth position.
Examples of how the damage occurs may include a baby being born with its head and neck pulled to the side as the shoulders pass through the birth canal. Another example is during a breech birth when the infant’s arms are raised above its head. This can stretch the nerves. Also, it is possible that during a head-first birth, the infant’s head will be pulled too forcefully, causing the stretching and damage.
In some cases, the damage to the brachial plexus nerves during childbirth is considered preventable and the medical caregiver may be found negligent. For instance, if a doctor opts to not perform a Cesarean section, it may result in difficult labor and subsequent damage to the nerves. Incorrect use of instruments, like forceps, or simply using too much force on the infant may also be the fault of the doctor or midwife.
Brachial Plexus Palsies
Injury to these nerves causes one of several types of conditions called palsies. The most common is Erb’s palsy in which the upper arm is affected. If the nerves that control the lower part of the arm are affected it is sometimes called Klumpke’s palsy or paralysis. In some cases, any type of palsy caused by the brachial plexus damage is simply called Erb’s palsy or brachial plexus palsy. When all five nerves of the brachial plexus are damaged it is called global palsy.
Brachial plexus palsies are the result of damage to the nerves that control the arms. The result is a weakness in the arm, loss of sensation, or even paralysis. In most cases of palsies, the symptoms can be seen right after birth. 
These include a lack of movement, or weaker movement, in one arm as compared to the other, an arm being bent inwards at an awkward angle, or a weaker grip in one hand. A baby with a brachial plexus palsy will also likely lack the Moro reflex on one side.
In the vast majority of cases of Erb’s palsy caused during childbirth, the infant will recover within three to six months and face no lasting effects of the nerve damage.  This is because most cases of the palsy are caused by mild damage to the nerves. Most infants recover with time and gentle physical therapy.
Physical therapy is used to promote the natural healing of the nerves and to help an infant develop more muscle strength in the affected arm. Parents can be guided by a physical therapist and shown how to practice the techniques in between sessions. A therapist may use a range of motion exercises and gentle massage.
In more severe cases of brachial plexus injury, therapy and time may not be enough to heal the nerves. If an infant shows no signs of improvement by six months, a doctor may recommend surgery to repair the damaged nerves.  A nerve graft can be used to repair those nerves that have been stretched beyond their limits or torn. This involves patching in a donor’s nerve.
In the most extreme cases, in which a nerve has been completely torn from the spinal cord, a nerve transfer may be performed. This involves using a donor nerve to completely replace all or part of a damaged brachial plexus nerve.
Donor’s nerves come from another part of the body. Recovering from surgery on nerves takes a long time, and in the case of infant brachial plexus injuries, full recovery may never be possible.
The outlook for most infant brachial plexus injuries is very good. Most infants will see full recovery within three to six months of birth with just natural healing and physical therapy.  These babies will likely not have any lasting symptoms of the palsy.
Those with more severe damage, however, will probably have lifelong symptoms including some degree of weakness or paralysis as well as diminished sensation in the affected arm.
If you feel that your child’s brachial plexus injury was caused by doctor negligence or wrongdoing, you may have a case. Many parents with children facing lifelong consequences from this kind of palsy sue the hospital or doctor for damages to get compensation for their child.
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