Brachial Plexus Injuries
Table of Contents
- What is the Brachial Plexus?
- What is a Brachial Plexus Injury?
- Symptoms of a Brachial Plexus Injury
- Causes of Brachial Plexus Injuries
- Diagnosis of Brachial Plexus Injury
- Treatment of a Brachial Plexus Injury
- Complications of Brachial Plexus Injury
The brachial plexus is a complex network of nerves that begin near the shoulder and neck. The nerves actually begin at the level of the spinal cord in the cervical area and are responsible for controlling function of the shoulder, elbow, wrist, and hand. The brachial plexus looks like a bundle of electrical cable all wrapped up in insulation.
The brachial plexus consists of nerves that are motor and nerves that are sensory. The motor nerves send signals from the brain to move muscles in the arm and hand. The sensory nerves send signals from the periphery to the brain. When the brachial plexus is injured, both sensory and motor nerves are affected.
The brachial plexus is a fragile bunch of nerves. It can be damaged by having pressure put upon it, stretching the nerves and cutting the nerves. They can be pulled away from the shoulder such as would occur during a fall from a motorcycle or bicycle. Nerves can even pull away at the site of their origin in the neck.
When the nerve is injured, signals from the brain and the arm are prevented from passing back and forth and there is lack of movement and numbness in the arm. When the nerve fibers are completely cut, the part of the nerve distal to the cut is dead; however, its myelin sheath persists. The proximal end is still alive and can, over time, heal and extend down the now empty myelin sheath to recover function.What is a Brachial Plexus Injury?
Brachial plexus injuries can be minor and completely recoverable. They can also be severe enough that permanent disability of the arm is the ultimate outcome. The brachial nerve can be stretched, sometimes to the point of avulsion by pushing the shoulder downward while pulling the head away from the shoulder.
Such an injury can happen in childbirth. When the shoulders are stuck in the birth canal and the doctors pull on the head and put the head in a lateral position to get the shoulders out, the brachial plexus is stretched and can break, resulting in disability to the baby’s arm on the side the neck was stretched on.
Brachial plexus injuries can happen in motorcycle injuries, contact sports, automobile accidents, and falls from a great height. The brachial plexus can also be injured as a result of tumors, inflammation of the tissues or from thoracic outlet syndrome, where structures pinch off the brachial plexus due to congenital birth defects, such as an extra rib, and poor posture at the workplace. Minor injuries may improve spontaneously; severe brachial plexus injuries need to go to surgery.
Brachial plexus injury or “brachial plexus palsy” is found in both adults and children. It has a lifetime prevalence rate of approximately 1.2 percent. In adults, it usually affects young, healthy adults with fifty percent of the patients between the ages of 19 and 34 years old. Male patients represent 89 percent of all injuries to the brachial plexus.
Brachial plexus palsy occurs in childhood and it happens during the birth process most of all. It is estimated to occur in about 0.38 to 1.56 per 1000 live births. Newborns who had brachial plexus palsy most often were children of diabetic women who weighed greater than 4.5 kilograms at the time of birth. The risk of these injuries increases with increased birth weight and with births that had a failed vacuum extraction.
Brachial plexus palsy has been found in 44-70 percent of traumatic injuries, including those that occur in the sporting arena, work-related injuries, and motorcycle injuries. Brachial plexus injuries happen in 4.2 percent of motorcycle accidents. Snowmobilers seem to have a high risk as well of having brachial plexus injuries.Symptoms of a Brachial Plexus Injury
The symptoms of a brachial plexus injury vary depending on where the injury occurred to the nerve bundle and on how severe the injury was. It almost always affects just one arm.
In milder injuries, such as is seen in contact sports, the brachial plexus gets stretched. Athletes feel “stingers” or “burners” as a result of slight injury to the nerve. The main symptoms of a minor injury include:
- Numbness or weakness in the arm
- Feeling an electric shock go down the arm
- Feeling a burning sensation go down the arm
- Symptoms lasting a few seconds up to a few days
In more severe injuries, the tendon is torn or ruptured. The worst injury happens when there is an avulsion of the nerve root from the spinal cord. These are the main symptoms seen in a severe injury:
- The arm can be used but not the fingers
- There is a lack of feeling in the entire arm
- There is paralysis of the entire arm
- Severe pain in the shoulder or arm
As mentioned, even the complete disruptions of the nerve can heal but it takes a long time for this to happen.Causes of Brachial Plexus Injuries
The major causes of brachial plexus injury include:
- Contact sports. This is especially found in football and wrestling.
- Difficult births. The injury occurs when the shoulders are stuck in the birth canal.
- Trauma. It can occur in motorcycle accidents, automobile accidents and boating accidents. Penetrating wounds, such as a dog bite or knife injury can damage the brachial plexus.
- Parsonage-Turner syndrome. This is a rare inflammation of the brachial plexus following no known injury.
Most brachial plexus injuries come from stretching of the nerve bundles or from an avulsion injury, where the nerve is torn away from the spinal cord. Scar tissue can build up around the nerve, resulting in a disruption of the nerve impulse. Injures to the brachial plexus involves damage to C5-T1 nerve fibers. The nerves can be torn from an area in front of the clavicle or an area behind the clavicle.
Traumatic injuries of the brachial plexus are generally from sports injuries, motorcycle accidents, high-speed car accidents, and ATV accidents. A fall from a height can land on the shoulder, separating it from the neck. Gunshot wounds and knife wounds can contribute to brachial plexus injuries.
There are actually three types of brachial plexus injuries. They include:
- Upper brachial plexus injury, which involved excessive lateral neck flexion. A forceps delivery can do this, leading to Erb’s palsy. There is a lack of the lateral rotators of the arm flexors, hand extensor muscles and shoulder.
- Whole brachial plexus injury, which is more severe.
- Lower brachial plexus injury, in which the 8th cervical nerve and the nerves of T1 are injured. It affects the flexor muscles of the wrist and fingers, as well as the intrinsic muscles of the hand. It leads to what’s called Klumpke’s paralysis.
There are two mechanisms of action going on in brachial plexus injuries. One of these mechanisms is traction on the nerves and the other is heavy impact onto the nerves. Together these mechanisms cause disruption of the brachial plexus. Traction is also called a stretch injury. It is caused by a widening of the space between the neck and the shoulder. There can be downward or upward traction of the arm, which cause different types of injury.
Impact to the shoulder can also crush the brachial plexus. If the impact is great, all levels of the brachial plexus are affected. Depending on the location of the impact, damaging lesions can result in a rupture of the nerves or an avulsion of nerves. Some impact injuries include a clavicle fracture, shoulder dislocation, and hyperextension of the arm.
There are several classifications of injury that are graded according to their severity. Three are described here:
- Neurapraxia. This is the mildest type of injury. Nerve conduction is disrupted but not the continuity of the axon. Recovery is spontaneous.
- Axonotmesis. There is axonal degeneration with loss of continuity of the axon but with preservation of the connective tissue around the nerve fiber.
- Neurotmesis. This is the most severe type of injury in which the axon and the connective tissue around the nerve lose their continuity. This needs surgery with recovery not a guarantee.
The following tests can be used to diagnose brachial plexus injury:
- Nerve Conduction Study. This is a test that can tell how fast nerve impulses travel through a nerve. The nerve is stimulated by an electrode and its speed is measured more distally on the nerve.
- Electromyography. This is a test that measures the nerve signals arriving at various muscles in the arm. Needles are inserted into the muscle and the electrical activity in the muscle is picked up.
- MRI Exam. Using radio waves and a strong magnet to show cross-sectional images of the shoulder area. It can show soft tissue fairly well and thus can show the extent of the injury to the brachial plexus. It can show if the nerve has just been stretched or whether it has been severed.
- CT Scan. CT myelography uses contrast dye injected into the spinal cord, showing a detailed picture of the cord and spinal nerve roots. It can show areas of avulsion of the nerves.
If the nerve has been stretched but not broken, it has a good chance of spontaneous recovery. Sometimes, during the healing process, scar tissue forms that needs to be surgically removed.
Other times, a nerve graft is necessary. This involves taking a less important nerve and splicing it onto the nerves that have been cut or torn. It increases the chance that the nerve will heal into one piece over time.
In yet another procedure, a nerve transfer can be performed. The surgeon takes a lesser nerve attached to the spinal cord and attaches it to the place where the nerve was avulsed. Nerve tissue only grows about an inch every month so it can take years to recover nerve function to aspects of the arm.
In muscle transfer, a lesser muscle is transferred to your arm to replace muscle that has deteriorated because of nerve injury.
Doctors can also give pain control, which treats the constant burning sensation in the shoulder. Often, opioid medications are given. Antidepressant medication like tricyclics can be used to treat pain as can anticonvulsant medication like gabapentin, which acts on nerve pain. A TENS unit or transcutaneous electrical nerve stimulator can be given to override nerve impulses from the painful brachial plexus.Complications of Brachial Plexus Injury
While most people heal without complication, there are a few complications of brachial plexus injury that need mentioning. These include:
- Stiff joints. This happens when the arm is paralyzed and can’t move the joints around.
- Loss of feeling. This increases the risk of burning yourself or injuring yourself.
- Pain. You can have chronic pain associated with damaged nerves
- Muscle atrophy. While the nerves regenerate, the muscles can lose their bulk.
- Permanent disability. This can range from mild hand weakness to total arm paralysis. Permanent disability. How well you recover from a serious brachial plexus injury depends on a number of factors, including your age and the type, location and severity of the injury. Even with surgery, some people experience permanent disability, ranging from weakness in the hand, shoulder or arm to paralysis.
If you or a loved one has suffered a brachial plexus injury as a result of someone else's negligence and would like to discuss your legal options with an experienced Sacramento Personal Injury Attorney, contact us online or call us at 916.921.6400 to set up a FREE consultation.
Photo from http://www.assh.org/handcare/hand-arm-injuries/Brachial-Plexus-Injury