Traumatic Brachial Plexus Injury


Definition

The brachial plexus (brachial means arm and plexus mean communication or meeting point) refers to the nerves that exit the cervical spine and pass down to the shoulder and arm. Five major nerves comprise the brachial plexus: C5, C6, C7, C8, and T1 (C refers to cervical [or neck] and T refers to thorax [or chest]). These nerve pass under the skin in the neck and axilla, where they are vulnerable to injury. When the neck and arm are forced away from each other during trauma (e.g., car accidents, motorcycle accidents, falls) the brachial plexus nerves can be stretched or torn apart. If the force is severe, these nerves can even be pulled away from the spinal cord where they originate. Damage to these nerves causes pain, numbness, and weakness in the shoulder, arm, and hand. The pain can be quite severe, and is often described at burning, pins and needles, or crushing. In general, the C5 nerve controls the rotator cuff muscles and shoulder function, C6 controls flexing the arm at the elbow, C7 partially controls the triceps and wrist flexion, and C8/T1 controls hand movements. Several patterns of injury occur, the most common is referred to as an Erb's palsy. This is when C5 and C6 are predominantly affected. These patients are unable to lift their arm or flex at the elbow. Severe atrophy can occur in the shoulder muscles. Another pattern of injury is when C8/T1 is mostly damaged. These patients have hand weakness and pain. Some finger movement may remain, however. The most severe type of injury is when the arm is completely paralyzed due to extensive brachial plexus injury.


Diagnosis A brachial plexus injury is diagnosed with a thorough history and physical examination. Imaging of the spine with either MRI or CT myelography is important for determining any detachment of the nerves from the spinal cord, which determines prognosis and treatment. Electrical testing also helps guide treatment and predict outcome, however, in general, it should not be performed until 3 weeks after injury. Direct imaging of the brachial plexus is usually not helpful with currently available techniques. It is important to see a physician who specializes in examining, diagnosing, and treating brachial plexus injury within the first few weeks after the accident.

Treatment Options In general, patients are observed for spontaneous recovery during the first 3 months after injury. Many patients regain some function during this time. Surgery is not immediately performed because many people may spontaneously recovery without treatment. Furthermore, delicate nerves that may have spontaneously recovered may be injured with early surgery. During this waiting period, pain is aggressively controlled and physical therapy is performed. Imaging of the cervical spine and electrical testing is also performed. No medication is currently available to hasten recovery. When paralysis remains at 3 months, and electrical testing does not indicate an early recovery, then exploratory surgery is often indicated. Recovering nerves are protected. Injured, non-functional nerves are exposed and examined with both a microscope and intraoperative electrical testing. When possible, injured nerves are repaired or replaced, which allows recovery. Repairing nerves with surgery gives them the opportunity to regenerate themselves. Nerve regeneration progresses about one inch per month. Therefore, even after successful surgery, it can take up to 6 to 12 months before the regenerating nerves reach their target muscle and for movement to occur. Surgery is usually scheduled between 3 and 6 months after injury. If you wait much longer than this then the chances of surgery working decreases with time. The exact timing and type of surgery is often different for each patient. Therefore, it is important for the patient to be evaluated early so that they may consider all of their treatment options. Despite how well the surgery goes, the chance of recovery is somewhat uncertain. In addition to factors we do not understand, surgical success depends on the type of injury, the nerve injured, the age of the patient, motivation of the patient, and timing of repair. On average, there is a 50% chance surgery for each nerve will allow movement to return. This number may be as high as 90% for certain nerves and injuries. Your surgeon will provide you with an estimate about your chances of recovery. A "success" is defined as strength against both gravity and some resistance. In general, greater the distance a nerve has to regenerate, the less likely there will be a good recovery.

Surgery Three general types of brachial plexus surgery are performed:

  • Erb's palsy repair (shoulder/elbow weakness)

  • Complete brachial plexus reconstruction

  • Isolated nerve transfers

Each patient may undergo a combination of procedures. Erb's palsy surgery requires an incision along the side of the neck and/or the clavicle. The injured C5 and C6 nerves are identified and examined. Depending on the injury, one or more of the following is performed (see technologies and techniques available section): scar tissue is removed, the nerves are re-attached directly or with nerve grafts from the leg, or nerve transfers are performed. This surgery takes about four to six hours. Severe injuries require a complete exposure of the brachial plexus. Although muscle and bone are preserved, the incision can be long, passing from the neck and over the shoulder. The nerves are examined and reconstructed with multiple nerve grafts and transfers. This surgery can take up to 8-12 hours. When nerves are found detached from the spinal cord on preoperative imaging, then select nerve transfers away from the site of injury may be recommended. The incisions for these transfers are often placed above the clavicle, behind the shoulder, under the arm, or near the wrist. Your average nerve transfer takes about 90 minutes per nerve transferred. Although certain brachial plexus techniques are associated with postoperative pain (e.g., intercostals nerve transfers), in the majority of patients incisional pain is minimal. Nerve pain before surgery may or may not improve immediately after surgery. More commonly, nerve pain slowly improves as the nerves regenerate.

Complications Although complications are uncommon, they can occur. A frank discussion with your surgeon prior to surgery is mandatory. Because of long surgery and large incisions, wound infections may occur in some patients. Damage to important arteries and veins going to the arm may occur, which can lead to loss of limb. Fortunately this is so rare it hardly ever occurs. Additional numbness near the neck or chest may occur, but this usually goes away in a number of months. Additional paralysis is possible, but this is rare considering any functioning nerves are either not exposed, or operated on very gently. Trouble breathing, especially when exercising, may occur after surgery and can be related to new diaphragm weakness, fluid on the lung, or air compressing the lung. The latter two of which may require chest tube drainage. The wound is often mildly swollen for a few weeks after surgery. This is normal and goes away with time. If sural nerve grafts are taken from the legs, then a patch of numbness on the outside of the foot almost always occurs, even though some patients do not notice it. This numbness may diminish over time. Because the sural nerve carries no motor fibers, foot paralysis does not occur after removing the nerve graft.

Day of Surgery All brachial plexus surgery is performed under general anesthesia with intraoperative electrical testing and microscopic magnification. You should not eat or drink after midnight the day before surgery. Medications may be taken with a sip of water the morning of surgery. You wake in the operating room and may see your family an hour later in the recovery room. Depending on the extent of surgery, you may discharged the same day, or a few days later. Pain is well controlled and you are encouraged to sit in a chair and even walk within the first day after surgery. This movement prevents muscle spasms, which reduces pain.

Recovery During the first two weeks after surgery you wear a sling to protect the arm and let the wound heal. Pain medication is prescribed as needed. One week after surgery you visit your surgeon who checks your wound and removes any sutures. After about two weeks, physical therapy is prescribed. For the first three months, therapy concentrates on shoulder and elbow range of motion. Immediately after surgery your paralysis should be the same. However, when movement eventually returns, strengthening exercises are performed. Recovery often takes one year or longer.

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