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Advances in the Surgical Treatment of Brachial Plexus Injuries

Traumatic injuries of the brachial plexus refer to stretching, avulsion, or rupture of a group of nerves that come from the spinal cord in the neck. Avulsion tells us the nerve root is torn from the spinal cord where it attaches.

Rupture refers to a complete tear across the nerve dividing it into two or more parts. The upper part is still attached to the spinal cord. Plexus refers to the entire group of nerves as they first start out with several main branches that divide to form a much larger number of nerve groups. The plexus starts at the neck but travels under the clavicle (collar bone) and down the arm.

These nerves provide both sensation (pain, temperature, touch, vibration) and motor function (muscle contraction) for the entire upper extremity including the shoulder, arm, wrist, and hand.

Brachial plexus injuries are usually caused by some type of trauma such as a car accident, fall onto an outstretched arm (especially if the head and face are turned away from that side), and stretching or pulling on the hand, wrist, or forearm. Gunshot wounds, knife lacerations, and other blunt open injuries are also likely causes of nerve avulsion or rupture.

Surgery is often needed to reconstruct the nerve. Surgical techniques have improved quite a bit in the last 10 years. The author of this review (an upper extremity orthopedic surgeon who specializes in trauma) has put together a summary of what the surgeon needs to know in making the diagnosis and establishing a plan of care for these patients.

The first step is making the diagnosis. Typically, any medical diagnosis depends on understanding the history (what happened) and carrying out an examination. With trauma to the nerves, the mechanism of injury is important because it often dictates whether surgery is needed and how soon. For example, a sharp injury that cuts the nerve will require immediate surgical treatment, whereas, forced traction (e.g., from a fall) may recover with time and conservative care.

To take that a step farther, the type of surgery may also be determined by what happened. Nerves that are avulsed close to the spinal cord are treated differently than nerves torn farther down the arm.

The decision isn't made just on the basis of the patient's history. Additional tests are given to find out as much as possible about what is and isn't working with each nerve. CT scans, MRIs, and electrodiagnostic tests add important information.

Electrodiagnostic tests include nerve conduction studies and electromyography (EMG). These tests provide information about the sensory nerve cells' and motor nerve cells' function. The results of the test help surgeons predict if recovery will occur and how long it might take.

With nerve avulsion, there's very little chance the nerve will repair itself and recover. The risk of scar tissue interfering with surgery pushes the date of surgery up considerably (within three to six weeks of the injury). For injuries further down (away from the spinal cord), there's a chance that (with enough time) the nerve can repair and recover. This can take up to six months or more so surgery can be put off a bit longer.

When surgery is done, the surgeon must choose among several different approaches, each with their own specific surgical techniques. When there is a clean cut through the nerve, it is possible to stitch the two ends of the nerves back together in what is referred to as a direct repair.

But most of the time, there are multiple nerves that involve both sensory and motor function. In these cases, it may be necessary to perform nerve grafting, nerve transfers, or even muscle transfers. The nerves used depend on the location of the primary (main) nerve injury and the muscles (motion) affected.

The brachial plexus has many nerves that branch off to each part of the arm from the shoulder on down to the fingers. Nerves selected for grafting or transfer differ according to whether the injured nerve is up high affecting the upper arm or down lower creating problems in the forearm, wrist, or hand.

The author describes each nerve affected and the possible replacements that can be used. Choosing the donor nerve can be challenging. It's best to use one that is above the lesion and therefore has not been affected by the injury.

Data on outcomes from studies already published are reviewed. Over time these studies have provided some valuable information about which nerves work best as donors to replace the damaged brachial plexus. It is even possible to take selected nerve tissue from the opposite arm as a donor graft for the injured arm.

A muscle transfer is another new technique developed over the last few years. Surgeons have figured out which muscles can be used to replace muscles that have permanently lost nerve innervation. Function is the goal, so restoring elbow flexion or touching the fingers together is often what surgery tries to achieve.

And finally, the newest surgical technique under investigation for nerve injuries is the use of a nerve conduit. A nerve conduit (also referred to as an artificial nerve graft) uses synthetic materials to create a guided pathway for nerve tissue growth. The nerve ends and gap between the ends are enclosed within a tube composed of biological or synthetic materials.

The nerve conduit is being tried for patients with large distances between the two ends of the torn nerve. The distance is too great to use direct suturing of the two stumps of a severed nerve without tension. This approach has worked for small sensory nerves that have been injured but its use with mixed (sensory and motor) function is still being studied.

In summary, brachial plexus injuries can be complex, difficult to treat, and devastating for the patient. Every effort must be made to establish a correct diagnosis (which nerve is affected, location of the lesion, severity of the lesion) in order to plan treatment specific to that problem. Recent advances in the surgical repair and reconstruction of traumatic brachial plexus injuries has opened up treatment options and improved results.

Reference: Raymond A. Pensy, MD. Traumatic Brachial Plexus Injuries. In Current Orthopaedic Practice. September/October 2010. Vol. 21. No. 5. Pp. 462-466.