Brachial Plexus Injury
Brachial plexus is a network of nerves that originates at the spinal cord in the neck and passes down your upper arm from under your collar bone.
The brachial plexus starts with 5 nerve roots. These include nerve roots from the lower cervical vertebrae known as C5, C6, C7 and C8 and a nerve root from the first thoracic vertebrae known as T1. These nerves join to form the upper, middle and lower trunks of the brachial plexus which finally split into the nerves that supply your arms, controlling your shoulder, elbow, wrist and hand. An injury to any part of these nerves can stop signals to and from the brain and partially or completely paralyze your arms.
Types of brachial plexus injury may include:
- Neurapraxia: minimally stretched nerves or stretched nerves that are not torn
- Nerve rupture: Overstretched nerve that is torn
- Avulsion of nerves-nerves detached from the spinal cord
Minor injuries of the brachial plexus such as neurapraxia may recover on their own without any therapy, but surgery is necessary for treatment of nerve rupture or nerve avulsion.
Any form of trauma that pushes your head away from your shoulder can stretch or tear the nerves of the brachial plexus. Various conditions may cause a brachial plexus injury in adults. They include:
- Vehicular accidents, especially motorcycle accidents
- industrial accidents where a hand gets caught in a machine
- Heavy objects falling onto the shoulders
- Nerve compression caused by a growing tumor
- Bullet or knife wounds
- Collisions during contact sports
- Abnormally positioned arm during surgery
Signs and Symptoms
Brachial plexus injury most often affects only one arm and its symptoms vary based on the location and severity of the injury. Some of the signs and symptoms include:
- Muscle weakness, lack of shoulder and hand movements or paralysis. Lack of shoulder, elbow or wrist movement occurs if C5 to C7 nerves are injured, whereas inability to flex the wrist and fingers occurs if C8 and T1 are injured.
- An electric shock or burning sensation running down your arm
- Loss of sensation leading to numbness in whole or part of your upper limb
- Pain ranging from mild, to severe in case of nerve root avulsion
Your doctor will first take your medical history, conduct a clinical examination and wherever necessary, order tests to complete the diagnosis of brachial plexus injury.
Imaging tests such as Magnetic resonance imaging (MRI) and Computerized tomography (CT), using a contrast dye, may be ordered to visualize the nerve damage.
Your doctor may ask for nerve conduction studies and electromyography (EMG) to evaluate the muscle response of your injured arm. Your doctor will insert small electrodes into the muscle and ask you to contract that muscle. This records the electrical activity of the contracted muscles and determines the ability of the muscles to respond when its nerves are stimulated.
The speed of nerve impulses is determined by nerve conduction studies. The time taken for impulses to pass from one electrode to the other is assessed and recorded.
A brachial plexus injury is treated based on the type and severity of the damage.
Midly stretched nerves, without serious internal damage (neuropraxia) will usually recover on their own over time. Your doctor may prescribe medication and request for regular electrical stimulation therapy or transcutaneous electrical nerve stimulation (TENS) to relieve pain. This procedure involves the stimulation of damaged nerves by passing a mild electric current over them.
Physical therapy may also be recommended after a few weeks for gentle mobilization of the shoulder, elbow, wrist and fingers to avoid stiffness.
If complete recovery is not observed within 2 to 3 months, surgery is usually mandatory.
Your doctor may recommend surgery after 3 months in case of partial paralysis or anytime within 2 months in case of complete paralysis. Delaying the surgery beyond a specified time may increase the risk of muscle atrophy, thus diminishing the chances of recovery
Your surgeon will repair the torn nerve by performing nerve reconstruction surgery with direct neurorrhaphy, nerve graft, nerve transfer or muscle transfer depending on the severity of the injury.
Direct neurorrhaphy involves identifying the damaged nerves and directly suturing the two cut ends of the damaged nerve back together.
Nerve graft surgery involves replacing a damaged section of the nerve with a nerve removed from another part of your body.
Neurotisation or nerve transfer surgery involves transferring an intact but less important normal nerve to the lower end of the damaged nerve to. The nerves can be transferred from within the plexus (intraplexal neurotisation) or from elsewhere (extraplexal neurotisation).
Muscle transfer surgery may be necessary if the arm muscles have deteriorated. This involves transfer of a muscle or tendon from another part of your body (like the back or leg) to the damaged part of your arm. This is usually necessary in cases which present late.
Risks and Complications
As with any surgery, there are risks involved. Associated risks of nerve reconstruction surgery may include:
- Some tingling and weakness in areas from which nerves have been borrowed to reconstruct the damage nerves.
- Failure to improve
After the surgery you will have to wear a sling for the first few weeks to protect your arm and aid in wound healing. Your doctor may prescribe medications to relieve pain. Physical therapy involving range of motion exercises for the elbow, shoulder and hand may be advised a few weeks later. You also may be instructed to perform strengthening exercises after your arm movements are regained.
It may take more than a year to achieve complete improvement after surgery. Various factors which influence recovery after brachial plexus surgery are: location and extent of the injury, age of the patient and time interval between the injury and surgery. Younger patients recover faster, whereas recovery is slower (and usually incomplete) in patients over 45 to 50 years of age.
Adults with injury to the C5 and/or C6 nerves generally experience near complete recovery.
Patients with complete paralysis and injury to the C5, C6 and C7 nerves may experience difficulty in achieving complete recovery to the original extent.
For patients with complete paralysis (C5,6,7,8 and T1) usually cannot expect complete recovery. However some recently developed techniques which involve direct transfer of nerves from the opposite (normal) brachial plexus have shown some striking results.