Brachial Plexus Injury

Introduction

The brachial plexus is a bundle of nerves that originate at the spinal cord near the neck. These nerves innervate your shoulder, elbow, hand and wrist providing feeling and movement.

Any form of trauma that pushes your head away from your shoulder can stretch or tear these nerves. An injury to the brachial plexus may stop signals to and from the brain and even paralyse the affected arm.

Brachial plexus injuries can occur during birth or in adults from trauma. Minor injuries of the brachial plexus may recover without any therapy, but surgery may be necessary for severe injuries.

Causes

In adults, injuries to the brachial plexus occur most commonly by collisions during contact sports. Damage can also be caused by motor accidents, or bullet or knife wounds.

Injury to the brachial plexus can occur during the birthing process if the baby’s shoulder gets stuck in the birth canal requiring external force to be delivered. This force can stretch or tear the nerves and is called obstetric brachial plexus palsy. This type of injury is commonly seen in larger than average babies born to diabetic mothers.

Other causes for brachial plexus birth palsy include:

• Extended period of labour
• Breech presentation- baby positioned with feet or buttocks near the vaginal opening

Signs and Symptoms

Brachial plexus injury usually affects only one arm and its symptoms vary based on the location and severity. Some of the signs and symptoms include:

• Electric or burning sensation running down your arm
• Muscle weakness
• Numbness
• Complete paralysis from shoulder to fingers
• Incomplete paralysis, where movement may be retained in some parts of the hand like the fingers, wrist and arm, with paralysis in the remaining parts
• Neck pain

Diagnosis

Your doctor will first take your medical history, conduct a clinical examination and order tests to diagnose brachial plexus injury.

The muscle response of your injured arm is evaluated by electromyography. 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. Your doctor will place electrode patches on the surface of your skin and pass mild electric impulses to stimulate the nerves. The time taken for impulses to pass from one electrode to the other is assessed and recorded.

Imaging tests such as Magnetic resonance imaging (MRI) and Computerized tomography (CT), using a contrast dye, can also be used to visualise the nerve damage.

Treatment

A brachial plexus injury is treated based on the type and severity of the damage. Injuries where the nerves are stretched instead of torn will usually recover on their own in time. Frequent examination by your physician over the first three to six months following injury is necessary to assess signs of nerve recovery.

Your doctor may prescribe medications or suggest transcutaneous electrical nerve stimulation therapy (TENS) to relieve the pain. TENS involves stimulating the damaged nerves by passing an 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 contractures of the extremity.

Patients may regain nerve function within several months following the injury. If there is no recovery within this time, however, and in cases of incomplete or complete paralysis, surgical repair may be required.

Early surgery is recommended within 3-6 months due to the risk of muscle atrophy. Surgery is indicated for obstetric brachial plexus palsy if physical therapy over 3 to 6 months does not improve your baby’s condition. In most cases however, newborns with brachial plexus palsies usually begin to recover within weeks of birth, and surgery is rarely necessary.

Surgery

Your surgeon will repair the torn nerve by performing nerve reconstruction surgery with either a nerve graft or nerve transfer. Sometimes a muscle transfer may also be performed depending on the patient’s condition.

Nerve graft surgery involves replacing a damaged section of the nerve with a nerve removed from another part of your body.

Nerve transfer surgery involves connecting the torn nerve with a less important nerve from the spinal cord.

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 to the damaged part of your arm.

Risks and Complications

As with any surgery, there are risks involved. Associated risks of nerve reconstruction surgery may include the following:

• Bleeding
• Infection
• Failure to improve
• Tingling and weakness to the upper extremity