Brachial Plexus - Structural Pattern, Possible Injuries, Diagnosis, and Treatment Plan

What Is Brachial Plexus?

The brachial plexus is a bundle of nerves present in one's neck and shoulder. It is responsible for controlling all the muscular movements and sensations to and from the spinal cord to either arm. When trauma happens to the neck region, the brachial plexus gets injured, causing numbness, pain, and weakness in the shoulders, arms, and hands.

How Is the Brachial Plexus Structured to Control the Arm Function?

Nerves forming brachial plexus emerge as a cluster of nerve roots from the neck and shoulder portion of the spinal cord. They fuse and form a network at the shoulder level and connect with all the nerves in the arms. Their function is to control all the big and small activities of the arms, hands, and wrists. Feelings on the arms like pain, pressure, heat, cold, and vibrations are accurately communicated and perceived by the brain through the brachial plexus. The nerves known as the musculocutaneous nerve, axillary nerve, median nerve, radial nerve, and ulnar nerve are the five important extensions of the brachial plexus.

What Causes a Brachial Plexus Injury?

The most common reason for injury is trauma. When the arm gets pulled or stretched beyond normal levels, the brachial plexus tends to get injured. Particularly when the arm is pulled down and the head is pushed in the opposite direction. The trauma can be due to anything ranging from automobile collisions, falls, gunshot wounds, and sports accidents to knife injury. It happens in newborns during a breech delivery (bottom first), prolonged labor, or trauma while passing through the birth canal.

What Are the Types of Brachial Plexus Injury?

Depending upon the amount of impact and severity of the trauma, injuries vary in degree of damage. The possible damages may be:

1. Avulsion - A severe and irreparable damage to the brachial plexus where it actually gets pulled out of the spinal cord, detaching completely from its point of origin.

2. Stretch - Where the nerves get pulled and stretched (neuropraxia) but do not break. It may heal on its own or with minor surgical repair.

3. Rupture - Partial or complete tear of the nerves due to forceful pulling or stretching. Surgical repair is possible for some individuals.

Below listed are the types of injury caused by the damage to the brachial plexus mentioned above:

• Upper-Trunk Palsy Injury: Causes weakening or paralysis of the shoulders and muscles of the upper arm. The individual may not be able to raise the arm or bend at the elbow. Also, there may be a loss of sensation in the shoulder, the outer portion of the arm, and the thumb.

• Lower-Trunk Palsy Injury: The hands may lose their function, and the individual may be unable to perform any fine motor activities that involve the small muscles of the hands, like buttoning a shirt or tying shoelaces, etc. The finger tends to shrink inwards to look like a claw over time. Additionally, there will be a loss of sensation in the ring finger and small finger.

• Pan-Plexus Palsy Injury: Leads to a ‘flail limb,’ meaning complete paralysis of the arm and hand. This happens due to severe injuries causing damage to nerves at all levels.

• Gunshot Wounds: Nerves either get bruised or stretched depending on the speed of the bullet during an ambush. This may recover on its own over time though damage to adjacent blood vessels requires immediate repair.

• Penetrating Wounds: Where a sharp instrument like a knife may cut the nerves into segments. This does not heal on its own and requires surgical repair.

What Are the Symptoms Suggestive of a Brachial Plexus Injury?

Based on the location and severity of damage to the nerves, symptoms may differ. The common symptoms are:

1. One experiences severe neuropathic pain that lasts for a long period. The pain is worst when the injury is closer to the spinal cord and least when it is farther.

2. Numbness and weakness with a possible burning sensation over the shoulders, arms, and hands.

3. Inability to move and function with the affected parts.

4. Loss of sensation.

How Are Brachial Plexus Injuries Diagnosed?

The doctor will determine the severity of nerve damage and location of injury by asking questions about the incident of trauma. This is followed by a physical examination involving various movements and sensory stimuli of the shoulders, arms, and hands. Tests are conducted to determine the level of function controlled by each nerve group in the brachial plexus. Additional tests include:

• Imaging studies such as X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI) of the area of injury to visualize the damage.

• Electrodiagnostic studies help confirm the diagnosis by evaluating the strength of nerve signals sent from the brachial plexus to different groups of muscles, which is indicative of functional impairment levels.

How Is a Brachial Plexus Injury Treated?

It is important to treat the injuries to the brachial plexus within a stipulated time frame from the event of injury to accomplish maximum recovery. Mild injuries may recover spontaneously in a few weeks to months after trauma. Meanwhile, one has to attend periodic monitoring and follow-up consults to ensure nerve healing. The other treatment modalities are:

1. Surgical correction of the damaged nerves to restore functional abilities. One may attempt a nerve repair, nerve grafting procedure, or a never transfer to repair the damages. Tendon and muscle transfers are also attempted to regain the lost functions.

2. Pain medications to help with the associated neuropathic pain.

3. Physical and occupational therapies are recommended to prevent the muscles from going flaccid as regrowth and repair of nerves take a long time. Every surgical repair needs to be followed by a rehabilitation period to regain physical function.

Conclusion:

Since more and more people are indulging in high-energy sports and high-speed motor vehicles, the incidence of brachial plexus injury is increasing every year. Mild to moderate injuries usually heal over time, and individuals can regain the functional abilities of their hands. Whereas severe injuries often require surgical correction. If one suffers from a neck or shoulder injury and has trouble moving or feeling the arm, the symptoms should be discussed with an expert medical professional and do the needful. Early intervention always brings in the best outcomes in a brachial plexus injury.