Brachial Plexus Injury: Causes, Types, and Risk Factors Explained
The brachial plexus is a complex network of nerves that sends signals from the spine to the shoulder, arm, and hand. When these nerves are damaged, it can lead to significant discomfort and functional impairment. A brachial plexus injury often results in pain within the affected nerve distribution area, accompanied by loss of muscle control, diminished sensation, and numbness in the skin. These symptoms can vary widely depending on the location and severity of the injury.
Common Symptoms of Brachial Plexus Damage
Individuals suffering from this condition may experience sharp or burning pain radiating from the neck down the arm, muscle weakness, or even complete paralysis in severe cases. Sensory changes such as tingling, numbness, or hypersensitivity are also frequently reported. The extent of the disability depends on which part of the brachial plexus is injured—upper, lower, or the entire network.
Main Types of Brachial Plexus Injuries
Upper brachial plexus injuries typically affect the C5-C6 nerve roots and are often caused by trauma when the shoulder is forcefully pulled downward while the neck is pushed sideways—commonly seen in motorcycle accidents. Lower brachial plexus injuries, involving the C8-T1 nerves, usually result from direct arm traction, such as grabbing onto something during a fall. Complete brachial plexus injuries impact all major nerve roots (C5–T1), leading to total loss of movement and sensation in the arm and hand.
Primary Causes of Brachial Plexus Damage
Several factors can lead to brachial plexus injuries, each associated with different mechanisms of trauma:
1. Open (Penetrating) Injuries
These occur due to sharp-force trauma, such as knife wounds or stab injuries, where external objects directly damage the nerve structures. Gunshot wounds and other forms of penetrating trauma can also sever or lacerate the delicate nerve fibers, requiring immediate surgical evaluation and intervention.
2. Traction (Stretch) Injuries
This is one of the most common causes, especially in high-impact accidents like car crashes or sports collisions. When the head and neck are suddenly forced away from the shoulder—such as during a fall or collision—the brachial plexus nerves can be stretched beyond their limits, leading to partial or complete rupture. Athletes, particularly in contact sports like football or rugby, are at increased risk.
3. Radiation-Induced Nerve Damage
Prolonged exposure to radiation therapy, especially in cancer treatment targeting the neck or chest region, can cause delayed nerve damage. This type of injury, known as radiation-induced brachial plexopathy, may develop months or even years after treatment and often presents with progressive weakness and sensory loss.
4. Birth-Related Compression Injuries
During difficult deliveries, especially when the baby's shoulders become stuck (shoulder dystocia), excessive pressure can stretch or tear the infant's brachial plexus nerves. This is commonly referred to as obstetric brachial plexus palsy and can affect newborns' ability to move their arms or hands. While many cases resolve spontaneously, some require physical therapy or surgical correction.
Understanding the underlying causes and types of brachial plexus injuries is crucial for timely diagnosis and effective treatment. Early medical assessment can significantly improve recovery outcomes, whether through conservative management or advanced surgical techniques. If you or a loved one experiences unexplained arm weakness or persistent nerve pain after trauma, consulting a neurology or orthopedic specialist is strongly recommended.