Brachial Plexus Injury: Causes, Risk Factors, and Mechanisms Explained

Brachial plexus injuries can result from a wide range of causes, broadly categorized into traumatic and non-traumatic origins. Understanding these underlying factors is essential for accurate diagnosis, effective treatment, and long-term recovery planning. These nerve injuries affect the network of nerves responsible for controlling movement and sensation in the shoulder, arm, and hand—making them particularly impactful on daily function and quality of life.

Non-Traumatic Causes of Brachial Plexus Damage

One major category of brachial plexus injury stems from non-traumatic, or compressive, conditions. A common example is Thoracic Outlet Syndrome (TOS), where the space between the collarbone and first rib narrows, placing pressure on the brachial plexus nerves. This chronic compression can lead to pain, numbness, muscle weakness, and reduced coordination in the upper extremities.

In other cases, benign or malignant tumors located in the neck region may directly impinge upon the brachial plexus. Notably, some tumors originate from the nerve tissue itself—such as brachial plexus schwannomas, which are typically slow-growing and arise from the Schwann cells surrounding peripheral nerves. While often non-cancerous, their presence can still disrupt nerve signaling and require surgical intervention if symptoms worsen.

Traumatic Injuries: The Leading Cause of Brachial Plexus Damage

Approximately 92% of brachial plexus injuries are caused by trauma, with motor vehicle accidents being the most frequent culprit. During high-impact collisions, sudden lateral flexion or stretching of the neck and shoulder—often referred to as "traction injury"—can severely strain or even avulse (tear away) the nerve roots from the spinal cord. This specific type of injury, known as brachial plexus avulsion, represents one of the most severe forms of nerve damage and usually results in significant functional loss.

Other Common Traumatic Scenarios

Besides car crashes, about 5% of cases stem from falls from significant heights, such as construction accidents or extreme sports incidents. The force generated upon landing—especially when the shoulder bears the brunt of impact—can stretch or rupture the delicate nerve network.

Direct physical trauma, including blunt force injuries from heavy objects striking the shoulder, can also lead to partial or complete nerve disruption. Additionally, penetrating injuries like stab wounds or lacerations in the neck area pose a serious risk, as sharp objects can sever nerve fibers instantly, requiring urgent medical evaluation and potential surgical repair.

Why Early Diagnosis Matters

Recognizing the mechanism of injury is crucial for determining prognosis and treatment options. Whether due to compression, tumors, or acute trauma, timely imaging studies (like MRI or nerve conduction tests) help clinicians assess the extent of damage. Early intervention significantly improves outcomes, especially in cases involving nerve regeneration or reconstructive surgery.

In summary, brachial plexus injuries vary widely in cause and severity. From chronic compression syndromes to catastrophic trauma, each scenario demands a tailored approach to care. Raising awareness about these causes not only supports better patient education but also enhances prevention strategies and advances in neurological rehabilitation.