Brachial Plexus Injury: Understanding Symptoms, Types, and Functional Impacts
Brachial plexus injuries can significantly impair upper limb function and are often the result of trauma, birth complications, or surgical complications. These injuries affect a network of nerves that originate from the spinal cord in the neck and control movement and sensation in the shoulder, arm, and hand. Depending on the location and severity, brachial plexus damage is classified into three main types: upper trunk injury, lower trunk injury, and total plexus involvement. Each type presents distinct clinical patterns and functional limitations.
Upper Trunk Brachial Plexus Injuries
Upper trunk injuries, typically involving the C5 and C6 nerve roots, are among the most common forms of brachial plexus damage. This type of injury often results from sudden stretching of the neck and shoulder, such as during motorcycle accidents or difficult childbirth. Patients with upper trunk lesions experience significant motor deficits in the shoulder and elbow.
Key Functional Limitations
One of the hallmark signs is the inability to abduct or elevate the shoulder. The deltoid and supraspinatus muscles, which are essential for lifting the arm sideways and overhead, become weakened or paralyzed. Additionally, elbow flexion is severely impaired due to dysfunction of the biceps and brachialis muscles, both innervated by the musculocutaneous nerve.
While wrist flexion and extension may still be possible, these movements are often accompanied by reduced muscle strength. The forearm may also show limited supination and pronation, indicating compromised function of the radial and median-influenced muscles. Interestingly, finger movements usually remain relatively intact, preserving fine motor skills to some extent.
Sensory deficits are also prominent. Many patients report a loss of deep sensation throughout the upper extremity, including diminished proprioception and vibration sense, which can further complicate coordination and daily activities.
Lower Truncal and Total Brachial Plexus Injuries
In contrast, lower trunk injuries (involving C8 and T1 nerve roots) present a different clinical picture. These injuries frequently lead to symptoms resembling ulnar nerve paralysis, affecting the intrinsic muscles of the hand and causing clawing of the fingers, particularly in the ring and little fingers.
Associated Nerve Involvement
The medial cutaneous nerves of the forearm and arm are commonly affected, resulting in numbness along the inner side of the forearm. There may also be partial impairment of the median and radial nerves, contributing to weakness in grip strength and reduced ability to extend the wrist and fingers.
Despite these hand and sensory issues, patients with isolated lower trunk injuries often retain better function in the shoulder, elbow, and wrist joints. Movements like shoulder abduction and elbow flexion may remain preserved, offering a degree of independence in basic arm use.
Total Brachial Plexus Palsy
In cases of complete brachial plexus injury, all major nerves from C5 to T1 are disrupted. This leads to a flail limb—complete loss of motor control and sensation from the shoulder down to the fingertips. Recovery is more challenging and often requires surgical intervention, such as nerve grafts or transfers, followed by extensive rehabilitation.
Early diagnosis and multidisciplinary management—including neurology, orthopedics, and physical therapy—are crucial for optimizing outcomes. Advanced imaging techniques like MRI and electrodiagnostic studies help pinpoint the level and extent of nerve damage, guiding treatment decisions.
Understanding the specific patterns of weakness and sensory loss associated with each type of brachial plexus injury enables healthcare providers to tailor rehabilitation strategies and set realistic recovery goals for patients. Whether recovering from trauma or managing long-term disability, timely intervention plays a vital role in restoring function and improving quality of life.