A brachial plexus injury (BPI) affects the network of nerves (C5 through T1) that transmits signals from the spinal cord to the shoulder, arm, and hand. This network controls movement and sensation in the upper limb. Whether a BPI qualifies as a disability depends entirely on the degree of damage and the resulting long-term functional loss. Disability status relies heavily on the severity and permanence of the impairment.
Defining the Brachial Plexus and Resulting Functional Limitations
The brachial plexus consists of five spinal nerve roots (C5 through T1) that merge and recombine to form the peripheral nerves of the arm. This network powers the muscles and provides sensation to the entire upper extremity. Injuries typically result from extreme traction or stretching, often seen in high-impact trauma like motor vehicle accidents.
A BPI immediately causes a loss of motor control and sensation in the affected limb. This manifests as muscle weakness, lack of feeling, or complete paralysis in the shoulder, arm, or hand. The specific area of functional loss depends on the location of the damage within the plexus.
Damage to the upper plexus (C5 and C6) results in Erb’s Palsy, primarily affecting shoulder and elbow function. Individuals often struggle to lift or bend the elbow. Conversely, injury to the lower nerve roots (C8 and T1) causes Klumpke’s Paralysis, leading to loss of movement and sensation predominantly in the wrist and hand, sometimes resulting in a “claw hand” posture. These limitations directly impact the ability to grasp and lift.
Classifying Severity and Permanence of Nerve Damage
Recovery potential depends on the classification of nerve damage, which determines if the functional loss is temporary or permanent. Physicians classify the injury’s physical extent, ranging from a mild stretch to a complete tear. The mildest form is neurapraxia, where the nerve is temporarily blocked but not torn, resulting in transient loss of function.
A more significant injury is axonotmesis, where the internal fibers (axons) are damaged, but the protective outer sheaths remain intact. This requires the axon to regrow slowly to reconnect with the muscle, a process taking many months. A rupture, or neurotmesis, involves a complete tear of the nerve fiber and its protective sheaths, requiring surgical intervention and offering no chance of spontaneous recovery.
The most severe injury is an avulsion, where the nerve root is torn completely from the spinal cord itself. An injury of this magnitude represents a permanent functional loss because the nerve cannot reattach or regenerate from the spinal cord. This distinction between a reversible physiological block (neurapraxia) and an irreversible anatomical tear (rupture or avulsion) is the medical basis for determining long-term impairment. Permanent functional impairment, resulting from severe injuries, is a prerequisite for official disability recognition.
Criteria for Official Disability Recognition
For a brachial plexus injury to be officially recognized as a disability by administrative bodies, such as the Social Security Administration (SSA), the resulting impairment must meet specific, rigorous criteria. The injury must be severe enough to prevent an individual from engaging in substantial gainful activity, meaning they cannot perform work that provides a certain monthly income. Furthermore, the condition must be expected to last for a continuous period of at least twelve months.
The administrative review focuses on documented functional limitations, not just the diagnosis. The claimant must provide comprehensive medical evidence, including nerve conduction studies, muscle strength tests, and physician reports detailing motor and sensory loss. The required level of impairment is severe, such as complete paralysis or an extreme limitation in the use of the affected upper extremity.
Since a BPI often affects only one arm, the impairment must significantly restrict activities of daily living (ADLs) that require two hands, such as lifting or fine motor tasks. If the unilateral injury does not meet the severity threshold alone, it may qualify if combined with other existing impairments or if both upper extremities are affected. The administrative body assesses the total impact of the permanent condition on vocational capacity and independent function.