Types of brachial plexus injuries
In general, nerve injuries are grouped into four types.
- When nerve function is temporarily blocked but the nerves are not disrupted; known as neuropraxia. Infants who have this condition recover spontaneously, usually within the first 3 months of life, with no long-term problems.
- Nerve fibers (axons) are disrupted but the surrounding nerve sheath is only partially so or not at all; known as axonotmesis. This type of nerve injury requires regrowth of the nerve fiber to the target muscle. As a result, recovery takes longer, and may be incomplete. Nerve fibers grow in adults at about 1 inch per month, which means many months will be required for the axon to grow down to the muscles in the arms. In infants, however, the axon may regenerate more rapidly, and the distance to be covered is much less. Whether patients with this condition require surgical treatment depends on the number of disrupted nerve fibers and the whether scar tissue (neuroma) interferes with regrowth.
- Nerve fibers and their surrounding nerve sheaths are completely divided; known as neurotmesis.
- Nerve roots are disconnected from the spinal cord, this is known as avulsion.
The last two types are the most severe forms of brachial plexus palsy. Because of the extensive disruption, these injuries do not heal on their own. Surgical intervention during the first months of life is often recommended.
Upper brachial plexus palsy (Erb palsy)
Erb palsy is when the upper nerves of the brachial plexus are injured. This is the most common form of brachial plexus palsy. Children with Erb palsy have a difficult time raising the shoulder, turning their upper arm outwards, and bending their elbow. Sometimes, infants have no movement of the arm right after birth but begin to move the fingers and wrist within a few weeks. Shoulder and elbow movement recover more slowly.
Total brachial plexus palsy
Total brachial plexus palsy is the second most common pattern for brachial plexus palsy. Children who have total brachial plexus palsy have weakness in the entire arm. They have no movement of the arm, wrist or hand; the arm is limp. This type of injury is more often associated with nerve roots being detached from the spinal cord.
Lower brachial plexus palsy (Klumpke palsy)
Klumpke palsy occurs when the lower nerves of the brachial plexus palsy are injured. This is the least common type of brachial plexus palsy. Children who have this type of brachial palsy have weakness in the fingers, hands, wrist, but normal function of the shoulder and elbow.