Types of Brachial Plexus Nerve Injuries
Brachial plexus injuries or Erb's Plasy can be classified depending on the type of neuropathologic injury. There are four types of brachial plexus nerve injuries:
Neuropraxia : This is the least severe and most common of all the brachial plexus injuries occurring outside the spinal cord. This is a stretch injury where the nerve is not torn but damaged by stretching causing conduction block but no permanent structural damage to the nerve. Conduction block can last from hours to several weeks, but eventually fully recovers. When improper or excessive force is applied to pull the baby out, Erb's Palsy can result and the extent of shoulder injury is dependent on the amount of stretching.
Neuroma : When an injured brachial plexus nerve tries to repair itself, it forms scar tissue around the injury and interferes with the nerve sending signals to the muscles. The scar tissue forms specifically between the proximal and distal ends of the nerve to form a neuroma. Recovery can be limited because it can be difficult for nerve cells to regenerate through the neuroma. The condition may require surgical intervention with nerve reconstruction and/or secondary tendon transfers.
Rupture : In this injury, the nerve tears outside the spinal cord causing damage to the nerve cells, and supporting blood and connective tissue. If only the nerve cells are damaged they can recover and regrow fully. In some instances, surgical repair may be necessary.
Avulsion : This is the most severe injury of Erbs palsy with the nerve being completely removed and torn off from the spinal cord. It usually occurs at the nerve rootlets at or close to the spinal cord. This is a less common form of brachial plexus injury. It can cause difficulty with breathing due to injury to the nerve to the diaphragm. Avulsion injuries do not recover spontaneously and so it is crucial that these patients be identified for early interventions.