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Nerve Damage
Nerve damage occurs as a result of nerve defects, such as severed nerves. As a result, a loss of function occurs and surgery is required to replace function. Once a nerve is transected, damage does not only affect the site locally. The axon length as well as the functional brain response are affected by nerve damage. Locally, axonal degeneration occurs in the form of disintegration due to calcium dependent proteolytic processes because the axon is no longer connected to the soma, its nutritive source.1
As seen in Figure 1, the local response to a transected nerve involves a number of factors. Sprouts (SPR) form from the nerve ending, and each sprout has growth cones (GC). Schwann cells (SC), mast cells (MC), and fibroblasts (FB) infiltrate the damaged site for axonal regeneration to occur. However, axonal misdirection often occurs, which generally leads to some if not all loss of function.2
Figure 1. Local cellular response after nerve transection.2
Statistics
Approximately 8 million surgical procedures for tissue or organ related complications occur annually in the US. The medical costs surrounding this staggering number about $400 billion.3
More specifically, in 2004, 360,000 suffered from some form of peripheral nerve injury, either via upper extremity damage or systemic diseases. 2.8% of trauma patients suffer from peripheral nerve injury, in which permanent disability could occur. In addition, periperhal nerve injury causes 8,648,000 restricted activity days.4