Nerve injury

Nerve injury
Micrograph of a nerve with a decrease in myelinated nerve fibres (pink) and an abnormal increase in fibrous tissue (yellow), as may be seen in nerve injuries. HPS stain.
Specialty	Neurology

Nerve injury is an injury to a nerve. There is no single classification system that can describe all the many variations of nerve injuries. In 1941, Seddon introduced a classification of nerve injuries based on three main types of nerve fiber injury and whether there is continuity of the nerve.^[1] Usually, however, nerve injuries are classified in five stages, based on the extent of damage to both the nerve and the surrounding connective tissue, since supporting glial cells may be involved.^[2]

Unlike in the central nervous system, neuroregeneration in the peripheral nervous system is possible.^[2][3][4] The processes that occur in peripheral regeneration can be divided into the following major events: Wallerian degeneration, axon regeneration/growth, and reinnervation of nervous tissue. The events that occur in peripheral regeneration occur with respect to the axis of the nerve injury. The proximal stump refers to the end of the injured neuron that is still attached to the neuron cell body; it is the part that regenerates. The distal stump refers to the end of the injured neuron that is still attached to the end of the axon; it is the part of the neuron that will degenerate, but the stump remains capable of regenerating its axons.

The study of nerve injury began during the American Civil War and greatly expanded during modern medicine with such advances as use of growth-promoting molecules.^[5]