Peripheral nerve damage is categorized in the Seddon classification based on the extent of damage to both the nerve and the surrounding connective tissue since the nervous system is characterized by the dependence of neurons on their supporting glia. Unlike in the central nervous system, regeneration in the peripheral nervous system is possible.

Types of nerve damage

The lowest degree of nerve injury in which the nerve remains intact but its signaling ability is damaged is called neurapraxia.

The second degree in which the axon is damaged, but the surrounding connecting tissue remains intact is called axonotmesis.

The last degree in which both the axon and connective tissue are damaged is called neurotmesis.[2]

1.Wallerian degeneration Distal axon degeneration, following section or severe injury, with

degeneration of the myelin. The process occurs within 7-10 days of injury and this portion of the nerve is inexcitable electrically.

2. axon degeneration Distal degenerated nerve is inexcitable electrically. Regeneration can occur since the basement membrane of the

Schwann cell survives and act as a skeleton along which tha axon regrows up to a rate of about 1mm per day.

3. Demyelination Segmental destruction of the myelin sheath occurs without axonal

damage. The primary lesion affects the Schwann cell and causes marked slowing of conduction or conduction block.

Local demyelination is caused by inflammation, eg: Guillain-Barre syndrome.

Autonomic nerve damage may produce the following symptoms:Inability to sense chest pain, such as angina or heart attackToo much sweating (known as hyperhidrosis) or too little sweating (known as anhidrosis)LightheadednessDry eyes and mouthConstipationBladder dysfunctionSexual dysfunction

Damage to motor nerves may produce the following symptoms:WeaknessMuscle atrophyTwitching, also known as fasciculationParalysis

Sensory nerve damage may produce the following symptoms:PainSensitivityNumbnessTingling or pricklingBurningProblems with positional awareness

In some instances, people with nerve damage will have symptoms that indicate damage to two, or even three, different types of nerves. For instance, you might experience weakness and burning of your legs at the same time.