Nerve injury occurs when there is injury to the nervous tissue. Nerve injuries can be classified into neurapraxia, axonotmesis, and neurotmesis. Neurapraxia is the least severe type of nerve injury. This means that the affected individual can have complete recovery as the axon is intact despite an interruption in nerve conduction due to myelin damage. Neurapraxia usually occurs when there is ischemia or nerve compression. The average recovery period for neurapraxia takes about 6 to 8 weeks.
Axonotmesis is a more severe injury to the nerve where the axon is affected while the epineurium is maintained. Axonotmesis may cause paralysis and is mostly seen when there is a crush injury. When the object causing the crush injury is removed in time, the axon can regenerate and recover. In axonotmesis, there is interruption of the myelin sheath and axon. Due to loss of axonal continuity, it can result in Wallerian degeneration.
Neurotmesis is nerve injury without any potential of recovery. It occurs when there is severe laceration, contusion, or stretching of the nerve. In neurotmesis, the encapsulating connective tissue and axon lose their continuity. However, peripheral nerve injury is classified in 5 stages based on the severity of damage to the nerve and surrounding tissue. Regeneration in the peripheral nervous system is possible. During peripheral regeneration, the processes that can occur are Wallerian regeneration, nerve reinnervation, and axon growth or regeneration.
Symptom #1: Changes in Sensation
When nerve injury occurs, changes in sensation such as paresthesia, hypersensitivity, loss of proprioception, and loss of sensation for touch may occur. Paresthesia is an abnormal sensation on the skin that can be described as numbness, prickling, or burning.
In nerve injury, hypersensitivity such as sensitivity to light touch may occur. Some individuals also report symptoms such as decreased sensation to pain, heat, or coldness. Loss of proprioception refers to the loss of self-awareness of body position and self-movement.