Nerves run throughout the body, carrying signals to and from the brain and spinal cord. When there is any injury to the body there is always a risk that a nerve may be damaged. This can be either temporary or permanent depending on the type and severity of nerve injury. It may give rise to varying signs and symptoms depending on what type of nerve is affected as well as its location and the main organs that the damaged nerve normally supplies.
How to Spot Nerve Damage
It is important to understand what nerves are and how it works in order to understand what happens when nerves are damaged.
Nerves are essentially transmission lines that allow for signals to travel throughout the body. These signals are electrical in nature, formed by the movement of electrolytes into and out of the nerve. Signals jump between nerve cells by chemical messengers known as neurotransmitters. Nerves also have an insulating layer known as the myelin sheath which helps with the conduction of nerve signals.
Some nerves carry signals from a part of the body to the brain. The signals contain information about the environment or a region of the body and therefore these nerves are also known as sensory nerves. Other nerves carry signals from the brain to a part of the body Most of the time these signals are to muscles that contract and relax to perform certain movements. Therefore these nerves are also known as motor nerves.
Nerves may be damaged in a number of ways. It can be classified according to the mechanism by which the nerve is damaged, such as due to trauma (injury), abnormal immune activity (autoimmune), infections, or with endocrine diseases like in diabetes. It can also be classified according the type of damage, such as if the nerve is compressed, stretched or severed (cut), if the insulating layer is damaged or where there is problems with signal transmission across nerve junctions.
Read more on nerve injury.
Therefore nerve damage will either affect the transmission of sensory signals or motor signals. This will present as distortions in sensations or problems with movement. The presentation may also vary depending on whether the damaged nerve is part of the autonomic or somatic nervous system, the specific nerve or location of the nerve where the damage occurs and even how it is damaged. It is also important to note that sometimes the problem may stem from the brain and the nerves carrying signals to and from the brain may not be damaged or dysfunctional.
How to Diagnose Nerve Damage
Nerve damage should be diagnosed by a medical professional. It may also require certain diagnostic investigations such as a nerve condution study. This test measures the speed of the electrical impulse through a specific nerve. However, there are a host of signs and symptoms that may be present which are an indication of nerve damage.
Read more on damaged nerve diagnosis.
Pain is one of the common signs of nerve injury. It may vary in nature from burning pain to sharp shooting pains. Depending on where the nerve injury occurs, pain may only be distributed along the area that the nerve supplies. Nerve pain is known as neuralgia or neuropathic pain.
The pain may be due to the tissue damage around the nerve but can also arise from the nerve itself. Injury to the nerve may cause impulses in the pain fibers to be abnormally generated and pain is perceived even if there is no surrounding tissue damage.
Numbness is another possible consequence of nerve damage. The loss of sensation may be partial where a person can feel touch, temperature or pain but to a lesser degree. On the hand, there may be a total loss of sensation where a person is unable to feel any sensation even with intense stimulation.
This numbness can affect the entire length of the nerve but usually only affects the area after (distal) the point where the nerve is damaged. Sometimes the less of sensation is not immediate. Instead it develops gradually and worsens until a person has no sensation at all.
Apart from pain on one extreme and numbness on the other, there may be a host of different sensations that a person may experience due to nerve damage. This may include tingling, prickling (“pins and needles”), burning, itching and formication (sensation of insects crawling on the skin).
These sensations occur as a result of a sensory nerve being abnormally stimulated as a result of the damage. These abnormal sensations are known as paresthesias. It may occur on its own, or accompany pain and numbness. Sometimes it can persist even when the damage to the nerve resolves.
Weakness or Paralysis
Since nerves carry signals to muscles, damage to a motor nerve may affect muscle activity. The nerve signals not only determine which nerve contracts but also the force of he contraction. A damaged nerve may therefore result in muscle weakness to varying degrees.
In severe cases there may be paralysis, where the muscle does not contract at all. The affected area may therefore be unable to move. Muscle weakness and paralysis may be temporary or permanent, depending on the type of nerve damage and severity.
Muscles eventually shrink if there is no nerve stimulation to cause at least occasional contraction. This shrinking is known as atrophy. It will affect muscle groups that are weak or those that ae paralyzed. The latter will lead to more severe atrophy but occasional movement of these muscles, even passive movement, can minimize atrophy.
Muscle twitching is another possible sign of nerve damage. This is where the muscle contracts and relaxes rapidly and unintentionally. These contractions are minor and may be barely noticeable. Persistent or repetitive twitching my be a sign of nerve damage, especially if it is accompanied by one or more of the symptoms above.
Coordination depends on correctly perceiving the environment and position through the senses and controlling movement as required. Therefore coordination may be affected if there is nerve damage. This can vary from moving a limb or appendage to maintaining balance when standing or walking.