The peripheral nervous system (PNS) is the network of nerves that is outside the central nervous system (formed by the brain and spinal cord) and whose job is to transmit signals about physical sensations from the periphery to the brain.
When these nerves work badly, because they are damaged or destroyed, this is a peripheral neuropathy.
The SNP includes different types of nerves with their own specific functions; Some types are:
- Sensory nerves (responsible for transmitting sensations, such as pain and touch).
- Motor nerves (responsible for controlling muscles).
- Autonomic nerves (responsible for regulating the body’s automatic functions, such as blood pressure and bladder function).
- Peripheral neuropathy can affect a group of nerves or all three together. In any case, when a peripheral neuropathy occurs, the normal functioning of the nerves is interrupted, so that they can send pain signals when there is nothing that causes it, or they can not send a painful signal even if something is causing damage.
This nerve involvement may be due to a wound, a systemic disease, an infection or a hereditary disorder.
Symptoms of peripheral neuropathy
The symptoms of peripheral neuropathy vary according to the type of neuropathy.
Sensory neuropathy can show the following symptoms:
- Tingling and numbness
- Sensation of pins and needles and hypersensitivity.
- Increased pain or inability to feel pain.
- Loss of the ability to detect changes in temperature.
- Loss of coordination and proprioception.
- Burning or shooting pains, which may get worse at night.
- Sensory neuropathy can also cause ulcers in the feet and legs, infection and gangrene.
Motor neuropathy affects the muscles and shows the following symptoms:
- Muscle weakness, which causes instability and difficulty making small movements.
- Loss of muscle mass.
- Muscle spasms and cramps.
- Muscular paralysis
If the autonomic nerves are affected, there may be vegetative problems related to sweating, tolerance to heat, bowel function or bladder; In addition to changes in blood pressure, which can cause dizziness.
It must be borne in mind that, in both cases, these symptoms can also indicate other conditions, hence the importance of informing the doctor about all symptoms perceived in case of attending a consultation.
Causes of peripheral neuropathy
Many types of neuropathy are idiopathic (of unknown cause), but there are several conditions that can trigger them. Thus, diabetes is the most common cause of chronic peripheral neuropathy, since high blood sugar levels damage nerves.
Other conditions and potentially causal injuries include:
- Chronic kidney disease: if the kidneys do not function normally, the resulting imbalance of salts and chemicals can cause peripheral neuropathy.
- Infections: Herpes zoster, HIV infection, Lyme disease and others can cause nerve damage.
- Guillain-Barré syndrome: this is a specific type of peripheral neuropathy triggered by a viral infection.
- Some autoimmune disorders: especially rheumatoid arthritis and systemic lupus erythematosus (SLE).
Other causes that can lead to peripheral neuropathy, could be:
- Excessive alcohol consumption.
- Some medications (such as chemotherapy and treatment for HIV).
- Deficiency of certain vitamins (such as vitamin B12, B1, B6 and E).
- Ingestion of poisons and toxins, such as insecticides and solvents.
- Some types of cancer, including lymphoma and multiple myeloma.
- Chronic liver disease
In addition, disorders of small blood vessels can reduce the blood supply to the nerves, which causes nerve tissue damage. Neuromas (benign tumors that affect nerve tissue) can also cause neuropathic pain.