Is polyneuropathy a neurological condition?
Polyneuropathy is classified as a neurological condition because it affects the nervous system, specifically the peripheral nervous system. Unlike diseases that affect the brain or spinal cord, the nerves outside the central nervous system are affected here. Despite this, the symptoms can be pronounced and lead to both pain, disability and impaired quality of life. Therefore, examination and treatment usually take place within neurological care.
Who is affected by polyneuropathy?
Polyneuropathy can occur at any age, but is significantly more common in the elderly. The risk increases with certain diseases and conditions that affect the metabolism, blood supply or structure of the nerves. The most common cause is diabetes, where prolonged elevated blood sugar gradually damages the nerves. Vitamin deficiencies, especially a lack of vitamin B12, can also lead to nerve damage. In some people, despite extensive investigation, no clear underlying cause can be determined, which is then called idiopathic polyneuropathy.
Common symptoms of polyneuropathy
The symptoms of polyneuropathy vary depending on the types of nerves that are affected and how pronounced the nerve damage is. Usually, the longest nerves are affected first, which means that the symptoms often begin in the toes and feet. Many describe a gradually increasing sensory impairment with numbness, tingling or a burning pain. Over time, the symptoms can spread up to the lower legs and hands.
In addition to sensory impairment, polyneuropathy can also cause muscle weakness and impaired balance. This is because the motor nerves that control muscle movements are affected. In more advanced cases, the muscles can become weaker and decrease in volume. If the autonomic nerves are affected, symptoms may instead manifest as dizziness when standing up, stomach and intestinal problems, altered sweating or problems with the bladder and sexual function.
Causes of polyneuropathy
Polyneuropathy is in most cases not a disease in itself, but the result of an underlying effect on the nervous system. The most common cause is diabetes, but long-term alcohol consumption can also lead to nerve damage. Vitamin deficiency, especially a deficiency of vitamin B12, folate or vitamin B6, is another important and often treatable cause. With increasing age, the function of the nerves can gradually deteriorate, which is likely related to changes in blood supply, metabolism and the repair ability of nerve cells. When no clear cause can be identified, the term idiopathic polyneuropathy is used.
One of the most common known causes of polyneuropathy is diabetes. It is not entirely clear exactly why diabetes leads to nerve damage, but several mechanisms are believed to work together. Prolonged elevated blood sugar can contribute to the formation of harmful substances around the nerves and cause oxidative stress. At the same time, the blood vessels that supply the nerves can be affected, leading to a reduced supply of oxygen and nutrients. This combination makes the nerves particularly vulnerable and can gradually impair their function. Alcohol is another common cause of polyneuropathy. With prolonged and high alcohol consumption, the nerves can be damaged in several ways. Alcohol can lead to a deficiency of important B vitamins, especially vitamins B1 and B12, which are necessary for the function of the nerves. In addition, alcohol itself and the breakdown products that form in the body can have a direct toxic effect on the nerve tissue. Overall, this can lead to both sensory impairment and muscle weakness.
In kidney failure, polyneuropathy can occur as a result of the kidneys no longer being able to clean the blood effectively enough. When waste products and other harmful substances accumulate in the blood, they can negatively affect the nervous system. This form of nerve damage often develops gradually and can improve if kidney function is stabilized or with dialysis treatment.
Vitamin B12 deficiency is a well-known and important cause of polyneuropathy, not least because it is often treatable. Vitamin B12 plays a central role in the structure and function of nerves. Deficiency can occur if the absorption of the vitamin in the gastrointestinal tract is impaired, for example in diseases of the stomach or intestines, after surgical procedures or in the absence of intrinsic factor. Long-term B12 deficiency can lead to both peripheral nerve damage and effects on the spinal cord.
Polyneuropathy can also occur as a result of other diseases, such as infections, inflammatory conditions, autoimmune diseases and cancer. In these cases, nerve damage is often part of a more extensive disease process, where the immune system or inflammatory processes damage the nerve tissue.
Certain drugs and chemical substances can also cause polyneuropathy. This includes certain cytostatics used in cancer treatment, but also long-term exposure to chemicals or nitrous oxide. Harmful use of nitrous oxide can also cause polyneuropathy in younger people and is also often associated with damage to the spinal cord, especially through the inactivation of vitamin B12.
Finally, there are hereditary forms of polyneuropathy, the most common of which is Charcot-Marie-Tooth disease. This disease occurs in several different variants and is caused by genetic changes that affect the structure or function of the nerves. The symptoms often begin in young age and develop slowly over time, with increasing muscle weakness and reduced sensation, especially in the feet, lower legs, hands and forearms. Difficulty walking and stumbling are common, and many people eventually need various types of aids such as orthopedic shoes or orthoses. Although the disease cannot be cured, there is treatment and support that can reduce the symptoms and make everyday life easier.
A special and unusual form of polyneuropathy is Guillain-Barré syndrome. This is an acute inflammatory nerve disease in which the immune system attacks peripheral nerves in connection with an infection, often in the respiratory tract or gastrointestinal tract. Symptoms develop rapidly, usually over days to weeks, and often begin with weakness or numbness in the legs. Then the arms, facial muscles and, in severe cases, the respiratory muscles can be affected. Guillain-Barré syndrome can be life-threatening and often requires hospitalization. Treatment usually consists of immunoglobulin or plasma exchange to slow the course of the disease and speed up recovery.
How is polyneuropathy diagnosed?
The diagnosis of polyneuropathy is based on a comprehensive assessment in which the doctor weighs together symptoms, medical history and findings during a neurological examination. The examination focuses on sensation, muscle strength, reflexes and balance. To confirm nerve involvement, neurophysiological examinations such as nerve conduction studies and electromyography are often used, which can show how well the nerves and muscles are functioning.
A broad investigation is also carried out to identify possible underlying causes. This is crucial because treatment is largely determined by what caused the nerve damage.
Are there specific blood tests for polyneuropathy?
There are no blood tests that can directly confirm polyneuropathy, but blood tests play a central role in the investigation. The aim is to identify diseases or conditions that can explain the nerve damage and that in some cases are treatable.
Common tests include checking vitamin status, especially vitamin B12 and folate, as well as blood sugar and long-term blood sugar to detect diabetes. Thyroid tests, liver and kidney tests, and inflammation markers are often analyzed to rule out other systemic causes. If autoimmune or inflammatory nerve disease is suspected, more targeted immunological analyses may be necessary.
Treatment of polyneuropathy
Treatment of polyneuropathy is tailored to the underlying cause. If the cause can be treated, for example by correcting a vitamin deficiency or improving blood sugar control in diabetes, symptoms can sometimes stabilize or improve. In other cases, where the nerve damage is more permanent, treatment focuses on symptom relief.
Nerve pain is often treated with medications that are specifically designed for neuropathic pain. Physiotherapy and balance exercises can be important for maintaining mobility and reducing the risk of falls. Lifestyle measures, such as reducing alcohol intake and adjusting physical activity, can also have a significant impact on the course of the disease.
