What is Polyneuropathy?

Polyneuropathy is a medical condition that causes dysfunction in multiple peripheral nerves throughout the body. According to statistics from the National Institute of Neurological Disorders and Stroke (NINDS), an estimated 20 million people in the United States have peripheral neuropathy, and most of them have polyneuropathy. In the following article, let’s delve deeper into this condition. 

1. What is Polyneuropathy?

Polyneuropathy is a medical condition that causes damage to multiple peripheral nerves throughout the body. Peripheral nerves are located outside the brain and spinal cord and are responsible for communication between the central nervous system and the rest of the body. Therefore, when polyneuropathy occurs, signals transmitted from various parts and organs cannot be sent promptly to the brain and spinal cord.   

Approximately 1-3% of the population suffers from polyneuropathy, with older adults accounting for 5-8% of cases. The disease not only causes sensory and motor impairment (or both) but also affects the autonomic nerves that regulate functions such as digestion, bladder control, blood pressure, and heart rate.

In terms of classification, there are over 100 different types of peripheral neuropathy, and most of them fall under polyneuropathy. There are two main types of polyneuropathy:   

• Acute polyneuropathy: This type is relatively rare, with symptoms occurring suddenly and severely. The cause can be an immune response, an infection that damages nerves, or Guillain-Barré syndrome. Acute polyneuropathy often has a good chance of successful treatment in a short period.

• Chronic polyneuropathy: Symptoms occur over a long period (more than 8 weeks) and are difficult to treat. The cause can be a consequence of chronic diseases like diabetes, kidney failure, or it may be idiopathic (unknown cause) 

2. Characteristics of Polyneuropathy

Depending on the underlying cause, the symptoms of polyneuropathy can vary. The most common ones include:

Acute polyneuropathy (such as Guillain-Barré syndrome) often occurs suddenly in both legs, then spreads to the arms. Symptoms include muscle weakness, tingling sensations in the hands and feet, and loss of sensation. Notably, the nerves that control and regulate breathing can be affected, leading to a high risk of respiratory failure.

Chronic polyneuropathy typically affects sensory nerves. Usually, the feet are affected first, with sensations of tingling, numbness, burning pain, and loss of vibration sense and position sense (not knowing where the hands and feet are). Due to the loss of position sense, walking and moving become difficult for the patient, and they may stumble or fall frequently. This can lead to muscle weakness, atrophy, and stiffness if the patient doesn’t exercise regularly.

Diabetic polyneuropathy often causes tingling or burning sensations in the hands and feet (also known as distal polyneuropathy). The pain is usually more intense at night and worsens with touch or temperature changes. Patients may lose the sensation of pain, leading to frequent injuries. This type of joint injury is medically referred to as neurogenic arthropathy (Charcot joints).

Polyneuropathy also affects the autonomic nerves responsible for controlling involuntary functions in the body (blood pressure, heart rate, digestion, salivation, urination). Typical symptoms of this type include constipation, sexual dysfunction, and sudden changes in blood pressure. Pale skin, dry skin, and decreased sweating are also common. Some less common symptoms include loss of bowel control and urinary incontinence.

Patients with hereditary polyneuropathy, such as Charcot-Marie-Tooth disease, may experience hammertoes, high arches, and spinal curvature. Other sensory abnormalities or muscle weakness symptoms may be milder than in other types of polyneuropathy.

3. Risk Factors for the Disease

Polyneuropathy can occur in anyone, but it is most common in older adults. In particular, individuals who have or are currently experiencing the following conditions have a higher risk of developing the disease. Specifically:

• Diabetes: It is the highest risk factor for polyneuropathy, especially in patients who do not have good control of their blood sugar levels. According to a study of over 1,400 people with type 2 diabetes, up to 20% of them have polyneuropathy.
• Alcohol addiction: Alcohol damages nerve tissue and prevents the body from absorbing nutrients, contributing to neuropathy.
• Autoimmune diseases: The immune system attacks the body, causing damage to nerves and other organs. Some autoimmune diseases such as Sjogren’s syndrome, celiac disease, Guillain-Barré syndrome, rheumatoid arthritis, and lupus can lead to polyneuropathy.
• Bacterial or viral infections: Some infections can lead to neurological disorders, including Lyme disease, shingles, hepatitis B and C, and HIV/AIDS.
• Bone marrow disorders: Disorders of abnormal protein production in the blood, bone cancer, and lymphoma.
• Frequent exposure to toxins and chemicals: Polyneuropathy can occur due to frequent exposure to industrial chemicals such as arsenic, lead, and mercury. Drug abuse can also be a risk factor.
• Genetic disorders: Some hereditary nerve diseases, such as Charcot-Marie-Tooth disease, can lead to polyneuropathy.
• Hypothyroidism: Thyroid dysfunction can also be a cause of polyneuropathy, although this is not common.
• Kidney disease: Peripheral neuropathy due to uremia is a form of polyneuropathy affecting 20-50% of kidney patients – according to data from the Center for Peripheral Neuropathy.
• Liver disease: Research indicates that peripheral nerve diseases are very common in people with cirrhosis.
• Medication use: Chemotherapy and certain medications for HIV/AIDS can cause peripheral neuropathy.
• Nutritional deficiencies: Deficiencies in vitamins B1, B6, B12, and vitamin E can lead to polyneuropathy, as these vitamins play an important role in the health of the central nervous system.
• Physical or emotional trauma: Repetitive movements like typing, accidents, or other injuries can damage peripheral nerves.

It’s not always easy to pinpoint the exact cause of polyneuropathy. Cases where the cause remains unclear are referred to as idiopathic neuropathy, which is commonly seen in the chronic polyneuropathy group.

Patients who have or are currently experiencing the aforementioned conditions, or are experiencing symptoms suggestive of polyneuropathy, should visit medical facilities for screening, examination, and timely treatment.

The article above has provided you with comprehensive information about polyneuropathy, its characteristics, and the high-risk groups for the condition. If you notice yourself or those around you exhibiting symptoms suggestive of polyneuropathy, please offer advice and proactively seek medical attention for timely examination and treatment.

References: Healthline.com, Medicalnewstoday.com, Msdmanuals.com, Mountsinai.org