Polyneuropathy: Causes, Symptoms, Diagnosis and Treatment

Polyneuropathy: causes, symptoms, diagnosis, and treatment

Polyneuropathy is a type of peripheral neuropathy that simultaneously affects multiple peripheral nerves. These nerves play an essential role in transmitting messages between the central nervous system (brain and spinal cord) and the rest of the body. Depending on the progression of the disease, polyneuropathy can be acute, with a sudden onset, or chronic, developing gradually, often over several months or even years.^[1] In this article, we will tell you more about its causes and symptoms, as well as how it can be diagnosed and treated!

Causes of polyneuropathy: risk factors and associated conditions

Polyneuropathy can have various causes. Acute polyneuropathy, for example, can be caused by certain infections (e.g., diphtheria), diseases where the immune system attacks the peripheral nervous system (e.g., Guillain-Barré syndrome), or certain toxins (e.g., tri-ortho-cresyl phosphate, thallium).^[2]

In the case of chronic polyneuropathy, the cause is often unknown. Known causes include a long list of conditions, including:

• diabetes mellitus;
• infections (e.g., hepatitis C, HIV infection, Lyme disease, shingles);
• autoimmune disorders (e.g., systemic lupus erythematosus, vasculitis);
• vitamin B12 deficiency and other nutritional deficiencies;
• hypothyroidism;
• kidney failure;
• hereditary neuropathies (such as Charcot-Marie-Tooth disease);
• cancer.^[2][3]

Other possible causes or factors that may contribute to the development of chronic polyneuropathy include:

• excessive alcohol consumption;
• toxic substances (e.g., arsenic, mercury, lead);
• some medications (including certain antibiotics).^[2][3]

Diabetes mellitus is the most common cause of chronic polyneuropathy. In fact, it can cause several forms of polyneuropathy, known as diabetic neuropathy.^[2]

Symptoms of polyneuropathy

The symptoms of polyneuropathy can vary considerably, depending on the type and severity of nerve damage.

Acute polyneuropathies, such as Guillain-Barré syndrome or those caused by toxins, have a sudden onset, usually starting in both legs and progressing to the arms. Characteristic symptoms include weakness, tingling sensations, or loss of sensation. In some cases, the muscles controlling breathing can be affected, leading to respiratory failure.^[1][2]

On the other hand, chronic polyneuropathies primarily affect sensation. Typically, the legs are affected first, but there are cases where symptoms begin in the hands.^[2] Common symptoms include:

• tingling sensations;
• numbness;
• burning sensations;
• impaired vibration sense and proprioception;
• balance and coordination problems;
• muscle weakness and atrophy.^[2]

Diabetic neuropathy usually causes tingling or painful burning sensations in the hands and feet. This condition is known as distal polyneuropathy. The pain may be more severe at night and can be worsened by touch or sudden temperature changes. In some cases, sensitivity to cold or pain may be affected, leading to injuries from prolonged pressure or other trauma. Without pain as a warning, joints may be prone to injury.^[2][3]

Polyneuropathy can also affect the nerves of the autonomic nervous system, which controls the body's physiological processes, such as blood pressure, heart rate, digestion, salivation, and urination. Typical symptoms in such cases include constipation, sexual dysfunction, and fluctuations in blood pressure, including sudden drops in blood pressure when standing up (orthostatic hypotension). The skin may become pale and dry, and sweating may decrease. In rare cases, fecal or urinary incontinence may occur.^[2]

People with hereditary polyneuropathy, such as Charcot-Marie-Tooth disease, may exhibit "hammer toes," high arches, and a curved spine (scoliosis).^[2]

Diagnosing polyneuropathy

Diagnosing polyneuropathy involves a thorough evaluation of the patient's medical history and symptoms, as well as a series of tests to determine the specific cause and rule out other conditions with similar symptoms (e.g., fibromyalgia, multiple sclerosis).

The tests and investigations used may include:

• blood and urine tests;
• MRI;
• CT scan;
• electromyography;
• biopsy.^[1][3]

Treatment of polyneuropathy

Treatment of polyneuropathy involves a combination of medications, therapies, and medical procedures. Drug treatment may include medications to treat/manage associated conditions (e.g., antidiabetic drugs), analgesics, antidepressants, and antiepileptics. Procedures used in the treatment of polyneuropathy include TENS (transcutaneous electrical nerve stimulation), plasmapheresis (plasma exchange), and immunoglobulin therapy. Physical therapy and the use of orthoses may also be helpful.^[1][2][3]

Specific treatment depends on the cause of polyneuropathy. For example, in the case of diabetes, proper blood glucose management can slow its progression and even improve symptoms. Treatment of cancer, multiple myeloma, liver, or kidney failure can lead to slow recovery. If polyneuropathy is caused by medications or toxins, discontinuing the drugs or avoiding toxin exposure can sometimes reverse it. When the cause cannot be corrected, treatment will focus on relieving pain and addressing issues related to muscle weakness.^[2]

The prognosis for people diagnosed with polyneuropathy depends on its cause, the affected nerves, and the severity of the damage. In some cases, symptoms improve after treating the cause, while in others, the effects are permanent, or symptoms may worsen over time. As with many other conditions, prevention is easier than treatment, and avoiding risk factors and properly managing conditions associated with polyneuropathy are the best ways to reduce the risk of polyneuropathy!

Bibliography

1. Leonard, Jayne. “What to Know about Polyneuropathy” Medical News Today, 29 Apr. 2017. Accessed 2 Sept. 2024.
2. Rubin, Michael. “Polyneuropathy”, MSD Manual Consumer Version, MSD Manuals, 4 Mar. 2024. Accessed 2 Sept. 2024.
3. “What to Know about Polyneuropathy”, Verywell Health, 2022. Accessed 2 Sept. 2024.