Polyneuropathy – Causes & Diagnostics

Polyneuropathy is a disease of the peripheral nervous system. This includes all nerves located outside the central nervous system (brain and spinal cord). Depending on its course and severity, polyneuropathy (also called peripheral polyneuropathy or peripheral neuropathy (PNP)) can have serious consequences. This makes it all the more important to recognize it as early as possible and treat it accordingly. In this article, we inform you about possible triggers, symptoms, diagnosis and treatment approaches.

What are the causes?

Polyneuropathy, which translates as disease of many nerves, can have just as many causes. In an estimated 20 percent of all cases, these causes cannot be clearly determined; this is referred to as idiopathic polyneuropathy. The most common triggers in Europe are diabetes mellitus and alcoholism.

Other causes can include:

• Bacterial and viral infections (e.g. Lyme disease, glandular fever, HIV, shingles, herpes simplex infections, diphtheria)

• Metabolic disorders due to vitamin deficiency (B12 and others)

• Medications and toxins (e.g. heavy metals, solvents, lead, arsenic, thallium)

• Inflammatory changes in the blood vessels

• Disorders of the autoimmune system (e.g. Guillain-Barré syndrome)

• Genetic diseases (e.g. hereditary motor and sensory neuropathy)

• Hormonal disorders (e.g. thyroid diseases)

• Cancer

• Kidney diseases

• Liver diseases

Nerve damage caused by medications, toxins or heavy metals is called toxic polyneuropathy.

Which diagnostic procedures are suitable?

If polyneuropathy is suspected, neurologists carry out a whole series of examinations to determine the cause and extent of the disease:

Case history

First, your medical history is taken: your physician asks you about complaints and previous illnesses. During this conversation, be sure to inform them about any medications you are taking and also about possible toxins you come into contact with!

General examination

Among other things, your reflexes are tested and your skeleton is examined for possible malformations. If you suffer from scoliosis, a high-arched foot or claw toes, this could be an indication of hereditary polyneuropathy. The neurologist also checks your sense of vibration using a tuning fork.

Blood tests

The following blood tests, among others, are carried out in the laboratory:

• Vitamin B12 status

• Glucose tolerance test

• Long-term blood sugar

• Liver and kidney values

• Antibodies against infectious diseases (e.g. Lyme disease)

• Elevated inflammation markers

• Heavy metal exposure

ECG and ultrasound

An electrocardiogram shows whether the autonomic nerve fibers of the heart have been affected. An ultrasound examination of the bladder determines whether it can still be emptied completely. In autonomic polyneuropathy, bladder function is often affected.

Electromyography

This procedure tests electrical muscle activity. It can determine whether motor disorders are caused by the muscle itself or by the nerves supplying it. If there is a disorder of nerve function, this indicates polyneuropathy.

Electroneurography

When measuring nerve conduction velocity, an electrical current is sent through the nerve pathways. If the impulses are conducted with a noticeable delay, this is an indication of polyneuropathy.

Quantitative sensory testing

Here, the physician tests your response to stimuli such as pressure, temperature and vibration. Seven different sensory tests of the skin allow conclusions to be drawn about nerve damage. They also help to identify which nerve fibers are damaged and how far the damage has progressed.

Nerve biopsy

This procedure is only used in certain cases, for example in diabetics whose nerves are damaged on only one side of the body. Examining a sample of nerve tissue can help find the cause of polyneuropathy: it provides indications of whether an autoimmune disease, vasculitis or a hereditary disease could be the trigger.

Genetic testing

Genetic material is usually only examined if polyneuropathy has already occurred frequently in the affected person's family. Further indications are foot deformities or deformations of the skeleton.

Read more:
Polyneuropathy – symptoms & treatment options

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