Polyneuropathy: short overview
- What is polyneuropathy? A group of diseases in which several or many peripheral nerves are damaged. These are the nerves outside the central nervous system (brain and spinal cord). Polyneuropathy is also called “peripheral polyneuropathy” or “peripheral neuropathy” (PNP).
- Symptoms: depending on which nerves are damaged Frequently, there is, for example, sensation of discomfort, tingling, pain and numbness in legs and/or arms, muscle weakness, muscle cramps and paralysis, bladder emptying disorders, constipation or diarrhoea, impotence, etc.
- Examinations: physical examination, electroneurography (ENG), electromyography (EMG), blood tests etc.
- Causes: mainly diabetes mellitus and alcohol abuse. Other causes are other acquired diseases or poisoning. More rarely, polyneuropathy is genetically determined. Sometimes no cause can be found at all.
- Therapy: If possible, the cause is eliminated or treated. In addition, the symptoms can be specifically treated (painkillers, TENS, antidepressants, antispasmodic agents, physiotherapy, alternating baths, wraps, orthopaedic aids, etc.)
In polyneuropathy, peripheral nerves are damaged. These can be, for example, nerves that command muscle contractions (motor nerves) or control digestion or breathing (autonomic nerves). Often nerves are also affected, which are responsible for the sensitive sensation of touch, temperature, pressure and vibration (sensitive nerves).
Early if you notice that you have, for example, sensations in your feet or coordination problems when walking. Then the family doctor and, together with him, the neurologist can go on cause research before the nerve is permanently damaged. Moreover, the recovery of nerves takes time – and therefore patience. Those who are treated early and well can be more likely to be symptom-free again.
There are people in whom the disease has a genetic cause. The people affected are then correspondingly younger. However, the symptomatic polyneuropathies, which are much more common, mainly affect older people. Nerve suffering is here for example a concomitant symptom of diabetes, vitamin deficiency diseases or alcohol dependency.
Unfortunately it is not easy to discover – often it is real detective work. Statistically speaking, only about 50 to 60 percent find a reason for the complaints and can then often treat them directly. Nevertheless, there are some things that can be done without knowing the cause of the relief, for example physiotherapy or gait training. Vitamin B complexes support the nerves in healing. And last but not least, there are also drugs that can alleviate the pain.
Which polyneuropathy symptoms occur in a patient therefore depends on the damaged nerves. Accordingly, a distinction is made between motor, autonomic and sensitive disorders.
Polyneuropathy symptoms can also be classified according to their distribution in the body:
- In most cases the polyneuropathy symptoms affect both feet or both arms. It’s called symmetrical polyneuropathy. If the nerve damage occurs on one side of the body only, asymmetric polyneuropathy is present.
- If the nerve damage mainly affects areas of the body that are remote from the trunk (such as feet, hands), it is a distal polyneuropathy). Much less frequently, the disease extends to parts of the body close to the trunk (proximal polyneuropathy).
Polyneuropathy symptoms: Sensitive nerves
Nerves that lead from the skin to the brain are called “sensitive”. They inform the brain, for example, about touch, pressure, temperature or pain stimuli or vibrations. If this sensitivity is disturbed by polyneuropathy, the perception in arms and legs suffers. The toes are often the first to be affected. For example, there is sensation of discomfort, tingling or stinging, burning pain.
Feelings of numbness are also possible polyneuropathy symptoms. If these occur in the legs, those affected have coordination problems when walking, for example.
If the temperature sensation is disturbed, injuries can occur more easily. Polyneuropathy patients, for example, do not notice that their footbath is much too hot. People with pronounced polyneuropathy can also perceive pain only to a lesser extent. This also increases the risk of injury.
Most polyneuropathies are associated with sensitive disorders.
Polyneuropathy symptoms: Motor nerves
Motor nerves transmit commands from the brain to the skeletal muscles. The commands cause a muscle to contract (contract). In motor polyneuropathy, these nerves are damaged. As a result, the muscles in question lose strength. In the worst case muscle paralysis occurs. Muscle cramps are also possible.
In general, when tissue is insufficiently or not at all activated by the supplying nerves for a longer period of time, it degenerates: it shrinks and disappears. This happens particularly quickly in the skeletal muscles. Thus, motor polyneuropathy can lead to muscle atrophy in severe cases.
Polyneuropathy symptoms: Autonomic nerves
The autonomous (vegetative) nerves control the function of internal organs such as the heart, lungs, stomach, intestines, genitals and bladder. They are not subject to the will. For example, you cannot consciously command the heart muscle to contract.
If autonomic nerves are damaged, serious or even life-threatening symptoms can occur. For example, if intestinal nerves are damaged in a polyneuropathy, diarrhoea or constipation may occur. If the nerves that regulate bladder function are affected, urination, i.e. the emptying of the bladder, is disturbed. Nerve damage in the lungs can cause respiratory arrest. If the autonomic polyneuropathy affects nerves in the heart muscle, dangerous cardiac arrhythmia can result.
Polyneuropathy symptoms at a glance
In the following table you will find important polyneuropathy symptoms at a glance:
|Sensitive symptoms||Motor symptoms||Autonomic symptoms|
|Tingling, formication||Muscle twitching||Pupil disorders|
|Stinging||Muscle cramps||Water retention (oedema)|
|Furry and numb||Muscle weakness||Ulcers|
|Feeling of being constricted||Muscular atrophy||reduced sweating|
|Feelings of swelling||Heartbeat at rest|
|Sense of unpleasant pressure||Gastric paralysis (gastroparesis)|
|Feeling like walking on cotton wool||Diarrhoea, constipation|
|Gang insecurity (especially in the dark)||disturbed urination|
|lack of temperature sensation||Impotence (Erectile Dysfunction)|
|painless wounds||Dizziness / fainting when getting up|
Diabetic polyneuropathy: Symptoms
In the case of polyneuropathy due to diabetes mellitus, the symptoms develop insidiously. The first to be damaged are usually the sensitive nerve fibres. Those affected then notice, for example, a numbness or tingling in the legs. Many also feel a burning pain in their feet (“burning feet syndrome”).
These polyneuropathy symptoms are particularly noticeable at rest or at night. Some patients say that they can barely stand the weight and touch of the blanket.
Diabetic polyneuropathy often leads to a reduced perception of pain. Then small injuries often go unnoticed. Because in many cases the blood circulation is also disturbed in diabetes, poorly healing wounds can develop. This usually happens on the feet (diabetic foot syndrome). The affected tissue may even die (necrosis). Most diabetics are affected by polyneuropathy on both feet or legs.
As the disease progresses, polyneuropathy can also spread to autonomous nerves. Possible consequences are, for example, difficulty swallowing, vomiting and alternating diarrhoea and constipation. Urinary incontinence and erectile dysfunction (men) can also turn out to be symptoms of polyneuropathy.
Alcoholic polyneuropathy: symptoms
Alcoholic polyneuropathy is also widespread. It usually progresses slowly. Most of those affected have nerve disorders in the legs, both of them (symmetric polyneuropathy): pain, sensation, sensitivity disorders, muscle atrophy and severe muscle relaxation (paresis) occur. For example, the affected persons can then no longer stand properly.
In severe cases, polyneuropathy symptoms also develop in the eye area, such as pupil disorders and paralysis of the eye muscles
In some cases, alcoholic polyneuropathy also proceeds without symptoms.
Polyneuropathy: causes and risk factors
Doctors now know more than 200 different causes of polyneuropathy. The most common cause of nerve damage is diabetes (diabetic polyneuropathy) or alcohol (alcoholic polyneuropathy).
Polyneuropathy in diabetes
Diabetic polyneuropathy is the most common form of polyneuropathy. It can occur in both type 1 and type 2 diabetes.
It is estimated that every second diabetic develops a polyneuropathy in the course of his or her life. The decisive factor is whether and how well the diabetes is treated: Diabetics whose blood sugar values are poorly adjusted fall ill particularly early and with particular severity with polyneuropathy.
The mechanisms by which a permanently elevated blood sugar level damages the nerves have not yet been clarified in detail.
- On the one hand, the high blood sugar can directly damage the nerves: Experts assume that the sugar molecules form reactive compounds with different proteins. These attack the nerve cells and damage them irrevocably over time.
- On the other hand, the high blood sugar level damages the tiny blood vessels in the body (microangiopathy). This can lead to nerves no longer being supplied with sufficient oxygen and nutrients. Their function suffers as a result. Over time, the undersupplied nerves can even die off.
In most cases, this nerve damage proceeds insidiously in diabetes patients. So the polyneuropathy symptoms are slowly developing. The nerve damage also proceeds differently with each patient. The type and severity of symptoms can therefore vary considerably.
Polyneuropathy due to alcohol
The second most common trigger of polyneuropathy is alcohol, namely chronic alcohol consumption. Again, the exact mechanisms leading to the nerve damage are not yet fully understood. However, studies indicate that alcohol can directly affect the nerves. This mechanism is considered to be mainly responsible for the nerve damage in alcoholics.
A second factor may make matters worse: alcoholism is often associated with malnutrition. Many alcoholics have a poor and unbalanced diet. Among other things, this can lead to a lack of vitamin B12. However, this vitamin is very important for the function of the nervous system. A vitamin B12 deficiency could therefore further promote nervous disorders in alcoholics. Because even on its own it can cause polyneuropathy.
Other causes of polyneuropathy
Other possible causes of polyneuropathy include
- Vitamin B12 deficiency (for example in vegans or after stomach surgery)
- Renal diseases
- Liver diseases
- Disorders of thyroid function (under- and over-function)
- Toxins (such as arsenic, lead) and drugs (especially cancer drugs)
- Solvents (e.g. hydrocarbons such as benzene or trichloroethene, alcohols such as methanol; therefore toxic polyneuropathy is recognised as an occupational disease in certain occupational groups such as painters or floor layers – after appropriate testing)
- Some infections with bacteria or viruses (Lyme borreliosis, diphtheria, mononucleosis, shingles, herpes simplex infections, HIV, etc.)
- Guillain-Barré syndrome (an autoimmune disease)
- Cancer (polyneuropathy can be the first sign of this)
Most polyneuropathies are triggered by such diseases or poisoning. More rarely, nerve damage is genetically determined. There are several congenital diseases that are accompanied by polyneuropathy. These include HMSN (hereditary motor sensitive neuropathy), of which there are several subtypes.
In about 20 percent of all patients, the cause of polyneuropathy remains unexplained.
If nerve toxins such as alcohol, heavy metals or drugs damage the nerves, it is a “toxic polyneuropathy”.
Which part of the nerve cells is damaged?
Each nerve cell is composed of a cell body and a nerve extension (axon). The axon can be up to one meter long. One can imagine the nerve extensions like cables. The body protects its “nerve cables” with an insulating layer. This is called the myelin layer or myelin sheath. In addition to its protective function, myelin has another task: it accelerates the transmission of electrical nerve signals.
Depending on which part of a nerve cell is damaged, a distinction is made between demyelinating and axonal polyneuropathy:
Demyelinating polyneuropathy is characterized by the disintegration of the protective marrow layer (myelin layer). If, on the other hand, the axon itself is affected, it is an axonal polyneuropathy. In the case of shapes, they can also appear in combination. Then myelin sheaths and axons are equally damaged.
Polyneuropathy: examinations and diagnosis
If you notice possible polyneuropathy symptoms, you should consult a doctor immediately. If the nerve damage is detected early and its cause treated, this has a positive effect on the course of polyneuropathy.
The doctor will first talk to you in detail to take your medical history (anamnesis). He has the complaints described to him in detail and asks how long they have existed. He also inquires about any pre-existing or underlying diseases (such as diabetes, kidney disease, hypothyroidism, etc.). Also inform the doctor about any medication you are taking and any toxins you may be exposed to, for example, at work.
Important for the clarification of a polyneuropathy are also data on drug and alcohol consumption. You should answer your doctor’s questions openly and honestly. This is the only way he can find the right cause for the nerve disorders.
Studies and tests
Following the interview, the doctor will examine you physically. During this process, the doctor tests your reflexes (such as the Achilles tendon reflex), for example. It also checks whether your pupils react correctly to incident light. The doctor also pays attention to possible malformations of the skeleton (deformities). For example, claw toes and hollow foot can be an indication that polyneuropathy is hereditary.
Further investigations will follow. Some of these are performed on every patient, others only in certain cases:
In electroneurography (ENG), the nerve conduction velocity is measured. To do this, the doctor sets a small electronic impulse at at least two different points on a nerve. Then it measures the time until the reaction (contraction) of the corresponding muscle. In polyneuropathy, this nerve conduction velocity is usually reduced.
During electromyography (EMG), the electrical muscle activity is tested. In the case of motor disorders such as muscle weakness or muscle paralysis, it is thus possible to find out whether the problem lies with the muscle itself or with the nerves supplying it. If the EMG shows that the nerve function is disturbed, this indicates a polyneuropathy.
In the quantitative sensory examination, the doctor checks how a nerve reacts to certain stimuli such as pressure or temperature. In this way it can be determined whether the sensitivity of the nerve is impaired – as in polyneuropathy. In this way, nerve damage can be easily detected. However, the investigation is very time-consuming. In addition, the patient must be able to concentrate and cooperate well. For this reason, the method is not routinely used to clarify polyneuropathy.
An electrocardiogram (ECG) can provide information about whether the autonomous nerve fibres of the heart are damaged.
By means of ultrasound examination of the bladder, the doctor can determine whether there is any residual urine in the bladder after urination. If so, the bladder emptying is probably impaired. This happens very often in autonomic polyneuropathy.
In a nerve biopsy, a tiny sample of nerve tissue is taken through a small skin incision. The tissue sample is then examined diagnostically under the microscope. However, this investigation is only carried out in very specific cases. It may be necessary, for example, in diabetics in whom only nerves on one side of the body are damaged (asymmetric diabetic polyneuropathy). Even if the doctor suspects leprosy to be the cause of the nerve damage, he can perform a nerve biopsy.
A skin biopsy is also only performed in selected cases. A tiny piece of skin is punched out (for example on the lower leg) and examined in detail.
Blood tests are primarily used to identify common and treatable causes of nerve damage. Less frequent causes can also be detected by means of certain laboratory values. Some examples of laboratory tests for polyneuropathy:
- Increased inflammation values (such as CRP, white blood cells, etc.) can indicate an inflammatory cause of the nerve damage.
- An oral glucose tolerance test (oGTT) indicates how well the body can process sugar. Abnormal test results may indicate that diabetes (or a precursor stage thereof) is still undiscovered. The fasting blood glucose is also very meaningful in this context.
- In the case of known diabetes, the HbA1c value (“long-term blood sugar”) is particularly important: it indicates how well the diabetes has been controlled in recent months.
- The vitamin B12 status is measured to check whether there is a possible deficiency.
- If the liver or kidney values are outside the norm, the polyneuropathy may be caused by liver or kidney disease. Liver damage can also be caused by alcohol abuse.
- If there is a suspicion that a certain infectious disease is causing the polyneuropathy, special blood tests are useful. For example, a suspected Lyme disease can be clarified by searching for antibodies against Borrelia bacteria in the blood of the patient.
A genetic test is indicated when there are several cases of polyneuropathy in a family. Then the suspicion is obvious that it is a hereditary nerve damage.
The same applies if the patient has certain deformities of the foot (claw toes, hollow foot) or other deformities of the skeleton (such as scoliosis). They are typical for hereditary polyneuropathy. The doctor can then have the patient’s genetic material examined for corresponding changes (mutations).
Effective polyneuropathy therapy involves eliminating or treating the cause of the disease, if possible. This is called a causal or causal therapy. For example, alcoholics should go into withdrawal. For diabetic patients, the blood sugar must be tightly adjusted. If a vitamin B12 deficiency has been diagnosed, one should eat a more balanced diet and compensate for the deficiency with a vitamin supplement. If toxins or drugs are the cause of polyneuropathy, they must be avoided if possible.
Many polyneuropathy symptoms can also be treated specifically. This symptomatic therapy can supplement a causal therapy, if such a therapy is possible. The following therapeutic measures are used, for example:
In many polyneuropathy patients, the nerve damage causes burning pain. These can be relieved with pain therapy. The doctor often recommends painkillers such as ASS (acetylsalicylic acid) or paracetamol. He will select an individually suitable dosage for each patient.
For very severe nerve pain he may also prescribe so-called opioids under certain circumstances. These are very powerful painkillers, but they have two disadvantages: On the one hand, their effect may diminish over time. To relieve the pain, higher and higher dosages are then necessary. On the other hand, opioids can cause addiction. Their use must therefore be carefully monitored by a doctor.
In the case of very persistent polyneuropathy pain, it may be advisable for the patient to be treated by a pain therapist. The latter is specialized in the therapy of chronic pain.
For nerve pain, antispasmodic drugs (antiepileptic drugs) such as gabapentin or pregabalin can also help. They ensure that the nerve cells are less excitable. The nerve pain will subside. Therapy with antispasmodics is “crept in”, i.e. one starts with a low dose, which is then slowly increased until the desired effect is achieved. This prevents side effects. In addition, the doctor will regularly examine the patient’s blood during the treatment. Antiepileptic drugs can change certain blood values.
In the context of pain therapy, mood-lightening agents (antidepressants) such as amitriptyline are often used. They inhibit the transmission of pain signals in the spinal cord. Although this does not relieve the patient of pain, it does make it more bearable. As with antispasmodic drugs, a “creeping in” of the therapy is also recommended for antidepressants (low dose at the beginning, then gradual dose increase). This reduces the risk of side effects such as a drop in blood pressure, cardiac arrhythmia or problems with urination.
Some polyneuropathy patients with nerve pain benefit from the so-called TENS (transcutaneous electrical nerve stimulation), also called stimulation current therapy. An electrode is placed on the painful skin region. It is connected to a small portable device. If necessary, the patient can emit gentle electrical impulses via the electrode into the skin area at the push of a button. This can dull the pain.
How this is possible, one does not know exactly. But there are different theories. For example, some experts suspect that the electrical impulses release the body’s own pain-relieving messenger substances (endorphins).
The effectiveness of TENS for nerve pain has not yet been scientifically proven.
Physical therapies can be particularly helpful in cases of sensitive and motor disorders of polyneuropathy. These include, for example, physiotherapy, alternating baths, electrotreatment of paralyzed muscles and hot and cold compresses. Among other things, these procedures can increase blood circulation and strengthen weakened muscles. In addition, physical therapy helps polyneuropathy patients to remain mobile despite pain and other restrictive symptoms.
Further therapeutic measures
Depending on the type and extent of the complaints, further therapeutic measures may be considered. Some examples:
Polyneuropathy patients with frequent calf cramps can try taking magnesium. The active ingredient quinine may also help.
If polyneuropathy patients have great difficulty walking, orthopaedic aids are useful. If, for example, the so-called peroneal nerve in the leg is damaged, affected persons can hardly or no longer lift the foot. Then a special splint or a special shoe/boot will help.
If the polyneuropathy causes a feeling of fullness, nausea and vomiting, patients should change their eating habits: Better than a few large meals are then a few small dishes that are eaten throughout the day. In addition, nausea and vomiting can be relieved with prescription drugs (metoclopramide or domperidone).
Patients suffering from constipation should drink a lot, eat a high-fibre diet and exercise regularly. For acute diarrhoea in polyneuropathy, the doctor may prescribe a drug (such as loperamide).
Autonomic disorders in polyneuropathies include, for example, circulatory problems when getting up from a lying or sitting position (orthostatic hypotension): the affected persons become dizzy or even faint due to a sudden drop in blood pressure. For prevention, patients should always stand up slowly. Support stockings can also help: They prevent the blood from sinking into the legs when you get up and thus cause circulation problems. Regular muscle training is also useful. If necessary, the doctor can also prescribe medication against low blood pressure.
If polyneuropathies cause bladder weakness, patients should go to the toilet regularly (for example, every three hours) – even if there is no urge to urinate. Then not too much residual urine can collect in the bladder. This promotes bladder infection.
Impotence (erectile dysfunction) can be caused both by the polyneuropathy itself and by drugs such as antidepressants. In the second case, patients should discuss with their doctor whether the medications can possibly be discontinued. If this is not possible, or if the impotence persists afterwards, affected men can use a vacuum pump. The doctor may also prescribe a sexual enhancer (Sildenafil etc.).
Polyneuropathy: course and prognosis
The course of polyneuropathy can be positively influenced by removing or treating the trigger (if possible). Various therapies can also be used to relieve the symptoms. Nevertheless, many patients wonder: Is polyneuropathy curable?
In principle, the earlier the nerve damage is detected and treated, the better the prognosis. Unfortunately, polyneuropathy is often asymptomatic for a long time or the first mild symptoms are not taken seriously. At the time of diagnosis, the disease is already well advanced. Often, irreversible nerve damage is already present due to polyneuropathy. Healing is then no longer completely possible. With the right treatment, however, attempts are made to prevent further nerve damage caused by polyneuropathy and to improve existing symptoms.
- How to treat polyneuropathy – holistic and effective: The first lainen comprehensible guide for sufferers (Sigrid Nesterenko, Rainer Bloch, 2017)
- Polyneuropathy: How to overcome excruciating nerve pain (Udo Zifko, 2017, Springer)
- Polyneuropathy and Restless Legs: Living with numb feet, aching and restless legs (Christian Schmincke, 2017, Springer)