Polyneuropathy is a disease of the peripheral nervous system of various causes, associated with muscle weakness and sensory disturbances. The human nervous system, with the brain as its highest authority, serves to control and regulate all bodily and organ functions. Polyneuropathy can therefore have serious consequences. You can learn interesting facts about the causes, symptoms, diagnosis and treatment of polyneuropathy here.
The peripheral nervous system
Basically, a distinction is made between the central nervous system and the peripheral nervous system. Here, the central nervous system (CNS) includes all nerve structures above the level of the spinal cord, including the brain, and the peripheral nervous system (PNS) includes all peripheral nerve fibers, i.e., all nerves outside the brain and spinal cord. Like fine branches of a tree, the nerve fibers of the peripheral nervous system arise from the spinal cord and make contact with the “executive organs” such as muscles, skin or internal organs. The exchange of information takes place through control impulses directed away from the brain as well as information directed to the brain, for example from the sensory organs or the skin. The seemingly passive act of standing upright alone requires an enormous amount of coordination from the brain in order to coordinate incoming information from sensory organs such as the vestibular system, eyes or touch sensors in the skin with the control of important muscle groups, especially the legs. These processes, which take place predominantly in the subconscious, are of course much more complicated in the case of complex movement sequences. The ability to feel, which is present in healthy humans, presupposes the existence of numerous, differently specialized sensors in the skin for the sense of touch, the sense of warmth and cold, or the sense of pain, and the transmission of the corresponding information via the nervous system. The sensory qualities just described are conducted in the nerve just as impulses from the brain to the muscles are conducted by specific fibers.
What is polyneuropathy?
A neuropathy is the collective term for a wide variety of diseases of the peripheral nervous system, which can lead to various symptoms, such as impaired perception or painlessness. If a large number of nerves are affected, it is called a polyneuropathy.
Causes of polyneuropathy
Polyneuropathy can have a wide variety of causes and therefore also occurs in a wide variety of forms. The following diseases or factors can be considered as triggers of polyneuropathy:
- Diabetes mellitus
- Diseases of the immune system
- Poisonings
- Alcoholism
- Vascular diseases
- Rheumatic diseases
- Tumors
- Kidney diseases
The polyneuropathies are thus often an expression or reaction of the peripheral nervous system to a disease or damage that affects the organism as a whole. We present the different forms of polyneuropathy here.
Symptoms of polyneuropathy
On the basis of the predominantly affected nerve quality, the pattern of affection as well as the course, quite different manifestations of polyneuropathy are distinguished. Depending on which functions of the nerves are particularly affected, one speaks of sensory, motor, or autonomic polyneuropathies:
- Sensitive nerves, for example, are responsible for the sensation of touch, vibration, or temperature. Sensitive polyneuropathies are therefore associated with sensory disturbances or skin insensations, for example, numbness, stinging, itching, tingling, disturbed temperature sensation, or lack of pain sensation in burns or injuries of the skin. In diabetics, this often affects the feet and legs.
- Motor nerves are responsible for carrying commands from the brain to skeletal muscles so that, for example, a muscle contracts. Motor polyneuropathies can therefore result in muscle paralysis, muscle wasting and muscle spasms.
- Autonomic nerves (also vegetative nerves) affect the function of internal organs, for example, heart, stomach, intestines or lungs. Thus, they do not control conscious processes, but those that occur unconsciously. An autonomic polyneuropathy can therefore lead to very different symptoms, from incontinence or diarrhea, to erectile dysfunction or reduced sweat production, to life-threatening symptoms such as respiratory arrest or cardiac arrhythmias.
In addition, there are also mixed forms of polyneuropathy (for example, sensorimotor polyneuropathy), in which a combination of different signs may occur.
Diagnosis of polyneuropathy
The diagnosis of polyneuropathy results from:
- The patient’s symptoms
- The neurological examination findings
- Blood tests
- Special examination procedures of the musculature and peripheral nerves, which allow differentiation of the individual forms of polyneuropathy.
An important distinguishing criterion, which also allows a better causal clarification of the disease, is whether the nerve damage predominantly affects the inner conducting cord of the nerve or rather the outer sheath, also called myelin sheath. The latter acts as “electrical insulation” and is of considerable importance for the conduction velocity of the nerve. By testing electrical muscle activity (electromyography, EMG) and determining nerve conduction velocities (electroneurography, ENG), damage to the “nerve insulation” can be distinguished from damage to the nerve fibers themselves, which can be important for both diagnosis and treatment. In addition, other investigative procedures, such as ultrasonography (for example, of the urinary bladder), ECG (to check heart function), or biopsy of the skin or nerves, may be used.
Treatment of polyneuropathy
Treatment options for each form of polyneuropathy depend on the underlying cause. For immune-related polyneuropathies such as Guillain-Barré syndrome, panarteritis nodosa, or rheumatoid arthritis, immune-suppressive therapies are the primary treatment options. Specifically, cortisone, azathioprine or other substances are used. Other alternative methods for Guillain-Barré syndrome include the administration of so-called immunoglobulins or plasmapheresis, in which harmful immune factors are washed out of the body. For the therapy of diabetic polyneuropathy, effective control of the diabetic metabolic state through weight reduction, medication or insulin is crucial. The sensory disturbances, pain and muscle cramps in the legs also respond in individual cases to preparations such as carbamazepine or thioctazide. In cases of poisoning, spontaneous or medicinal removal of the respective toxic substance from the body is the first priority. In alcoholism, strict abstinence from alcohol and administration of vitamin B1 preparations are required.
Other forms of therapy
Polyneuropathies that occur in the context of other underlying diseases, such as kidney damage or tumors, are treated along with the therapy of the underlying disease. Sometimes pain therapy with analgesics, antispasmodics, antidepressants, or so-called transcutaneous electrical nerve stimulation (TENS), better known as stimulation current therapy, is also used to treat a polyneuropathy. Forms of physical therapy, for example physiotherapy or alternating baths, can also help to relieve symptoms and treat the causes.
Is polyneuropathy curable?
In most cases, the earlier polyneuropathy is diagnosed, the better the prognosis, as symptoms usually worsen over time without appropriate treatment. Early therapy can usually have a positive effect on the course of the disease, especially if the causes can be eliminated. However, if the disease remains unnoticed for a long time, severe, irreversible nerve damage can occur. Therefore, a cure is not always possible.
Polyneuropathy: prevention
Possibilities for prevention of polyneuropathy exist in cases of poisoning and, in some cases, diabetes (through optimal blood glucose control), but not in immune-related polyneuropathies. Nevertheless, rapid recognition of such a nerve disease or underlying primary diseases is also crucial in order to prevent severe damage by early treatment.
