Polyneuropathy is a relatively common problem that accompanies many diseases. “Poly-” means “many” and “–neuropathy” means a neural disorder. Therefore, polyneuropathy is a condition related to dysfunction of more nerves. Typically, most visibly affected are the longest nerves in the body, i.e. the nerves of the lower extremities.
There are many peripheral nerves in our body. Some of them bring motoric information out of the central nervous system towards the muscles and other take information about sensitivity, pain, and ambient temperature from the peripheral tissues back into the central nervous system.
For example, when you put your hand into warm water, the information about the high temperature is transferred via the nerve fibers from the skin and deeper tissues into the spinal cord and from there it gets into the brain. The information is evaluated and you feel an uncomfortable pain. The brain urges us to get rid of the pain and pull the hand out. This information is transmitted from the brain to the spinal cord, and to the nerves controlling the muscles of the affected extremity to perform the desired movement.
(Note: If you think about it, the man is with the exception of changing emotions able to respond to any stimulus and only movement. Sometimes it is a whole body movements, sometimes the movement of muscles allowing speech and articulation, eye muscle movements, etc..)
There are numerous possible causes of neuropathy. Chronic alcoholism is probably the most common as regular excessive alcohol intake damages the nerve fibers and nerve cells. Another common cause is the lack of vitamins of B-complex (eg. vitamin B1 or vitamin B5). Disruption of the nerves also accompanies chronic cases of diabetes and the polyneuropathy may occur in patients with malignant diseases and patients receiving chemotherapy.
There are also less common causes of polyneuropathy such as certain immune inflammations of blood vessels (vasculitides), other autoimmune processes and a particular neurological disease known as Guillain-Barré syndrome.
The symptoms are related to impaired ability of neural transmission of neuroelectric signals. They include numbness, decreased sensitivity and tingling sensations of the extremities. The decreased sensitivity in the affected body parts may be dangerous as it may lead to more frequent unnoticed and underestimated injuries due to the decreased or missing sense of pain. Polyneuropathy is an important element in the development of diabetic foot in patients with diabetes.
The polyneuropathy may less commonly affect the motoric nerves resulting in muscle weakness, muscle atrophy or even in muscle paralysis. This occurs especially in the disease known as the Guillain-Barré syndrome. This disease has quite dramatic symptoms including muscle paralysis of the lower extremities, which moves gradually upwards until it affects nerves coming out of thoracic or even cervical spine. The most serious complication is paralysis of breathing muscles, which threatens the patient with suffocation. When the patient survives, the disease tends to slowly disappear.
A case of suspected polyneuropathy should be examined by a neurologist. The patient undergoes physical examination and electromyography (EMG). The electromyography serves to evaluate the conduction of neuroelectric signals by the nerves and muscles and to determine the diagnosis and severity of the neuropathy. In addition, when the neuropathy is confirmed, it is necessary to find its cause, especially rule out chronic alcoholism or diabetes. A search for any present autoimmune disease is much more challenging and many causes of polyneuropathy stay undiagnosed.
The treatment is difficult. In the majority of cases, the doctors prescribe vitamins of the B complex, but the outcome is rather controversial. If possible, the underlying cause should be identified and treated (alcoholism, diabetes, etc). Proper care of the lower extremities is essential in patients with diabetes and polyneuropathy to prevent the development of diabetic foot syndrome. Quite special approach is necessary in patients with Guillain-Barré syndrome (see related article).