Polyneuropathy: what it is, symptoms and causes

Numbness begins in the toes: in the evening socks seem stretched over someone else's skin, and the soles stop distinguishing the coolness of the floor. Then tingling, burning or a shooting pain is added. Polyneuropathy is a multiple lesion of peripheral nerves, and it is easier to understand it by knowing which fibers are affected.

Polyneuropathy: what it is

Peripheral nerves are a network running from the brain and spinal cord to all parts of the body. Some fibers transmit commands to muscles, others carry sensations of pain, heat and cold to the brain, and still others control blood pressure, breathing and digestion. Polyneuropathy is a multiple lesion of such nerves, usually symmetrical and beginning in the most distal parts of the limbs.

It is estimated that in the UK peripheral neuropathy affects almost every tenth person over 55 years of age.

By course, acute forms (up to four weeks), subacute (up to eight) and chronic (longer than eight weeks) are distinguished.

Symptoms of polyneuropathy

The picture depends on which fibers are affected.

• Motor nerves: weakness and aching in the muscles, problems with balance and walking, cramps, twitching, reduction in muscle volume.
• Sensory nerves: tingling, numbness or pain in the hands and feet, inability to feel heat, cold or pain, pain from light touch.
• Autonomic nerves: too fast or too slow pulse, difficulty swallowing, excessive or scanty sweating, nausea, diarrhea or constipation, urinary disorders.

Sensations range from barely noticeable to very severe. They usually persist constantly, but may appear in waves.

Causes of polyneuropathy

The most common cause is diabetes mellitus of both types: against the background of long-term elevated glucose levels, nerves are damaged, and this condition is called diabetic polyneuropathy. The list of other causes is broad — nerve injury or compression, viral infections such as shingles, side effects of certain medications, alcohol abuse. HIV and Lyme disease, autoimmune diseases, kidney and liver diseases, contact with lead and mercury, smoking, vitamin B12 deficiency and hereditary gene changes are also mentioned. Sometimes the cause cannot be found.

Types of polyneuropathy

By extent, mononeuropathy is distinguished — damage to one nerve, multiple mononeuropathy — to several, and polyneuropathy, when nerves throughout the body are affected. Polyneuropathy is the most common and begins with the longest fibers, so the first symptoms appear in the feet; over time the process seems to rise higher and reaches the hands. By origin, forms are divided into acquired — infectious-inflammatory, vascular, toxic, metabolic, paraneoplastic — and hereditary.

How polyneuropathy is diagnosed

The doctor asks about complaints, past illnesses and family history, and performs a physical examination. Then examinations are prescribed to find the cause: blood tests, genetic tests, electroneuromyography — measurement of the electrical activity of nerves and muscles, assessment of autonomic fiber function, nerve or skin biopsy, and if necessary tomography to see what is compressing the nerve. The earlier the diagnosis is made, the higher the chance of limiting damage and preventing complications.

Possible complications and when to see a neurologist

The prognosis depends on the cause and on which nerves are affected. Sometimes the condition improves after the underlying disease is eliminated, sometimes the damage remains persistent or slowly progresses. Among serious complications is a foot ulcer: due to loss of sensation it is easy to miss, and without treatment it suppurates, leads to gangrene and in severe cases to amputation. When nerves controlling the heart and blood vessels are affected, blood pressure support or, rarely, a pacemaker may sometimes be required.

Pain, tingling or loss of sensation in the feet, impaired balance, weakness, a non-healing wound on the foot — these are reasons to see a doctor, who will refer to a neurologist if necessary. People with diabetes and other high risks need regular examinations even without complaints.

Polyneuropathy itself is not a reason to call an ambulance; 103/112 — for signs that threaten life, for example if a stroke or heart attack is suspected, and in other cases a doctor's consultation is needed.

The text is for reference: it explains what happens to the nerves, but does not replace consultation with a doctor who sees your particular case.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer