Neuropathy (neuralgia): what it is, symptoms and causes

Numbness in the feet, tingling in the fingers, burning pain — this is often how neuropathy begins. Behind these sensations lies damage to the peripheral nerves, the "wiring" that connects the brain to the skin, muscles and internal organs. Let us explain the mechanism, symptoms and causes.

What neuropathy is and what it is called

Neuropathy is a general term for damage to peripheral nerves: one or more nerves are damaged and stop transmitting signals correctly. In reference books such conditions appear under the designation of peripheral nerve disorders, and "neuritis" and "peripheral neuritis" are listed among the names of the same disorders; the doctor clarifies the difference in terminology. In the UK, peripheral neuropathy affects almost one in ten people over the age of 55, and more than a hundred types of such disorders have been described.

Peripheral neuropathy: how nerves are affected

The peripheral nervous system is a network of fibers outside the brain and spinal cord. Sensory fibers carry signals of pain and touch to the brain, motor fibers control muscles, and autonomic fibers regulate blood pressure and the function of internal organs. A damaged fiber distorts the message or loses it altogether.

The most common form is polyneuropathy: a symmetrical process that begins with the longest fibers. That is why the first sensations arise in the feet, then rise higher and later reach the hands. By the rate of development, acute forms (up to 4 weeks), subacute (4–8 weeks) and chronic (longer than 8 weeks) are distinguished; the acute autoimmune variant — Guillain–Barré syndrome — was described by the French neurologists Guillain and Barré in 1916.

Symptoms and signs of neuropathy

The main signs: numbness and tingling in the feet or hands, burning, stabbing or shooting pain, loss of balance and coordination, muscle weakness, especially in the feet. The sensations may be constant, but can also come in waves.

• sensory fibers — tingling, numbness, pain in the hands and feet, inability to feel heat, cold or pain;
• motor — weakness and aching muscles, impaired gait and balance, cramps, twitching, loss of muscle bulk;
• autonomic — pulse that is too fast or too slow, difficulty swallowing, excessive or insufficient sweating, vomiting, diarrhea or constipation, urinary problems.

Severity ranges from mild to significant, developing over days or months; such disorders are generally not life-threatening. A separate risk area is the foot: with reduced sensation, a cut or ulcer goes unnoticed, becomes infected, and in severe cases gangrene is possible.

Causes: diabetes, toxins, medications and others

The most common culprit is diabetes mellitus of both types: persistently high glucose levels damage nerves, and this condition is called diabetic polyneuropathy. The list is broad thereafter: injuries and nerve compression, viral infections such as shingles, HIV and Lyme disease, alcohol abuse, smoking, vitamin B12 deficiency, kidney and liver disease, autoimmune diseases, hereditary forms such as Charcot–Marie–Tooth disease, contact with lead and mercury. Sometimes the cause cannot be found.

Neuropathy after chemotherapy

Antitumor treatment is a known cause: both chemotherapy and radiation therapy can damage peripheral nerves. Cisplatin, paclitaxel and vincristine are listed among toxic polyneuropathies. Symptoms depend on which nerves are affected. If the cause can be eliminated, the nerves may recover over time, but in some people the damage remains permanent or gradually worsens.

How it is diagnosed and when to see a neurologist

A reason for a visit is pain, tingling or loss of sensation in the feet, impaired balance, weakness, a non-healing cut on the foot. People with diabetes need regular check-ups with testing of nerve function. The doctor will ask about your medical history and family history, examine you and order tests: blood tests, genetic tests, studies of the electrical activity of nerves and muscles, testing of autonomic nerve function, nerve or skin biopsy, CT or MRI. If necessary, you will be referred to a neurologist. The earlier the diagnosis is made, the higher the chance of limiting the damage.

Neuropathy by itself is not a reason to call an ambulance; 103 or 112 — for sudden breathing or swallowing problems.

This text is for reference and does not replace a doctor's consultation: with unclear sensations, it is wiser to discuss them with a neurologist.

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