Polyneuropathy: Symptoms, Causes & Treatment

What Is Polyneuropathy?

Polyneuropathy is a condition in which multiple peripheral nerves throughout the body become damaged or diseased, causing symptoms like numbness, tingling, burning pain, and muscle weakness. The condition typically affects the longest nerves first, which is why symptoms usually begin in the feet and gradually spread upward over time.

The body's nervous system consists of the brain, spinal cord, and a vast network of peripheral nerves that extend throughout the body. These peripheral nerves carry signals between the brain and spinal cord (the central nervous system) and the rest of the body, controlling sensation, movement, and automatic functions like heart rate and digestion. When multiple peripheral nerves are damaged simultaneously, the condition is called polyneuropathy.

The term "polyneuropathy" comes from Greek roots: "poly" meaning many, "neuro" meaning nerve, and "pathy" meaning disease. Unlike conditions that affect a single nerve (mononeuropathy), polyneuropathy involves widespread nerve damage that typically follows a symmetrical pattern, affecting both sides of the body equally.

The peripheral nervous system can be divided into different types based on their function. The somatic nervous system controls voluntary movements and carries sensory information about touch, temperature, and pain. The autonomic nervous system controls involuntary functions like heart rate, blood pressure, sweating, and digestion. Polyneuropathy can affect any or all of these nerve types, leading to a wide variety of possible symptoms.

How Nerve Damage Progresses

In polyneuropathy, nerve damage typically begins at the farthest ends of the longest nerve fibers and gradually works its way toward the spine. This is why symptoms almost always start in the toes and feet before eventually affecting the lower legs. In more advanced cases, the hands and forearms may also become involved, creating what doctors call a "stocking-glove" distribution of symptoms.

The nerves can be damaged in several ways. The myelin sheath, a protective coating that surrounds nerve fibers and helps electrical signals travel quickly, may break down (demyelination). Alternatively, the nerve fibers themselves (axons) may degenerate. Some types of polyneuropathy involve both processes. The type and pattern of damage often provides clues about the underlying cause.

Types of Polyneuropathy

Polyneuropathy can be classified in several ways. Based on the time course, it may be acute (developing over days to weeks), subacute (weeks to months), or chronic (developing slowly over months to years). Most cases of polyneuropathy are chronic. Based on the predominant type of nerve fiber affected, polyneuropathy may be primarily sensory (affecting sensation), motor (affecting muscle control), autonomic (affecting involuntary functions), or mixed.

What Are the Symptoms of Polyneuropathy?

The most common early symptoms of polyneuropathy are numbness and tingling ("pins and needles") that start in both feet and gradually spread upward. Other symptoms include burning pain, a sensation of walking on cushions, extreme sensitivity to touch, dry skin on the feet, and problems with balance. As the condition progresses, muscle weakness may develop.

The symptoms of polyneuropathy develop because damaged nerves cannot properly transmit signals between the brain and the rest of the body. The specific symptoms depend on which types of nerve fibers are affected—sensory, motor, or autonomic. Most people with polyneuropathy experience a combination of sensory symptoms, with motor and autonomic symptoms potentially developing as the condition progresses.

Symptoms typically begin gradually and worsen slowly over months to years. Many people first notice symptoms only occasionally, perhaps describing their feet as "falling asleep" more easily or feeling unusually cold. Over time, symptoms become more persistent and pronounced. The slow progression can make it difficult to pinpoint exactly when the condition began.

Sensory Symptoms

Sensory symptoms are usually the first and most prominent feature of polyneuropathy. The most common early complaint is numbness or reduced sensation in the feet, often described as feeling like wearing thick socks or walking on cotton wool or cushions. This numbness makes it difficult to feel the floor properly when walking and can affect balance.

Many people also experience positive sensory symptoms—abnormal sensations that occur without any external stimulus. Tingling or "pins and needles" (paresthesia) is very common. Some people describe crawling sensations, electric shock feelings, or a sense that their feet are wrapped tightly. These sensations may come and go at first but often become constant as the condition progresses.

Pain is another significant symptom for many people with polyneuropathy. This neuropathic pain often has distinct characteristics that differentiate it from other types of pain. Common descriptions include burning, stabbing, shooting, or electric shock-like sensations. The pain may worsen at night, disturbing sleep. Some people develop allodynia, where normally painless stimuli (like light touch or bedsheets against the skin) cause pain.

Temperature perception is frequently affected. People may have difficulty distinguishing hot from cold, which can lead to accidental burns or frostbite injuries. The skin on the feet often becomes very dry because the nerves that control sweating are damaged.

Motor Symptoms

As polyneuropathy progresses, motor nerves may become involved, leading to muscle weakness. This typically starts in the small muscles of the feet, causing difficulty lifting the front of the foot (foot drop) and toes. People may notice they trip more frequently or have difficulty walking on uneven surfaces.

Muscle weakness tends to progress gradually. Walking becomes more difficult, and people may have trouble climbing stairs, getting up from chairs, or rising from a seated position. The muscles may visibly shrink (atrophy) due to reduced nerve stimulation. In severe cases, the hands and forearms may also become weak, making it difficult to grip objects, button shirts, or perform fine motor tasks.

The combination of sensory loss and muscle weakness significantly increases fall risk. Many people with polyneuropathy experience repeated falls, which can lead to serious injuries, particularly in older adults.

Autonomic Symptoms

The autonomic nervous system controls functions that happen automatically without conscious thought. When these nerves are damaged, various body systems may malfunction. Cardiovascular autonomic neuropathy can cause blood pressure to drop suddenly when standing up (orthostatic hypotension), leading to dizziness or fainting.

Gastrointestinal symptoms may include constipation, diarrhea, or alternating between the two. Some people develop gastroparesis, where the stomach empties too slowly, causing nausea, bloating, and feeling full quickly after eating small amounts. Bladder function may be affected, leading to difficulty emptying the bladder completely or incontinence.

Sweating patterns may change—some people sweat excessively in certain areas while being unable to sweat in others. Men may experience erectile dysfunction. These autonomic symptoms can significantly impact quality of life and may require specific treatment approaches.

When Should You See a Doctor for Numbness or Tingling?

You should consult a healthcare provider if you experience persistent numbness, tingling, or unusual sensations in your feet that don't go away, especially if symptoms are gradually spreading or if you also notice muscle weakness. Seek immediate medical attention if numbness develops suddenly, particularly if accompanied by weakness in the legs or arms.

Many people initially dismiss early symptoms of polyneuropathy, attributing them to "sleeping wrong" or normal aging. However, early diagnosis is important because identifying and treating the underlying cause can sometimes slow or halt nerve damage progression. The sooner treatment begins, the better the potential outcome.

Schedule an appointment with your doctor if you notice any of the following symptoms that persist for more than a few days:

• Numbness or reduced sensation in your feet or hands
• Tingling or "pins and needles" sensations that don't go away
• Burning pain in your feet, especially at night
• A feeling like you're wearing socks when you're not
• Difficulty feeling the floor when walking
• Increased clumsiness or difficulty with balance
• Muscle weakness in your legs or feet

What Causes Polyneuropathy?

Polyneuropathy has many potential causes. Diabetes is the most common, responsible for about one-third of cases. Other causes include chronic alcohol use, vitamin B12 deficiency, kidney disease, certain medications, infections, autoimmune conditions, and hereditary disorders. In up to 30% of cases, no specific cause can be identified (idiopathic polyneuropathy).

Understanding the underlying cause of polyneuropathy is crucial because treatment depends largely on addressing that cause. The extensive list of potential causes reflects how many different factors can damage peripheral nerves. A thorough medical evaluation is needed to identify the specific cause in each individual case.

Diabetes (Diabetic Neuropathy)

Diabetes mellitus is by far the most common cause of polyneuropathy in developed countries. Up to 50% of people with diabetes develop some form of neuropathy during their lifetime. The risk increases with longer duration of diabetes and poor blood sugar control. Diabetic neuropathy can occur in both type 1 and type 2 diabetes.

High blood sugar levels damage nerves through several mechanisms. Elevated glucose can lead to the formation of harmful substances that accumulate around nerves. Additionally, diabetes often damages small blood vessels that supply nerves with oxygen and nutrients. Poor blood circulation further contributes to nerve damage. These combined effects explain why good blood sugar control is essential for preventing and managing diabetic neuropathy.

Alcohol

Chronic heavy alcohol consumption is a significant cause of polyneuropathy. Alcohol can damage nerves both directly (through toxic effects of alcohol and its breakdown products) and indirectly (by causing nutritional deficiencies, particularly of B vitamins). Alcoholic neuropathy often develops gradually in people with years of heavy drinking.

The combination of direct nerve toxicity and nutritional deficiency makes alcoholic neuropathy particularly challenging. Even if someone stops drinking, nerve damage may not fully reverse if it has been severe or prolonged. However, stopping alcohol and correcting nutritional deficiencies can prevent further damage and sometimes allow partial recovery.

Vitamin Deficiencies

Several vitamins are essential for nerve health, with vitamin B12 being particularly important. B12 deficiency can occur due to inadequate dietary intake (especially in strict vegans), inability to absorb the vitamin (due to stomach surgery, certain medications, or conditions affecting the stomach lining), or increased requirements.

Other B vitamins, including B1 (thiamine), B6 (pyridoxine), and folate, also play roles in nerve function. Interestingly, excessive B6 intake (usually from supplements) can paradoxically cause neuropathy. Vitamin E deficiency, though rare, can also cause nerve damage. Nutritional deficiencies are often treatable if identified early.

Kidney Disease

Chronic kidney disease can lead to polyneuropathy through a condition called uremic neuropathy. When the kidneys cannot adequately filter waste products from the blood, toxic substances accumulate that can damage nerves. Uremic neuropathy typically develops in advanced kidney disease but may improve with dialysis or kidney transplantation.

Medications and Toxins

Many medications can cause polyneuropathy as a side effect. Chemotherapy drugs are well-known culprits, with certain agents (like vincristine, cisplatin, and taxanes) carrying particularly high risks. Other medications associated with neuropathy include certain antibiotics, heart medications, and drugs used to treat HIV.

Recreational drug abuse can also cause nerve damage. Nitrous oxide (laughing gas) abuse has emerged as a significant cause of polyneuropathy, particularly among young people. The gas inactivates vitamin B12, leading to severe nerve and spinal cord damage even with relatively brief exposure.

Infections and Immune Conditions

Various infections can trigger polyneuropathy. Lyme disease, HIV, hepatitis C, and leprosy are among the infectious causes. Some infections damage nerves directly, while others trigger immune responses that attack nerve tissue. Autoimmune conditions like rheumatoid arthritis, lupus, and Sjögren's syndrome can also cause neuropathy.

Hereditary Causes

Some forms of polyneuropathy are inherited. Charcot-Marie-Tooth disease is the most common hereditary neuropathy, existing in many genetic forms. These conditions typically begin in childhood or early adulthood and progress slowly. Family history of neuropathy or related symptoms may provide important diagnostic clues.

Idiopathic Polyneuropathy

Despite thorough investigation, no specific cause can be identified in up to 30% of polyneuropathy cases. This "idiopathic" polyneuropathy is more common in older adults and may represent age-related nerve degeneration. While frustrating for patients and doctors alike, the lack of an identifiable cause doesn't prevent symptom management.

How Is Polyneuropathy Diagnosed?

Polyneuropathy is diagnosed through a combination of medical history, neurological examination, and specialized tests. Doctors assess sensation, reflexes, and muscle strength. Key diagnostic tests include nerve conduction studies (electroneurography) to measure how well electrical signals travel through nerves, electromyography (EMG) to evaluate muscle function, and blood tests to identify underlying causes.

Diagnosing polyneuropathy involves two main goals: confirming that neuropathy is present and identifying its underlying cause. The diagnostic process typically begins with a detailed medical history and physical examination, followed by various laboratory and electrodiagnostic tests as needed.

Medical History and Physical Examination

Your doctor will ask detailed questions about your symptoms, including when they started, how they've progressed, and what makes them better or worse. Information about your medical history, medications, alcohol use, diet, family history, and occupational exposures helps narrow down potential causes.

The neurological examination assesses various aspects of nerve function. Sensory testing evaluates your ability to perceive light touch, pinprick, temperature, and vibration. Reduced vibration sense in the feet, tested using a tuning fork, is often an early finding in polyneuropathy. The doctor will also check your reflexes at the ankles and knees—diminished or absent reflexes are common in polyneuropathy.

Muscle strength testing helps identify motor nerve involvement. The doctor may examine your skin for dryness, color changes, or ulcers that could indicate nerve damage. Your gait and balance will likely be assessed, as neuropathy often affects walking patterns.

Blood Tests

Blood tests help identify many potential causes of polyneuropathy. Common tests include:

• Blood glucose and HbA1c: To check for diabetes
• Vitamin B12 and folate levels: To identify deficiencies
• Kidney function tests: To assess for uremic neuropathy
• Thyroid function: Thyroid disorders can affect nerves
• Liver function tests: Liver disease can cause neuropathy
• Complete blood count: To check for anemia and other abnormalities
• Inflammatory markers: Elevated levels may suggest autoimmune causes

Additional specialized tests may be ordered based on clinical suspicion, including tests for specific infections, autoimmune antibodies, or genetic markers.

Nerve Conduction Studies (Electroneurography/ENeG)

Nerve conduction studies are the gold standard for confirming polyneuropathy and characterizing its type. During this test, small electrodes are placed on the skin over specific nerves. A mild electrical stimulus is applied, and the speed and strength of the nerve signal are measured. This helps determine whether the nerve's outer coating (myelin) or the nerve fiber itself (axon) is primarily affected.

The test may feel slightly uncomfortable due to the electrical stimulation, but it's generally well-tolerated and causes no lasting effects. The procedure typically takes 30 minutes to an hour, depending on how many nerves are tested.

Electromyography (EMG)

EMG evaluates muscle electrical activity and can provide additional information about nerve damage. A thin needle electrode is inserted into muscles to record electrical signals. This helps distinguish between nerve problems and primary muscle diseases, and can show how long nerve damage has been present.

Lumbar Puncture

A lumbar puncture (spinal tap) may be needed if your symptoms developed rapidly or if Guillain-Barré syndrome or other inflammatory conditions are suspected. The test involves removing a small sample of cerebrospinal fluid to analyze for abnormal protein levels or signs of infection.

Other Tests

Quantitative sensory testing uses specialized equipment to precisely measure sensation thresholds for temperature, vibration, and other stimuli. Skin biopsy can assess small nerve fiber density in cases where standard nerve conduction studies are normal but small fiber neuropathy is suspected. Nerve biopsy is rarely needed but may be performed in unclear cases.

How Is Polyneuropathy Treated?

Polyneuropathy treatment focuses on three main areas: treating the underlying cause, managing symptoms (especially pain), and preventing complications. Treatment varies depending on the specific cause—for example, controlling blood sugar in diabetic neuropathy or stopping alcohol in alcoholic neuropathy. Pain medications, physical therapy, and proper foot care are important components of management.

There is no single cure for polyneuropathy, but effective treatment strategies can address underlying causes, relieve symptoms, and help maintain function. The treatment approach must be individualized based on the type of neuropathy, its cause, and the specific symptoms each person experiences.

Treating Underlying Causes

When a specific cause can be identified, treating it is the first priority. For diabetic neuropathy, achieving and maintaining good blood sugar control is essential. While this cannot reverse existing nerve damage, it can prevent further progression and may reduce symptoms. People with diabetes should work closely with their healthcare team to optimize glucose management.

For alcohol-related neuropathy, stopping alcohol consumption is crucial. This may require support from addiction specialists, support groups, or rehabilitation programs. Nutritional supplementation, particularly B vitamins, is typically provided. With abstinence and proper nutrition, some nerve function may recover over time.

Vitamin deficiencies are treated with supplementation. B12 deficiency may require injections rather than oral supplements if absorption is impaired. Identifying and addressing the cause of the deficiency prevents recurrence. For medication-induced neuropathy, the offending drug is stopped or changed if possible, though this must be balanced against the need for the medication.

Pain Management

Neuropathic pain can be challenging to treat because it doesn't respond well to typical pain relievers like ibuprofen or acetaminophen. Several classes of medications have proven effective for neuropathic pain:

Antidepressants: Certain antidepressants, particularly tricyclic antidepressants (like amitriptyline) and serotonin-norepinephrine reuptake inhibitors (like duloxetine), are often first-line treatments for neuropathic pain. These work by affecting pain signaling pathways in the nervous system, independent of their effects on mood.

Anticonvulsants: Medications originally developed for epilepsy, such as gabapentin and pregabalin, are frequently used for neuropathic pain. They work by calming overactive nerve signals. These medications are typically started at low doses and gradually increased.

Topical treatments: Lidocaine patches and capsaicin cream can provide localized relief. These are particularly useful when pain is limited to specific areas and can reduce the need for systemic medications.

It's important to have realistic expectations about pain treatment. Medications typically reduce pain intensity by 30-50% rather than eliminating it completely. Finding the right medication or combination often requires patience and may involve trying several options.

Physical Therapy and Rehabilitation

Physical therapy plays an important role in managing polyneuropathy. A physical therapist can design an exercise program to maintain muscle strength, improve balance, and enhance overall fitness. Regular exercise also helps manage conditions like diabetes that may underlie the neuropathy.

Balance training is particularly important given the increased fall risk. Specific exercises can improve proprioception (the sense of body position) and help compensate for sensory loss. Occupational therapy may help with adaptations for daily activities affected by hand weakness or numbness.

Foot Care

Proper foot care is essential for everyone with polyneuropathy, but especially for those with diabetes. Reduced sensation means you may not feel injuries, blisters, or infections developing. These can progress to serious wounds or ulcers if not caught early.

Regular podiatry appointments can help catch problems early. Custom orthotic insoles may improve comfort and distribute pressure more evenly. In some cases, special protective footwear or braces may be recommended.

Assistive Devices

Various assistive devices can help maintain independence and safety. Ankle-foot orthoses (AFOs) can help with foot drop, making walking safer and easier. Canes or walkers may be appropriate for those with significant balance problems. Handrails and grab bars at home reduce fall risk.

What Can You Do to Manage Polyneuropathy at Home?

Self-management of polyneuropathy includes daily foot inspection and care, regular gentle exercise, avoiding alcohol and tobacco, maintaining a healthy weight, controlling blood sugar if diabetic, and taking prescribed medications as directed. Lifestyle modifications can significantly impact symptom management and disease progression.

While medical treatment is important, much of polyneuropathy management happens at home through daily self-care practices. Taking an active role in your care can help slow progression, reduce symptoms, and maintain quality of life.

Physical Activity

Regular physical activity offers multiple benefits for people with polyneuropathy. Exercise helps control blood sugar (important for diabetic neuropathy), maintains muscle strength, improves circulation, and can reduce pain. Even modest activity is beneficial—the goal is to move regularly rather than to achieve high-intensity workouts.

Choose activities you enjoy and can do safely. Walking, swimming, and cycling are often good options. Water exercises are particularly helpful as the water provides support while allowing movement. Start slowly and gradually increase duration and intensity. If balance is a concern, consider exercises that can be done while seated or holding onto a stable surface.

Lifestyle Modifications

If you smoke or use tobacco products, quitting is one of the most important things you can do. Smoking damages blood vessels and worsens circulation to nerves that are already compromised. Nicotine also has direct toxic effects on nerves. Various resources are available to help quit smoking, including medications, counseling, and support programs.

Alcohol should be avoided or strictly limited. Even moderate alcohol consumption can worsen neuropathy symptoms and interfere with medications. For those with alcohol-related neuropathy, complete abstinence is necessary to prevent further nerve damage and allow maximum recovery.

Maintaining a healthy weight reduces stress on weakened muscles and joints and helps control diabetes. A balanced diet rich in fruits, vegetables, whole grains, and lean proteins provides the nutrients nerves need to function optimally.

Managing Daily Life

Protect your feet and hands from temperature extremes. Test bath water with your elbow (where sensation is usually intact) before stepping in. Use oven mitts and be careful around hot surfaces. In cold weather, wear warm socks and gloves to prevent frostbite, which you might not feel.

Make your home safer to prevent falls. Remove throw rugs, ensure adequate lighting, install handrails, and keep frequently used items within easy reach. Non-slip mats in bathrooms and sturdy grab bars can prevent serious injuries.

What Is Guillain-Barré Syndrome?

Guillain-Barré syndrome (GBS) is a rare but serious form of polyneuropathy where the immune system attacks the nerves, usually triggered by an infection. Unlike typical polyneuropathy, GBS develops rapidly over days to weeks and can cause severe weakness and even paralysis. Most people recover with treatment, but some may have lasting effects.

Guillain-Barré syndrome represents a distinct and more urgent form of polyneuropathy. While typical polyneuropathy develops slowly over months to years, GBS progresses much faster—symptoms often peak within two to four weeks. This rapid progression and potential severity make GBS a medical emergency requiring hospital care.

GBS occurs when the body's immune system mistakenly attacks peripheral nerves. This autoimmune response is usually triggered by a preceding infection, commonly affecting the respiratory tract or gastrointestinal system. Infections with bacteria like Campylobacter jejuni (from undercooked poultry) or viruses including influenza are recognized triggers.

Symptoms Progress Rapidly

GBS typically begins with weakness and tingling in the legs that ascends over hours to days. The weakness can progress to the arms, face, and breathing muscles. Unlike typical polyneuropathy, weakness is often more prominent than sensory symptoms. Some people develop facial weakness or difficulty swallowing.

In severe cases, weakness may progress to paralysis affecting the muscles needed for breathing. This is why people with suspected GBS require hospitalization for monitoring and potentially intensive care support.

Treatment and Recovery

GBS is treated with therapies that modulate the immune system. Intravenous immunoglobulin (IVIG) provides antibodies that help reduce the immune attack on nerves. Plasma exchange (plasmapheresis), which removes harmful antibodies from the blood, is an alternative treatment. Both can shorten recovery time and reduce severity.

Most people with GBS eventually recover substantially, though recovery can take months to years. The weakness typically plateaus and then gradually improves. Some people make a complete recovery, while others have lasting weakness or sensory changes. Physical rehabilitation plays an important role in recovery.

What Is Charcot-Marie-Tooth Disease?

Charcot-Marie-Tooth (CMT) disease is the most common inherited form of polyneuropathy, affecting about 1 in 2,500 people. It causes progressive muscle weakness and sensory loss, primarily in the feet, legs, hands, and forearms. While there is no cure, treatment focuses on maintaining function through physical therapy, bracing, and sometimes surgery.

Charcot-Marie-Tooth disease encompasses a group of hereditary conditions that affect peripheral nerves. Named after the three physicians who first described it, CMT exists in many genetic forms, each involving mutations in genes important for nerve function or structure.

CMT typically begins in childhood or early adulthood, though age of onset varies. Early symptoms often include difficulty running, frequent ankle sprains, or high arches and hammertoes. Weakness and wasting of muscles in the lower legs can give a characteristic "inverted champagne bottle" appearance. The hands and forearms are often affected later.

Living with CMT

While CMT cannot be cured, many people live full and active lives with the condition. Treatment focuses on maintaining function and preventing complications. Physical therapy helps preserve muscle strength and flexibility. Ankle-foot orthoses or other braces improve walking safety and reduce fatigue.

Foot problems are common in CMT due to muscle imbalances that deform the feet. Properly fitted shoes and custom orthotics are important. Some people benefit from surgery to correct severe foot deformities or tendon problems. Occupational therapy can help with hand weakness affecting daily activities.