Understanding Neuropathy: Types, Causes, Symptoms, and What You Need to Know
Quick Summary: Neuropathy affects approximately 13.5% of US adults aged 40 and older, causing nerve damage that leads to pain, numbness, and weakness. This comprehensive guide explains the different types of neuropathy, their causes, symptoms, and how they progress—helping you understand this common but often misunderstood condition.
What Is Neuropathy?
Neuropathy, also called peripheral neuropathy, occurs when nerves outside the brain and spinal cord become damaged. These peripheral nerves form a communication network connecting the central nervous system to muscles, skin, and internal organs throughout the body. When this network is damaged, the resulting disruption can cause weakness, numbness, pain, and various other symptoms depending on which nerves are affected.
The peripheral nervous system consists of three main types of nerves: sensory nerves that detect sensations like temperature and pain, motor nerves that control muscle movement, and autonomic nerves that regulate involuntary functions such as heart rate, blood pressure, digestion, and bladder control. Neuropathy can affect any or all of these nerve types, leading to a wide range of symptoms and complications.
How Common Is Neuropathy?
Neuropathy is far more prevalent than many people realize. Research shows that approximately 13.5% of US adults aged 40 and older have peripheral neuropathy. The condition becomes increasingly common with age—affecting 10.4% of middle-aged adults (40-69 years) and jumping to 26.8% to 39.2% in adults over 70 years old. Globally, about 2.4% of the population is affected by peripheral nerve disorders, with prevalence increasing to 8% in older populations.
Among people with diabetes, the numbers are even more striking. Between 27% and 40% of adults with diabetes develop neuropathy, with approximately half of all individuals with type 1 or type 2 diabetes experiencing some form of nerve damage during their lifetime. However, neuropathy is not exclusively a diabetic condition—11.6% of adults without diabetes also develop peripheral neuropathy, highlighting that many other causes exist.
Understanding Different Types of Neuropathy
Neuropathy is classified in several ways based on the number of nerves affected, the type of nerve fibers involved, and how the condition progresses. Understanding these classifications helps clarify the diverse presentations of this condition.
Classification by Number of Nerves Affected
Mononeuropathy involves damage to a single peripheral nerve. Physical injury, trauma, or prolonged pressure on a nerve are the most common causes. Carpal tunnel syndrome is the most frequent example, accounting for approximately 90% of all mononeuropathy cases. This compression of the median nerve in the wrist causes pain, numbness, and tingling in the thumb, index finger, and middle finger, often resulting from repetitive wrist motions like typing or assembly line work.
Mononeuritis Multiplex occurs when multiple separate, non-contiguous nerves are damaged either simultaneously or sequentially. This pattern is often associated with chronic illnesses such as diabetes, vasculitis, lupus, rheumatoid arthritis, or viral infections. The condition causes pain, weakness, and abnormal sensations in the specific areas supplied by the affected nerves.
Polyneuropathy represents the most common form, accounting for the greatest number of peripheral neuropathy cases. This condition involves widespread malfunction of multiple peripheral nerves throughout the body at the same time. Symptoms typically appear symmetrically on both sides of the body and follow a "length-dependent" pattern, starting in the feet and hands before potentially spreading upward.
Classification by Nerve Fiber Type
Sensory Neuropathy affects nerves that carry sensations from the skin to the brain. Common symptoms include numbness, burning sensations, tingling, and acute pain—especially in the hands, feet, legs, and arms. A dangerous consequence is the inability to feel extreme temperatures or pain, which can result in unnoticed injuries.
Motor Neuropathy damages nerves that control voluntary muscle movement. This leads to muscle weakness, difficulty walking, problems grasping objects, impaired balance and coordination, and sometimes falls. In severe cases like Guillain-Barré syndrome, motor neuropathy can develop acutely with rapidly progressing symptoms.
Autonomic Neuropathy occurs when nerve damage affects bodily organs and involuntary functions. This can impact the cardiovascular system (causing irregular heartbeat, blood pressure drops, dizziness), digestive system (resulting in constipation, diarrhea, nausea, bloating), bladder function, sexual function, and temperature regulation (excessive or insufficient sweating). Autonomic neuropathy most commonly develops in people with long-standing type 1 or type 2 diabetes.
Small Fiber vs. Large Fiber Neuropathy
Small Fiber Neuropathy affects small-diameter myelinated A-delta fibers and unmyelinated C fibers that transmit pain, temperature sensation, and autonomic signals. Symptoms include burning pain, numbness, tingling, sensitivity to touch, and autonomic dysfunction such as sweating abnormalities or gastrointestinal problems. Notably, strength remains preserved and standard nerve conduction studies appear normal, making diagnosis more challenging.
Research shows that small fiber neuropathy affects approximately 53 per 100,000 people worldwide, though this estimate may be low as many cases go undiagnosed. The condition develops very slowly, and studies indicate that between 13% and 36% of people with small fiber neuropathy eventually develop large fiber involvement.
Large Fiber Neuropathy affects larger myelinated nerve fibers that control muscle movement and transmit sensations of vibration, touch, and position. Symptoms include loss of balance, impaired coordination, difficulty sensing where limbs are in space, muscle weakness, and reduced ability to feel vibrations and light touch—often described as feeling like wearing gloves or socks. Unlike small fiber neuropathy, large fiber damage shows up clearly on standard nerve conduction studies.
Additional Classification Types
Proximal Neuropathy affects nerves in the hips, buttocks, thighs, legs, chest, or stomach. Pain is typically concentrated on one side of the body and rarely spreads to the opposite side. This type is most commonly found in adults over age 50.
Focal Neuropathy involves sudden damage to a single nerve, causing localized pain, numbness, tingling, or weakness. Symptoms can include double vision, facial weakness, or partial paralysis depending on which nerve is affected. Most people recover within several weeks to months without specific intervention.
What Causes Neuropathy?
Peripheral neuropathy stems from numerous causes, ranging from metabolic conditions to physical injuries. Understanding the underlying cause is essential for proper management.
Diabetes and Metabolic Conditions
Diabetes stands as the most common identifiable cause of peripheral neuropathy in the United States. Among people with diabetes, between 6% and 51% develop peripheral neuropathy depending on factors like age, diabetes duration, glucose control, and whether they have type 1 or type 2 diabetes. The mechanism involves hyperglycemia-induced formation of advanced glycation end products that damage nerve fibers over time.
Diabetic neuropathy prevalence increases dramatically with disease duration. Research shows that 35% of people with type 2 diabetes already have neuropathy at the time of diagnosis, and this percentage climbs to over 50% in those over age 70. Poor blood sugar control significantly accelerates nerve damage, while associated cardiovascular risk factors—including elevated triglycerides, obesity, hypertension, and low HDL cholesterol—compound the problem.
Metabolic syndrome components, even in people without diabetes, are strongly associated with peripheral neuropathy risk. Impaired glucose tolerance, excess body weight, and other metabolic abnormalities can damage nerves through similar mechanisms as full diabetes.
Autoimmune Diseases
Various autoimmune conditions can trigger peripheral neuropathy when the immune system mistakenly attacks the body's own nerves. These include Sjögren's syndrome, lupus, rheumatoid arthritis, Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, and vasculitis. Additionally, some cancers related to immune system dysfunction can cause polyneuropathy as a paraneoplastic syndrome.
Infections
Certain viral and bacterial infections can damage peripheral nerves either directly or through inflammatory responses. Known infectious causes include Lyme disease, shingles (herpes zoster), hepatitis B and C, leprosy, diphtheria, and HIV. Globally, leprosy remains a common cause of peripheral neuropathy, with the highest prevalence in Southeast Asia.
Vitamin Deficiencies and Nutritional Factors
Essential vitamins play crucial roles in nerve health, and deficiencies can lead to neuropathy. Particularly important are B vitamins (B-1, B-6, and B-12), vitamin E, and copper. Vitamin B-12 deficiency is especially common in older adults, vegetarians, vegans, and people with absorption problems. Conversely, excessive intake of certain vitamins, particularly vitamin B-6, can also cause nerve damage.
Alcohol Use Disorder
Alcohol-associated polyneuropathy affects 22% to 66% of people with chronic alcoholism. The condition develops through multiple mechanisms: direct toxic effects of alcohol on nerves, nutritional deficiencies (especially B vitamins) common in people with alcohol use disorder, and poor absorption of essential nutrients due to gastrointestinal damage.
Medications and Chemotherapy
Numerous medications can cause peripheral neuropathy as a side effect. Chemotherapy-induced neuropathy has gained increasing clinical importance, with prevalence often stated at 30% to 40% depending on the specific drugs and regimen used. Cisplatin primarily causes large fiber neuropathy leading to painless ataxia, while vincristine can cause predominantly small fiber involvement with pain. Other medications associated with neuropathy include certain antibiotics (metronidazole, fluoroquinolones), antiretroviral drugs for HIV, and some blood pressure medications.
Physical Injuries and Compression
Traumatic injuries from motor vehicle accidents, falls, or sports injuries can sever or damage peripheral nerves. Prolonged pressure on nerves—from extended periods of immobility, repetitive motions, use of crutches, wearing casts, or poor ergonomics—can also cause nerve damage. Entrapment neuropathies occur when nerves become compressed at specific anatomical sites, with carpal tunnel syndrome being the most common example.
Inherited Disorders
Hereditary neuropathies run in families and result from genetic mutations. Charcot-Marie-Tooth disease represents the most common genetic sensorimotor polyneuropathy, specifically type 1a. Other inherited conditions include Friedreich ataxia and giant axonal neuropathy, each with distinct genetic causes and progression patterns.
Other Medical Conditions
Additional causes include kidney disease, liver disease, hypothyroidism (underactive thyroid), bone marrow disorders such as monoclonal gammopathies and amyloidosis, and exposure to toxic substances including industrial chemicals and heavy metals like lead and mercury. In approximately 20% to 30% of cases, no clear cause can be identified—a condition termed idiopathic peripheral neuropathy.
Recognizing the Symptoms of Neuropathy
Neuropathy symptoms vary widely depending on which nerve fibers are affected and the severity of damage. Most neuropathies are "length-dependent," meaning symptoms develop first in the body's farthest nerve endings—typically the feet—and may progress upward toward the torso. Some neuropathies are non-length-dependent, with symptoms starting around the torso or moving unpredictably to different body parts.
Sensory Symptoms
The most frequently encountered symptoms include gradual onset of numbness, prickling, or tingling in the feet or hands that can spread upward into the legs and arms. Many people experience sharp, jabbing, throbbing, or burning pain that often worsens at night, disrupting sleep. Extreme sensitivity to touch is common, including allodynia—pain from stimuli that normally don't cause pain, such as bedsheets touching the feet.
People may describe feeling as if they're wearing gloves or socks when they're not. Reduced sensitivity to temperature changes and pain creates dangerous situations where burns, cuts, or other injuries can occur without immediate awareness. Loss of position sense—knowing where body parts are in space—can leave someone unable to coordinate complex movements, fasten buttons, or maintain balance when their eyes are shut.
Motor Symptoms
Motor nerve damage causes muscle weakness, particularly in the feet and legs, making walking difficult. Lack of coordination and frequent falling become concerning issues. Muscle wasting (atrophy) may develop in advanced cases, and deep tendon reflexes become diminished or absent. The characteristic "stocking-glove" pattern of sensory loss combined with weakness creates significant functional impairment.
Autonomic Symptoms
When autonomic nerves are affected, symptoms depend on which organs and glands are involved. Common manifestations include heat intolerance, excessive sweating or inability to sweat normally, bowel problems (constipation, diarrhea, bloating), bladder control difficulties, digestive issues, and blood pressure drops causing dizziness or lightheadedness upon standing (orthostatic hypotension). Sexual dysfunction and abnormal heart rate are also possible.
Symptom Progression and Timeline
Most peripheral neuropathies develop gradually over months to years, though some progress rapidly. Symptoms in their early stages may be mild and easy to dismiss, but they typically worsen without addressing the underlying cause. In some cases, particularly focal neuropathies, symptoms improve spontaneously within weeks or months and may not require specific intervention.
Neuropathic pain is sometimes worse at night, significantly disrupting sleep quality and overall wellbeing. The pain can result from nerve receptors firing spontaneously without triggers or from problems with signal processing in the spinal cord. This chronic pain, combined with functional limitations, substantially impacts quality of life.
How Neuropathy Is Diagnosed
Diagnosing peripheral neuropathy requires a systematic approach combining detailed medical history, physical examination, and specialized testing. Healthcare providers investigate symptoms, family history, occupational exposures, medication use, alcohol consumption, dietary habits, and any underlying medical conditions.
Physical and Neurological Examination
A thorough neurological examination assesses sensory function (testing ability to feel touch, temperature, pain, vibration, and position), motor function (evaluating muscle strength, tone, and coordination), reflexes (checking deep tendon reflexes), and autonomic function. Advanced neuropathy may show the characteristic stocking-glove pattern of sensory loss, absent reflexes, muscle wasting, and weakness.
Electrodiagnostic Testing
Nerve conduction studies measure how fast electrical signals move through nerves, helping identify large fiber involvement and determine whether nerve damage is axonal or demyelinating. Electromyography (EMG) evaluates how muscles respond to nerve signals and can detect patterns consistent with neuropathy. However, these standard tests only evaluate large nerve fibers and appear normal in isolated small fiber neuropathy.
Specialized Tests for Small Fiber Neuropathy
Skin biopsy for evaluating intraepidermal nerve fiber density has become a gold standard for diagnosing small fiber neuropathy. A small punch biopsy from the foot and thigh examines nerve fiber density under specialized microscopy. Quantitative sudomotor axon reflex testing assesses sweat gland nerve function, and quantitative sensory testing measures sensory perception thresholds.
Laboratory Testing
Blood tests screen for underlying causes including diabetes and prediabetes (hemoglobin A1c, fasting glucose, oral glucose tolerance test), vitamin levels (B-12, folate, B-6, vitamin E), thyroid function, kidney and liver function, autoimmune markers, and infections. Additional testing may investigate genetic factors, toxic exposures, or rare conditions depending on clinical presentation.
Risk Factors for Developing Neuropathy
Understanding risk factors helps identify who may be more susceptible to developing peripheral neuropathy. Strong risk factors include diabetes—especially with poor blood sugar control—where the risk increases approximately five-fold for long-standing disease in middle-aged adults. Age itself is a major factor, with prevalence more than tripling from middle age to older adulthood.
Male sex roughly doubles the risk compared to females across age groups. Greater height increases risk 1.5 to 3-fold, possibly because longer nerve fibers are more vulnerable to damage. Black race shows 1.3 to 1.5 times higher risk compared to white race, with social determinants of health such as food insecurity and lack of health insurance also playing significant roles, particularly in Hispanic populations.
Other important risk factors include alcohol misuse, vitamin deficiencies (especially B-12), chronic infections, autoimmune diseases, kidney or liver disease, thyroid disorders, exposure to toxins, repetitive motions in occupational settings, peripheral artery disease, obesity, hypertension, elevated triglycerides, low HDL cholesterol, low physical activity, and family history of hereditary neuropathy.
Understanding How Neuropathy Damages Nerves
While many different diseases can lead to peripheral neuropathy, the mechanisms of nerve injury follow similar patterns. The two primary pathological processes are axonal degeneration and demyelination, though mixed patterns commonly occur.
Axonal Degeneration
In axonal neuropathy, the nerve fiber itself (axon) degenerates following a pattern that starts distally (farthest from the cell body) and progresses proximally. The distal portions are particularly vulnerable because they're furthest from the cell body that provides metabolic support. The proposed mechanism involves impaired delivery of local axonal survival factors, resulting in increased intracellular calcium levels that trigger calcium-dependent cytoskeletal breakdown. Diabetes, HIV, hepatitis C, and Guillain-Barré syndrome exemplify diseases causing axonal degeneration.
Demyelinating Neuropathy
Demyelinating neuropathies involve damage to the myelin sheath—the fatty insulating layer surrounding nerve axons. Like insulation around electrical wiring, myelin is essential for rapid signal transmission. When damaged, nerves cannot transmit electrical signals efficiently, leading to slowed conduction velocities detectable on nerve studies. Certain autoimmune conditions and hereditary disorders cause primarily demyelinating patterns.
The Impact of Neuropathy on Quality of Life and Mortality
Beyond the immediate symptoms, peripheral neuropathy carries significant long-term health implications. Research demonstrates that neuropathy is independently associated with increased mortality risk. Studies show all-cause mortality rates of 57.6 per 1,000 person-years in adults with both diabetes and peripheral neuropathy, 34.3 in adults with peripheral neuropathy but no diabetes, 27.1 in adults with diabetes but no peripheral neuropathy, and 13.0 in adults with neither condition.
After adjusting for other risk factors, peripheral neuropathy increases all-cause mortality risk by 49% in people with diabetes and 31% in those without diabetes. Cardiovascular mortality risk increases 66% in diabetic individuals with neuropathy. These findings underscore that decreased sensation in the feet represents an under-recognized risk factor for mortality in the general population.
Complications Associated with Neuropathy
Peripheral neuropathy can lead to serious complications affecting safety, function, and overall health. Loss of sensation creates particular risks—people may experience burns, skin injuries, and wounds without feeling pain as warning signals. Feet and other areas lacking sensation can sustain injuries that go unnoticed, potentially progressing to serious infections.
Among people with diabetes, peripheral neuropathy significantly increases the risk of foot ulcers, with approximately 25% developing a foot ulcer during their lifetime. Ninety percent of hospital admissions for diabetic foot ulcers relate to peripheral neuropathy and infection, and diabetes accounts for 83% of all major amputations in the United States. Between 14% and 24% of people with diabetic foot ulcers ultimately require amputation.
Weakness and loss of sensation contribute to impaired balance and increased fall risk, which can lead to fractures and other injuries—particularly concerning in older adults. Autonomic dysfunction can cause dangerous blood pressure fluctuations, cardiac arrhythmias, digestive complications, and bladder problems that significantly impact daily functioning.
Special Considerations for Different Populations
Certain populations face heightened risks or unique presentations of neuropathy. Older adults show dramatically higher prevalence—nearly 40% in those over 70—often complicated by multiple contributing factors including age-related changes, accumulated comorbidities, and medication side effects. Cognitive changes may make symptom reporting more challenging, and fall risk from neuropathy carries more serious consequences.
People with diabetes require particularly vigilant monitoring, as approximately half will develop some form of neuropathy. The combination of sensory loss, poor wound healing, and infection risk creates a dangerous triad requiring aggressive preventive care including daily foot inspections, proper footwear, blood sugar control, and regular professional foot examinations.
Cancer survivors receiving chemotherapy need ongoing neuropathy screening, as chemotherapy-induced neuropathy affects 30% to 40% of patients depending on treatment regimens. Symptoms may persist long after treatment concludes and can progress even after chemotherapy stops. Approximately 40% of chemotherapy-induced neuropathy cases involve chronic pain requiring long-term management.
Frequently Asked Questions
Can neuropathy affect only one part of the body?
Yes, mononeuropathy affects a single nerve in one area, commonly seen in conditions like carpal tunnel syndrome. However, the most common form is polyneuropathy, which affects multiple nerves throughout the body, typically starting in the feet and hands.
Is neuropathy always painful?
No, not all neuropathy is painful. Some people experience primarily numbness and tingling without significant pain, while others have severe burning or stabbing pain. About half of all polyneuropathy cases involve pain. Small fiber neuropathy tends to be more painful than large fiber types.
Why do neuropathy symptoms often start in the feet?
Most neuropathies are "length-dependent," meaning the longest nerve fibers are affected first. Since the nerves reaching your feet are the longest in your body, they're most vulnerable to metabolic, toxic, or nutritional factors that damage nerves. Symptoms typically start in the toes and gradually progress upward.
Can neuropathy symptoms come and go?
Neuropathic pain can fluctuate in intensity and may be worse at certain times, often at night. However, nerve damage itself usually persists once established. Some focal neuropathies improve spontaneously, and symptoms may stabilize for years before progressing. Acute inflammatory neuropathies like Guillain-Barré syndrome may improve substantially with appropriate intervention.
Does everyone with diabetes develop neuropathy?
No, not everyone with diabetes develops neuropathy, though the risk is substantial. Between 27% and 51% of people with diabetes develop peripheral neuropathy depending on factors like diabetes duration, blood sugar control, and overall health. Maintaining good glucose control, managing cardiovascular risk factors, and healthy lifestyle choices significantly reduce risk.
What's the difference between neuropathy and nerve pain?
Neuropathy refers to nerve damage or dysfunction, while neuropathic pain is a specific type of pain caused by that nerve damage. Not all neuropathy causes pain—some people experience numbness, weakness, or autonomic symptoms without pain. Conversely, neuropathic pain is always related to some form of nerve dysfunction.
Can neuropathy affect internal organs?
Yes, autonomic neuropathy affects nerves controlling internal organs and involuntary body functions. This can impact the cardiovascular system (heart rate, blood pressure), digestive system (stomach emptying, bowel function), bladder control, sexual function, and sweat glands. Autonomic involvement is most common in long-standing diabetes but can occur with other causes.
How long does it take for neuropathy to develop?
Most peripheral neuropathies develop gradually over months to years. However, some forms like Guillain-Barré syndrome can progress rapidly over days to weeks. Focal neuropathies from injury may cause sudden symptoms, while toxic or metabolic neuropathies typically evolve slowly as exposure or underlying conditions persist.
Is neuropathy more common in men or women?
Research shows that men have approximately twice the risk of developing peripheral neuropathy compared to women across all age groups. The reasons for this sex difference are not completely understood but may relate to differences in nerve fiber density, hormonal factors, and varying prevalence of risk factors like diabetes and alcohol use disorder.
