Peripheral sensorimotor neuropathy is a condition that impacts both movement and sensation due to damage to the nerves located outside the brain and spinal cord, affecting how the body responds to touch, temperature, and how muscles work together.

What Is Peripheral Sensorimotor Neuropathy?

Peripheral sensorimotor neuropathy is a bodywide process that damages nerve cells located outside the central nervous system, which consists of the brain and spinal cord. The term peripheral refers to nerves that extend throughout the body, reaching the hands, feet, arms, legs, and other areas. When these nerves become damaged, the condition affects both sensory function, which allows us to feel sensations, and motor function, which controls movement.^[1]

This condition represents a specific type of peripheral neuropathy where both types of nerve damage occur together. The nervous system relies on bundles of long nerve fibers called axons to transmit signals. Some of these nerve fibers are wrapped in a protective coating called myelin sheath, which helps signals travel quickly and efficiently. When either the nerve fiber itself or this protective covering becomes damaged, the nerve may slow down or stop working altogether.^[1]

Sensorimotor polyneuropathy specifically damages nerve cells, the axons that extend from them, and the myelin sheath that covers many nerves. The damage to the myelin causes nerve signals to slow down or stop entirely, while damage to the nerve fiber or the entire nerve cell can cause the nerve to cease functioning. This widespread damage explains why the condition affects multiple nerves throughout different parts of the body rather than just a single nerve.^[1]

Epidemiology: How Common Is This Condition?

Peripheral neuropathy as a whole is quite common, affecting millions of people. About 2.4 percent of people globally have some form of peripheral neuropathy. The condition becomes significantly more common as people age. Among individuals who are 45 years old and older, the prevalence rises to between 5 and 7 percent.^[3]

One community-based study found that in the family medicine setting, approximately 8 percent of persons aged 55 years and older have peripheral neuropathy. When looking specifically at people with type 2 diabetes mellitus, one of the most common causes of neuropathy, the prevalence reaches 26.4 percent.^[12]

Peripheral neuropathy can affect anyone regardless of age, sex, race, ethnicity, or personal circumstances. However, certain groups face higher risks depending on the underlying cause. The condition is especially common among people with age-related diseases, meaning the risk of developing peripheral neuropathy increases as individuals get older.^[3]

Causes of Peripheral Sensorimotor Neuropathy

Peripheral sensorimotor neuropathy can result from a wide variety of underlying conditions and circumstances. The most common treatable causes include diabetes mellitus, hypothyroidism, and nutritional deficiencies.^[12] Understanding what causes nerve damage helps doctors determine the best approach to treatment and management.

Nerve damage can be caused by autoimmune disorders, which occur when the body’s immune system mistakenly attacks its own tissues. In these cases, the immune system targets the peripheral nerves, causing inflammation and damage. Conditions such as Sjögren syndrome represent examples of autoimmune causes of sensorimotor polyneuropathy.^[1]

Metabolic disorders represent another major category of causes. Diabetes is one of the most common causes of neuropathy in the United States. Chronic kidney disease and low thyroid function can also lead to nerve damage. These conditions alter the body’s normal metabolic processes in ways that harm nerve cells over time.^[1]

Toxic exposures and certain medications can damage peripheral nerves. Alcoholic neuropathy develops in people with chronic alcohol abuse. Drug-related neuropathy, including damage from chemotherapy medications used to treat cancer, represents another important cause. Various toxins in the environment can also harm nerves.^[1]

Infections can lead to sensorimotor polyneuropathy as well. HIV/AIDS can cause nerve damage, as can various other infections. Some cancers produce substances that damage nerves even when the cancer itself is not directly pressing on the nerves, a phenomenon called paraneoplastic neuropathy.^[1]

Some neuropathies are hereditary, meaning they are passed down through families due to genetic factors. Others result from decreased blood flow to the nerves, conditions that put pressure on nerves, or diseases that destroy the connective tissue that holds cells and tissues together. Inflammation of the nerves themselves, such as in chronic inflammatory neuropathy or Guillain-Barré syndrome, can also cause sensorimotor polyneuropathy.^[1]

Nutritional deficiencies, particularly of vitamins B12, B1, and E, can lead to nerve damage. Amyloid polyneuropathy, where abnormal protein deposits accumulate and damage nerves, represents another cause. Parkinson disease has also been associated with the development of sensorimotor polyneuropathy.^[1]

Risk Factors

Certain factors increase an individual’s risk of developing peripheral sensorimotor neuropathy. Age is a significant risk factor, with the condition becoming more common in people over 45 years old. This increased risk relates partly to the higher prevalence of age-related diseases that can cause nerve damage.^[3]

People with diabetes face substantially elevated risk. Among those with type 2 diabetes, more than one quarter may develop peripheral neuropathy. Poor blood sugar control appears to increase this risk, as chronically elevated blood sugar levels can damage nerves throughout the body over time.^[12]

Chronic alcohol consumption represents a major modifiable risk factor. Alcohol can be directly toxic to nerve tissue, and people who drink heavily over long periods are at increased risk for developing alcoholic neuropathy. Stopping alcohol consumption is an important part of preventing further nerve damage in these cases.^[1]

Individuals undergoing treatment for cancer, particularly those receiving chemotherapy, face increased risk due to the potential nerve-damaging effects of these medications. People with chronic kidney disease, hypothyroidism, or other metabolic conditions also have elevated risk.^[1]

Nutritional deficiencies increase risk, particularly deficiencies in B vitamins and vitamin E. People who have difficulty absorbing nutrients due to digestive conditions or those with restricted diets may be at higher risk. Having certain infections, including HIV/AIDS, or having been exposed to various toxins also increases the likelihood of developing sensorimotor neuropathy.^[1]

Individuals with autoimmune disorders face elevated risk, as their immune systems may attack their own peripheral nerves. Having a family history of hereditary neuropathy means genetic factors may increase risk as well.^[1]

Symptoms of Peripheral Sensorimotor Neuropathy

The symptoms of peripheral sensorimotor neuropathy vary depending on which nerves are affected and how severely they are damaged. Because this condition affects both sensory nerves, which allow us to feel sensations, and motor nerves, which control movement, symptoms can involve both feeling and function.^[1]

Decreased feeling represents one of the hallmark symptoms. This can affect touch, pain, vibration, or the ability to sense where body parts are positioned. The loss of sensation may occur in any area of the body but most commonly affects the feet and hands first. Many people describe experiencing numbness that gradually spreads from the toes upward into the legs and from the fingers upward into the arms.^[1]

Pain is another common and often distressing symptom. People with sensorimotor neuropathy frequently describe sharp, jabbing, throbbing, or burning pain. Some experience tingling sensations often described as pins and needles. Others report abnormal feelings in affected areas, a symptom called neuralgia. The pain can be severe enough to interfere with daily activities and sleep.^[1]

Some individuals develop extreme sensitivity to touch, where even light contact that would normally not be painful becomes uncomfortable or painful. This heightened sensitivity, combined with other sensory disturbances, can make wearing shoes or clothing uncomfortable.^[2]

Motor symptoms involve difficulties with movement and muscle function. Weakness of the face, arms, legs, or other body areas is common. Some people notice muscle twitches or experience muscle atrophy, which is the thinning or wasting away of muscles. Difficulty using the arms, hands, legs, or feet can develop, affecting the ability to perform fine motor tasks or to walk properly.^[1]

Balance problems frequently occur because the condition affects both the ability to feel where the feet are positioned and muscle strength. This combination leads to difficulty walking and an increased risk of falls. Many people with sensorimotor neuropathy report not being able to feel the ground under their feet, which makes maintaining balance challenging.^[1]

In severe cases, some people may experience difficulty swallowing or breathing, or even paralysis. Diminished reflexes, most commonly at the ankle, are often found during physical examination.^[1]

The timeline for symptom development varies considerably. Some neuropathies develop gradually over years, with symptoms slowly worsening. Others can start suddenly and become severe within hours to days, as seen in conditions like Guillain-Barré syndrome. Symptoms usually occur on both sides of the body and most often begin at the ends of the toes first before progressing upward.^[1]

Prevention of Peripheral Sensorimotor Neuropathy

While not all cases of peripheral sensorimotor neuropathy can be prevented, particularly those due to hereditary causes, many risk factors are modifiable. Taking steps to address these risk factors can help prevent the condition from developing or slow its progression.^[3]

For people with diabetes, maintaining good blood sugar control is crucial. Ensuring diabetes is well controlled through lifestyle changes, medication, or both may help improve neuropathy or at least stop it from getting worse. Regular monitoring of blood glucose levels and working closely with healthcare providers to adjust treatment as needed plays an important role in prevention.^[10]

Lifestyle modifications can significantly reduce risk. Stopping smoking is important, as smoking can damage blood vessels and reduce blood flow to nerves. Cutting down on alcohol or avoiding it entirely prevents alcoholic neuropathy and reduces the risk of further nerve damage in those who already have some degree of neuropathy.^[10]

Maintaining a healthy weight through balanced nutrition and regular exercise helps prevent metabolic conditions that can lead to neuropathy. Exercise itself has been found to be beneficial, with studies showing that moderate-intensity exercise programs are safe and can improve symptoms in people with peripheral neuropathy. Regular physical activity can help improve balance, strength, walking speed, and mobility confidence while reducing fear of falling.^[17]

Ensuring adequate nutrition, particularly sufficient intake of B vitamins and vitamin E, helps protect nerve health. Vitamin B12 deficiency, for example, can be treated with B12 injections or tablets, and correcting this deficiency may improve or prevent neuropathy.^[10]

Regular health screenings can help detect conditions that might lead to neuropathy before they cause significant nerve damage. This includes screening for diabetes, thyroid problems, vitamin deficiencies, and other metabolic conditions. Early detection and treatment of these conditions may prevent the development of neuropathy or catch it in its early stages when intervention may be most effective.^[12]

For people taking medications known to potentially cause nerve damage, such as certain chemotherapy drugs, working with healthcare providers to monitor for early signs of neuropathy and adjusting treatment when possible can help minimize nerve damage.^[1]

Pathophysiology: What Happens in the Body

To understand the pathophysiology of peripheral sensorimotor neuropathy, it helps to know how nerves are structured and how they work. Neurons, the cells that make up nerves, send and relay signals through the nervous system using both electrical and chemical signals. Each neuron consists of a cell body, which is the main part of the cell, and an axon, a long extension that carries signals away from the cell body.^[3]

Many peripheral nerve axons are wrapped in myelin, a thin layer made of fatty compounds. This myelin sheath acts like insulation around an electrical wire, helping signals travel quickly along the nerve. At the end of the axon are small extensions called synapses where the electrical signal converts to a chemical signal that can be passed to nearby nerve cells.^[3]

The peripheral nervous system includes motor nerves, which control muscle movement, and sensory nerves, which transmit information about touch, temperature, pain, and other sensations. In sensorimotor polyneuropathy, both types of nerves are affected. The damage can occur to different parts of the nerve structure, including the nerve cells themselves, the axons, and the myelin sheath.^[1]

When the myelin sheath is damaged, nerve signals slow down or stop. This is because without proper insulation, the electrical signals cannot travel efficiently along the nerve fiber. This slowing of signals manifests as the various symptoms of neuropathy, including decreased sensation and slowed reflexes.^[1]

Damage to the nerve fiber or the entire nerve cell is even more serious and can cause the nerve to stop working altogether. When sensory nerves are damaged, the brain receives incorrect information or no information at all about sensations like touch, temperature, and pain. This explains why people with neuropathy may not feel injuries, may experience numbness, or may feel pain when there is no actual harmful stimulus.^[1]

When motor nerves are damaged, the signals from the brain telling muscles to contract do not reach their destination properly. This results in muscle weakness. Over time, muscles that are not receiving proper nerve signals begin to shrink, a process called atrophy. The loss of motor control combined with decreased sensation leads to the balance problems and difficulty walking that are common in sensorimotor neuropathy.^[1]

The peripheral nervous system consists of all the nerves outside the brain and spinal cord, extending throughout the body. Because sensorimotor polyneuropathy is a systemic process, it affects nerves throughout the body rather than just in one location. Most neuropathies are length-dependent, meaning the longest nerves are affected first and most severely. This explains why symptoms typically start in the toes and feet, which are furthest from the central nervous system, before progressing upward toward the body’s center.^[4]

The specific mechanisms by which different underlying causes damage nerves vary. In diabetes, chronically elevated blood sugar levels can directly damage nerve cells and also harm the small blood vessels that supply nerves with oxygen and nutrients. In autoimmune conditions, the immune system attacks components of the peripheral nerves, causing inflammation and destruction. In toxic exposures, whether from alcohol, medications, or environmental toxins, these substances are directly harmful to nerve tissue.^[1]

In conditions involving inflammation, such as chronic inflammatory neuropathy or Guillain-Barré syndrome, the swelling around nerves compresses them and interferes with their function. In hereditary neuropathies, genetic defects cause abnormalities in the structure or function of nerve components, leading to progressive damage over time.^[1]

Regardless of the underlying cause, the end result is disrupted nerve signaling. Signals that should be sent are not sent, signals are sent when they should not be, or errors change the messages being transmitted. This disruption in communication between the peripheral nervous system and the central nervous system produces the constellation of sensory and motor symptoms that characterize peripheral sensorimotor neuropathy.^[4]