Peripheral nerves are the nerves outside of the brain and spinal cord. They relay information between the central nervous system (CNS), and all other parts of the body. The brain and spinal cord are part of the CNS.
Polyneuropathy affects several nerves in different parts of the body at the same time. In cases of mononeuropathy, just one nerve is affected.
Polyneuropathy can affect nerves responsible for feeling (sensory neuropathy), movement (motor neuropathy), or both (sensorimotor neuropathy).
It may also affect the autonomic nerves responsible for controlling functions such as digestion, the bladder, blood pressure, and heart rate.
Although the exact number of people with polyneuropathy is not known, the National Institute of Neurological Disorders and Stroke (NINDS) estimate that approximately 20 million people in the United States have some form of peripheral neuropathy, and most of them have polyneuropathy.
Types of polyneuropathy
Neuropathy is a problem with the nerves. This can arise from numerous underlying conditions.
There are more than 100 types of peripheral neuropathy, and most of these are polyneuropathies.
Each type is classified according to the type of nerve damage, the underlying cause, and the symptoms that it produces.
For example, diabetic neuropathy occurs in people with diabetes, whereas idiopathic neuropathy appears to have no known cause.
There are three main patterns of polyneuropathy:
- Chronic symmetrical peripheral neuropathy: Most polyneuropathies are chronic and develop over many months.
- Multiple mononeuropathy: There is damage to at least two separate nerve areas.
- Acute symmetrical peripheral neuropathy: This is rare. The most common cause is Guillain-Barré syndrome, a condition that can be fatal.
Some neuropathies can take years to develop, but others become severe within hours to days of onset.
Causes and risk factors
A variety of medical conditions and other factors can cause polyneuropathy, including:
- Diabetes: This can be a significant risk factor, especially if blood glucose levels are poorly controlled. One study of more than 1,400 people with type 2 diabetes found that every fifth person had diabetic neuropathy.
- Alcohol abuse: Alcohol can damage nerve tissue, and alcohol abuse is often associated with nutritional deficiencies that contribute to neuropathy.
- Autoimmune conditions: The immune system attacks the body, causing damage to nerves and other areas. Conditions include Sjogren's syndrome, celiac disease, Guillain-Barré syndrome, rheumatoid arthritis, and lupus.
- Bacterial or viral infections: Certain infections can lead to neuropathy, including Lyme disease, shingles, hepatitis B, hepatitis C, and HIV.
- Bone marrow disorders: Examples of these include abnormal proteins in the blood, some forms of bone cancer, and lymphoma.
- Exposure to toxins: Toxic neuropathy may be caused by exposure to industrial chemicals such as arsenic, lead, mercury, and thallium. Drug or chemical abuse is also a risk factor.
- Hereditary disorders: Certain conditions, such as Charcot-Marie-Tooth disease, are forms of hereditary neuropathy.
- Hypothyroidism: An underactive thyroid may lead to polyneuropathy, although this is uncommon.
- Kidney disease: Uremic neuropathy is a form of polyneuropathy that affects 20 percent to 50 percent of people with kidney disease, according to the Center for Peripheral Neuropathy.
- Liver disease: Research indicates that peripheral neuropathy is very common in those with cirrhosis of the liver.
- Medications: Chemotherapy, along with some drugs used to treat HIV/AIDS, can cause neuropathy.
- Poor nutrition: Deficiencies of vitamins B-1, B-6, B-12, and E may lead to polyneuropathy, as these are vital for nerve health.
- Physical trauma or injury: Repetitive motion such as typing, accidents, or other injuries can damage peripheral nerves.
Some cases of polyneuropathy have no known cause. These are known as idiopathic neuropathy.
Polyneuropathy can produce a variety of symptoms, depending on which nerves are affected.
Symptoms associated with sensory or motor nerve damage can include:
Polyneuropathy can cause shooting or burning pains in the limbs.
- pins and needles
- difficulty using the arms, legs, hands, or feet
- increased pain (such as burning, stabbing, freezing, or shooting pains)
- sleep problems due to night-time pain
- inability to feel pain
- extreme sensitivity to touch
- inability to sense temperature changes
- lack of coordination
- increased episodes of falling
- changes to the skin, hair, or nails
- foot and leg ulcers
- skin and nail infections
- muscle weakness
- muscle twitching
Symptoms associated with autonomic nerve damage include:
Other conditions with similar symptoms
Fibromyalgia and polyneuropathy may have similar symptoms, but the cause of fibromyalgia is unknown.
Similarities also exist between multiple sclerosis and peripheral neuropathy.
Conditions associated with polyneuropathy
There are many conditions associated with polyneuropathy, including:
Coordination issues and difficulties with movement are common symptoms of polyneuropathy. This may lead to further injuries.
- celiac disease
- Charcot-Marie-Tooth Disease
- Guillain-Barré Syndrome
- hepatitis B
- hepatitis C
- kidney disease
- liver disease
- Lyme disease
- osteosclerotic myeloma
- pernicious anemia (vitamin B-12 deficiency)
- rheumatoid arthritis
- Sjogren's syndrome
Common complications associated with polyneuropathy include:
- Falls and injury: A lack of balance and coordination, along with muscle weakness, can lead to an increase in falls and injuries sustained from falls.
- Burns and skin damage: Numbness and an inability to feel pain or temperature changes can lead to accidental burns, cuts, and other damage to the skin.
- Infections: Injuries, burns, and cuts, particularly on the legs and feet, can go unnoticed, leading to an increased risk of infection.
Diagnosis is based upon medical history, a physical exam, and neurological evaluation. Depending on the person's symptoms, tests may be ordered.
The doctor will take a detailed review of all symptoms, lifestyle factors, and family history.
They will also check the patient's height, weight, pulse, blood pressure, and temperature. The heart, lungs, and abdomen may also be checked to rule out alternative physiological causes.
Blood tests may be ordered to check for diabetes, thyroid function, immune function, nutrient deficiencies, and other factors that may cause polyneuropathy.
There may be some simple tests to check reflexes, muscle strength, sensitivity to temperature and other sensations, coordination, and posture.
Other tests that may be used in the diagnosis of polyneuropathy include:
- MRI or CT scan: These imaging techniques look for tumors, herniated disks, or other abnormalities that may be affecting nerve function.
- Electro-diagnostic tests: These non-invasive tests measure the electrical activity in the muscles and nerves, helping to detect nerve damage. Examples are electromyography and nerve conduction velocity.s
- Biopsies: The doctor may remove a small portion of a nerve, or sample of the skin, to test for abnormalities in nerve function or nerve endings.
The American Academy of Family Physicians recommend that peripheral neuropathy treatment address the underlying disease process, correct nutritional deficiencies, and aim to provide relief from symptoms.
Available treatments include medication, medical therapies and procedures, and alternative treatments.
Several different medications are available to treat neuropathy and its symptoms. These include:
- Medications for associated conditions: Conditions that may be causing polyneuropathy should be managed through various treatments, including medication if recommended by a doctor. Examples include insulin for diabetes and thyroid hormones for hypothyroidism.
- Pain medications: Over-the-counter pain relief can be beneficial for those with mild to moderate pain. These medications should not be taken on a long-term basis.
- Prescription medications: Some antidepressants, such as a group of medications called TCAs (including amitriptilyne or nortriptilyne), can be used, and another group called SNRIs, such as duloxetine, may also help. Corticosteroid injections could possibly be used for mononeuropathies, and some seizure medications such as gabapentin or pregabalin may help.
A variety of medical procedures are available. They include:
Chiropractors can help treat the symptoms of polyneuropathy.
- Transcutaneous electrical nerve stimulation: Electrodes send a gentle current of electricity through the skin. This can help with pain and sensitivity.
- Plasma exchange: People with inflammatory or autoimmune conditions may benefit from this therapy. The practitioner removes blood from the body, then separates antibodies and other proteins from the blood, before returning the blood to the body.
- Immune globulin therapy: Those with inflammatory and autoimmune conditions are given high levels of proteins to act as antibodies, which helps with immune function.
- Physical therapy: People with muscle weakness or coordination issues may find physical therapy helpful.
- Orthotic and other devices: Braces, canes, casts, splints, walkers, and wheelchairs may provide support and pain relief to those with neuropathy of the hands, feet, legs, and arms.
If neuropathy is caused by pressure on a nerve, surgery may be recommended.
Alternative and complementary treatments may offer relief to some people with polyneuropathy. Examples include:
However, these remedies have not been widely studied.
Prevention and outlook
Preventing polyneuropathy involves limiting the risk factors and managing underlying conditions. A person with polyneuropathy may not be able to avoid all risk factors, but some lifestyle choices may reduce the risk. These are:
- avoiding alcohol
- avoiding exposure to toxins, including cigarette smoke
- limiting factors that contribute to physical trauma or injury, such as repetitive actions and restrictive positions
- getting enough sleep and physical activity to support immune function
- eating a balanced diet rich in vitamins and minerals
- considering vitamin B-12 supplements if a vegan or vegetarian
Managing underlying conditions
Managing any underlying conditions can help to prevent the onset of the condition. Those with diabetes and other conditions related to polyneuropathy should closely follow the treatment plan devised by their doctor, as well as ensure that they attend all check-ups.
The outlook for polyneuropathy varies and can depend on the underlying cause, which nerves are damaged and the extent of the damage.
For some people, treating the underlying cause can lead to improvements. For others, the damage is permanent. In some cases, symptoms may get worse over time.
When to see a doctor
If any of the symptoms of polyneuropathy are experienced such as weakness, pain, or tingling in the hands or feet it is important to see a doctor.
Implementing a treatment plan as soon as possible is important to manage symptoms and prevent further nerve damage.
Neuropathy commonly refers to dysfunction or diseases of the nerves.
Neuropathies are group of disorders that occur due to some damage to nerves. Any traumatic injuries or diseases like infections, metabolic disorders and exposure to toxins can cause damage to nerves in any part of body resulting in neuropathy.
It is noted that generally it is peripheral nervous system which is mostly affected. This system is located outside of brain.
Neuropathy can affect motor nerves as well as sensory nerves. The motor nerves control movements and sensory nerves control sensations like heat or cold etc.
In some cases like that in autonomic neuropathy, the internal organs of body like blood vessels, heart, etc. are affected.
Classification and Types of Neuropathy
Neuropathy can be classified into different categories based on the types of nerves or the location of the nerves that are affected or according to the disease that is causing it.
Broadly Neuropathy Can Be Categorized As Follows Depending On The Number Of Nerves Affected.
- Mononeuropathy – Single nerve is affected. Common examples are carpal tunnel syndrome, radial nerve palsy, ulnar nerve palsy as well as peroneal nerve palsy.
- Multiple Mononeuropathy – In this case, more than one nerve gets affected.
- Polyneuropathy – Term used when many peripheral nerves get involved. The most common examples are diabetic neuropathy and Guillain Barre syndrome.
As mentioned earlier, neuropathies are of different types based on the nerves that are affected.
Types of Neuropathy
Autonomic Neuropathy: In this condition the autonomic nerves are affected. Autonomic nerve damage has an impact on internal organs like heart, gastrointestinal and genitourinary system and involuntary functions are affected, which can lead to abnormal heart rate and blood pressure, reduced ability to perspire, bowel and bladder dysfunction, sexual dysfunction, and thinning of the skin.
Compressive Neuropathy: Also know as entrapment neuropathy, this refers to isolated peripheral nerve injury that occurs at definite locations where nerve gets constricted in a fibrous tunnel or gets deformed by fibrous band. The nerve can be injured by direct compression or stretching forces causing mechanical injury. Carpal tunnel syndrome and ulnar neuropathy at the cubital tunnel are the most common examples.
Hereditary Neuropathies: This is a group of inherited disorder affecting generally peripheral nervous system. Hereditary neuropathies can be categorized into four types: Hereditary sensory and autonomic neuropathy, hereditary sensorimotor neuropathy; hereditary sensory neuropathy as well as hereditary motor neuropathy. CMT disease, one of hereditary sensorimotor neuropathy, is most common type of neuropathy. Symptoms vary depending on type and may include symptoms like pain, numbness and tingling in extremities, weakness, and decreased muscle bulk, especially in lower legs and feet.
Diabetic Neuropathy: Diabetic neuropathy is the term used for damage to the nerves in the body that is done due to high blood sugar levels from diabetes. Often the symptoms develop slowly over the years and can vary depending upon the nerves that are affected. Symptoms may include heartburn, bloating, swallowing problems, nausea, constipation, or diarrhea.
Peripheral Neuropathy: The nerves of the peripheral nervous system i.e., the nervous system that is outside of the brain and the spinal cord, are damaged. This condition is called peripheral neuropathy, and most commonly the nerve axons are damaged. Peripheral neuropathy often causes numbness, pain, burning and tingling sensation in the arms, hands, legs and feet.
Pathophysiology of Neuropathy
Peripheral nervous system is the group of nerves that connect the central nervous system to the internal organs and muscles and transmit sensations throughout the entire body making sensation possible. The important clinical symptoms of peripheral neuropathy include pain, burning, numbness, tingling and aching of the distal limbs, as well as itching or extreme sensitivity to even the slight touch such as to a cloth or towel. These symptoms are generally bilateral and are more pronounced at night; and affect the legs more than the hands.
The pathological features of isolated neuropathies include a varying combination of focal demyelination and Wallerian degeneration.
Angulation and stretch injuries are main mechanisms of a nerve injury when there is ulnar neuropathy along with gross deformity of elbow joint as well as thoracic outlet disease. Continuous compression of nerves due to external forces also tends to cause focal nerve injuries like ulnar neuropathy at elbow and lesions in other branches of ulnar nerve in hand.
Causes and Risk Factors of Neuropathy
About 35% of neuropathies fall under idiopathic where cause of it is unknown. Diabetes is cause for another 35% of neuropathies and about half of people with diabetes develop some type of neuropathy. Rest of cases of neuropathies has various possible causes like:
- Pressure or trauma to nerves, most commonly from typing.
- Nutritional issues and vitamin deficiency.
- Autoimmune disorders like rheumatoid arthritis, lupus, Guillain Barre Syndromes.
- Tumors pressing on nerves.
- Infections and diseases like liver dysfunction, kidney dysfunction, Lyme disease, thyroid dysfunction etc.
- Inherited disorders.
- Exposure to toxins and certain drugs and cancer treatment.
There can be several risks for neuropathy. People suffering from diabetes who have poor control over their blood sugars are more prone to suffer from neuropathy. Individuals who have undergone organ transplantations, AIDS, or have immune suppression are at higher risk of developing neuropathy. Alcohol abuse or vitamin deficiency, particularly B vitamins, places at increased risk of neuropathy.
Signs and Symptoms of Neuropathy
Neuropathy symptoms depend on various factors, mainly the location of the affected nerves and the type of nerves that are affected i.e., sensory, motor, or autonomic. Some types of neuropathy may affect all the three types of nerves. Some of the neuropathies may arise suddenly while others develop gradually over a period of time, sometimes years. Some of the common symptoms are:
- Pins and needles in affected body parts. This can also be termed as tingling and prickling sensation.
- Burning sensation in the legs and feet and as the condition progresses it may also develop in the arms and hands.
- Stabbing, sharp pains which are more pronounced at night, sometimes described as electric-like pain, which starts from the legs and feet and progresses to the hands.
- Muscle weakness.
- Coordination problems.
- Increased susceptibility to skin infections and foot ulcers and other problems that affect the feet.
In autonomic neuropathy, patients may experience symptoms such as hypotension i.e., low blood pressure, where the patient may feel dizzy when getting up from sitting or lying position, accelerated heartbeat i.e., tachycardia, problems with balance, coordination problems, nausea, vomiting, dysphagia i.e., swallowing difficulties, diarrhea, bowel or bladder incontinence, problem emptying the bladder completely, impotence, erectile dysfunction, reduced ability to perspire, and thinning of the skin.
Diabetes is one of the most common causes of peripheral neuropathy though other causes can include infections, metabolic disorders, traumatic injuries, and exposure to toxins. Peripheral neuropathy often causes numbness, pain, burning and tingling sensation in the arms, hands, legs and feet. Symptoms can exist for any length of time, but they often improve with time, specifically in cases where there is an underlying condition that can be cured.
Peripheral neuropathy can eventually lead to dysesthesia where the patients' sense of touch is affected.
Motor nerve damage leads to symptoms that have an effect on the muscles such as cramps, spasms and muscle weakness. This type of neuropathy commonly leads to loss of balance and coordination. Patients may find difficulty with walking or running and feel heaviness in the legs, stumble frequently, or tire easily. Damage to nerves in the arms may make it difficult to do day to day activities like opening jars, turning door knobs and carrying bags.
Sensory nerve damage leads to symptoms such as impaired position sense, numbness, tingling, pinching and pain. Pain is often described as freezing, burning, or electric-like, and many patients report a sensation of wearing an invisible stocking or glove. These sensations are generally worse at night, and can become severely painful. Sensory nerve damage can eventually lead to lessening or absence of sensation, where nothing at all is felt.
Treatment for Neuropathy
There are a variety of treatments available for neuropathy that range from oral medications, creams to special diets and therapies that stimulate the nervous system. Antidepressants are a favored treatment for neuropathies as they relieve the neuropathic pain in people without depression. Anticonvulsants block calcium channels on neurons to limit pain and hence these are also frequently used in treatment. Narcotic and opioid treatments are also used to treat the condition, but are less favored because of risk of dependency, however, opioids have been consistently effective in reducing pain.
For some types of neuropathy, treatment with a topical anesthetic such as lidocaine is recommended. Capsaicin cream is also used to treat neuropathic pain.
Alternative therapies for peripheral neuropathy include Botox, cannabinoids, dietary supplements, chiropractic massages, meditation, yoga, cognitive therapy, and accupuncture.
Neuromodulators are also used in treatment of neuropathy. These include both implantable and non-implantable technologies such as implanted spinal pumps, spinal cord stimulators, electrodes that stimulate the motor cortex of the brain, and deep brain stimulators (DBS).
Investigations for Neuropathy
Peripheral neuropathy cannot be easily diagnosed in many cases. The standard diagnostic process begins with a full medical history and physical and neurological exams to analyze muscle strength and tone, tendon reflexes, examination of sensations, and posture and coordination. Other tests may include:
- Blood tests to measure the levels of vitamin B12, thyroid function tests, and urinalysis.
- Electromyography (EMG) and nerve conduction study (NCV).
- Nerve biopsy, where a small portion of nerve is removed and examined.
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