Classifications of
Peripheral Neuropathy
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Mononeuropathies are neuropathies that involve only one nerve and can be very painful. If you have more than one mononeuropathy, it may be called mononeuropathy multiplex or multifocal mononeuropathy. |
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Peripheral Polyneuropathies involve a number of nerves and are typically distributed in a "stocking and glove" distribution bilaterally - meaning they affect both feet, both legs and/or both hands. These can be classified in a number of ways. |
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Sensory neuropathy is neuropathy of the nerves that control your ability to feel pain, temperature, position and touch. These nerves can become "hypersensitive" and can cause significant pain. Damage to sensory nerves may also make your feet feel numb or like you are walking on cushions or blocks of wood and can affect your ability to feel an injury and your ability to keep your balance. |
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Motor neuropathy is neuropathy of the nerves that control your ability to move your muscles, your coordination and your ability to walk. |
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Sensory-motor neuropathy means that both sensory and motor nerves are impaired. |
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Autonomic Polyneuropathies involve the nerves that regulate biological activities that you do not control consciously, such as digesting food, sweating and heart and gland functions. If you have peripheral neuropathy, your feet and hands may not sweat and can become cracked and dry, putting you at risk of other complications. |
Symptoms of
Peripheral Neuropathy
Symptoms of neuropathy depend on the types of nerves affected and can affect people in many different ways.
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Sensory neuropathy symptoms include: |
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Pain – Neuropathic pain is often described as burning, shooting, stabbing, like electrical shocks, pins and needles and throbbing. Painful symptoms are often more common in the earlier phases of sensory neuropathy. Many times the pain is worse at night and can interrupt sleep and make it difficult to walk, wear shoes, exercise or even tolerate sheets touching your feet! This pain may last for years in some cases. In other cases, the pain progresses to numbness, but may still return from time to time. |
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Numbness or loss of sensation – This is the inability to feel touch, temperature or vibration. This numbness may be described as feeling like you are wearing stockings and gloves, or that you are walking on sponges, cushions or blocks of wood. Some people describe that it feels like their feet are not touching the ground. Numbness in the hands makes it difficult to use your fingers to write, button clothing, pick up small objects, etc. |
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Loss of balance – This is due to the inability to feel uneven surfaces, such as when you walk outside. Neuropathy may cause you not to feel the position of your feet and ankles (known as proprioception) and whether your feet are up or down. If you cannot feel the position of your feet, it becomes very difficult to maintain your balance, especially with your eyes closed. |
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Motor neuropathy symptoms include: |
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Muscle weakness – When your muscles feel weak, you can lose your ability to walk and do activities that require coordination. Sometimes people have to wear braces to better control their muscles. In severe cases, people may have to use a wheelchair. |
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Twitching/Restless Leg Syndrome – Some people develop twitching, tics or a condition called restless leg syndrome (RLS) when motor nerves are affected by peripheral neuropathy. RLS is characterized by unpleasant sensations in the legs and an uncontrollable urge to move them for relief. People affected with RLS describe the sensations as burning, creeping, tugging, or like insects crawling inside the legs. The sensations range in severity from uncomfortable to irritating to painful. |
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Foot Drop – With severe motor neuropathy, some people lose the ability to raise the foot at the ankle. When this occurs, walking can be difficult and can result in a slapping motion. Some people may have to wear a brace to control this slapping motion. Foot drop may also be caused by injuries or surgery when certain nerves are damaged. |
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Painful muscle cramps or spasms – Cramping can occur in the muscles, especially when the motor nerves and muscles are not getting enough blood flow. |
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Autonomic neuropathy – Autonomic neuropathy in general refers to damage of the nerves that control involuntary muscles and function such as the ability to digest food, urinate, maintain blood pressure, breath, sweat, etc. Involuntary functions are body functions that typically occur without you needing to think about them. When autonomic nerves are damaged by disease or toxins, these bodily functions can be affected. |
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Inability to sweat – This makes it difficult to control body temperature, especially when it is hot outside or during exercise if you become over-heated. |
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Digestion problems (also called Gastroparesis) – These are due to nerve damage in the stomach and intestines which can cause diarrhea, constipation, difficulty swallowing and problems controlling blood sugar in diabetes. |
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Inability to control heart beat or feel a heart attack – When nerves in the area of the heart are affected, you may have abnormal heart response to activity or you may lose the ability to feel a heart attack. This condition is called a “silent heart attack” and can mean you do not seek treatment in a timely manner. |
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Trouble breathing – People with severe autonomic neuropathy may have damage to the nerves that control the diaphragm – a large muscle that controls breathing. |
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Loss of bladder control – Symptoms may include diminished sensation of the need to urinate, overflow incontinence and inability to empty your bladder completely, which can lead to urinary tract infections. |
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Sexual problems including erectile dysfunction (ED) can be caused by autonomic neuropathy. |
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Dizziness or fainting when standing (postural orthostatic hypotension) which is caused by the inability to maintain blood pressure. |
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Inability to detect low blood sugars (hypoglycemia) in people with diabetes – Normally low blood sugars will cause shakiness, palpitations and sweating. People with autonomic neuropathy may develop “hypoglycemia unawareness” which can cause them not to seek treatment immediately. |
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Other Symptoms of Peripheral Neuropathy |
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Changes in skin, hair, nails – People with neuropathy may develop very dry, itchy skin due to the the lack of sweating and lack of blood flow. Skin may crack and peel. Some people lose the hair on the legs and feet and may develop more frequent fungal infections in their feet and toenails – or may lose their toenails entirely. |
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Wounds that don’t heal – Sores may not heal properly in people with neuropathy, and sometimes they are not discovered right away due to loss of sensory nerve function. Poor microvascular blood flow to the skin may cause wounds that do not heal for years in some cases. In fact, peripheral neuropathy is the leading cause of lower extremity amputations. |
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Degeneration of bone, cartilage and ligaments – People with peripheral neuropathy may also see their foot bones and the ligaments that hold them in place degenerate to the point where they develop what is known as Charcot Foot. At the latest stages of Charcot foot, the foot develops a rocker bottom as the foot bones fracture and may require special shoes to prevent callous formation and wounds. |
Causes of
Peripheral Neuropathy
The causes of peripheral neuropathy are many and varied and in some patients, may have several contributing factors. It is often difficult to pinpoint the cause, leading to many people being diagnosed with “idiopathic neuropathy” – a neuropathy of unknown origin.
Idiopathic Neuropathy
Idiopathic Neuropathy can be very frustrating to people who have it. There can be many causes and sometimes more than one can contribute to the nerve damage. It can be as simple as undiagnosed diabetes, since high blood sugars may go on for years undetected. It could be complicated by drugs, toxins, infections, vitamin deficiencies, heredity and autoimmune conditions. Below is a description of some of the known causes of peripheral neuropathy. More and more things are being found to cause peripheral neuropathy, so don’t lose hope of finding the cause of your neuropathy.
Diabetic Peripheral Neuropathy (DPN)
Diabetes mellitus, characterized by high blood sugar levels, is a leading cause of peripheral neuropathy in the United States
and Canada. About 60 to 70 percent of people with diabetes have mild to severe forms of neuropathy. People with diabetes either have Type 1 diabetes (an autoimmune condition that destroys the pancreatic cells that make insulin) or Type 2 diabetes (a condition typically of obesity characterized by insulin resistance and often accompanied by high blood pressure and high cholesterol).
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DPN is a microvascular complication, which means it is a disease of the small blood vessels that supply the nerves with nutrients. Other microvascular complications of diabetes include diabetic nephropathy (kidney damage) and diabetic retinopathy (eye damage). Often these three complications go hand in hand and the Diabetes Control and Complications Trial (DCCT) showed that tight blood glucose control was critical to prevention of these complications. |
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Recent research suggests that diabetic peripheral neuropathy is caused by endothelial dysfunction (poor function of the cells that line the blood vessels) and a lack of appropriate release of nitric oxide. Nitric oxide is an important molecule which allows the blood vessels to properly dilate, controls blood pressure and is important for the many growth factors that rebuild tissue and bone as part of healing. Many people with diabetes have high blood pressure, and research suggests that high blood glucose scavenges nitric oxide and endothelial dysfunction prevents the production of normal amounts of nitric oxide. |
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In some cases, just because you have diabetes, it may not be the only cause of your neuropathic symptoms! In cases where DPN is complicated by other factors such as nutritional deficiencies, thyroid disease, kidney or liver disease, vascular disease, anemia, spinal problems, etc. those issues should also be addressed. Below are some of the many non-diabetic conditions that can also cause peripheral neuropathy. |
Pre-Diabetic Neuropathy
Pre-diabetes is characterized by glucose intolerance and is believed to also begin causing nerve damage and other complications of diabetes. If you have ever been told you are have “borderline diabetes,” you either already have diabetes, or are at significant risk of developing diabetes and peripheral neuropathy if you do not take appropriate measures to lose weight and address the other vascular risks associated with diabetic neuropathy. If you have ever been diagnosed with Gestational Diabetes during pregnancy, you are also at higher risk of developing pre-diabetes or diabetes.
Non-Diabetic Peripheral Neuropathies
Nutritional/Vitamin Deficiencies
Certain vitamins and minerals are essential for healthy nerve function and healthy blood flow to the nerves. Lack of these vitamins and minerals can cause lack of blood flow and nerve function deficits. If you have difficulty digesting food, have an eating disorder or are just not eating properly, you may have a vitamin deficiency. Some of the most important vitamins and minerals for blood vessel and nerve health include the following: |
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Vitamins E, B1 (thiamine), B6, B12 |
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Niacin |
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Folic acid |
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Magnesium |
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Alpha Lipoic Acid |
Kidney or Liver Disease
The kidneys and liver are very important organs for eliminating drugs, toxins and waste substances from the body and maintaining chemical balance in the body. When these organs do not function properly as a result of infection, inflammation or other types of damage, their dysfunction can result in neuropathy. |
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Kidney disease – Kidney disease is a microvascular complication and one of the most common complications of diabetes. People who are on kidney dialysis can have abnormally high amounts of toxic substances in the blood that can severely damage nerve tissue. A majority of patients who require dialysis because of kidney failure develop polyneuropathy. |
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Alcohol Abuse and Liver Disease – Alcohol abuse may cause neuropathy directly, or can cause vitamin and nutritional deficiencies that can lead to neuropathy. In addition, liver disease can lead to neuropathies as a result of chemical imbalances and abnormally high levels of toxic substances. |
Peripheral Vascular Disease (PVD)
PVD includes any vascular disease that affects the peripheral blood vessels in the legs and feet.
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Microvascular Disease: Most people think of heart attack and stroke when they think of vascular disease. These are very serious “macrovascular” (large blood vessel) complications of vascular disease. However, when you have vascular disease in the extremities, you do not have to have large blood vessel disease to suffer from neuropathy. You may have “microvascular” disease in the small capillaries that feed your nerves and skin. If you have high blood pressure, high cholesterol or have ever had a bypass surgery, you suffer from vascular disease, which will also be present in all the other blood vessels in your body. Conditions such as Raynaud’s Syndrome, a disease that causes rapid vasoconstriction of capillaries and lack of microvascular blood flow to the feet and/or hands, can cause extreme neuropathic pain. |
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Peripheral Venous Disease (Venous Insufficiency) – This is disease of the veins in the lower extremities and causes swelling and pooling of blood in the lower legs, ankles and feet. Veins are the blood vessels that return blood flow to the heart, lungs and other organs to drop off waste products and receive additional nutrients and oxygen. Venous insufficiency can be due to damage to a vein caused by an injury or surgery or may be caused by smoking or general vascular disease. When the valves of the veins are damaged, the blood pools in the lower legs and there is not proper oxygen exchange. Toxins and wastes build in the blood and can cause pitting edema and wounds. Often the legs have a discoloration or purple blotches called hemasiderin. Although there is swelling, there is actually poor blood flow in the area and the blood is hypoxic, which means it lacks oxygen. Neuropathy in this condition may be caused by a lack of oxygen or nutrients to the nerves, or may be caused by the swelling impinging on the nerves. |
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Peripheral Arterial Disease (PAD) – Arteries are the large blood vessels that carry oxygen and nutrients from the heart to the extremities. Disease of the arteries may be caused by plaque build-up in the arteries of the legs or abdomen and is more common in smokers. This plaque may cause a blood clot or clots to block blood flow to the lower extremities. PAD is characterized by intermittent claudication (calf muscle spasms during activity), lack of blood flow to the lower extremities, severe pain called ischemic pain, non-healing wounds, lack of hair and toenails and in the worst cases, gangrene and amputations. |
Anemias
Anemia is a common blood disorder that occurs when the level of healthy red blood cells (RBCs) in the body becomes too low. This can lead to health problems because RBCs contain hemoglobin, which carries oxygen to the body's tissues. Anemia can cause fatigue and stress on bodily organs and can cause significant neuropathic pain. Anemia can be caused by many things, but some of the causes are excessive destruction of RBCs, blood loss and inadequate production of RBCs. It can result from inherited disorders, nutritional problems (such as an iron or vitamin deficiency), infections, some kinds of cancer, or exposure to a drug or toxin. Some types of anemia are:
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Vitamin Deficiency Anemias |
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Pernicious anemia - caused by B12 vitamin deficiency or if the body cannot properly absorb vitamin B12 |
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Folate anemia – caused by a lack of folic acid |
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Iron deficiency anemia – caused by a lack of iron |
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Hemolytic Anemias |
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Sickle cell anemia – This is a severe form of inherited anemia found most commonly in people of African heritage. In this condition, the red blood cells stretch into abnormal sickle shapes. This leads to premature destruction of RBCs, chronically low levels of hemoglobin, and recurring episodes of pain, as well as problems that can affect virtually every other organ system in the body. |
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Thalassemia – Another type of inherited hemolytic anemia |
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Aplastic Anemia – when the body doesn’t make enough RBC’s which can occur during radiation therapy, chemotherapy, with certain toxins and medications and bone marrow infections. |
Pharmaceutical Drugs
Pharmaceuticals can be life-saving, but in some cases, they can cause peripheral neuropathy. Some of the drug classes that can cause peripheral neuropathy are below. If you have a pre-existing problem that causes peripheral neuropathy such as diabetes, vascular disease or alcoholism, these drugs may be more likely to cause peripheral neuropathy.
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Chemotherapy/Cancer Drugs – Cisplatin, Vincristine, Paclitaxel, Etoposide, Tenoposide, Thalidomide, Interferon, Docetaxel, Oxaliplatin, Bortezimib |
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Antibiotics and antivirals – Metrinidazole - Flagyl®, Nitrofurantoin, Thalidomide, INH (Isoniazid), Stavudine (Zerit®) |
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Cholesterol lowering drugs (Statins) |
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Anticonvulsants (Phenytoin - Dilantin®) |
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Anti-alcohol drugs (Disulfiram) |
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Heart or blood pressure medications (Amiodarone, Hydralazine, Perhexiline) |
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Skin treatment drugs (Dapsone) |
Infections
Bacteria and viruses can attack the nerves causing pain and numbness. Some of those known to cause peripheral neuropathy include:
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Viral infections that can cause peripheral neuropathy |
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HIV/AIDS |
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Herpes varicella-zoster (Shingles) |
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Herpes simplex |
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Cytomegalovirus |
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Epstein-Barr virus (Mononucleosis, Chronic Fatigue Syndrome |
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Hepatitis B and C |
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Bacterial infections that can cause peripheral neuropathy |
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Lyme Disease – caused by a tick bite |
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Leprosy – rare in the U.S.
and Canada today often caused loss of fingers and toes |
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Dyptheria – rare in the U.S.
and Canada due to widespread vaccination program |
Autoimmune and Inflammatory
Neuropathies
These
are neuropathies caused by inappropriate response of the body’s
own immune system. Autoimmune disorders are believed to develop
as the result of the body’s response to a virus or bacterial
infection. Instead of attacking the pathogen, the body instead
starts to attack an organ or tissue within the body. The exact
cause of autoimmune conditions is unknown. In some cases, the
body’s immune response causes so much inflammation, that the
inflammatory response causes peripheral neuropathy. These
conditions often ebb and flow in alternating patterns of
remission and relapse. Below is a partial list of some of the
autoimmune and inflammatory conditions known to cause peripheral
neuropathy.
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Inflammatory Neuropathies |
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Guillain-Barre’ Syndrome |
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Chronic
inflammatory demyelinating polyneuropathy (CIDP) |
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Multifocal
motor neuropathy |
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Amyloidosis |
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Sarcoidosis |
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Autoimmune
disorders that can cause peripheral neuropathy |
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Rheumatoid Arthritis |
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Lupus |
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Celiac
Disease |
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Type 1
Diabetes |
Nerve
Impingements
When nerves are compressed in any way, a neuropathy
can develop. The most common types of conditions that may cause
nerve impingements and neuropathic pain and numbness are caused
by inflammation in the area that impinges on the nerves. This
inflammation can be caused by:
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Spinal problems -
spinal stenosis, spinal compression, herniated or ruptured
disk, sciatica |
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Tumors and cancers
- as they grow, can impinge on nerves and cause pain or
numbness |
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Physical
injury, trauma or surgery -
When an
injury is sustained to an area, nerves may be cut or damaged
or compressed.
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Connective
tissue disorders -
Chronic
inflammation leads to the progressive destruction of
connective tissue, making nerve fibers more vulnerable to
compression injuries and infections. Joints can become
inflamed and swollen and entrap nerves, causing pain |
How is Peripheral Neuropathy
Diagnosed?
Diagnosing peripheral neuropathy is often difficult because the
symptoms are highly variable and the causes are so varied. A
thorough neurological examination is usually required and involves
an extensive patient history (including symptoms, nutrition, work
environment, social habits, exposure to toxins, history of
alcoholism, risk of HIV or other infectious disease, and family
history of neurological disease). A specialist called a Neurologist
may be the best doctor to help you diagnose your condition if your
primary care physician cannot determine a cause.
Blood tests that may identify the cause of peripheral neuropathy
would include tests for diabetes, cardiovascular disease,
connective tissue disorders, cancer, kidney or liver
dysfunction, hormonal imbalances, abnormal immune system
activity, infections, antibodies, toxins and vitamin
deficiencies.
Physical tests to determine the extent and type of peripheral
neuropathy
would include tests of muscle strength, as well as evidence of
fasciculation or muscle cramps. These types of tests indicate
motor fiber involvement. Evaluation of a patient’s ability to
sense vibration, light touch, body position, temperature, and
pain reveals sensory neuropathy and may indicate whether small
or large sensory nerve fibers are affected.
Computed tomography, or CT scan,
is a noninvasive, painless process used to produce
two-dimensional images of organs, bones, and tissues.
Magnetic resonance imaging (MRI)
can provide more extensive information and examine muscle
quality and size and determine whether a nerves have sustained
compression damage.
Electromyography (EMG)
involves inserting a fine needle into a muscle to compare the
amount of electrical activity present when muscles are at rest
and when they contract. EMG tests can help differentiate between
muscle disorders and peripheral neuropathies.
Nerve conduction velocity (NCV)
tests can quantitatively measure the extent of
nerve damage and can determine whether the neuropathy is caused
by degeneration of the myelin sheath or the axon.
Nerve biopsy
involves removing and examining a sample of nerve tissue, most
often from the lower leg. Although this test can provide
valuable information about the degree of nerve damage, it is an
invasive procedure that is difficult to perform and may itself
cause neuropathic side effects. Many experts do not believe that
a biopsy is always needed for diagnosis.
Skin biopsy
is a test in
which doctors remove a thin skin sample and examine nerve fiber
endings. This test offers some unique advantages over NCV tests
and nerve biopsy. Unlike NCV, it can reveal damage present in
smaller fibers; in contrast to conventional nerve biopsy, skin
biopsy is less invasive, has fewer side effects, and is easier
to perform.
What Treatments are Available?
If you
have an inherited form of peripheral neuropathy, there are no
medical treatments today. However, there are therapies for many
other types of peripheral neuropathy. Any underlying condition is
treated first, as often this will, in itself, often resolve the
neuropathy. Peripheral nerves have the ability to regenerate, as
long as the nerve cell itself is not dead. Symptoms often can be
controlled, and eliminating the causes of specific forms of
neuropathy often can prevent new damage.
Treatment of Neuropathic Pain
Neuropathic pain can difficult to control. Anodyne Therapy
has been approved by Health Canada for the following
indications:
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Temporarily reducing disturbances of skin
sensation due to diabetic and other peripheral neuropathies
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Used adjunctively with physical therapy,
temporarily increases balance and fall risk of patients with
diabetic and other peripheral neuropathies
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Temporarily increases local circulation and
reduces pain
Anodyne
Therapy is a non-invasive, drug-free way to relieve neuropathic
pain and works in three ways:
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Increases circulation to nerves and tissues
in the treatment area where there is lack of blood flow
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Reduces inflammation and swelling and relaxes
muscle spasms that may be causing nerve impingement or
compression
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Directly on the nerves to relieve pain
Drugs for neuropathic pain include over the counter medications,
anti-seizure medications and some classes of antidepressants.
Topical creams such as capsaicin which is made of an extract of
chili pepper may help relieve neuropathic pain. Injections of
local anesthetics such as lidocaine or topical patches
containing lidocaine may relieve more severe neuropathic pain.
If inflammation is the cause, sometimes injections of cortisone
are used to reduce inflammation that may be impinging on nerves.
In the most severe cases, doctors can surgically
destroy nerves; however, the results are often temporary and the
procedure can lead to complications.
Treatment of Systemic Diseases
Strict control of blood glucose levels has been shown to reduce
neuropathic symptoms and help people with diabetic neuropathy
avoid further nerve damage. Managing your cholesterol and blood
pressure to healthy levels can help prevent blood vessel damage
that may limit circulation to nerves. Correcting hormonal
imbalances may be important to preventing damage as well.
Autoimmune and Inflammatory peripheral neuropathies may require
drugs to suppress the immune system such as prednisone,
cyclosporine, or azathioprine. Plasmapheresis - a procedure in
which blood is removed, cleansed of immune system cells and
antibodies, and then returned to the body - can limit
inflammation or suppress immune system activity. High doses of
immunoglobulins (IVIG), proteins that function as antibodies,
also can suppress abnormal immune system activity.
With toxic or drug-related peripheral neuropathies, removing the
source of the toxin will sometimes allow the nerves to
regenerate if the nerve cell itself is not dead.
Treatment of Balance and Other Physical
Impairments
Physical or Occupational Therapy should be considered for people
with balance issues and other physical impairments that have
caused functional limitations. Hand or foot braces can
compensate for muscle weakness or alleviate nerve compression.
Orthopedic shoes can improve gait disturbances and help prevent
foot injuries in people with a loss of sensation. If breathing
becomes severely impaired, mechanical ventilation can provide
essential life support.
Healthy Lifestyle
If
you have peripheral neuropathy, it is even more important to
keep a healthy lifestyle which includes maintaining a healthy
weight, not smoking, eating a balanced diet, correcting vitamin
deficiencies, limiting alcohol intake and avoiding exposure to
toxins.
A
physician-supervised exercise program can reduce muscle spasms,
improve muscle strength, and prevent muscle deterioration.
Certain diets can improve gastrointestinal symptoms caused by
autonomic neuropathy. Quitting smoking is very important because
smoking constricts the blood vessels that supply nutrients to
the peripheral nerves and can worsen neuropathic symptoms. Foot
care and wound treatment in people with diabetes and others who
have an impaired ability to feel pain can prevent long term
complications.
In summary, since many neuropathies
are aggravated by the lack of a healthy lifestyle, maintaining a
healthy lifestyle can be one of the best things you can do to
reduce the symptoms and prevent further nerve damage in
peripheral neuropathy.
Additional Resources
The Neuropathy Association
www.neuropathy.org
Canadian Diabetes Association
www.diabetes.ca
Canadian Neuropathy Association
www.canadianneuropathyassociation.org
Health Canada
www.hc-sc.gc.ca/dc-ma/diabete/index-eng.php
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