(mentions CMT) What Is Neuropathy? What Causes Neuropathy?

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What Is Neuropathy? What Causes Neuropathy?

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Neuropathy is a collection of disorders that occurs when nerves of the

peripheral nervous system (the part of the nervous system outside of the brain

and spinal cord) are damaged. The condition is generally referred to as

peripheral neuropathy, and it is most commonly due to damage to nerve axons.

Neuropathy usually causes pain and numbness in the hands and feet. It can result

from traumatic injuries, infections, metabolic disorders, and exposure to

toxins. One of the most common causes of neuropathy is diabetes.

Neuropathy can affect nerves that control muscle movement (motor nerves) and

those that detect sensations such as coldness or pain (sensory nerves). In some

cases - autonomic neuropathy - it can affect internal organs, such as the heart,

blood vessels, bladder, or intestines.

Pain from peripheral neuropathy is often described as a tingling or burning

sensation. There is no specific length of time that the pain exists, but

symptoms often improve with time - especially if the neuropathy has an

underlying condition that can be cured. The condition is often associated with

poor nutrition, a number of diseases, and pressure or trauma, but many cases

have no known reason (called idiopathic neuropathy).

In the United States, about 20 million people suffer from neuropathy. Over half

of diabetes patients also suffer from the condition. '

How is neuropathy classified? Peripheral neuropathy can be broadly classified

into the following categories:

Mononeuropathy - involvement of a single nerve. Examples include carpal tunnel

syndrome, ulnar nerve palsy, radial nerve palsy, and peroneal nerve palsy.

Multiple mononeuropathy - two or more nerves individually affected.

Polyneuropathy - generalized involvement of peripheral nerves.

Examples include diabetic neuropathy and Guillain-Barre syndrome.

Neurophathies may also be categorized based on a functional classification

(motor, sensory, autonomic, or mixed) or the type of onset (acute - hours or

days, subacute - weeks or months, or chronic - months or years).

The most common form of neuropathy is (symmetrical) peripheral polyneuropathy,

which mainly affects the feet and legs on both sides of the body.

What causes neuropathy?

About 30% of neuropathy cases are considered idiopathic, which means they are of

unknown cause. Another 30% of neuropathies are due to diabetes. In fact, about

50% of people with diabetes develop some type of neuropathy. The remaining cases

of neuropathy, called acquired neuropathies, have several possible causes,

including:

Trauma or pressure on nerves, often from a cast or crutch or repetitive motion

such as typing on a keyboard

Nutritional problems and vitamin deficiencies, often from a lack of B vitamins

Alcoholism, often through poor dietary habits and vitamin deficiencies

Autoimmune diseases, such as lupus, rheumatoid arthritis, and Guillain-Barre

syndrome

Tumors, which often press up against nerves

Other diseases and infections, such as kidney disease, liver disease, Lyme

disease, HIV/AIDS, or an underactive thyroid (hypothyroidism)

Inherited disorders (hereditary neuropathies), such as Charcot-Marie-Tooth

disease and amyloid polyneuropathy

Poison exposure, from toxins such as heavy metals, and certain medications and

cancer treatments

Who gets neuropathy?

Risk factors for peripheral neuropathy include several conditions and behaviors.

People with diabetes who poorly control their blood sugar levels are very likely

to suffer from some neuropathy. Autoimmune diseases such as lupus and rheumatoid

arthritis also increase one's chance of developing a neuropathy. People who have

received organ transplants, AIDS patients, and others who have had some type of

immune system suppression have a higher risk of neuropathy. In addition, those

who abuse alcohol or have vitamin deficiencies (especially B vitamins) are at an

increased risk. Neuropathy is also more likely to occur in people with kidney,

liver or thyroid disorders.

What are the symptoms of neuropathy?

Neuropathy symptoms depend on several factors, chiefly where the affected nerves

are located and which type of nerves are affected (motor, sensory, autonomic).

Several types of neuropathy affect all three types of nerves. Some neuropathies

suddenly arise while others come on gradually over the course of years.

Motor nerve damage usually leads to symptoms that affect muscles such as muscle

weakness, cramps, and spasms. It is not uncommon for this type of neuropathy to

lead to a loss of balance and coordination. Patients may find it difficult to

walk or run, feel like they have heavy legs, stumble, or tire easily. Damage to

arm nerves may make it difficult to do routine tasks like carry bags, open jars,

or turn door knobs.

Sensory nerve damage can cause various symptoms, such as an impaired sense of

position, tingling, numbness, pinching and pain. Pain from this neuropathy is

often described as burning, freezing, or electric-like, and many report a

sensation of wearing an invisible " glove " or " stocking " . These sensations tend

to be worse at night, and can become painful and sever. On the contrary, sensory

nerve damage may lead to a lessening or absence of sensation, where nothing at

all is felt.

Autonomic nerve damage affects internal organs and involuntary functions and can

lead to abnormal blood pressure and heart rate, reduced ability to perspire,

constipation, bladder dysfunction, diarrhea, incontinence, sexual dysfunction,

and thinning of the skin.

How is neuropathy diagnosed?

Peripheral neuropathy is often not easy to diagnose. It is not a single disease,

but a symptom with often several potential causes. The standard diagnostic

process begins with a full medical history with physical and neurological exams

that will examine tendon reflexes, muscle strength and tone, the ability to feel

sensations, and posture and coordination. Blood tests are also common in order

for doctors to measure levels of vitamin B-12. Other common tests include

urinalysis, thyroid function tests, and a nerve conduction study that includes

electromyography (to measure electrical discharges produced in muscles).

Physicians may also recommend a nerve biopsy, where a small portion of nerve is

removed and examined under a microscope.

How is neuropathy treated?

There are a variety of treatments available for peripheral neuropathy. They

range from traditional pills and creams to special diets and therapies that

stimulate the nervous system. Antidepressants, especially tricyclics and

selective serotonin-norepinephrine re-uptake inhibitors (SNRI's), are a favored

treatment for neuropathies. They will relieve neuropathic pain in non-depressed

persons.

Another class of medicines commonly prescribed for neuropathy is that of

anticonvulsants. These medicines block calcium channels on neurons to limit

pain. Opioid narcotic treatments for neuropathy are used as well to treat the

condition, but are less favored because of the risk of dependency. However,

opioids have been the most consistently effective in reducing pain.

For some types of neuropathy, such as post-herpes neuralgia, physicians

recommend treatment with a topical anesthetic such as lidocaine. Topical

applications of capsaicin (the chemical that makes peppers hot) has also been

used to treat neuropathic pain.

Alternative therapies for peripheral neuropathy include cannabinoids (an class

of chemicals found in marijuana), Botulinum Toxin Type A (better known as

Botox), NMDA antagonists (such as ketamine), dietary supplements (such as alpha

lipoic and benfotiamine), chiropractic massages, yoga, meditation, cognitive

therapy, and accupuncture.

A final class of therapies for neuropathy are called neuromodulators. These

include both implantable and non-implantable technologies (electrical and

chemical) such as spinal cord stimulators, implanted spinal pumps, electrodes

that stimulate the motor cortex of the brain, and methods called deep brain

stimulation.

How can neuropathy be managed and prevented?

There are several ways to manage neuropathy and prevent its symptoms. Good foot

health is important, especially for diabetics. Patients should check feet for

blisters, cuts, or calluses and avoid tight fitting shoes and socks. Doctors can

recommend an exercise plan that will reduce neuropathy pain and control blood

sugar levels.

Patients should also quit smoking and eat healthful meals. Massages of hands and

feet may also aid neuropathy management by stimulating nerves and temporarily

relieving pain. Finally, it is advised to avoid prolonged pressure on knees or

elbows in order to prevent new nerve damage.

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