Neuropathy

What is the Nervous System?

 

There are two major divisions of the nervous system.  The central nervous system which includes the brain and the spinal cord and the peripheral nervous system which includes the peripheral nerves and muscles.  

There are 3 types of peripheral nerves:  

- Sensory nerves perform functions such as sensing touch, pain and temperature on the skin.  They are also involved in balance.  

- Motor nerves communicate with muscles to help us move. 

- Autonomic nerves control involuntary muscles such as those involved with the heart, digestion and urination.  

What is Neuropathy?

 

When imbalance of the body manifests in the peripheral nervous system (in the nerves), it is known as a “neuropathy”.  Sensory, motor and autonomic nerves can be involved. Neuropathy is a disruption in the communication between our extremities and the brain leading to abnormal sensation, motor control and/or balance.  Because the nerves also communicate with blood vessels, there can be abnormalities of blood circulation causing discoloration of the skin. 

 

The most common forms of neuropathy involve the longest nerves in the body, so the feet are most often affected followed by the hands.  The longest nerves are typically affected first because of the great amount of energy required to carry nutrients to the nerve endings.  The nutrients required by the nerves endings in the feet must travel all the way from the nerve cell body which is located near the spinal cord. The small blood vessels that supply the nerve endings to the feet may also be affected, and therefore the necessary supply of oxygen and blood born nutrients do not reach the nerve endings leading to unhealthy nerves.

What Causes Neuropathy?

 

There are at least 5 main ways that nerves are damaged preventing normal nerve function and health:

1. Toxic exposure 

2. Nutritional imbalances 

3. Inflammation or infection affecting the nerve, nerve covering or involving the blood vessels supplying the nerve 

4. Direct trauma or compression to a nerve or group of nerves

5. Genetic causes

Nerve disorders may present as ‘mono’neuropathies affecting a single nerve or ‘poly’neuropathies affecting multiple nerves.  Mononeuropathies are most commonly caused by trauma or external compression.   On the other hand, almost anything that causes dis “ease” in the body can lead to polyneuropathy.  A wide variety of environmental factors (diet, sedentary life-style, toxic exposure, alcohol, infections and medications such as chemotherapy that are used for cancer treatment) are known to be associated with polyneuropathy.  Conditions associated with neuropathy include blood sugar dysregulation, diabetes, obesity, hypertension, abnormal blood lipid accumulation, vitamin deficiencies, autoimmune conditions and bone marrow disorders.  Many of the conditions associated with neuropathy are preventable and treatable.

 

What are Symptoms of Neuropathy?

 

There are many symptoms of neuropathy depending on the type of nerves involved and the distribution in the body.  Most commonly, symptoms are in the feet and legs followed by the hands and include symptoms from involvement of the: 

1. sensory nerves: numbness, tingling, burning, pain, gait imbalance or incoordination

2. motor nerves: weakness, atrophy in the muscles, cramping and twitching in the feet and calves

3. autonomic nerves: skin color changes particularly on the feet, loss of hair on the legs, light-headedness, sexual dysfunction, changes in urination, changes in sweating and constipation.

Treatments for neuropathy 

 

It is important to address any root cause environmental factors and medical conditions that are associated with or may be contributing to neuropathy.  An anti-inflammatory approach to the treatment of neuropathy includes nutrition, exercise, toxin avoidance and stress reduction in addition to symptomatic treatment for nerve pain and discomfort.  

1. Diet and lifestyle

Proper nutrition is crucial for health including the health of the nervous system. Foods to support an anti-inflammatory, neuroprotective life-style include whole foods with a high phytonutrient density, low-glycemic-load, protective anti-oxidants, soluble fiber and high-quality dietary fats. 

 

Inflammatory foods such as sugar, heavily processed flour, genetically modified foods, chemical additives and artificial sweeteners, heavily processed oils and fats, conventionally raised meats and pesticide laden produce are best avoided as they may disrupt normal gut integrity and contribute to blood sugar dysregulation and systemic inflammation.

2. Exercise and physical therapy
Exercise is paramount to health including the health of the brain and peripheral nerves.  Studies have shown that moderate to rigorous exercise is protective against health-related conditions associated with neuropathy.   
In syndromes of blood sugar dysregulation such as diabetes and metabolic syndrome sixty minutes of regular exercise 3-4 times per week improved the body’s ability to regenerate nerve-endings as shown in biopsies of the skin. 
 
Moderate physical exercise is anti-inflammatory, improves gut, brain and nerve health and contributes to maintenance of a healthy body weight and muscle mass.  Always consult with your healthcare professional before starting a new exercise program.

3. Acupuncture 

Acupuncture involves inserting very thin needles into acupuncture points which are located throughout the body.  Acupuncture has been utilized in the East for centuries and thought to balance Chi, one name for our vital life force energy.  In the West, acupuncture is growing in popularity for the treatment of a variety of pain syndromes including neuropathy.  A large scientific review revealed the benefit of acupuncture over usual medical care alone for diabetic neuropathy and carpal tunnel syndrome. The positive studies used acupuncture points located near to affected peripheral nerves suggesting that acupuncture has a direct effect on the nerve tissues.  Research also suggests that the effects of acupuncture may in part be due to alterations in brain plasticity.  A gentle electrical stimulation is often placed through the acupuncture needles to optimize pain relief.  Generally, a course of 6-12 acupuncture treatments, 1-3 times per week is recommended to determine if it will be of benefit.  Once benefit is noted, less frequent treatments may be sufficient.

4. Movement based therapies such as Tai Chi and yoga

Tai Chi is a traditional Chinese martial art that has been practiced for many centuries consisting of deep diaphragmatic breathing and relaxation with slow, gentle movements and postures.  It is known for improving balance, flexibility and mental focus.  Studies of Tai Chi for neuropathy show improved blood sugar regulation, balance and symptoms of neuropathy.  Additionally, Tai Chi has been shown to improve immune function in diabetic patients. 

Yoga is an ancient practice of body postures, conscious breathing and mental focus.  Frequent and consistent practice of gentle yoga has been shown to be beneficial for various neurological disorders, pain, and diabetes in multiple studies. The practice of yogic postures as well as yogic breathing improves the function of the autonomic nervous system including heart function. 

5. Vitamins and Supplements

There are well-tolerated vitamins and supplements with evidence showing benefit in neuropathy and neuropathic pain.  Historically, physicians have avoided recommending nutraceuticals and herbs due to the lack of rigorous federal regulatory oversight of these compounds as well as potential interactions with pharmaceutical agents. These are important concerns. Nutraceutical treatment should be used under the guidance of a healthcare professional. 

Alpha-Lipoic Acid 

Alpha-Lipoic Acid is a naturally occurring fatty acid that can be found in many foods in very small amounts such as yeast, spinach, broccoli, potatoes, and organ meats.  It is an anti-oxidant and thought to be protective against free radical damage.  ALA in supplement form has been extensively studied and used in Europe for the treatment of neuropathy associated with diabetes. Both IV and oral forms of ALA have been shown to improve symptoms of neuropathy and may help to protect against further nerve damage.  It is generally well tolerated but side-effects can include nausea, vomiting and dizziness.  A side-effect of IV treatment is low blood sugar. 

 

Acetyl-l-carnitine (ALC) 

Acetyl-l-carnitine is an amino acid that is naturally occurring in the body. It helps produce energy.  As a supplement, it has been extensively studied in Europe in neuropathy associated with diabetes.   Studies have shown ALC to improve the pain of diabetic neuropathy.  Additionally, there is evidence that it can aid in nerve regeneration.  Although generally well-tolerated, there is a potential for gastrointestinal side-effects such as nausea, vomiting or diarrhea.

Vitamin D

Research has noted an association between low vitamin D levels and the presence and severity of neuropathy in diabetes and after chemotherapy.  Vitamin D levels can be monitored by a simple blood test.   Supplementation and brief daily sun exposure as well as foods rich in Vitamin D may be recommended to keep Vitamin D levels within the normal range.

Blog post: Outside is Good Medicine

B Vitamins

There is scientific evidence to support the use of B vitamins for neuropathy especially when there is a deficiency of B vitamins in the body.  Vitamin B12 deficiency is particularly common in the US secondary to diet, medication use, and the reduced vitamin absorption which occurs with aging.  Some forms of B vitamins may be better able to be used by the body.  These forms are the methyl-folate form of folate, methylcobalamin form of vitamin B12, pyridoxal-5-phosphate form of vitamin B6 and benfotiamine form of vitamin B1.  There is clinical trial evidence supporting the use of these B vitamins to reduce the symptoms of neuropathy associated with diabetes.  A cautionary note is that very high and sustained dosages of vitamin B6 at greater than 200mg daily may cause toxicity leading to neuropathy.  

6. Pharmaceuticals

Antidepressants

All antidepressants require chronic treatment in order to see a beneficial effect on pain.  The improvement in pain seen with antidepressants is independent of the presence of depression.

 

Tricyclic Antidepressants (amitriptyline, desipramine)

This category of drugs has been used for neuropathy pain since the 1980’s and has a very good track record of success regarding pain relief.  However, the side-effects limit its use.  More common side-effects, known as anti-cholinergic side-effects, include dry mouth, dizziness and constipation.  A side-effect of concern is confusion, especially in the elderly or in those who are on other medications that can similarly cause confusion.  For younger patients, this drug may be a good choice, especially if there is pain-related insomnia, because another side-effect of this class of drugs is drowsiness.  Therefore, it can be used as a sleep aid.

 

5-HT and norepinephrine reuptake inhibitors (Duloxetine, Venlafaxine)

This class of anti-depressant drugs is newer than the tricyclic antidepressants, and is considered to be better tolerated, with a similar degree of pain relief.  Duloxetine is FDA approved for the treatment of neuropathy associated with diabetes.  More common side-effects of this class of medications include nausea, sleepiness, excessive sweating, loss of appetite and constipation.

Anticonvulsants

All anti-convulsant medications require chronic treatment in order to see a beneficial improvement in neuropathy pain.  Both gabapentin and pregabalin are commonly used as first-line medications for management of neuropathy pain.  According to scientific studies, they have a modest effect on nerve pain.

 

Gabapentin 

A large scientific analysis concluded that less than half of patients treated with gabapentin will have worthwhile pain relief.  The side-effects are dizziness, sleepiness, weight gain and confusion.  Although most side-effects can be avoided by slowly titrating up on the dosage.

 

Pregabalin

Pregabalin is FDA approved for treatment of the neuropathy pain associated with diabetes.  Three large clinical found that pregabalin helped neuropathy pain, but the improvement was small.  Drowsiness, confusion and weight gain can also be seen with this drug.

Pharmaceutical drugs are generally used in neuropathy to suppress pain symptoms.  For the most common forms of neuropathy, there are no current pharmaceuticals to improve nerve function or to facilitate nerve repair, and the benefits as far as pain relief tend to be modest.  Therefore, the most important measures include treatment of the root causes of the neuropathy as discussed above (See What Causes Neuropathy?). 

 

There are several classes of drugs used for neuropathy pain.  These include antidepressants, anticonvulsants and topical medications.  Generally 

speaking, drugs in the anti-depressant, anti-convulsant and topical categories can be used for first-line treatment in the symptomatic management of nerve pain.  The choice of medications depends on factors such as side-effect profile, experience of the physician, and potential drug interactions.

Dietary Essential Fatty Acids

Omega-3 fatty acids found in foods such as salmon, walnuts and flaxseed are crucial to nerve health. Myelin, the covering of nerves, is comprised of 70% fats.   Essential fatty acids (EFAs) cannot be made by the body and must be supplied by the diet, and EFAs and cholesterol are required for myelin health and function.  Omega-3 fatty acids in supplement form have been found to be protective against peripheral nerve damage from chemotherapy and may also improve the nerves’ ability to regenerate.

Gamma-linolenic acid (GLA), is an omega-6 fatty acid found in evening primrose oil and borage oil.  GLA is an essential component of myelin and studies support the use of GLA to improve nerve function in neuropathy associated with diabetes. 

Curcumin

Curcumin is a natural component of turmeric root. It is one of the most widely used and researched natural medicines for pain. Curcumin has been shown to lower oxidative stress, pain, and inflammation as well as have neuroprotective effects. 

Topical Medications

Topical medications for neuropathy include capsaicin and lidocaine.  Topicals are applied directly onto the skin in the affected area.  Therefore, they are best used when the area of pain is well-circumscribed.  Also, because topical medications act locally on the nerves and are not well absorbed into the blood stream, they are a good choice when trying to avoid side-effects or interactions with other medications.

Capsaicin

Capsaicin is a chemical derived from hot peppers.  It is used topically to alleviate neuropathy pain, but as expected, it results in a burning sensation when applied.   Therefore, it should never be applied on cuts, wounds, mucous membranes, face or near the eyes.  A clinical study has shown that capsaicin cream is as effective for painful neuropathy associated with diabetes.  

 

Lidocaine

Topical lidocaine comes in a patch that is applied to the affected area.  It has been shown to alleviate localized nerve pain associated with shingles and diabetes.

Immune modulating treatments 

There are pharmaceutical drugs that improve nerve function and nerve repair for neuropathy caused by rare autoimmune conditions such as chronic inflammatory demyelinating neuropathy (CIDP), multi-focal motor neuropathy with conduction block (MMN) and vasculitis.  Steroids or intravenous immunoglobulin (IVIG) along with other medications that modulate the immune system are helpful for these autoimmune forms of neuropathy.

See Dr. Rowin's recent publication in the journal Muscle and Nerve
- May 2019