• Peripheral Neuropathy

    Definition

    Peripheral neuropathy is damage to the peripheral nerves. These are the nerves that connect your spinal cord to the rest of your body.
    Peripheral Nerves of the Foot
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    Causes

    Many diseases and conditions can cause peripheral neuropathy. The damage may occur due to:
    • Malnutrition
    • Compression from repetitive stress
    • Cancer
    • Trauma
    • Inflammation of nerves or blood vessels
    • Infection
    • Toxins
    • Medications
    • Hereditary syndromes
    • Unknown causes
    Diseases that can damage peripheral nerves include (but are not limited to):
    Compression commonly occurs when nerves are pinched or trapped somewhere along their course, such as:
    Toxins that can damage the peripheral nerves include:
    Many medicines can lead to peripheral neuropathy. A partial list includes:
    • Chemotherapeutic agents to treat cancer, such as vincristine, paclitaxel, and cisplatin
    • Anti-HIV medications, such as didanosine and zalcitabine
    • Anti- tuberculosis medications, such as isoniazid and ethambutol
    • Other antimicrobial drugs such as dapsone, metronidazole , chloroquine, and chloramphenicol
    • Psychiatric medications, such as lithium
    • Other medications, such as amiodarone, aurothioglucose, phenytoin, thalidomide, colchicine, cimetidine, disulfiram, hydralazine, and high levels of vitamin B6
    Other causes of peripheral nerve damage include:
    • Vitamin deficiencies, such as thiamin, B12 , and vitamin E deficiency
    • Injury
    • A tumor pressing on a nerve
    • Exposure to cold or radiation
    • Leprosy
    • Acute or chronic demyelinating polyneuropathy
    • Porphyria
    • Paraneoplatic syndromes
    • Genetic disorders, such as Charcot-Marie-Tooth disease or hereditary motor and sensory neuropathy
    • Prolonged treatment in the intensive care unit

    Risk Factors

    Factors that may increase your risk of getting peripheral neuropathy include:
    • Diabetes
    • Alcohol abuse
    • Autoimmune diseases, such as rheumatoid arthritis or celiac sprue
    • Family member with peripheral neuropathy
    • Exposure to toxins or medications known to cause neuropathy
    • Vitamin deficiency, such as thiamin and vitamin B12
    • HIV infection
    • Pressure on a nerve—may occur with repetitive stress injuries
    • Hospitalization treatment in the intensive care unit

    Symptoms

    Damage to the peripheral nerves often results in sensory and motor symptoms in the:
    • Arms
    • Legs
    • Hands
    • Feet
    Other parts of the body can also be affected. Symptoms depend on which nerves are involved. They can range from mild to severe and may seem worse at night. Sensations and pain may occur in the upper or lower limbs and move toward the trunk, such as from the feet to the calves.
    Symptoms include:
    • Numbness or reduced sensation
    • Tingling
    • Pain, often a burning or sharp, cutting sensation
    • Sensitivity to touch
    • Muscle twitches
    • Muscle weakness
    • Muscle cramping
    • Difficulty with walking
    • Loss of coordination or balance
    • Paralysis
    If untreated, peripheral neuropathy can lead to:
    • Loss of reflexes and muscle control
    • Muscle atrophy—loss of muscle bulk
    • Foot deformities
    • Foot ulcers
    • Injuries to the feet that go unnoticed and become infected
    • Autonomic dysfunction—sweating, bowel and bladder dysfunction, cardiovascular effects
    • Difficulty breathing
    If you have motor or sensory neuropathy, you may also have autonomic neuropathy. This is associated with symptoms such as:
    • Problems regulating blood pressure
    • Constipation
    • Erectile dysfunction

    Diagnosis

    The doctor will ask about your symptoms and medical history. A physical exam will be done. It may include examining:
    • Muscle strength
    • Reflexes
    • Balance
    • Coordination
    • Ability to feel vibration, temperature, and light touch
    • Semmes-Weinstein monofilaments test—measures sensation in the feet using a fine flexible wire
    Additional tests may also include:
      You may need to have tests of your bodily fluids and tissues. This can be done with:
      • Blood tests, such as glucose, vitamin B12 level, and thyroid function tests
      • Serum/urine electrophoresis
      • Genetic testing
      • Spinal tap , also called a lumbar puncture
      • Nerve or muscle biopsy —rarely
      • Nerve fiber density skin biopsy
      You may need to have your nerves and muscles tested. This can be done with: You may need to have pictures taken of your bodily structures. This can be done with:
    • Your doctor may need to evaluate other family members for this condition.

    Treatment

    Treatment may include:

    Treatment for the Underlying Illness or Exposure

    Treating the underlying illness can decrease symptoms or make them go away. For instance, if it is caused by diabetes, controlling blood sugar levels may help. In some cases, neuropathy caused by medications or toxins is completely reversed when these substances are stopped or avoided. Correction of vitamin B12 deficiency often improves symptoms.

    Physical Therapy

    Certain exercises may help stretch shortened or contracted muscles and increase joint flexibility. In long-standing cases, splinting the joint may be required to protect and rest it, while maintaining proper alignment.
    Orthotics, such as supports and braces, may help with:
    • Deformities
    • Balance issues
    • Muscle weakness
    Maintaining physical activity is also important.

    Medications

    Prescription and over-the-counter (OTC) pain medicines are often used to ease discomfort.
    Drugs to treat depression and prevent convulsions sometimes relieve neuropathy symptoms. These medicines are often given at lower dosages. Commonly used antidepressants include:
    • Amitriptyline
    • Nortriptyline
    • Desipramine
    • Imipramine
    • Duloxetine
    Commonly used anticonvulsants may include:
    • Gabapentin
    • Carbamazepine
      • According to the Food and Drug Administration (FDA), patients of Asian ancestry who have a certain gene, called HLA-B*1502, and take carbamazepine are at risk for dangerous or even fatal skin reactions. If you are of Asian descent, the FDA recommends that you get tested for this gene before taking carbamazepine. If you have been taking this medication for a few months with no skin reactions, then you are at low risk of developing these reactions. Talk to your doctor before stopping this medication.
    • Pregabalin
    For severe and potentially life-threatening cases, such as Guillain-Barre syndrome, treatment includes:
    • IV immunoglobulins
    • Plasmapheresis —done to exchange plasma in the blood

    Other Therapies

    These therapies are aimed at reducing symptoms:

    Surgery

    Surgery can relieve the pressure on nerves. For example, surgeons commonly release fibrous bands in the wrist to treat carpal tunnel syndrome .

    Prevention

    • Manage chronic medical conditions with the help of your doctor. If you have diabetes, visit a podiatrist for yearly exams.
    • Eat a healthful diet that is low in saturated fat and rich in whole grains, fruits, and vegetables.
    • Be sure to get the right amounts of thiamin and vitamin B12.
    • Limit your alcohol intake to a moderate level. This means two or fewer drinks per day for men and one or fewer for women.
    • Avoid:
      • Toxic chemicals
      • Repetitive movements
      • Prolonged pressure on joints, especially elbows and knees

    RESOURCES

    American Chronic Pain Association http://www.theacpa.org

    The Neuropathy Association http://www.neuropathy.org

    CANADIAN RESOURCES

    Canadian Diabetes Association http://www.diabetes.ca

    Health Canada http://www.hc-sc.gc.ca

    References

    Baron R, Binder A, Wasner G. Neuropathic pain: diagnosis, pathophysiological mechanisms, and treatment. Lancet Neurol. 2010;9(8):807-819.

    Diabetic neuropathies: the nerve damage of diabetes. National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health website. Available at: http://diabetes.niddk.nih.gov/dm/pubs/neuropathies/index.aspx . Updated June 25, 2012. Accessed February 21, 2013.

    Dyck PJ, Thomas PK, Dyck PJ, Thomas PK, eds. Peripheral Neuropathy . 4th ed. Philadelphia, PA: Saunders; 2004.

    Fermaglich J. Merritt's Neurology . 11th ed. Chicago, IL: Lippincott Williams & Wilkins; 2005.

    Karlsson P, et al. Epidermal nerve fiber length density estimation using global spatial sampling in healthy subjects and neuropathy patients. J Neuropathol Exp Neurol. 2013 Mar;72(3):186-93.

    Peripheral neuropathy. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/ . Updated November 15, 2012. Accessed February 21, 2013.

    Samuels MA, Feske SK. Office Practice of Neurology . Philadelphia, PA: Churchill Livingstone; 2003.

    Williams O. Introduction to and clinical evaluation of peripheral neuropathies. In: Gilman S, ed. MedLink Neurology. San Diego, CA: MedLink Corporation.

    12/20/2007 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : 2007 safety alerts for drugs, biologics, medical devices, and dietary supplements: Carbamazepine (marketed as Carbatrol, Equetro, Tegretol and generics). Medwatch. US Food and Drug Administration website. Available at: http://www.fda.gov/medwatch/safety/2007/safety07.htm#carbamazepine .

    10/5/2009 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Feng Y, Schlösser FJ, Sumpio BE. The Semmes Weinstein monofilament examination as a screening tool for diabetic peripheral neuropathy. J Vasc Surg. 2009;50:675-682,682.

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