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 © 2009 Nucleus Medical Media, Inc.

Causes

Many diseases and conditions can cause peripheral neuropathy. The damage may occur due to:

• Lack of oxygen
• Malnutrition
• Compression
• Cancer
• Trauma
• Inflammation
• Toxins
• Medications
• Unknown causes

Diseases that can damage peripheral nerves include:

• Diabetes ( type 1 or type 2)
• Alcoholism
• AIDS
• Lyme disease
• Rheumatoid arthritis
• Uremia from chronic kidney failure
• Autoimmune disorders
• Hypothyroidism
• Viral infections (such as hepatitis)

Compression commonly occurs when nerves are pinched or trapped somewhere along their course, such as:

• Carpal tunnel syndrome (nerve in the wrist)
• Sciatica (nerve roots forming the sciatic nerve in the back of the legs as they exit the spine)

Toxins that can damage the peripheral nerves include:

• Lead
• Mercury
• Thallium
• Organic solvents (hexacarbons)
• Pesticides (organophosphates)
• Carbon disulfide
• Arsenic
• Acrylamide
• Diphtheria toxin
• Alcohol

Many medications can lead to peripheral neuropathy. A partial list includes:

• Chemotherapeutic agents to treat cancer (eg, vincristine, paclitaxel, cisplatin, suramin)
• Anti-HIV medications (eg, didanosine, zalcitabine)
• Anti- tuberculosis medications (eg, isoniazid, ethambutol)
• Other antimicrobial drugs (eg, dapsone, metronidazole, chloroquine, chloramphenicol)
• Psychiatric medications (eg, lithium)
• Other medications (eg, amiodarone, aurothioglucose, phenytoin, thalidomide, colchicine, cimetidine, disulfiram, hydralazine, high levels of vitamin B6)

Other causes of peripheral nerve damage include:

• Vitamin deficiencies ( thiamin and B12 deficiency, often related to alcoholism, 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 ( Charcot-Marie-Tooth disease, Dejerine-Sottas disease, and Refsum’s disease)
• Prolonged treatment in the intensive care unit

Risk Factors    TOP

These factors increase your chance of developing this condition. Tell your doctor if you have any of these risk factors:

• Diabetes (about 60% of people with diabetes have peripheral neuropathy)
• 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 (thiamin and vitamin B12)
• HIV infection
• Pressure on a nerve (may occur with repetitive stress injuries)
• Hospitalization treatment in the intensive care unit

Symptoms    TOP

Damage to the peripheral nerves often results in sensory (feeling) and motor (strength) 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 (eg, 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

Diagnosis    TOP

The doctor will ask about your symptoms and medical history. She will also do a physical exam, which may include:

• 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:

• Blood tests (including glucose, vitamin B12 level, and thyroid function tests)
• Electromyography (EMG) —measures and records electrical activity generated in muscle in response to nerve stimulation
• Nerve conduction studies —measures the speed and degree of electrical activity in a nerve to determine if it is functioning normally
• Serum/urine electrophoresis (protein analysis)
• Genetic testing
• Evaluation of family members
• Spinal tap for demyelinating disorders
• Nerve or muscle biopsy (rarely)

Treatment    TOP

Treatment may include:

Prevention    TOP

• Manage chronic medical conditions with the help of your doctor. If you have diabetes, visit a podiatrist for yearly exams.
• Eat a healthful diet, one 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