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):

• Diabetes — type 1 or type 2
• Alcoholism
• AIDS
• Lyme disease
• Rheumatoid arthritis
• Uremia from chronic kidney failure
• Autoimmune disorders
• Hypothyroidism
• Viral infections like 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
• Pesticides
• Carbon disulfide
• Arsenic
• Acrylamide
• Diphtheria toxin
• Alcohol

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:
  • Electromyography (EMG)
  • Nerve conduction studies (NCS)
• You may need to have pictures taken of your bodily structures. This can be done with:
  • MRI scan
  • CT scan
• Your doctor may need to evaluate other family members for this condition.

Treatment

Treatment may include:

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