Jose G. Veliz, M.D. M.S.A.
Medical Director
Palomar Pain Management Center
Pomerado Pain Management Center

Posted January 20, 2009

What is Peripheral Neuropathy?

The nervous system is divided up into the central nervous system and the peripheral nervous system.  The nervous system consists of the brain and the spinal cord.  The peripheral nervous system is located outside of the brain and spinal cord.  The peripheral nervous system consists of the following:

• Sensory nerves which transmit messages about sensations such as heat, pain or touch. 
• Motor nerves which transmit messages that control movement. 
• Autonomic nerves which are responsible for involuntary functions such as blood pressure, digestion, breathing and sexual function. 

Damage to the nerves in the peripheral nervous system is called peripheral neuropathy. 

Causes of Peripheral Neuropathy. 

Conditions associated with peripheral neuropathy include the following:

Symptoms:

The symptoms depend on whether or not sensory, motor, and/or autonomic nerves are affected.  One, two or all three types of nerves can be affected.   The symptoms also depend on whether or not one nerve is involved or whether, in addition, a large part or whole part of the body is affected. 

Sensory Nerves: 

• Nerve pain, tingling, numbness, burning sensations, changes in sensation or incoordination may occur with damage to sensory fibers.  Often, the sensation changes begin in the feet and progress toward the center of the body. 

Motor Nerves:

• Weakness, atrophy, cramps, paralysis, muscle twitching, lack of muscle control and lack of dexterity can occur when damage occurs to motor nerves. 

Autonomic Nerves:

• Involuntary or semi-voluntary functions are controlled by autonomic nerves.  As a result, damage to these nerves can result in the following: impotence, nausea or vomiting after meals, abdominal bloating, diarrhea, constipation, decreased ability to sweat, blurred vision, dizziness, incomplete bladder emptying, and/or loss of bladder control.

Diagnosis:

Your doctor will take a complete medical history and perform a physical examination. 

The patient history will include symptoms, social habits, exposure to any toxins, risk of infectious disease, work environment and any family history of neurological disease. 

The physical examination may include testing of light touch, reflexes, body position, vibration, pain, and temperature.  Comparing blood pressures in the sitting and standing position may also provide important information. 

Additional testing may include the following: 

• Lumbar puncture - examination of cerebrospinal fluid that surrounds the brain and spinal cord may reveal abnormalities. 
• Blood tests to check vitamin B-12 levels, folate levels, thyroid function, and fasting glucose. 
• Electromyograph (EMG) which is a recording of electrical activity in muscles.
• Nerve conduction velocity (NVC) tests
• Nerve biopsy
• Skin biopsy

Treatment:

Treating the Causes:

• Correct vitamin deficiencies
• Correct blood glucose levels in diabetes as strict control of blood glucose levels can lessen further nerve damage and reduce neuropathic symptoms. 
• Treat bacterial infections such as Lyme disease.
• Treat nerve compressions with physical therapy, injections or surgery.
• Treat autoimmune conditions with immunosuppressant drugs, plasmapheresis and/or high doses of immunoglobulins. 
• Avoid exposure to toxic chemicals
• Avoid repetitive movements which are contributing to nerve damage
• Minimize or eliminate alcohol consumption
• Use of dialysis in kidney failure
• Immediate treatment with antiviral medication and sympathetic nerve blocks in patients with post-herpetic neuralgia (Shingles).
• Foot braces can allow nerves to heal in those with a foot drop.

Treating the Pain:

• Acetaminophen (Tylenol) - avoid if you have a history of liver disease or kidney disease. 
• Non-steroidal anti-inflammatory medications (ibuprofen, aspirin, Naprosyn etc) - avoid these medications if you have a history of gastritis, peptic ulcer disease, or kidney disease. 
• Tricyclic antidepressants.  Examples include amitriptyline (Elavil) and nortriptyline (Pamelor). 
• Anti-seizure medications such as carbamazepine (Tegretol), phenytoin (Dilantin) and gabapentin (Neurontin). 
• Topical Lidocaine patches
• Capsaicin Cream
• Pregabalin (Lyrica)
• Duloxetine (Cymbalta)
• Careful footcare and wound care in people with diabetes. 
• Wrist braces can alleviate nerve compression in carpal tunnel syndrome
• Nerve entrapment may occasionally be corrected by surgical release of ligaments, tendons, muscles or bones. 

Resources:

http://www.pennhealth.com/ency/article/000593.htm?mode=print
http://www.hmc.psu.edu/healthinfo/pq/peripheralneuropathy.htm