What Causes Peripheral Neuropathy?

The nerves that connect the CNS to the rest of the body are called the PNS. Any damage to these nerves, due to disease, injury, drugs, or toxins, is called peripheral neuropathy.

The nervous system has two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The brain and spinal cord are part of the CNS. The nerves that connect the CNS to the rest of the body are called the PNS. Any damage to these nerves, due to disease, injury, drugs, or toxins, is called peripheral neuropathy. Peripheral neuropathy can affect many nerves (polyneuropathy), a single nerve (mononeuropathy), or a nerve group. 

The symptoms of peripheral neuropathy depend upon the type of nerve affected—nerves of muscle function (motor nerves), nerves of sensation (sensory nerves), or nerves of the involuntary nervous system (autonomic nerves, such as those innervating the heart and bowels).

• Motor nerves regulate the movement of all muscles under your conscious control (muscles used for walking, holding objects, or speaking).
• Sensory nerves help you feel your environment (feeling of a light touch, heat, cold, or pain). 
• Autonomic nerves control activities that you do not have conscious control of such as heartbeat, breathing, digesting food, and sweating.

Usually, neuropathies affect all three types of nerve fibers in varying degrees. 

The 24 symptoms and signs of peripheral neuropathy include:

1. Inability to feel touch and vibration sensations through your hands and feet. You feel like you are wearing some invisible “gloves” or “stockings.”
2. Severe stabbing or shooting pain
3. Tingling “pins and needles” sensation or electric shock-like pain
4. Inability to feel pain 
5. Inability to tell whether an object is hot or cold
6. Trouble grasping or picking up objects
7. Frequent tripping or stumbling while walking
8. Balance problems
9. Increased sensitivity to cold or heat
10. Burning sensation 
11. Extraordinary pain in response to touch or pressure
12. Loss of muscle fat
13. Muscle weakness
14. Trouble swallowing
15. Trouble passing urine
16. Constipation or diarrhea
17. Loss of bowel and bladder control
18. Dizziness or fainting
19. Excessive or no sweating
20. Palpitations or a sense of the racing, pounding heartbeat
21. Sexual disturbances
22. Breathing problems
23. Vision problems
24. Weakness

The various causes of peripheral neuropathy include:

• Diabetes
• Chemotherapy-induced neuropathy
• Genetic diseases
• Alcohol
• Vitamin deficiencies (for example, vitamin B12 deficiency)
• Chronic liver disease
• Chronic kidney disease
• Toxins (arsenic, lead, and mercury)
• HIV and certain other infections
• Autoimmune diseases (lupus)
• Hypothyroidism
• Certain cancers (lymphoma, multiple myeloma, etc.)
• Injury
• Certain drugs (certain antibiotics, anti-seizure drugs, etc.)
• Smoking

Treatment of peripheral neuropathy begins with treating the underlying cause, including infections, drugs, vitamin deficiencies, diabetes, etc. 

Treatment options include the following:

• Medications to provide pain relief:
  • Antidepressants  
  • Anti-seizure medicines 
  • Topical (on the skin) patches and creams containing lidocaine or capsaicin 
  • Narcotic medications are used in a few cases
• Hand or foot braces
• Steroids
• Orthopedic shoes 
• Splints
• People who report dizziness due to a sharp fall in blood pressure when getting up (orthostatic hypotension) can prevent this by standing up slowly and taking medications to prevent blood pressure fluctuations
• Psychotherapy
• Physical therapy
• A healthy and balanced diet
• Adopting a healthy lifestyle: regular exercise, refraining from smoking, maintaining a healthy weight, and limiting alcohol intake
• Surgery may be needed in some cases
• Transcutaneous electrical nerve stimulation (TENS): In this technique, a low voltage electrical current is applied to the nerves causing pain by placing electrodes on the skin.
• Immune suppressing or modulating treatment 
• Complementary treatment: acupuncture, lipoic acid, meditation/yoga, biofeedback, and herbal therapy.