Symptoms and Causes

The symptoms of peripheral neuropathy may depend on the type of peripheral nerves that have been damaged.  The three types of peripheral nerves are the motor, sensory and autonomic nerves. Some neuropathies affect all three types of nerves while others affect only one or two.

Motor nerves send impulses from the brain and spinal cord to all the muscles of the body.  They help muscles contract.  Motor nerve damage results to muscle weakness or paralysis.

Sensory nerves send messages from the muscles back to the spinal cord and the brain.  They allow a person to feel a wide range of sensations such as when an object is smooth or rough, hot or cold.  If a sensory nerve is damaged, one is likely to experience symptoms that may include tingling, numbness, pain and muscle weakness.  These symptoms often begin gradually.

Autonomic nerves control involuntary functions of the autonomic nervous system such as heart rate, blood pressure, sweating and digestion.  When autonomic nerves are damaged, a person may experience dizziness due to a sharp fall in blood pressure, sweating, diarrhea, constipation or problems with urination.

Peripheral neuropathies may be caused by environmental forces like exposure to poisons, diabetes (usually the main cause), trauma, viral infections, vitamin deficiencies or inherited genetic defects.  Unfortunately, the cause of many neuropathies remains unknown.