Neuropathy describes a condition in which a person suffers from peripheral nerve damage often associated with an underlying disease. Though not a disease itself, neuropathy is diagnosed in many people for whom no pre-existing cause can be determined. While less than 3% of the general population is affected, eventually 60% of diabetics will develop some degree of nerve damage.
The symptoms of neuropathy are usually the only method of diagnosis. One might suffer sensations similar to decreased circulation in the extremities, such as numbness, ranging from mild to severe, and pins and needles. Limbs feel alternately burning hot and icy cold, accompanied by sharp or dull pain and muscle fatigue. These feelings are associated with reduced fine motor coordination, possibly leading to paralysis at the worst extreme.
Our nerves are sensitive paths along which our body relays electrical information between our senses and our brain. One system of nerves branch out from our spinal cord to sense things like movement, pain, tactile sensation, temperature, etc. When damaged, these functions become scrambled or have reduced sensitivity. Something goes wrong in some part of the nerve. Perhaps it's in the myelin, the membranous lining of nerve cells in which axons float. Or it could be in the axons, which are connectors responsible for transferring the electrical impulses from one cellular body to the next. Even the nerve cells can get injured.
While it's easy to diagnose the nerve damage based on pain, it's difficult to treat because it is so commonly idiopathic, which means the doctor doesn't know why the patient has developed peripheral nerve damage. However, the causes we understand most are malnutrition, repetitive motion resulting in carpal tunnel syndrome, HIV/AIDS, diabetes, exposure to toxins or poisons, and inherited genetic disorders.
When a doctor can identify one of these causes, she can treat the pain at the source, by correcting malnutrition or treating diabetes for example. Unfortunately, if the neuropathy is idiopathic, the only available treatment is ongoing, temporary pain management, usually with pharmaceuticals. Researchers are still pursuing many paths of study to better understand the process that leads to such widespread neuropathy.