Neuropathy is a medical term describing disorders of the nerves of the peripheral nervous system (specifically excluding encephalopathy and myelopathy, which refer to the central nervous system.)[1] It is usually considered equivalent to peripheral neuropathy.

According to the most widely accepted definition, neuropathic pain is "initiated or caused by a primary lesion or dysfunction in the nervous system." Neuropathic pain cannot be explained by a single disease process or a single specific location of damage

It is very complicated to give the exact reasons of nerve pain. In general, With neuropathic pain, the nerve fibers themselves may be damaged, dysfunctional or injured. These damaged nerve fibers send incorrect signals to other pain centers. The impact of nerve fiber injury includes a change in nerve function both at the site of injury and areas around the injury.

Causes of Neuropathic Pain

Neuropathic pain often seems to have no obvious cause; but, some common causes of neuropathic pain include:

• Alcoholism
• Amputation
• Back, leg, and hip problems
• Chemotherapy
• Diabetes
• Facial nerve problems
• HIV infection or AIDS
• Multiple sclerosis
• Shingles
• Spine surgery

Neuropathic pain may be associated with abnormal sensations called dysesthesias which occur spontaneously and allodynias that occur in response to external stimuli. Neuropathic pain may have continuous and/or episodic (paroxysmal) components. The latter are likened to an electric shock. Common qualities of neuropathic pain includes burning or coldness, "pins and needles" sensations, numbness and itching. nociceptive pain is more commonly described as aching.

As much as 7% to 8% of the of the population is affected and in 5% it may be severe. Neuropathic pain may result from disorders of the peripheral nervous system or the central nervous system (brain and spinal cord). Thus, neuropathic pain may be divided into peripheral neuropathic pain, central neuropathic pain, or mixed (peripheral and central) neuropathic pain.

Central neuropathic pain is found in spinal cord injury, multiple sclerosis, and some strokes. Fibromyalgia, a disorder of chronic widespread pain, is potentially a central pain disorder and is responsive to medications that are effective for neuropathic pain.

Aside from diabetes (see Diabetic neuropathy) and other metabolic conditions, the common causes of painful peripheral neuropathies are herpes zoster infection, HIV-related neuropathies, nutritional deficiencies, toxins, remote manifestations of malignancies, genetic, and immune mediated disorders.

Neuropathic pain is common in cancer as a direct result of cancer on peripheral nerves (e.g., compression by a tumor), or as a side effect of chemotherapy, radiation injury or surgery.

What are the symptoms of neuropathic pain?

Symptoms depend on the type of nerves affected; motor, sensory, autonomic, and where the nerves are located in the body. One or more types of nerves may be affected.

Common symptoms associated with damage to the motor nerve are muscle weakness, cramps, and spasms. Loss of balance and coordination may also occur. Damage to the sensory nerve can produce tingling, numbness, and pain. Pain associated with this nerve is described in various ways such as the following: sensation of wearing an invisible "glove" or "sock", burning, freezing, or electric-like, extreme sensitivity to touch.

The autonomic nerve damage results in affects in involuntary functions. Symptoms from this type of damage include abnormal blood pressure and heart rate, reduced ability to perspire, constipation, bladder dysfunction (e.g., incontinence), and sexual dysfunction

neuropathic pain diagnosed?

A doctor will conduct an interview and physical exam. He or she may ask questions about how you would describe your pain, when the pain occurs, or whether anything specific triggers the pain.

neuropathic pain treated?

Neuropathic pain can be very difficult to treat with only some 40-60% of patients achieving partial relief.

In addition to the work of Dworkin, O'Connor and Backonja et al., cited above, there have been several recent attempts to derive guidelines for pharmacological therapy. These have combined evidence from randomized controlled trials with expert opinion.

Determining the best treatment for individual patients remains challenging. Attempts to translate scientific studies into best practices are limited by factors such as differences in reference populations and a lack of head-to-head studies. Furthermore, multi-drug combinations and the needs of special populations, such as children, require more study.

It is common practice in medicine to designate classes of medication according to their most common or familiar use e.g. as "antidepressants" and "anti-epileptic drugs" (AED's). These drugs have alternate uses to treat pain because the human nervous system employs common mechanisms for different functions, for example ion channels for impulse generation and neurotransmitters for cell-to-cell signaling.

Favored treatments are certain antidepressants e.g tricyclics and selective serotonin-norepinephrine re-uptake inhibitors (SNRI's), anticonvulsants, especially pregabalin (Lyrica) and gabapentin (Neurontin), and topical lidocaine. Opioid analgesics and tramadol are recognized as useful agents but are not recommended as first line treatments. Many of the pharmacologic treatments for chronic neuropathic pain decrease the sensitivity of nociceptive receptors, or desensitize C fibers such that they transmit fewer signals.

Some drugs may exert their influence through descending pain modulating pathways. These descending pain modulating pathways originate in the brainstem.