Neuropathic pain affects roughly 2-3% of the general population with an estimated cost of $40 billion per year in treatment related costs. But what causes it? Since Neuropathy is an umbrella term used to describe any abnormalities of nerve function and structure, the potential causes of neuropathy are seemingly endless.
Causes of Neuropathy:
Toxins – Exposure to lead, glue, solvents, and heavy metals like mercury can cause nerve damage. This can happen through proximity to these agents in the workplace, or through willful abuse.
Physical Injury – The most common cause of nerve injury. For example, spinal cord injury or disc herniation due to a fall or accident can lead to Neuropathic pain. Neuropathy can also be caused by holding still or retaining the same position for too long, as one finds with Carpal Tunnel Syndrome.
Disease – Chronic diseases may cause nerve damage as well. Some of these are Diabetes, CIDP, kidney disorders, or hyperthyroidism.
Virus – Herpes simplex, varicella-zoster and Epstein Barr can attack nerve tissue directly. Lyme disease and other bacterial infections can cause damage to nerves if untreated.
Autoimmune Disorders – Certain autoimmune disorders like lupus and rheumatoid arthritis affect the peripheral nervous system and can cause various types of neuropathic pain.
|Etiology||Terminology||Peripheral vs. Central Nervous System Etiology|
|Complex regional pain syndrome (CRPS), Type I (reflex sympathetic dystrophy or RSD)||Mixed?|
|Complex regional pain syndrome (CRPS), Type II (causalgia)||Mixed?|
|Radiculopathy||Peripheral > central|
|Stroke (cerebrovascular accident)||Central|
|Spinal cord injury||Central|
|Human immunodeficiency virus||Peripheral|
|Herpes simplex virus||Peripheral > central|
|Acute inflammatory demyelinating polyneuropathy (AIDP)||Mixed|
|Chronic inflammatory demyelinating polyneuropathy (CIDP)||Peripheral|
|Kidney disorders/renal failure||Peripheral > central|
|Vitamin deficiencies (beriberi, alcoholic pellagra, vitamin B12 deficiency)||Mixed|
|Vascular disorders||Peripheral > central|
|Chemical toxins (isoniazid, chemotherapy agents) (platinum, vinca alkaloids, taxanes), arsenic, thallium||Mixed|
Once the cause is determined, what exactly is the effect on the nerves themselves? There are several mechanisms thought to be responsible for the development of neuropathic pain. These include changes in the density of nerve fibers, alterations in the ion channels, abnormal firing of neurons, inflammation, and changes in ability to transmit signals to the CNS. The pathophysiology of each neuropathy is specific to the disease process causing it.
 Hall GC, Carroll D, Parry D, et al.: Epidemiology and treatment of neuropathic pain. the UK primary care perspective Pain. 2006; 122:156-162.
 Turk DC: Clinical effectiveness and cost-effectiveness of treatments for patients with chronic pain. Clin J Pain. 2002; 18:355-365.