Neuralgia is pain in one or more nerves that occurs without stimulation of pain receptor (nociceptor) cells. Neuralgia pain is produced by a change in neurological structure or function rather than by the excitation of pain receptors that causes nociceptive pain. Neuralgia falls into two categories: central neuralgia and peripheral neuralgia. This unusual pain is thought to be linked to four possible mechanisms: ion gate malfunctions; the nerve becomes mechanically sensitive and creates an ectopic signal; cross signals between large and small fibers; and malfunction due to damage in the central processor.
Neuralgia was first recognized by Silas Weir Mitchell, a neurologist in the American Civil War, who noticed hyperalgesia and chronic pain in patients who had nerve lesions in the extremities and also some cases where no lesion was observed: These causalgias were certainly major by the importance of the symptoms, but stemmed from minor neurological lesions". Mitchell termed the condition “causalgia” which has since become known as “Complex Regional Pain Syndrome Type 1 and Type 2” (CRPS). CRPS Type I is a syndrome that develops after an initiating noxious event ., and Type 2 describes a case when nerve damage is clear.
Neuralgia is often difficult to diagnose, and most treatments show little or no effectiveness. Diagnosis typically involves locating the damaged nerve by identifying missing sensory or motor function. This may involve tests such as an EMG test or a nerve conduction test. Neuralgia is more difficult to treat than other types of pain because it does not respond well to normal pain medications. Special medications have become more specific to neuralgia and typically fall under the category of membrane stabilizing drugs or antidepressants such as Cymbalta. The antiepileptic medication(AED) Lyrica was developed specifically for neuralgia and other neuropathic pain as a successor to Neurontin (gabapentin).