Every time we try cold, or pain, occurs in us an observable reaction: the synapses (nerve cells to allow all communicate between them and with other cells) they change their operating programm, change and stabilizes for days.

The phenomenon is called “functional plasticity” and brings up changes, sometimes irreversible, in the areas near or distant from the brain, creating what scientists call”Structural Plasticity” of the nervous system.

This dynamic serves to explain why a pain becomes chronic: the system-pain, can change the answers when one stimulus, a bump, a sunburn, but also an inflammation caused by a disease, are maintained for long time, with a sufficient Intensity.

It increases the excitability of neurons in the center and periphery and may arise hyperalgesia ( exaggerated perception of pain stimuli ) or allodynia , which transforms the non-painful stimuli , such mild skin contact in stimuli very painful and unbearable. These conditions often prevent a normal life.

These conditions often prevent a normal life . The painful sensations are not proportional to their cause are useful in the acute phase , when they still have a protective role in promoting repair of organic damage .

However, if for some reason , the natural plasticity of the nervous system is damaged these painful responses are prolonged in time and if they last more than three months, turns into cronic pain.