Applying cold therapy to an area with inflammation it causes the blood vessels to vasoconstrict (narrowing of the blood vessels) which reduces the amount of blood flow to the area. Blood carries inflammatory factors which are responsible for healing the body. Too much inflammation can be detrimental and painful. Therefore reduced blood flow will reduce the inflammatory factors coming to the area.
Cold therapy provides pain relief by temporarily slowing down the nerves' ability to send pain signals to the brain. When pain is caused by inflammation, reducing the number of cells (blood and inflammatory factors) in the area puts less pressure and causes less irritation to the nerves, therefore, reducing pain.
Improving Nerve Function
Cold therapy can be used to improve the nerve's ability to sense sensation. This works by changing the firing of the nerves which is related to how quickly the brain can receive a message relating to sensation. Different temperatures will have different effects on the firing of the nerves.