Neuropathic pain is the result of damage to the sensory part of a nerve. Nerves carry varied information to the spine and brain. They are made up of many nerve cells bundled together. When a nerve becomes damaged it can affect many types of function, including muscle control, temperature sense, position sense and pain. Pain is often the first sign of nerve damage. The nerve attempts to repair itself and forms microscopic nerve endings that fire off in rapid and prolonged ways. The result is a greatly increased pain signal arriving at the central nervous system. Additionally, because the presynaptic nerve is damaged, receptors used to turn down the pain on the presynaptic cell are also prevented from working. The result is excruciating and intractable pain sent to the brain and perceived by the mind, with no chance of Central Nervous System modification. This becomes even more complicated when the damage occurs or spreads to the part of the nervous system that normally controls automatic functions such as breathing and heart rate.