Excitotoxicity is a process through which nerve cells become damaged because they are overstimulated. A number of conditions are linked with excitotoxicity including strokes, traumatic brain injuries, multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's disease, and spinal injuries. Damage to the nerve cells results in corresponding neurological symptoms which can vary depending on which cells are damaged and how extensive the damage is. Once damaged, nerve cells cannot be repaired and the patient can experience permanent impairments.
The process through which excitotoxicity occurs starts with an elevation of glutamate. Glutamate is an excitatory neurotransmitter which acts to facilitate electrical signaling between nerve cells. When glutamate levels rise too much, however, they essentially jam a nerve cell in the open position, allowing calcium to flow freely into the cell. The calcium damages the structure and DNA of the cell, and creates a cascading reaction as cells die and release glutamate which floods neighboring cells, causing the damage to spread.
Several receptors on nerve cells are sensitized to glutamate, including the AMPA and NDMA receptors. Glutamate's ability to lock on to several receptors on nerve cells can work against it in cases of excitotoxicity because the compound can act quickly when it is present in the nervous system in high concentrations. The cascade of reactions linked with excitotoxicity can occur in both the brain and spinal cord and may lead to lasting damage if it cannot be identified and arrested. Treatment usually requires the attention of a neurologist.
Glutamate production in the body is normal and in fact desirable, because the body needs to be able to excite nerve cells to send signals. When the glutamate levels get too high, however, a patient is at risk of excitotoxicity. One way to address the problem is to introduce medications which will block the action of the glutamate and protect nerve cells. People who may be at risk for nerve damage as a result of excitotoxicity may be given medications which will help to block it.
Several claims have been made about foods which can supposedly be neurotoxic, causing damage to the nervous system through processes such as excitotoxicity. The veracity of these claims varies. The body of a healthy individual is equipped to process a very diverse diet, including one which includes foods with components which can potentially be dangerous in high levels. As long as people eat a balanced diet, they should be able to avoid dangerous buildups of neurotoxic compounds.