The root neuro comes from the Greek word meaning “nerve.” Toxicity means “the action of poisonous properties or materials.” Thus, neurotoxicity occurs when some toxic material affects the nerve tissue in an adverse way. Neurotoxicity can affect the central nervous system or the peripheral nervous system. The agent that causes neurotoxicity is called a neurotoxin or sometimes a neurolysin.
A neurotoxin is a substance that has the property of destroying the nerve cells called ganglion and cortical cells. A ganglion is a group of nerve cells that serves as a central point from which transmission of nerve impulses originate. Cortical cells are cells in the cerebral cortex of the brain. Neurotoxins may be natural substances that impair how nerves functions by blocking their electrical activities.
Examples of natural neurotoxins include the venom that certain animals use in defending themselves. This includes, for example, pufferfish, scorpions, snakes, and spiders. Synthetic neurotoxins include insecticides and nerve gas or nerve agents. The first nerve agents were developed from insecticides. However, neurotoxicity can also result from inadvertent exposure or overexposure to substances that are intended to have beneficial effects, or at least to do no harm. Examples include radiation treatment, chemotherapy. Everyday substances such as cosmetics and cleaning solvents have also been linked to neurotoxicity.
In general, neurotoxicity can have a variety of effects depending on the neurotoxin involved and the amount to which the body is exposed. Specifically for radiation treatment, for example, the degree of neurotoxicity can be linked to the cumulative dose of radiation, the individual size of doses, the duration of the radiation therapy, the volume of tissue receiving radiation, and the susceptibility of the individual. When chemotherapy leads to neurotoxicity, the degree of the neurologic side effects will be part of what determines whether the therapy should be discontinued.
The effects of neurotoxins can vary somewhat in type and severity. The most severe result is death. Other possible effects include muscle weakness, diminished sensation and loss of motor control, cognitive disturbances, tremors, and dysfunction of the autonomic nervous system. Since the autonomic nervous system controls the heart, when it is affected, the situation is critical.