A neurotoxin is a substance which inhibits the functions of neurons. Neurons are found throughout the brain and nervous system, and the function of these unique cells is critical for a variety of tasks, ranging from autonomic nervous system jobs like swallowing to higher-level brain function. Neurotoxins can work in a variety of ways, with the danger of exposure varying, depending on the neurotoxin involved and the dosage.
In some cases, neurotoxins simply severely damage neurons so that they cannot function. Others attack the signaling capability of neurons, by blocking releases of various chemicals or interfering with the methods of reception for such transmissions, and sometimes telling neurons to send false signals. A neurotoxin may also destroy neurons altogether.
The body actually generates some neurotoxins; many of the neurotransmitters produced to send messages across the nervous system can be dangerous in high amounts, for example, and sometimes the body produces neurotoxins as it responds to a threat to the immune system. Neurotoxins are also present in large numbers in the natural environment; some venomous animals produce neurotoxins, while heavy metals such as lead are also neurotoxins. Neurotoxins are also used by some governments for crowd control and warfare, in which case they are usually known as nerve agents.
Exposure to neurotoxins can cause dizziness, nausea, loss of motor control, paralysis, difficulty with vision, seizures, and strokes. In extreme cases, the results of exposure may include coma and eventual death as the nervous system shuts down. Especially when a neurotoxin inhibits the function of the autonomic nervous system, the body quickly starts to break down, because a number of important tasks are not being performed.
In the case of acute exposure, someone is exposed suddenly to a dose of a neurotoxin. A snake bite is an example of acute exposure. Chronic exposure involves slow exposure over time; heavy metals poisoning often takes the form of chronic exposure, with the unwitting victim taking in a small amount each day. The problem with heavy metals is that they build up in the body, rather than being expelled, so at a certain point, the victim will become sick.
A variety of techniques can be used to treat neurotoxin exposure. Many focus on supportive care, performing tasks which the body isn't doing until the patient is stable. In these cases, the patient may recover, but he or she will often experience side-effects related to the exposure later in life. Sometimes, chemicals can be used to block the function of a neurotoxin, or to help flush it from the body. In other cases, there is no cure for exposure, and the goal is to keep the patient comfortable.