Neurotoxicity is usually caused by a series of symptoms of central nervous system dysfunction that occur when an external toxic substance invades the organism and affects the central nervous system. In mild or moderate cases, the symptoms usually include dizziness, headache, nausea, vomiting, lack of mental concentration or uncoordination of the arms and legs, and relatively poor mental state, and there may be mild muscle tremors or convulsions in the limbs. In the case of severe poisoning, the patient will usually show blurred consciousness, and in serious cases, coma, twitching of limbs, shock, etc., and may also produce central respiratory depression leading to respiratory arrest and death.