There are many causes of vasospasm, such as: first, mental factors, mental tension, anxiety or irritability, can lead to vasospasm. Second, excessive exertion, or often stay up late and not enough rest, can also easily lead to the occurrence of vasospasm. Third, smoking and alcohol abuse, nicotine easily damage the endothelium, can lead to vasospasm. Fourth, cold or cold, cold will stimulate the blood vessels, vasoconstriction, can lead to vasospasm. The mechanism that causes vasospasm is mainly sympathetic excitation, or increased secretion of catecholamines, resulting in sustained vasospasm of the blood vessels. If the blood vessels are in spasm, but there are no symptoms, it is called asymptomatic vasospasm. If symptoms of functional deficit are present, it is called symptomatic vasospasm.