The incidence of intracranial arachnoid cysts is approximately 5/1000 and in general, most arachnoid cysts are detected occasionally (e.g., after a head injury, during a head CT, etc.). Of intracranial arachnoid cysts, about half are found in the temporal region. Should I have surgery if I have an arachnoid cyst? There are 3 types of temporal lobe arachnoid cysts: temporal lobe arachnoid cyst type 1: surgery is not necessary unless there are clear symptoms such as headache; temporal lobe arachnoid cyst type 2: surgery can be decided according to the actual situation; temporal lobe arachnoid cyst type 3, surgery is required. Timing of surgery: up to 3 years of age. Children with arachnoid cysts will have a great possibility that the brain tissue missing due to cyst compression will grow back after surgery if the surgery is done within 3 years of age.