What is an arachnoid cyst? Arachnoid cysts are congenital disorders caused by abnormal division of the arachnoid membrane during development. Most lesions appear early in childhood. The clinical presentation depends on the location of the cyst. There are often large lesions with mild symptoms. Typical manifestations include: 1) symptoms of increased intracranial pressure: headache, nausea and vomiting, drowsiness; 2) epilepsy; 3) sudden deterioration of the disease; 4) cranial bulge; 5) local symptoms/signs due to occupational effects; 6) incidental findings during the treatment of unrelated diseases. Treatment: Arachnoid cysts without occupational effects or symptoms do not require treatment, regardless of size and location. Surgical procedures: excision of the cyst wall, cranial drilling for transendoscopic cyst penetration, and cystic abdominal shunt. The best approach is to use a low-pressure tube to shunt the cyst into the abdominal cavity to perform a cystic abdominal shunt.