With the popularity of CT and MRI examinations, more and more people are diagnosed with “arachnoid cysts”, among which the more common ones are “occipital septal cyst”, “hyaline septal cyst “Do these diseases require treatment? Arachnoid cysts are congenital abnormalities in the development of brain tissue, resulting in localized impaired circulation of cerebrospinal fluid. Under normal circumstances, cerebrospinal fluid circulates in the subarachnoid space and ventricles, producing about 450 ml per day, which is absorbed and does not cause hydrocephalus or cysts. If the structure of the arachnoid is abnormal, more cerebrospinal fluid goes in and less comes out, which leads to gradual expansion of the cyst and causes symptoms. The pathological nature of the cyst itself is benign and not a tumor. Therefore, only cysts that keep increasing in size and cause symptoms need to be treated. If it does not cause symptoms and does not gradually increase in size, it can only be considered as a congenital structural abnormality, which is the same nature as a birthmark and does not require treatment. However, the difficulty is how to determine whether the symptoms such as headache or dizziness are caused by a “cyst”. Because of the high incidence of headaches and dizziness and the complexity of the causes, many people who do not have cysts or tumors in their brains also get headaches. So how can you tell? The following points can be used to determine: 1. Headaches and dizziness caused by cysts tend to get worse gradually and have a tendency to “worsen”. If the headache is repeated every year or every month, and the overall degree is about the same, it is often not caused by the cyst. 2. If the headache is accompanied by other symptoms of increased pressure in the brain, such as nausea and vomiting, loss of vision, epilepsy, hydrocephalus, and impaired consciousness, it is often caused by the cystic lesion. 3. (doctors need to help to judge, such as occipital pool cyst causing obstructive hydrocephalus, temporal lobe cyst compressing brain tissue causing epilepsy, suprasellar pool cyst causing gradual loss of vision, hyaline septal cyst causing hydrocephalus, etc.); optic papillar edema found during the examination of elevated brain pressure (doctors need to look at the fundus of the eye, because high brain pressure causes poor venous return of the optic papilla and swelling of the optic papilla in the fundus of the eye) Now, CT or MRI report There are many occipital pool cysts (located between the two cerebellum) and hyaline septal cysts (located between the lateral ventricles of the brain). In fact, such reports are not always correct, and many people I see who come to the clinic are stuck with such reports, in fact, most of the reports of occipital pool cysts are only the enlarged occipital pool (normal structure), and hyaline septal cysts are only the rare fifth ventricle (which can also be considered as normal structure). Therefore, simply put, it is the arachnoid cysts that cause worsening symptoms and have progressive enlargement that require treatment.