Arachnoid cysts, which are most commonly seen in the brain, can also be seen around the spinal cord. They form between the meninx, called the arachnoid membrane, and the brain or spinal cord. There is cerebrospinal fluid (CSF) inside the cyst. These cysts, which are mostly congenital, may also develop in other stages of life. They are usually asymptomatic. Therefore, they also can be diagnosed incidentally after an MR or tomography examination. Treatment is needed if they extremely compress the brain or block brain development in children. The symptoms appear according to the compressed brain regions. The most common symptom is headache. The ones located in the temporal region of the brain can lead to epileptic seizures. Depending on the increase in intracranial pressure, symptoms such as nausea, vomiting, and paralysis can be seen. By using surgical methods called endoscopic fenestration in the treatment, the arachnoid cyst is anastomosed to the other CSF pathways. Or with a silicone drain called a shunt, the fluid in the arachnoid cyst is anastomosed and by so the CSF is drained down to the peritoneum in the abdomen.