Arachnoid cysts are abnormal sacs filled with cerebrospinal fluid that grow on the surface of the brain and spinal cord. These cysts are typically non-cancerous and can occur in anyone, regardless of age or gender. Sometimes, they are discovered incidentally during an MRI or CT scan for another condition. The symptoms of arachnoid cysts can range from mild to severe, including headaches, seizures, and problems with motor function or balance. When discussing these cysts, they may also be referred to as arachnoid diverticula, meningeal cysts, or leptomeningeal cysts. Regardless of the term used, proper diagnosis and treatment are important for managing symptoms and preventing complications.