Arachnoid cysts are fluid-filled sacs in the brain or spinal cord. They can be present before birth or result from a head injury. They typically do not cause symptoms or require treatment. Many cysts ...

Arachnoid cysts are the most common type of brain cyst. They're not tumors, but cysts filled with cerebrospinal fluid (a clear liquid that surrounds your brain and spinal cord). Most people who have ...