Cysts are hollow cavities in tissue that are usually filled with fluid. They form after trauma, for example, inflammation or perfusion problems. In some cases, the cysts develop between the arachnoid layers, often without any apparent reason. Parasites such as tapeworms can also cause these tissue changes within the skull. Cysts can also develop in the spinal canal.
As with other changes in the brain, the symptoms depend greatly on the size and position of the cysts. Headaches, dizziness, nausea and epilepsy are the most common manifestations. Problems with movement, vision or speech can also occur, however.