Brain cysts are spheres that are filled with fluid almost like fluid-filled balloons in the brain. The fluid may contain blood, tissue, or minerals. Brain cysts tend to be benign or noncancerous and may not need to be treated; however, the type of cyst, its location, and any effects the cyst causes determine any treatment. The major types of brain cysts are arachnoid, colloid, dermoid, epidermoid, and pineal.
Arachnoid cysts are found in the space between the two innermost layers of the coverings of the brain known as the meninges. Treatment may simply require watching the cyst determine if it is growing or causing any problems. This is accomplished by successive brain scans. If the cyst is growing in an area that would cause a problem the physician may suggest surgery which typically involves draining the cyst and then surgically removing it. If removing the cyst is not feasible then it is often just drained as arachnoid cysts contain cerebral spinal fluid and the contents are absorbed into the brain (ref 1, 3).
These cysts begin developing in the embryo and contain a gelatinous substance called colloid. They may not be discovered for years; however, they are often located in the ventricles or spaces in the brain. They may block the flow of cerebral spinal fluid in the brain, which provides nutrients and cleanses the brain. Surgical removal is the common treatment; however, they are often in hard to reach places. The other option is to drain them or use a shunt, which is a passageway the surgeon makes to keep the cerebral spinal fluid flowing and drain the cyst (ref 1 & 2).
Dermoid cysts typically develop in the embryo as a result of cells destined to be skin or hair getting trapped in the brain cells. These cysts contain mature skin with hair follicles and sometimes sweat glands. These cysts may break open releasing their contents into the brain or spinal cord resulting in meningitis, an infection of the coverings of the brain. Dermoid cysts are typically treated by surgical removal. Sometimes the lining of the cyst cannot be completely removed from the brain and this will result in a new cyst growing, although this may take many years (ref 1).
Epidermoid cysts develop like dermoid cysts but do not contain hair follicles or sebaceous glands. These cysts contain a thick yellowish substance and may rupture releasing their contents in the brain and spinal cord resulting in meningitis. If these need to be treated this is typically accomplished via surgical removal. There are a few rare cases of these cysts developing into cancerous tumors and surgery and radiation treatment would be used in such cases (ref 1 & 2).
These occur in the pineal gland, which produces hormones important in various functions such as sleep. These cysts often cause no problems; however, sometimes they can result in headaches, difficulty looking up, difficulty walking, and may increase the fluid in the brain which leads to increased pressure in the brain (ref 2, 3). Treatment is surgical removal.