Benign conditions of the brain and spinal cord are non-cancerous. Cysts are sacs that contain fluid or semi-solid material. Cysts found in the brain and spinal cord may contain cerebrospinal fluid, blood, tissue or tumour cells.
Although cysts tend to be non-cancerous, they may be found in parts of the brain and spinal cord that control vital functions. They may also develop inside or beside low-grade or high-grade tumours. Usually only one cyst occurs. However, many tiny cysts may be found inside a high-grade tumour.
There are no known risk factors for cysts of the brain and spinal cord.
The signs and symptoms of a cyst in the brain and spinal cord are the same as those of tumours. The specific symptoms depend on the location of the cyst. They usually appear when the cyst is large enough to affect brain or spinal cord function.
If the signs and symptoms of a brain or spinal cord tumour are present, or if the doctor suspects a tumour, tests will be done to make a diagnosis. These tests will help the doctor determine if a cyst or tumour is present.
The different types of cysts are named for the type of tissue in which they begin or for the material they contain.
Arachnoid cysts, sometimes called leptomeningeal cysts, start in the subarachnoid space (the space between the arachnoid and pia mater layers of the meningesmeningesThe membranes that cover and protect the brain and spinal cord., which form a membrane-like covering around the brain and spinal cord). Arachnoid cysts occur:
Treatment options for arachnoid cysts may include:
Colloid cysts develop in the third ventricle. They likely begin to form when the central nervous system develops, while the baby is still in the womb. These cysts may sit quietly until adulthood when they grow large enough to block the flow of CSF, causing hydrocephalus (a buildup of CSF in the brain). A buildup of CSF increases the pressure in the brain, which causes symptoms.
The best treatment options for colloid cysts depend on the person’s anatomy and the location of the cyst. Treatment options may include:
Dermoid cysts likely develop during the early weeks of a baby’s development in the womb. Symptoms are noticed years after birth.
Dermoid cysts are usually removed by surgery. Cysts can regrow if they are not completely removed (including the sac-like lining). The growth may be very slow and it could be years before symptoms return.
Epidermoid cysts, also referred to as epidermoid tumours, likely develop during the early weeks of a baby’s development in the womb. They grow very slowly and it may be several decades before symptoms are noticed.
Epidermoid cysts are usually removed by surgery. Cysts can regrow if they are not completely removed (including the sac-like lining). The growth may be very slow and it could be years before symptoms return.
Cysts in the pineal gland are usually found by accident when the person has an MRI for other reasons. The reason they develop is unclear. It is unusual for pineal cysts to cause signs or symptoms. When they do, it is either because there has been increased CSF production or bleeding into the cyst.
Treatment for pineal cysts is active surveillance.
Both benign and malignant tumours may be associated with cysts. These cysts are sometimes called tumour cysts. An underlying tumour associated with a cyst is usually obvious because a CT or MRI scan shows a nodule or lump next to the cyst.
Treatment options for tumour-associated cysts depend on whether the tumour is low grade (benign) or high grade (malignant).