Brain and spinal cord cysts

Brain and spinal cord cysts are non-cancerous. Cysts found in the brain and spinal cord may contain cerebrospinal fluid (CSF), blood, tissue or tumour cells. They may be found in parts of the brain and spinal cord that control vital functions. Cysts may develop inside or beside tumours.

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 and usually appear when the cyst is large enough to affect brain or spinal cord function.

The different types of cysts are named for where they start 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 meninges). Arachnoid cysts occur in both adults and children and occur more often in males than in females. Some arachnoid cysts never grow or cause symptoms.

Treatments for arachnoid cysts include:

• Active surveillance for small cysts that aren’t causing symptoms.
• Surgery to remove or drain the cyst. Surgery may also be used to place a tube (shunt) to drain CSF and relieve pressure on the brain.

Colloid cysts develop in the third ventricle of the brain. They likely begin to form when the central nervous system develops, while the baby is still in the womb. These cysts may sit unchanged until adulthood when they grow large enough to block the flow of CSF, causing a buildup of CSF in the brain (hydrocephalus). A buildup of CSF increases the pressure in the brain which causes symptoms.

The type of treatment depends on the location of the cyst. Treatments for colloid cysts include:

• Active surveillance for small cysts that aren’t causing symptoms.
• Surgery to remove or drain the cyst. Surgery may also be used to place a tube (shunt) to drain CSF and relieve pressure on the brain.

Dermoid cysts likely develop during the early weeks of a baby’s development in the womb. Symptoms are noticed years after birth. Dermoid cysts often contain hair follicles, bits of cartilage or sebaceous glands that produce oils and fat. In older children and young adults, they are most often found in the lower end of the spine. In adults they are most often found at the lower back part of the brain.

Dermoid cysts are usually removed with surgery. Cysts can regrow if they are not completely removed. The growth may be very slow and it could be years before symptoms return.

Epidermoid cysts (also called 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 often contain remnants of skin cells or tiny pieces of cartilage.

Epidermoid cysts occur more often in the brain than in the spinal cord. These cysts often develop where the top part of the brain meets the brain stem, near the pituitary gland or along the skull. They are most common in middle-aged adults.

Epidermoid cysts are usually removed with surgery. Cysts can regrow if they are not completely removed. The growth may be very slow and it could be years before symptoms return.

Cysts in the pineal gland are usually found accidentally during an MRI that is being given for other reasons. It is unusual for pineal cysts to cause signs or symptoms and the cyst usually doesn’t grow very large. When they do grow or cause symptoms, it is either because there has been increased CSF production or bleeding into the cyst. Pineal cysts are rarely associated with underlying tumours.

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 noticeable because a CT scan or an MRI shows a nodule or lump next to the cyst.

Treatment for tumour-associated cysts depends on whether the tumour is low grade or high grade. Treating the tumour also treats the cysts that are associated with it.

• Low-grade tumours associated with cysts are usually treated with surgery.
• High-grade tumours associated with cysts may be treated with surgery, followed by radiation therapy with or without chemotherapy.