WHAT IS A BRAIN CYST?

Brain cysts, one of the common topics in pediatric neurosurgery, or cystic brain lesions can simply be described as fluid-filled sacs in the brain. They may be benign (non-cancerous) or malignant (cancerous). Benign means that the growth has not spread to other parts of the body. A cyst may contain blood, pus or another substance. In the brain, cysts sometimes contain cerebrospinal fluid (CSF). CSF is the clear fluid that bathes and protects the brain and spinal cord. Some brain cysts begin before birth.

Even if a brain cyst is not cancerous, it can still cause problems. The cyst may put pressure on brain tissue and cause symptoms such as headache, vision problems or nausea. If this happens, surgery may be needed to remove the cyst. On the other hand, if the cyst is small, not growing and not causing symptoms, follow-up by your pediatric neurosurgeon with periodic examinations and imaging may be enough.

What are the types of brain cysts?

1. Arachnoid cyst (leptomeningeal cyst): These cysts are often found incidentally on brain imaging in patients who have no complaints. They are located between the brain's own membranes, which are protective coverings around the brain. An arachnoid cyst contains cerebrospinal fluid (CSF), a fluid present in everyone's brain. They are most often seen in children, but may also be present in adults. This type of cyst is more common in boys and men. Arachnoid cysts are the most common brain cysts and the great majority require no treatment. Rarely, they become very large, and after special tests such as EEG, eye examination and developmental testing, surgery may be recommended. Treatment decisions consider the patient's current condition, overall development, neurological skills and age.
2. Colloid cyst: This is a cyst filled with a thick, gel-like material. It usually forms in one of the four ventricles of the brain. Ventricles are reservoirs for CSF in the brain. Colloid cysts usually occur in the third ventricle, a central part of the brain. They can block CSF flow and may cause positional headaches, meaning headaches that occur in certain body positions. They usually appear in adulthood, and if one is found, surgery will probably be recommended.
3. Dermoid cyst: This is a rare type of cyst. It forms when a few skin cells are trapped while the brain and spinal cord are developing before birth. These cysts may contain sweat gland cells or even hair follicle cells. They usually occur in children. Sometimes they connect to the skin surface and cause drainage or swelling under the skin. Depending on the patient, follow-up or surgery may be needed.
4. Epidermoid cyst: This is also called an epidermoid tumor. Like a dermoid cyst, it consists of tissue trapped while the brain and spinal cord are developing. Epidermoid cysts do not contain sweat glands or hair follicle cells. They grow very slowly and usually become apparent for the first time in adulthood. If they cause problems, they are usually treated surgically. Even though they are benign, they may grow again and require further surgery.
5. Pineal cyst: This occurs in the pineal gland in the middle of the brain. This type of cyst is usually found only on imaging performed for another reason. Pineal cysts rarely cause problems. If they grow, they may sometimes affect vision or increase intracranial pressure by disrupting CSF circulation. They can occur at any age.
6. Brain abscess: This may occur as a single cyst or multiple cysts anywhere in the brain. An abscess is usually caused by a bacterial infection, and sometimes by a parasite or fungus. Brain abscesses are dangerous. They usually require surgery and long-term antibiotic treatment.
7. Tumor cysts These are caused by benign or malignant tumors. They are not like the cysts described above and often require surgery and, when needed, additional treatments such as chemotherapy or radiotherapy.

What are the symptoms of a brain cyst?

Simple cysts often cause no symptoms and are discovered by chance. However, symptoms may vary widely depending on the cyst's size and location in the brain.

Symptoms differ from person to person. Common symptoms include:

• Headache
• Nausea and vomiting
• Vision problems, especially sudden loss of vision on both sides
• Involuntary movements, muscle weakness or paralysis
• Loss of balance or coordination
• Hearing loss or tinnitus (ringing in the ears)
• Altered state of consciousness, e.g. sleepiness or loss of consciousness
• Speech or language problems
• Personality changes or emotional changes
• Seizures - epileptic seizures

How is a brain cyst diagnosed?

In most cases, a brain cyst is diagnosed with computed tomography (CT) or magnetic resonance imaging (MRI). A radiologist evaluates these scans. This type of imaging allows the doctor to see the brain tissue and surrounding structures inside the skull. These tests also help identify the location and size of any cyst or tumor in the brain.

How is a brain cyst treated?

Treatment of a brain cyst usually depends on its type, location and size. If the cyst does not cause symptoms, the doctor will usually prefer monitoring it with regular MRI scans. If the cyst is growing or causing symptoms, treatment is often surgical. The contents of the cyst may be drained or the cyst may be removed completely. If there is infection inside the cyst, antibiotics may be needed.

In some cases, radiotherapy may be needed to prevent the cyst from forming again. Medication may also be needed to control symptoms caused by the cyst. These symptoms may include headaches, seizures and certain problems with brain function.

In every case, a person diagnosed with a brain cyst should consult a neurosurgeon to discuss treatment options and possible risks.

Important Points About Brain Cysts

• Brain cysts are fluid-filled sacs that can form in the brain. They can be non-cancerous (benign) or cancerous (malignant).
• Brain cysts can occur in children or adults. In some cases, they begin before birth but cause symptoms much later.
• If a brain cyst does not cause symptoms, it may be found on an imaging scan performed for another reason.
• Different types include arachnoid, colloid, dermoid, epidermoid, pineal, infectious and tumor cysts.
• Even if brain cysts are not cancerous, they can put pressure on brain tissue and cause symptoms. Sometimes a cyst can block the normal flow of cerebrospinal fluid (CSF), which can cause problems.
• Your neurologist or neurosurgeon may recommend surgical removal of the cyst. If the cyst is small and unlikely to cause symptoms, your healthcare provider may prefer to monitor it and see whether it remains stable.