What is a Colloid Cyst?

A colloid cyst is a benign growth found in the brain. These cysts contain a gelatin-like material made up of bodily substances, including old blood and cholesterol. Colloid cysts typically form in the third ventricle — one of four fluid-filled cavities found in the brain. They are often at or near the foramen of Monro, which is near the front of the third ventricle.

When a colloid cyst forms, it can block the flow of cerebrospinal fluid, which protects the brain and spinal cord from trauma. When the flow is disrupted, this could lead to hydrocephalus, which is the buildup of fluid in the ventricles within the brain.

Because of that, someone with a colloid cyst may experience neurological symptoms ranging in severity from mild to life-threatening. Colloid cysts are relatively rare, accounting for only 2% of all primary brain tumors.

Symptoms of Colloid Cysts

In many cases, colloid cysts do not cause symptoms. In cases where a patient is symptomatic, symptoms will vary depending on the size of the cyst and its exact location. Headaches are the most common symptom related to colloid cysts and typically result due to hydrocephalus and the backup of fluid. Beyond experiencing headaches, people with a colloid cyst may experience other neurological symptoms, including:

• Changes in vision
• Increased risk of falling
• Loss of consciousness
• Memory loss
• Nausea and vomiting
• Urinary incontinence

How Colloid Cysts Are Diagnosed

If a colloid cyst is suspected, a doctor will carefully review symptoms, talk through personal and family history and perform a thorough physical exam. Following this exam, he or she will also order diagnostic testing to confirm whether a cyst is present.

CT and MRI are often used to diagnose colloid cysts. A CT scan is typically used to determine whether acute hydrocephalus is occurring and can also be used to diagnose a colloid cyst. MRI, though, is the most commonly used diagnostic test, allowing doctors to effectively visualize the cyst and its characteristics.

Treatment for Colloid Cysts

Treatment will depend on whether a colloid cyst is asymptomatic or symptomatic. Asymptomatic cysts will need regular checkups by a doctor and imaging tests to ensure the size or severity of the cyst has not changed. If hydrocephalus is present, prompt treatment is necessary.

For life-threatening hydrocephalus, a doctor will first treat the hydrocephalus by placing a drain to remove excess cerebrospinal fluid from the brain. From there, treatment will focus on removing the colloid cyst itself.

There are multiple options for surgical treatment of colloid cysts:

• Craniotomy, in which part of the skull will be removed to allow for access to the colloid cyst
• Endoscopic removal, involving making a small incision in the scalp and a small hole in the bone, then passing a small tube into the brain to access the ventricles and;
• Stereotactic aspiration, involving making a small incision in the scalp and a small hole in the bone, but then uses a needle positioned in the brain to aspirate the colloid cyst and decrease its size.