Colloid cysts are benign tumors that typically grow along the roof of the third ventricle. Although they are often labeled as tumors, colloid cysts actually are thought to arise during embryonic development. The cyst, which contains a thick gelatinous fluid, can grow in size, and in this location can block the normal flow cerebrospinal fluid. As the fluid builds up in the ventricles (hydrocephalus), increased pressure on the surrounding brain causes headaches. Other symptoms may include confusion, difficulty walking, and brief interruption of consciousness. These cysts can often
sit in the brain, not making their presence known for many years into adulthood when they finally reach a large enough size to cause symptoms.
Symptoms, such as headache and nausea, usually are the result of increased intracranial pressure caused by the blockage of normal cerebrospinal fluid flow through the brain ventricular system. As the fluid and pressure buildup in the ventricles increases these tumors can lead to confusion, short-term memory difficulties, difficulty walking, and sudden deterioration with an abrupt loss of consciousness.
These tumors are diagnosed with a neurological history and examination followed by imaging studies of the brain, usually a computed tomography (CT) or magnetic resonance imaging (MRI) scan. The scan provides detail information regarding the exact size and location of the Colloid Cyst and identifies the presence of any associated hydrocephalus. In some cases, neurosurgeons may employ a stereotactic MRI scan. In this study, a high-resolution contrast MRI is performed and a three-dimensional brain model is constructed using a computer system that is used to perform minimally invasive surgery and allow for endoscopic removal of the tumor.
Small colloid cysts without any hydrocephalus or any symptoms can be observed over time with periodic imaging studies. For symptomatic colloid cysts the definitive treatment is with surgical removal. Surgical removal van be performed using microsurgical techniques with an approach to the ventricular system through which the tumor is removed. With the advent of minimally invasive endoscopic techniques, most colloid cysts are now being removed endoscopically. The endoscopic procedure involves making a small incision behind the hairline where a small access hole is made to the brain. Through the access port, a rigid fiberoptic camera is inserted into the ventricle and the colloid cyst is removed using specialized instruments that pass through channels in the endoscope. The cyst is coagulated and the contents are aspirated through a suction catheter. The cyst wall is removed and the attachment is dissected free all through the endoscope. This technique is significantly less invasive and disruptive of the surrounding brain. Following surgical removal most patients are monitored with annual surveillance MRI scans to make sure there is no evidence of tumor recurrence. Aside from removal of the tumor no other treatment is typically necessary.