Brain cysts are sacs filled with fluid and other organic debris. The majority of brain cysts can be classified into five basic types depending on their location and their composition. While brain cysts aren't tumours and many people with cysts never experience symptoms, cysts that steadily grow can cause headaches, dizziness, and in extreme cases, abrupt death. Cysts are most often detected by MRI or CAT scans after a patient complains of symptoms.
Almost all brain cysts form during fetal development. Arachnoid cysts are the most common type of brain cyst and contain cerebrospinal fluid. Colloid cysts form during embryonic development of the central nervous system, while dermoid and epidermoid cysts form during skin development and can contain cartilage, oil glands, and in the case of dermoid cysts, hair follicles. Pineal cysts are the most puzzling to researchers, who don't yet understand how or when these cysts form.
Arachnoid cysts are located within the membrane covering the brain and spinal cord. Colloid cysts are located in the centre of the brain, which makes full surgical removal extremely hazardous. Pineal cysts are found nestled next to the pineal gland while dermoid and epidermoid cysts can be found either in the brain or spinal column.
Arachnoid cysts most afflict children and adolescents, with males being four times more likely to be afflicted than females. Dermoid cysts also most often trigger symptoms in childhood, typically afflicting children younger than 10. Conversely, middle-aged adults are most likely to suffer symptoms from epidermoid cysts. Colloid cysts usually afflict adults, while pineal cysts can afflict any age group, showing no tendency to trigger symptoms among any specific demographic.
Symptoms and complications
Brain cysts can trigger headaches, fever and dizziness. The patient may also experience bouts of nausea and vomiting. In particularly severe cases, the afflicted person dies suddenly, without having experienced any prior symptoms. Cyst rupture can be particularly dangerous; the contents spill into the brain can lead to meningitis. Cyst growth can cause hydrocephalus, a condition in which blockage prevents normal flow of fluid through the brain, causing the fluid to accumulate to dangerous levels.
Surgical extraction is the most common treatment for dermoid and epidermoid cysts, but the locations of arachnoid and colloid cysts make invasive procedures particularly risky. Alternative treatments consist of draining the cyst while leaving the cyst walls intact or implanting a shunt to redirect the cyst's fluid. When a brain cyst is discovered that's not causing symptoms, it's most often monitored for growth and otherwise left alone.
- American Brain Tumor Association: Cysts
- Chicago Institute of Neurosurgery and Neuroresearch: Types of brain tumor related cysts
- National Institute of Neurological Disorders and Stroke: NINDS arachnoid cysts information page
- John Hopkins Medicine: Neurology and neurosurgery: Arachnoid cysts
- Neurological Consultants: Colloid cysts