Arachnoid+Cysts

Arachnoid cysts are the most common type of brain cyst. Arachnoid cysts are cerebrospinal fluid-filled sacs that are located between the spinal cord and brain as well as the arachnoid membrane. They are congenital lesions that occur as a result of the splitting of the arachnoid membrane. The cysts are fluid-filled sacs, not tumors, appearing in one of the three layers of tissue covering the central nervous system. Most cases present during infancy; however onset of symptoms may be delayed until adolescence when the cyst has enlarged. Arachnoid cysts that are located around the spinal cord are less common than those that appear inside the head. In a child's head, an arachnoid cyst can be located between the brain and the skull.
 * [|Arachnoid Cysts]**

**Primary Arachnoid Cysts** Such cysts are present at birth and are the result of developmental abnormalities in the brain and spinal cord that arise during the early weeks of gestation. The cyst has an incessant tendency to grow or recur but the growing mechanism is still a mystery and the mechanism by which they expand is not fully understood.

9 month old girl with an arachnoid cyst seen in an ultrasound

**Secondary Arachnoid Cysts**  Not as common as primary cysts, secondary arachnoid cysts develop as a result of head injury, meningitis, or tumors, or as a complication of brain surgery.

Multiple Cystic masses in the choroid plexus glomi

**Symptoms**
 * headaches
 * epileptic seizures
 * increased intracranial pressure
 * behavioral changes

** Treatment ** The need for treatment depends mostly upon the location and size of the cyst. If the cyst is small, not disturbing surrounding tissue, and not causing symptoms, some doctors will refrain from treatment. In the past, doctors placed shunts in the cyst to drain its fluid. With the help of microneurosurgical techniques and endoscopic tools that aid in minimally invasive surgery, more doctors are opting to surgically remove the membranes of the cyst or open the cyst so its fluid can drain into the cerebrospinal fluid and be absorbed. A shunt is a tiny tube (catheter) that drains cerebrospinal fluid from one place in the body to another.