Arachnoid Cysts in Children

What is an Arachnoid Cyst?

An arachnoid cyst is a type of brain cyst (fluid-filled sac) that occurs in the tissue between the skull and brain. The fluid in the cyst is normal brain fluid, and it’s not cancerous. Most arachnoid cysts are congenital, meaning a baby has the arachnoid cyst when they’re born.

These cysts can range in size. Most small cysts don’t cause any symptoms or need treatment. Some arachnoid cysts enlarge shortly after birth, and large cysts can put pressure on the brain and may require surgical treatment.

What are the signs and symptoms of an Arachnoid Cyst?

The signs and symptoms of arachnoid cysts vary based on the child’s age and the size and location of the cyst. The signs and symptoms may include:

• Delays in development
• Involuntary (cannot be controlled) head bobbing
• Seizures
• Visible lumps or protrusions on the head
• Abnormal head growth
• Headache
• Nausea and vomiting
• Problems with vision

Rarely, arachnoid cysts can rupture with head trauma, which causes acute headaches and requires emergency medical attention.

How is an Arachnoid Cyst diagnosed?

Doctors diagnose arachnoid cysts with scans that allow them to see images of the brain and skull, like a CT scan and MRI.

What causes an Arachnoid Cyst?

No one knows the exact cause of arachnoid cysts, but most arachnoid cysts are thought to be congenital, which means that a baby has had the condition since birth. Some arachnoid cysts are caused by scar tissue from a head injury or infection.

How is an Arachnoid Cyst treated?

Some children will need surgery to treat their arachnoid cyst, while many children won’t need any treatment. For children who need surgery, there are two types of surgical treatments. Both treatments drain fluid, relieve pressure on the brain and keep fluids from reaccumulating.

Your neurosurgeon may recommend a treatment called fenestration. In this procedure, neurosurgeons make openings in the cyst wall to allow fluid to drain into the normal fluid pathways in the body. This can be done either endoscopically (using a long, thin tube) or through microsurgery (using a microscope).

The other surgical treatment is called a shunt. In a shunt procedure, neurosurgeons insert a shunt (thin tube) in the cyst, and the shunt diverts the fluid to the abdomen where it is absorbed into the body. The shunt stays in place after the surgery.

Each child is unique, and recommendations for treatment are individualized based on the location and size of the cyst as well as the child’s age. Our renowned pediatric neurosurgeons are national experts in arachnoid cysts and we treat the most children with this condition in our region. That means our team is highly experienced in choosing the best treatment for each child and keeping the number of surgeries, risks and side effects to an absolute minimum.