When a scan shows an arachnoid cyst on your child’s brain or spine, it can feel overwhelming. Most arachnoid cysts are not cancer, do not spread, and never need surgery. But some cysts can cause headaches, seizures, pressure, developmental concerns, or fluid buildup.
At New Jersey Pediatric Neuroscience Institute, our pediatric neurosurgery team helps families understand what the cyst means, whether it needs treatment, and what the safest next step should be.
Parents Come to NJPNI For
- Pediatric neurosurgery evaluation
- Second opinions after MRI or CT scan
- Monitoring plans for stable cysts
- Endoscopic fenestration, open fenestration, and shunt options when surgery is needed
- Coordinated care with pediatric neurology when symptoms include headaches or seizures
Quick Answer for Worried Parents
An arachnoid cyst is a fluid-filled pocket that forms in one of the thin protective layers around the brain or spinal cord. The fluid inside the cyst is usually cerebrospinal fluid, the same clear fluid that naturally cushions the brain and spine.
Many children with arachnoid cysts need only monitoring. Surgery is usually considered only when the cyst is growing, causing symptoms, blocking normal spinal fluid flow, or putting pressure on important areas of the brain or spine.
What Is an Arachnoid Cyst?
The brain and spinal cord are covered by protective layers called meninges. One of these layers is the arachnoid membrane. Sometimes a pocket forms in this membrane and fills with fluid. That pocket is called an arachnoid cyst.
Arachnoid cysts can be found before birth, during childhood, or later after a CT scan or MRI is done for headaches, seizures, a head injury, developmental concerns, or another reason. Many are found by accident.
Is it a brain tumor?
No. An arachnoid cyst is not a brain tumor and it is not cancer. It is a collection of fluid. The key question is whether the cyst is simply present or whether it is causing pressure, symptoms, or changes over time.
Where do arachnoid cysts form?
Arachnoid cysts most often form around the brain, commonly near the side of the brain by the temple area. They can also form near the base of the skull, behind the eyes, near the back of the brain, or less commonly along the spinal cord.
What causes arachnoid cysts in children?
Most arachnoid cysts in children are congenital, which means the child was born with the cyst. These cysts likely form while the brain and surrounding membranes are developing before birth. In most cases, there is no clear cause and nothing a parent did caused it.
Less commonly, arachnoid cysts can develop after head trauma, infection, bleeding, inflammation, or prior surgery. These are sometimes called secondary arachnoid cysts.
Location matters. A small cyst in one location may not cause any issues, while a larger cyst in another location may affect fluid flow, balance, vision, seizures, hormones, or development.
Arachnoid Cyst Symptoms in Children
Symptoms depend on the cyst’s size, location, and whether it is pressing on the brain, spinal cord, nerves, or normal cerebrospinal fluid pathways.
Small arachnoid cysts
Small cysts often cause no symptoms. A child may have a completely normal exam, normal development, and no restrictions. In these cases, the neurosurgeon may recommend observation instead of surgery.
Larger or growing arachnoid cysts
Larger cysts can sometimes cause symptoms by pressing on nearby structures or blocking normal fluid flow. Possible symptoms may include:
- Headaches, especially headaches that are worsening or frequent
- Nausea or vomiting
- Seizures or seizure-like episodes
- Balance problems or clumsiness
- Vision changes, double vision, or abnormal eye movements
- Developmental delays in babies or young children
- Changes in school performance, behavior, or attention
- Weakness, numbness, or coordination problems
- Unusual head growth in infants
- Back pain, leg weakness, or numbness if the cyst is in the spine
Can an arachnoid cyst cause seizures?
Sometimes. Arachnoid cysts may be found during a seizure evaluation, but that does not always mean the cyst caused the seizure. NJPNI can help determine whether your child needs neurosurgical treatment, pediatric neurology care, EEG testing, seizure management, or a combination of care.
Can an arachnoid cyst cause hydrocephalus?
In some children, a cyst can block the normal movement of cerebrospinal fluid. This can lead to hydrocephalus, which means extra fluid builds up in the brain and increases pressure. If hydrocephalus is present, treatment may become more urgent.
How NJPNI Evaluates an Arachnoid Cyst
Arachnoid cyst treatment should not be based on the MRI report alone. The most important question is whether the cyst matches your child’s symptoms, exam findings, growth pattern, and imaging.
What we review
- Your child’s MRI or CT scan
- The cyst’s size and exact location
- Whether the cyst is pressing on the brain, spine, nerves, or fluid pathways
- Your child’s headaches, seizures, vomiting, balance, vision, development, or school concerns
- Whether the cyst has changed over time
- Whether symptoms may be coming from another neurological condition
Why pediatric neurosurgery matters: Children are not small adults. A child’s brain, skull, and nervous system are still developing. Pediatric neurosurgeons understand how an arachnoid cyst may affect a growing child and when it is safer to observe versus intervene.
NJPNI provides pediatric-focused evaluation for families across New Jersey who need answers after an MRI, CT scan, emergency room visit, seizure workup, or prenatal diagnosis.
Arachnoid Cyst Treatment in New Jersey
Treatment is personalized. Some children need only monitoring. Others may need surgery if the cyst is causing symptoms, growing, blocking fluid flow, or creating pressure.
Watchful monitoring
Observation is often the best choice when a cyst is small, stable, and not causing symptoms. Monitoring may include follow-up visits and repeat MRI or CT imaging to make sure the cyst is not growing or causing pressure.
For parents, “watching it” can sound scary. But monitoring is not ignoring the problem. It is a careful plan designed to avoid unnecessary surgery while still keeping your child safe.
Symptom-based treatment
If your child has headaches, seizures, developmental concerns, vision changes, or school difficulties, NJPNI looks at the full picture. Not every symptom is caused by the cyst, and treating the wrong problem can lead to unnecessary procedures.
When needed, NJPNI coordinates neurosurgery, pediatric neurology, epilepsy care, imaging review, and developmental support so families are not left trying to connect the dots alone.
Endoscopic cyst fenestration
Endoscopic fenestration is a minimally invasive surgical option for certain arachnoid cysts. The surgeon uses a small camera called an endoscope to create openings in the cyst wall. These openings allow the trapped fluid to drain into normal fluid spaces where the body can absorb it.
This approach may allow smaller incisions, less disruption to tissue, and a faster recovery compared with traditional open surgery, depending on the cyst’s location and anatomy.
Open cyst fenestration
Some cysts are better treated with an open approach. During open cyst fenestration, the surgeon creates a small opening in the skull to reach the cyst and make drainage openings in the cyst wall.
Open fenestration may be recommended when the cyst is large, complex, in a difficult location, or not suitable for an endoscopic approach.
Cystoperitoneal shunt placement
A cystoperitoneal shunt is a small tube that drains fluid from the cyst to the abdomen, where the body absorbs it. A shunt may be considered if the cyst is likely to refill, if fenestration is not the best option, or if long-term drainage is needed.
Because a shunt is an implanted device, your neurosurgeon will explain the benefits, risks, maintenance concerns, and reasons it may or may not be the right choice for your child.
When Does an Arachnoid Cyst Need Surgery?
Surgery is usually considered when the arachnoid cyst is clearly causing a problem or has a high risk of causing one. The decision depends on symptoms, imaging, age, cyst location, and whether the cyst is changing.
Surgery may be considered when there is:
- A cyst that is growing over time
- Pressure on the brain, spinal cord, or nerves
- Hydrocephalus or blocked cerebrospinal fluid flow
- Headaches strongly linked to the cyst
- Repeated vomiting or signs of increased pressure
- Seizures that may be related to the cyst
- Vision problems or balance changes
- Developmental concerns related to the cyst’s location or pressure
- Weakness, numbness, or spinal cord symptoms
Red-flag symptoms parents should not ignore
Call your child’s doctor promptly if your child has worsening headaches, repeated vomiting, new seizures, new vision changes, balance problems, weakness, unusual sleepiness, or a major change in behavior.
Seek emergency care right away if your child has a sudden severe headache, seizure, sudden weakness, trouble waking up, confusion, or a rapid change in alertness.
Pediatric Arachnoid Cyst Care: What Parents Ask Most
Will this affect my child’s development?
Many children with arachnoid cysts develop normally. If a cyst is large, growing, or pressing on important brain areas, the neurosurgeon may look more closely at milestones, walking, speech, behavior, learning, growth, and hormone-related changes.
Can my child go to school?
Most children with arachnoid cysts can attend school normally. If your child has headaches, seizures, vision changes, learning concerns, or recovery needs after surgery, NJPNI can help guide school accommodations and return-to-school timing.
Can my child play sports?
Many children can stay active, but sports guidance should be individualized. Contact sports may require a more careful discussion because head injury can rarely cause bleeding or other complications in or around the cyst. NJPNI can provide practical guidance for parents, coaches, and schools.
Do arachnoid cysts go away?
Most arachnoid cysts do not simply disappear, but many stay stable and never cause problems. The goal is not always to remove the cyst. The goal is to protect your child’s brain, development, comfort, and safety.
Treatment Risks and Recovery
Possible surgical risks
Every surgery has risks. Depending on the procedure, risks may include bleeding, infection, cerebrospinal fluid leak, cyst recurrence, need for another procedure, shunt blockage or infection if a shunt is placed, or symptoms not fully improving if the cyst was not the main cause.
Hospital stay
Hospital stay depends on the procedure, your child’s age, symptoms, and recovery. Some children go home relatively quickly after minimally invasive treatment, while others need a longer stay for monitoring.
Return to school, play, and normal routines
Recovery instructions are individualized. NJPNI will guide you on incision care, pain control, bathing, activity restrictions, follow-up imaging, school return, sports, and warning signs to watch for at home.
Your NJPNI neurosurgeon will explain the risks and benefits based on your child’s specific cyst, not a generic description.
Why Choose NJPNI for Arachnoid Cyst Treatment in NJ?
Pediatric neurosurgery expertise
NJPNI specializes in neurological and neurosurgical care for infants, children, teens, and young adults. Families come to NJPNI for clear answers, careful imaging review, and pediatric-focused treatment planning.
Second opinions for arachnoid cyst diagnosis
If your child was diagnosed elsewhere, told they may need surgery, or told to “just watch it” without a clear explanation, NJPNI can provide a second opinion. A second opinion can help confirm whether monitoring, additional testing, or surgery is the right path.
Coordinated care across neurosurgery and neurology
Some children with arachnoid cysts also need evaluation for headaches, seizures, developmental delays, hydrocephalus, or other neurological concerns. NJPNI brings pediatric neurosurgery and pediatric neurology together, helping families avoid fragmented care.
New Jersey access close to home
NJPNI serves families throughout New Jersey, including Morristown, Hackensack, Hamilton, Garwood, Hazlet, and surrounding communities. Telemedicine visits may also be available when appropriate.
Arachnoid Cyst FAQs
Is an arachnoid cyst dangerous?
Most arachnoid cysts are not dangerous and never cause symptoms. A cyst becomes more concerning if it grows, causes pressure, blocks fluid flow, causes hydrocephalus, or is linked to neurological symptoms.
Does every child with an arachnoid cyst need a neurosurgeon?
A pediatric neurosurgical review is helpful because it can clarify whether the cyst is harmless, needs monitoring, or may require treatment. This is especially important if your child has symptoms or if the cyst is large.
What is the best treatment for an arachnoid cyst?
There is no single best treatment for every child. The best plan may be observation, endoscopic fenestration, open fenestration, or shunt placement, depending on the cyst’s size, location, symptoms, and imaging findings.
Can an arachnoid cyst cause headaches?
It can, but not all headaches in a child with an arachnoid cyst are caused by the cyst. NJPNI evaluates the scan, symptoms, exam, and headache pattern to determine whether the cyst is likely related.
Can an arachnoid cyst cause seizures?
Sometimes. A cyst may be found during a seizure evaluation, but the cyst is not always the cause. NJPNI can coordinate pediatric neurosurgery and pediatric neurology care to determine the right treatment plan.
Can an arachnoid cyst come back after surgery?
Sometimes a cyst can refill or symptoms can return, especially if fluid drainage becomes blocked. Follow-up care and imaging help monitor for recurrence or shunt-related issues if a shunt was placed.
Need Answers About Your Child’s Arachnoid Cyst?
Whether your child was just diagnosed, you are worried about symptoms, or you want a second opinion before surgery, NJPNI can help you understand the MRI and the safest next step.
- Pediatric neurosurgery evaluation
- Second opinions for arachnoid cyst diagnosis
- Monitoring, endoscopic fenestration, open fenestration, and shunt options
- Coordinated care with pediatric neurology when needed
Serving children and families throughout New Jersey.