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Arachnoid Cyst

Arachnoid Cyst: What It Is, What It Does, and What You Can Do About It

You got a brain scan for something else — headaches, a fall, a seizure workup — and now someone is telling you there's a cyst in your brain. The word "cyst" next to the word "brain" is enough to stop your breathing for a second. Here's the reality: most arachnoid cysts are harmless, never cause symptoms, and never need treatment. But "most" is not "all," and if yours is causing problems, the path forward is less straightforward than anyone wants to admit.

This page covers what arachnoid cysts actually are, how they get diagnosed and treated, what accommodations look like when they affect your ability to work, and where to find people who understand what you're going through.

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Medical Overview

An arachnoid cyst is a fluid-filled sac that forms between the layers of the arachnoid membrane, one of three protective coverings around your brain and spinal cord. The fluid inside is cerebrospinal fluid (CSF) — the same clear fluid that normally surrounds and cushions your central nervous system.

Most arachnoid cysts are congenital, meaning you were born with them. They form when the arachnoid membrane splits abnormally during fetal development, trapping CSF in a pocket. Secondary arachnoid cysts — the ones that develop later — can result from head injury, infection, surgery, or tumors, but these are less common.

They are not cancer. They are not tumors. They are fluid-filled sacs with thin walls.

The most common location is the middle cranial fossa (the temporal region, near your ears). Other locations include behind the eyes, at the base of the skull, and along the spinal cord. Spinal arachnoid cysts are much rarer and most often appear in the thoracic (mid-back) region.

Males are affected roughly two to four times more often than females. Prevalence estimates run about 2.6% in children and 0.2% to 1.7% in adults, though many go undetected entirely because they cause no symptoms. About 3 in 100 children in the United States are thought to have one.

Most arachnoid cysts stay small and silent. They sit there for decades without causing trouble. The ones that cause problems are the ones that grow large enough to press on brain tissue, block the flow of cerebrospinal fluid, or — rarely — rupture.

When symptoms do occur, they depend on where the cyst is and how large it gets:

In rare cases, temporal lobe cysts have been associated with learning difficulties, ADHD-like symptoms, cognitive changes, and depression. A cyst pressing on different cranial nerves can cause facial pain, weakness, swallowing problems, or eye movement issues.

Cyst rupture is a medical emergency. It can cause sudden pressure changes, bleeding, or fluid buildup. A hard blow to the head is the typical trigger. If you have a known arachnoid cyst, wear a helmet during any activity with head injury risk.

Arachnoid cysts can run in families and are associated with certain genetic conditions including Marfan syndrome, Aicardi syndrome, and mucopolysaccharidosis. Most, however, are sporadic — no known family connection.

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Diagnosis and Treatment

Diagnosis usually happens by accident. A CT scan or MRI ordered for something else picks up the cyst. It shows up as a fluid-filled, thin-walled structure that follows the signal of normal cerebrospinal fluid on imaging.

When a cyst is found intentionally — because symptoms point to it — MRI is the preferred imaging tool. It shows size, location, and whether the cyst is pressing on nearby brain structures or nerves. Advanced imaging techniques (MRI cisternography, phase-contrast MRI) can determine whether the cyst communicates with the surrounding CSF space, which helps guide treatment decisions.

The most important thing imaging tells the doctor: is the cyst causing mass effect? That means, is it pushing on the brain, shifting structures, or blocking fluid flow?

Treatment follows a simple decision tree: if the cyst is not causing symptoms, leave it alone. Monitor it with periodic scans to make sure it doesn't grow. That's it. For every ten patients a neurosurgeon sees with an arachnoid cyst, eight or nine go home without surgery.

When surgery is needed, the options are:

Young children (under four) need closer monitoring than older children or adults because their cysts are more likely to grow. In babies, head circumference and fontanel tension are key indicators.

The outlook is generally good. Most cysts that need surgery respond well. The brain, especially in young children, can expand to fill the space left behind. Recurrence after complete fenestration is uncommon.

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Accommodation Strategies

Most people with arachnoid cysts will never need workplace accommodations because most cysts never cause symptoms. But for those whose cysts produce chronic headaches, fatigue, seizures, cognitive changes, or vision problems, accommodations can be the difference between holding a job and losing one.

Arachnoid cysts are not specifically listed in the ADA, but the functional limitations they cause — headaches, fatigue, seizure disorders, cognitive disruption — are covered under the law. You do not need to disclose the cyst itself. You only need to document the functional limitation and the accommodation that addresses it.

For chronic headaches and fatigue: For seizure risk: For cognitive symptoms (memory, attention, processing speed): For vision problems: The Job Accommodation Network (JAN) at askjan.org has detailed guidance on brain-related accommodation requests. The Brain Injury Association of America also publishes accommodation frameworks that apply to arachnoid cyst symptoms.

To request accommodations formally, start with a letter to your employer identifying the functional limitation and the specific accommodation. A doctor's note supporting the request strengthens it. You do not have to explain the full medical picture — just the limitation and what helps.

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Benefits and Disability

Arachnoid cysts do not have their own listing in the Social Security Administration's Blue Book. That does not mean you cannot qualify for disability — it means the SSA evaluates the symptoms and functional limitations the cyst causes, not the cyst itself.

Relevant SSA listings include: The severity of symptoms matters more than the diagnosis. The SSA wants to know: can you sustain work activity? Not whether you can do something on your best day, but what happens across a full workweek.

Two paths to disability exist: SSDI (Social Security Disability Insurance) if you have sufficient work history, and SSI (Supplemental Security Income) if you meet income and asset limits. You can apply for both simultaneously.

A doctor's detailed opinion explaining how the cyst affects your daily functioning and ability to work is one of the strongest pieces of evidence you can submit. Medical imaging alone is usually not enough — the SSA needs functional documentation.

The Medical-Vocational Guidelines (the "Grid Rules") can help people over 50 who have limited education and work history that involved physical labor.

Workers' compensation may apply if a workplace head injury caused or worsened the cyst. State laws vary significantly. Document everything — the injury, the imaging, the timeline of symptoms.

If your SSDI claim is denied (most are at the initial stage), appeal. Many cases are won at the hearing level with an Administrative Law Judge. A disability attorney who works on contingency can make a significant difference.

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Notable Public Figures

Public awareness of arachnoid cysts has been limited, but a few notable cases have brought attention to the condition.

Urban Meyer, the college football coach who led Ohio State to a national championship, publicly disclosed his arachnoid cyst diagnosis in 2018. He had surgery to address the cyst in 2014 and dealt with aggressive headaches that became debilitating during games. His case highlighted that arachnoid cysts can cause real, recurring symptoms even in high-functioning individuals, and that dismissing them as harmless is not always accurate.

Arachnoid cysts remain underrecognized partly because so many are asymptomatic. The people who have them and struggle often do so quietly, without a public face for the condition. This makes community spaces — forums, support groups, patient organizations — all the more important for people trying to figure out what's going on with their own bodies.

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Newly Diagnosed

You just found out you have an arachnoid cyst. Here is what actually matters right now.

Most arachnoid cysts do not need treatment. Read that twice. The odds are heavily in your favor that this cyst will sit there for the rest of your life and never cause a single problem. The doctor may want to do a follow-up scan in six to twelve months to confirm it's stable. After that, you may never need to think about it again. If you do have symptoms, the first step is figuring out whether the cyst is actually causing them. Headaches are common. Arachnoid cysts are common. Having both does not automatically mean one is causing the other. A neurologist or neurosurgeon needs to evaluate whether the cyst's size and location could plausibly explain your symptoms. This is not always straightforward, and you may encounter doctors who dismiss the cyst too quickly. If your symptoms are at the exact location of the cyst and nothing else explains them, push for a thorough evaluation. What to do now: One important pattern from patient communities: people with symptomatic arachnoid cysts often report difficulty getting doctors to take the cyst seriously. The standard medical teaching is that most cysts are incidental findings, and this can lead to premature dismissal when a cyst actually is causing problems. If you feel your concerns are being brushed off, seek a second opinion — ideally from a neurosurgeon who treats arachnoid cysts regularly. Pediatric neurosurgeons sometimes have the most experience, even for adult patients. *

Culture and Media

Arachnoid cysts barely exist in popular culture. There is no major film, book, or television storyline centered on the condition. This is partly because most cysts are asymptomatic and partly because the condition doesn't carry the dramatic narrative arc that media tends to favor — it's not progressive, it's not degenerative, and in most cases, it's not even noticeable.

Urban Meyer's 2018 disclosure brought the term into sports media briefly. News coverage at the time focused on explaining what an arachnoid cyst is and noting that most are benign — useful public education, though brief.

The cultural invisibility of the condition has a real cost. People who are symptomatic often find that nobody around them — family, coworkers, friends — has any framework for understanding what an arachnoid cyst is or what it can do. The phrase "it's just a cyst" becomes a minimization that symptomatic patients hear too often, from both their social circles and sometimes from their doctors.

Online patient communities have become the primary cultural space for arachnoid cyst awareness. Facebook groups, Reddit threads, and dedicated forums serve as the places where people share experiences, compare symptoms, and validate each other's struggles with a condition that the broader medical culture often treats as insignificant.

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Creators and Resources

Organizations: Medical Education: Podcasts: Online Communities: Clinical References: *

Key Statistics

Most people with arachnoid cysts will never know they have one. Of those who find out, most will never need treatment. Of those who need treatment, most will have good outcomes. The numbers are on your side.
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