Arachnoid Cysts: Causes, Symptoms, and Treatment
Medically reviewed by Sumiran Racherla, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Arachnoid Cysts?
Arachnoid cysts are managed by a neurologist, a doctor who treats brain and nerve conditions, and by a neurosurgeon when surgery is needed. Most cysts need only monitoring. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What are arachnoid cysts?
Arachnoid cysts are the most common brain cysts. They are not tumors. They are sacs filled with cerebrospinal fluid, the protective fluid that coats the brain and spinal cord. They form when the arachnoid membrane, one of the three membranes that cover the brain and spinal cord, splits and fluid collects inside.
They are usually found in a space at the base of the skull near the temporal lobe, the part of the brain that helps process memories, sights, and sounds. Less often, they form near the spinal cord. Most arachnoid cysts are present at birth. Some develop later in life after a head injury, infection, tumor, or surgery.
Symptoms
Most people with arachnoid cysts have no symptoms. When a cyst presses on the brain or spinal cord, it can cause problems. The most common symptoms of a cyst around the brain are:
- Headache.
- Nausea and vomiting.
- Seizures.
- Problems with hearing and vision.
- Vertigo, a spinning feeling.
- Problems with balance and walking.
Cysts near the spinal cord can press on the cord or nerve roots. This can cause back and leg pain, plus tingling or numbness in the legs or arms. People born with a cyst that causes symptoms usually show them early in life, most before age 20.
Causes and who gets it
Most arachnoid cysts are primary, meaning they are present at birth. They happen because of unusual brain or spinal cord development in the early weeks of pregnancy. Secondary cysts develop later after a head injury, infection, tumor, or surgery.
Men and boys are about four times more likely to have arachnoid cysts than women and girls. People with certain disorders, such as Aicardi syndrome, are more likely to have them. In rare cases, DNA changes may play a part.
How doctors diagnose it
Diagnosis usually involves a CT (computed tomography) or MRI (magnetic resonance imaging) scan of the brain or spinal cord. These scans help tell arachnoid cysts apart from other kinds of cysts. Because arachnoid cysts often cause no symptoms, many people learn they have one by chance during imaging done for another reason. Even with a headache, a found cyst is most likely an unrelated finding, but doctors still check each case carefully.
Treatment
The vast majority of arachnoid cysts need no treatment. Small cysts that do not disturb surrounding tissue and do not cause symptoms may not need treatment, but doctors recommend monitoring over time to make sure they do not grow. Head trauma near a cyst can cause it to grow or bleed, so protection from head injury matters.
When a cyst causes symptoms, surgery can help. Usually, treating the cyst makes symptoms go away or improve. Options include fenestration, which means cutting the cyst open so the fluid drains out, removing the cyst walls entirely, or rarely placing a shunt, a device that drains fluid to another part of the body. Surgery is almost always curative, but cysts can come back in rare cases.
When to see a doctor
Doctors often find these cysts by chance on scans done for headaches, dizziness, ringing in the ears, or changes in vision or hearing. If you have these symptoms, see a doctor. A cyst is rarely the cause of serious symptoms like hydrocephalus, ataxia, or cranial nerve impingement. But in rare cases emergency treatment is needed for fluid buildup or pressure on the brain. Call 911 right away for a seizure, a sudden severe headache, severe or repeated vomiting, confusion, unusual sleepiness, or sudden weakness or trouble speaking.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. This kind of doctor can arrange imaging, follow your cyst over time, and refer you to a neurologist or neurosurgeon when needed.
Common questions
Are arachnoid cysts dangerous?
Usually not. Most arachnoid cysts cause no symptoms and need no treatment. They are not tumors and are not cancer. Rarely, a cyst can grow, rupture, or press on the brain and cause problems that need urgent care.
Do arachnoid cysts go away?
They usually do not disappear, but there have been reports of cysts resolving on their own, especially after trauma. Treatment, when needed, is almost always curative, though cysts can come back in rare cases.
Why did I get an arachnoid cyst?
Most are present from birth and form during early brain development. Others follow a head injury, infection, tumor, or surgery. Men and boys are about four times more likely to have them. Often there is no clear reason.
Will I need surgery?
Not always. Doctors may recommend it when a cyst causes symptoms, based on the cyst's location, its pressure on nearby brain tissue, blocked fluid flow such as hydrocephalus, focal neurological deficits, headaches, or seizures. Monitoring with imaging is the usual plan for cysts that cause no problems.
Sources
- National Institute of Neurological Disorders and Stroke - Arachnoid Cysts
- NCBI Bookshelf - Arachnoid Cysts (StatPearls)
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
