Skip to main content

Arachnoid Cyst

What is an Arachnoid Cyst?

An arachnoid cyst is a sac filled with cerebrospinal fluid located between the brain or spinal cord and the arachnoid membrane, the middle of three delicate membranes, called meninges, which cover the brain and spinal cord. The majority of arachnoid cysts form outside the temporal lobe of the brain in an area known as the middle cranial fossa. Arachnoid cysts involving the spinal cord are more uncommon.

What You Can Expect at UTHealth Houston Neurosciences

At UTHealth Houston Neurosciences, neurologists, neurosurgeons, neuro-oncologists, and radiation oncologists work together to determine the care each patient needs, discussing treatment options as a group. This approach saves our patients time and money and allows our specialists to share each other’s insights, leading to better treatment decision-making and outcomes.

We first investigate options for nonsurgical treatment, including medical management, pain management, physical therapy, rehabilitation, and watchful waiting. When surgery is needed, our neurosurgeons routinely employ innovative, minimally invasive techniques. Throughout the treatment process, our team works closely with the doctor who referred you to ensure a smooth transition back to your normal care plan. While you are with us, you can expect expert care, excellent communication, and genuine compassion.

Causes of Arachnoid Cysts

Primary arachnoid cysts are present at birth and result from developmental abnormalities in the brain and spinal cord that arise during the early weeks of pregnancy. Secondary arachnoid cysts are less common and develop as a result of head injury, meningitis or tumors, or as a complication of brain surgery.

Early Signs of Arachnoid Cyst and Diagnosis

Most people with arachnoid cysts develop symptoms before the age of 20, and especially in the first year of life. Some people have cysts without symptoms. Males are four times more likely to have an arachnoid cyst than females.

Typical symptoms of an arachnoid cyst in the brain are headache, nausea and vomiting, seizures, hearing and visual disturbances, developmental delays in young children, vertigo, and difficulties with balance and walking. Spinal arachnoid cysts that compress the spinal cord or nerve roots may cause progressive back and leg pain and tingling or numbness in the legs or arms.

Diagnosis usually involves a brain or spine scan using diffusion-weighted MRI, which detects the motion of water molecules to help distinguish fluid-filled arachnoid cysts from other types.


Treatment options are unique to each patient, and vary based on the cyst’s size and location, as well as the patient’s age, overall health, and related factors. If the cyst is small and not disturbing surrounding tissue, your neurosurgeon may recommend watchful waiting and track the size of the cyst over time.

Untreated arachnoid cysts that continue to grow may cause permanent brain or spinal cord damage. In the past, doctors placed shunts in the cyst to drain its fluid. With today’s minimally invasive surgical techniques, there are options to remove the membranes of the cyst or drain it, allowing the surrounding cerebrospinal fluid to absorb it. Symptoms usually resolve or improve with treatment.

Clinical Trials

When conventional therapies prove unsuccessful, we provide our patients access to leading-edge clinical trials of investigational drugs and procedures.

View trials related to brain tumors here »

Brain Tumor Types

Acoustic neuroma
Arachnoid Cyst
Brain metastases
Choroid plexus tumor
Facts about brain tumors
Gamma Knife Radiosurgery
Germ cell tumor
Glioblastoma Multiforme (GBM)
Malignant meningioma
Pituitary adenoma and Cushing’s syndrome
Pituitary tumor
Skull base tumor

Contact Us

At UTHealth Houston Neurosciences, we offer patients access to specialized neurological care at clinics across the greater Houston area. To ask us a question, schedule an appointment, or learn more about us, please call (713) 486-8000, or click below to send us a message. In the event of an emergency, call 911 or go to the nearest Emergency Room.