What are arachnoid cysts?

Arachnoid cysts are fluid-filled sacs that develop between the central nervous system (brain and spinal cord) and the arachnoid membrane, one of three protective membranes that surround the central nervous system. Cells from the arachnoid layer produce cerebrospinal fluid, the fluid that protects and nourishes the brain and spinal cord. Consequently, arachnoid cysts are filled with cerebrospinal fluid.

Arachnoid cysts can be primary (present at birth) or secondary (arising due to disease or injury). Sometimes, cysts will develop without leading to symptoms. Most arachnoid cysts are harmless and produce no symptoms. If the cyst is large, however, it may press on the central nervous system, which can cause headaches, lethargy, and neurological damage. In these cases, the cyst may require surgical draining.

Arachnoid cysts usually develop before the age of 20 and are present in men more often than in women. Left untreated, large arachnoid cysts may lead to complications, such as hydrocephalus (fluid buildup in the skull), early onset of puberty, and visual impairment.

Seek immediate medical care (call 911) for serious symptoms of pressure on the brain, including a sudden, severe, unexplained headache or a seizure.

Seek prompt medical care if you have ongoing symptoms that may be related to the presence of an arachnoid cyst, such as unexplained headaches or a change in vision. Also seek prompt medical care if you are being treated for arachnoid cysts but mild symptoms recur or are persistent.


What are the symptoms of arachnoid cysts?

Small arachnoid cysts are usually symptomless and may not require treatment. If arachnoid cysts grow significantly, they may cause symptoms, such as headache, weakness and fatigue. In serious cases, symptoms may become life threatening. Symptoms occur far more frequently in children compared to adults. Serious symptom... Read more about arachnoid cystssymptoms


What causes arachnoid cysts?

Arachnoid cysts develop when cerebrospinal fluid, the fluid that surrounds and nourishes the brain and spinal cord, fills sacs that develop in the arachnoid mater, one of the layers of tissue that surrounds the brain. Often, arachnoid cysts are present at birth. These are called primary arachnoid cysts and are related to developmental abnormalities. Secondary arachnoid cysts can develop because... Read more about arachnoid cystscauses


How are arachnoid cysts treated?

If arachnoid cysts are small, they generally do not require treatment. But if they begin to press on the brain or spinal cord, treatment is necessary to alleviate symptoms.

Surgical treatment for arachnoid cysts

Surgery to treat arachnoid cysts is aimed at draining the fluid from the cyst or puncturing a hole in the arachnoid membrane, which forms the sac. Types of surg... Read more about arachnoid cyststreatments

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Aug 9, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Brain and Nerves