Arachnoid cyst

Arachnoid cysts are genetic or developed fluid-filled sacs that grow between the brain or spinal cord and the covering arachnoid membrane. The cysts usually accumulate protective cerebrospinal fluid, which prevents its normal drainage into the central nervous system. Arachnoid cysts are most commonly congenital and present at birth (primary arachnoid cysts), but can also develop later in life (secondary arachnoid cysts). Some secondary arachnoid cysts may develop as a reaction to brain surgery, trauma, tumours, head injury or infection.


Symptoms can usually go undetected for years. However, if the cyst grows large enough it can compress neighbouring areas of the brain or spinal cord, producing symptoms such as headache, nausea, vomiting, lethargy, dizziness, seizures, hearing problems, neurological problems, difficulties in balancing and walking, muscle spasms or weakness, bowel and bladder control problems, back pain, and tingling or lack of sensation in your arms and legs.

Diagnosis and Treatment Options

To diagnose arachnoid cysts in your child, we will usually evaluate your family’s medical history. We will do a physical and neurological examination of your child for signs and symptoms. We will also suggest diagnostic tests such as x-rays, computed tomography (CT) or magnetic resonance imaging (MRI) scans.

Treatment depends on the location and size of the cyst, as well as on the symptoms. Most arachnoid cysts cause no problems. Children without symptoms are monitored for cyst growth and changes but don’t need treatment. Cysts that cause symptoms should be surgically removed.

Cysts in the brain are generally treated with fenestration, where a small incision is made at the cyst and excess fluid is drained into the central nervous system. Sometimes a shunt may be required, which is a process where a catheter or narrow tube is inserted to divert excess fluid to a different part of the body. For cysts on the spinal cord, treatment involves surgical removal, shunting or fenestration.


  • Some confusion and neurological deficits
  • Rehabilitation
  • Radiation/ chemo therapy
  • Follow up MRI
  • Possible follow up surgery
  • Physiotherapy
  • Occupational therapy
  • Psychological support
  • Pain medication as required
  • Speech therapy


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