General Information

  • Arachnoid cysts arise during development from a splitting of the arachnoid membrane, one of the three coverings of the brain and spinal cord. They contain cerebrospinal fluid (CSF).
  • Arachnoid cysts that do not cause significant mass effect or symptoms, regardless of their size and location, do not require treatment.


  • Most arachnoid cysts that become symptomatic do so in early childhood. The exact symptoms depend upon the location of the cyst. Most of the time the cysts become large but cause only mild symptoms.
  • Typical symptoms include headache, nausea/vomiting, lethargy, seizures, mass protrusion in the skull, focal neurological signs and developmental delay.
  • Suprasellar cysts may have the following additional features:
    • Hydrocephalus due to obstruction of normal CSF circulation.
    • Endocrine symptoms such as early onset of puberty occur in up to 60 percent of patients.
    • Head bobbing and visual impairment.


  • Routine evaluation with computed tomography (CT) or magnetic resonance imaging (MRI) scan is usually satisfactory. CT scan shows a smooth bordered cystic mass with a density similar to CSF.
  • Expansion of the nearby bone confirms their chronic nature.



  • Surgical treatment is recommended with severe mass effect on surrounding structures or with symptoms. Available treatments include the following:
    • Drainage by needle aspiration or burr hole drainage.
      • Advantage: Simple and quick.
      • Disadvantage: A high rate of recurrence of the cyst and symptoms.
    • Surgery to open the cyst wall and open blocked CSF pathways.
      • Advantage: Permits direct inspection of the cyst and vascular structures and avoids permanent shunt in some cases.
      • Post-operative scarring may lead to a blockage of the openings, leading to re-accumulation.
    • Shunting of the cyst.

Scan Before the shunt Left posterior frontal arachnoid cyst


Scan after the cystoperitoneal shunt Complete resolution of arachnoid cyst. The shunt tube can be seen.








Advantage: The most simple procedure.

  1. Disadvantage: Patients becomes shunt dependent.
  2. High risk of shunt-related complications.