Arachnoid Cysts
The brain and spinal cord are surrounded and protected by three meninges or membranes: the dura mater, arachnoid mater and pia mater. Arachnoid cysts are fluid-filled sacs that form in the arachnoid space. The fluid inside an arachnoid cyst is normal cerebrospinal fluid (CNS). Arachnoid cysts are most commonly congenital and present at birth (primary arachnoid cysts), but can also develop later in life after surgery or trauma (secondary arachnoid cysts).
The exact cause of primary arachnoid cysts is not clear; it may result from lack of complete growth of the brain to fill the skull resulting in an empty space.
Most arachnoid cysts are incidentally found and do not cause symptoms and so do not require treatment.
Rarely, large arachnoid cysts can cause symptoms which include headaches, seizures, and other neurological problems.
Treatment depends on the location and size of the cyst, as well as on the symptoms.
If surgery is required, there are different types of surgeries:
- Fenestration, where a small incision is made at the cyst and excess fluid is drained into the CNS system.
- Your surgeon may alternatively perform shunting, a process which involves the insertion of a catheter or narrow tube to divert excess fluid to a different part of the body.
