Arachnoid Cysts are congenital lesions that arise during Brain
and Skull development from a splitting of the arachnoid membrane,
one of the covering layers of the Brain. This splitting results in
the formation of a cyst.
Most Arachnoid Cysts become symptomatic in childhood. The exact
symptoms depend upon the location of the cyst. These cysts can become
quite large and yet only cause mild symptoms.
Typical symptoms include:
Suprasellar Cysts (cysts laying above the "Sella Turcica"
- which is the bone compartment at the base of the skull that
houses the Pituitary Gland may have the following additional
- Mass protrusion in the skull
- Focal neurological signs secondary to pressure of surrounding structures
- Developmental delay
Almost all Arachnoid Cysts occur in relation to an arachnoid
cistern. The most common locations are the middle cranial fossa
(near the temporal lobe) and suprasellar (near the third ventricle).
However, cysts may be found anywhere within the intracranial
compartment, including the posterior cranial fossa.
- Hydrocephalus due to obstruction of normal cerebrospinal
- Endocrine symptoms occur in up to 60% of patients (such as
early development of puberty)
- Head bobbing
- Visual impairment
Routine evaluation with CT or MRI scan is usually satisfactory.
CT scans usually show a smooth bordered cystic mass composed
of a density similar to cerebrospinal fluid. There is no
enhancement with contrast administration. Expansion of the
nearby bone by remodeling is usually seen, confirming their
Arachnoid cysts that do not cause significant mass effect or
symptoms, regardless of their size and location, generally do
not require treatment. If there is significant or severe mass
effect on surrounding structures, or if there are symptoms, then
surgical treatment is recommended. The following table summarizes
the treatment options:
|Drainage by needle aspiration or burr hole drainage.
||Relatively simple and rapid technique.
||High rate of recurrence of the cyst and return of symptoms.
|Craniotomy with excision of the cyst wall and fenestration of the cyst into normal communication with CSF pathways.
||Permits direct inspection of the cyst. Avoids permanent shunt in some cases. Allows visualization of vascular structures.
||Post-operative scarring may lead to a blockage of the fenestration leading to reaccumulation. More invasive.
Burr Hole Access for Endoscopic Fenestration of Cyst to
Communicate into Normal CSF Pathways.
Shunting of the cyst.
Minimally Invasive Definitive Procedure.
Technically simplest procedure.
Technically more difficult. Procedure occasionally must be
converted to an open craniotomy.
Patient becomes shunt dependent. High risk of shunt-related
Arachnoid Cysts are an area of specific interest for the
Neurosurgeons and staff of Neurosurgical Consultants. Their
successful treatment in most cases involves the use, where
applicable, of highly advanced Minimally Invasive Microsurgical
Techniques. This revolutionary concept in Neurosurgery greatly
limits the amount of surgical exposure required and therefore,
limits the amount of tissue that is touched and retracted during
the operation. Some procedures incorporate Endoscopic Techniques,
which are conducted through very small holes in the skull. This
results in less post-operative pain, earlier mobilization,
diminished hospital stay, less risk for complications, an earlier
return to activities as well as lower overall costs.
Return to Top of Page
This page last edited on 2/20