Arachnoid Cysts are cerebrospinal fluid-filled sacs that may develop between the surface of the brain and the cranial base or on the arachnoid
membrane (one of the 3 membranes, dura mater, arachnoid, and pia mater, that cover the brain and the spinal cord). Arachnoid cysts appear on the arachnoid membrane, and they may also expand into the space between the pia mater and arachnoid membranes (subarachnoid space). While Arachnoid Cysts in general are not rare, they are extremely rare in some locations. Arachnoid Cysts do not usually appear within the two hemispheres of the brain (cerebrum) or within the cavities (ventricles) of the brain. Most cases begin during infancy, however onset may be delayed until adolescence. Symptoms of an Arachnoid Cyst are related to the cyst size and location. Small cysts are usually asymptomatic and are discovered only incidentally. Large cysts may cause cranial deformation or macrocephaly (enlargement of the head), producing such symptoms as headaches, seizures, hydrocephalus (excessive accumulation of cerebrospinal fluid), increased intracranial pressure, developmental delay, and behavioural changes. Other symptoms may include hemiparesis (weakness or paralysis on one side of the body) and ataxia (lack of muscle control). Come join others (parents and parents of children) that have an archanoid cyst associated with the brain.

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