Arachnoid Cysts

Arachnoid cysts are cerebrospinal fluid-filled sacs (cerebrospinal fluid is a clear fluid surrounding the brain and spinal cord) that may develop between the surface of the brain and the cranial base or on the arachnoid membrane - one of the 3 membranes that cover the brain and the spinal cord. (Read about "The Brain" "Nervous System") The National Institute of Neurological Disorders and Stroke (NINDS) says 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 (that means there are no symptoms) and are discovered only incidentally. Large cysts may cause cranial deformation or macrocephaly (enlargement of the head), producing such symptoms as headaches, seizures (Read about "Seizures"), hydrocephalus or excessive accumulation of cerebrospinal fluid (Read about "Hydrocephalus"), increased intracranial pressure, developmental delay and behavioral changes, according to NINDS. Other symptoms may include hemiparesis (weakness or paralysis on one side of the body) and ataxia (lack of muscle control). Arachnoid cysts most often occur in males.

NINDS says treatment for arachnoid cysts is symptomatic. When symptoms warrant, the surgical placement of a shunt may be required to remove pressure from the cyst.

Untreated, arachnoid cysts may cause permanent severe neurological damage due to the progressive expansion of the cyst(s) or bleeding, according to NINDS. With treatment, most individuals with arachnoid cysts can do well.

Related Information:

    Encephalopathy