When cerebrospinal fluid (colorless fluid present in the brain and spine) is covered by arachnoidal cells with collagen are called as arachnoid cysts. It is named as such, because it develops between the surface of the brain and the arachnoid membrane i.e., one of the three membranes that cover the brain and the spinal cord, or the cranial base. These are relatively common asymptomatic and benign lesions that actually are congenital disorder(birth defects). In most cases they begin during infancy, however, its onset usually occurs after adolescence.
Arachnoid cysts are found either on the brain or spine. The cysts in brain usually occur adjacent to the arachnoidal cistern and the cysts in spine can be extradural, intradural, or perineural (surrounding a nerve) and these have clear signs and symptoms as radiculopathy ( a condition in which one or more nerves are affected and do not work properly). The symptoms often occurs gradually and often depends upon the location of cyst which delays the diagnosis. If the cysts are small in size they have no signs and are discovered only by any incident, but if the size is large they have many symptoms which are described below.
- Enlargement (increase in size) of the head (macrocephaly) in children
- Headaches, such as migraine or tension type headache
- Bobble head doll syndrome
- Excessive accumulation of cerebrospinal fluid (hydrocephalus)
- Increase in intracranial pressure
- Behavioral changes
- Delay in development
- Weakness or paralysis on one side of the body (hemiparesis)
- Lack of muscle control (ataxia)
- Alzheimer’s disease
- Urinary incontinence
The main cause of arachnoid cysts is actually not known. Mostly these are developmental deformities that appear due to congenital splitting of arachnoid membrane. They can be hereditary disorders. Its diagnosis is done by MRI and do not require treatment, but if these cysts are symptomatic then treatment is required, as it may cause permanent severe neurological damage. Following procedures are applied to remove the cyst.
- Surgical treatment (resolve psychiatric manifestations)
- Fenestration or excision
- Capsular resection
- Needle aspiration or burr hole
- Endoscopic or laser-assisted techniques