====== Arachnoid cyst ======

{{ ::arachnoidcyst.png?200|}}

[[Arachnoid]] [[cyst]]s are [[cerebrospinal fluid]] covered by [[arachnoid mater]] and [[collagen]] that may develop between the surface of the brain and the cranial base or on the [[arachnoid]] membrane.
They can be located intracranially or in the spine
((Candela S, Puerta P, Alamar M, Barcik U, Guillén A, Muchart J,
García-Fructuoso G, Ferrer-Rodríguez E. [Epidemiology and classification of
arachnoid cysts in children]. Neurocirugia (Astur). 2015 Apr 2. pii:
S1130-1473(15)00030-5. doi: 10.1016/j.neucir.2015.02.007. [Epub ahead of print]
Spanish. PubMed PMID: 25843209.
)).

===== Epidemiology =====
Most cases begin during infancy; however, onset may be delayed until adolescence.

The prevalence of arachnoid cysts in children is 1-3%. They are more frequent in boys. They can be located intracranially or in the spine
((Candela S, Puerta P, Alamar M, Barcik U, Guillén A, Muchart J,
García-Fructuoso G, Ferrer-Rodríguez E. [Epidemiology and classification of
arachnoid cysts in children]. Neurocirugia (Astur). 2015 Apr 2. pii:
S1130-1473(15)00030-5. doi: 10.1016/j.neucir.2015.02.007. [Epub ahead of print]
Spanish. PubMed PMID: 25843209.
)).
----
The association between a [[dermoid cyst]] and [[arachnoid cyst]] is extremely rare and when it is present may suggest the existence of a common factor. Abbou et al. presented a unique case of a young girl who developed [[headache]] and [[ataxia]] as a result of an intracranial [[infratentorial dermoid cyst]] and an [[arachnoid cyst]] of the [[cerebellopontine angle]]. Complete removal of the [[dermoid cyst]] and [[drainage]] of the [[cyst]] leads to a full [[recovery]]. [[Dermoid]] and [[arachnoid cyst]] are two pathologies with a possible common embryogenic factor, early surgery can give a better [[outcome]] in the long term
((Abbou Z, Djennati R, Khalil Z. A rare association between a dermoid cyst and arachnoid cyst of the cerebellopontine angle: a case report. Pan Afr Med J. 2021 Nov 1;40:125. doi: 10.11604/pamj.2021.40.125.32040. PMID: 34909093; PMCID: PMC8641637.)).
===== Etiology =====

They are a rare condition thought to be congenital in nature. 

see [[Arachnoid Cyst associated chronic subdural hematoma]]

===== Classification =====
[[Intracranial arachnoid cyst]]

[[Spinal arachnoid cyst]]

[[Nontraumatic de novo arachnoid cyst]]

===== Clinical Features =====

see [[Intracranial arachnoid cyst clinical features]].

===== Treatment =====

[[Intracranial arachnoid cyst treatment]].



===== Complications =====

[[Intracranial arachnoid cyst complications]].