Intracranial arachnoid cyst

Intracranial arachnoid cysts are fluid-filled cavities that arise within the cranial arachnoid.

These cystic lesions are congenital.

Arachnoid cysts comprise 1% of all intracranial space-occupying lesions ¹⁾.

The prevalence in adults is approximately 1.4% with a female preponderance, while the prevalence in children is 2.6% ²⁾ ³⁾ ⁴⁾.

Intracranial arachnoid cysts have a predilection for the temporal fossa.

Arachnoid cysts can be classified as primary developmental cysts or secondary cysts. Primary cysts arise from the splitting of the arachnoid membranes in utero, resulting in the development of anomalous collections of cerebrospinal fluid (CSF). Secondary cysts are less common, often appearing after trauma, surgery, infection, or intracranial hemorrhage.

Intracranial cysts are classified as supratentorial, infratentorial, and supra-infratentorial (tentorial notch) ⁵⁾.

50-66% occurring within the middle cranial fossa in most series. Ten percent occur in the suprasellar and quadrigeminal regions and approximately 5% each in the posterior fossa and over the frontal convexities.

Supratentorial arachnoid cyst

see Supratentorial arachnoid cyst.

Intraventricular.

Quadrigeminal plate cistern

see Posterior fossa arachnoid cyst.

see Middle fossa arachnoid cyst.

Many theories have been postulated for etiopathogenesis of arachnoid cysts. Various hypotheses are: entrapment of CSF in a diverticulum; CSF flow changes leading to arachnoid cell layer tears during the formation of various cisternae; during embryological separation (at around 15th week of gestation) of arachnoid from the dura mater ⁶⁾.

see Intracranial arachnoid cyst clinical features.

see Intracranial arachnoid cyst treatment.

Spontaneous intracystic hemorrhage in an arachnoid cyst is a rare complication (although hemorrhagic arachnoid cyst is well known in the clinical setting of trauma), which may present with symptoms of raised intracranial pressure (headache, vomiting, altered sensorium) or focal neurological deficits depending on the location and is an indication for surgery ⁷⁾ ⁸⁾.

Although complications such as intracystic, subdural, and extradural hematomas are well known after a trauma, spontaneous hemorrhage in an arachnoid cyst is a rare and serious complication with atypical imaging features on cross-sectional imaging and only less than ten cases are documented in the literature ⁹⁾.

see Intracranial arachnoid cyst outcome.

see Intracranial arachnoid cyst case series.

see Intracranial arachnoid cyst case reports.

¹⁾

Albuquerque FC, Giannotta SL. Arachnoid cyst rupture producing subdural hygroma and intracranial hypertension: case reports. Neurosurgery. 1997 Oct;41(4):951-5; discussion 955-6. Review. PubMed PMID: 9316060.

²⁾

Al-Holou WN, Terman S, Kilburg C, Garton HJ, Muraszko KM, Maher CO. Prevalence and natural history of arachnoid cysts in adults. J Neurosurg. 2013 Feb;118(2):222-31. doi: 10.3171/2012.10.JNS12548. Epub 2012 Nov 9. PubMed PMID: 23140149.

³⁾

Al-Holou WN, Yew AY, Boomsaad ZE, Garton HJ, Muraszko KM, Maher CO. Prevalence and natural history of arachnoid cysts in children. J Neurosurg Pediatr. 2010 Jun;5(6):578-85. doi: 10.3171/2010.2.PEDS09464. PubMed PMID: 20515330.

⁴⁾

Pradilla G, Jallo G. Arachnoid cysts: case series and review of the literature. Neurosurg Focus. 2007 Feb 15;22(2):E7. Review. PubMed PMID: 17608350.

⁵⁾

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 Sep-Oct;26(5):234-40. doi: 10.1016/j.neucir.2015.02.007. Epub 2015 Apr 2. Spanish. PubMed PMID: 25843209.

⁶⁾ , ⁸⁾

Gunduz B, Yassa MIK, Ofluoglu E, et al. Two cases of arachnoid cyst complicated by spontaneous intracystic hemorrhage. Neurology India. 2010;58:312–15.

⁷⁾

Ide C, Coene BD, Gilliard C, et al. Hemorrhagic arachnoid cyst with third nerve paresis: CT and MR findings. Am J Neuroradiol. 1997;18:1407–10.

⁹⁾

Arora R, Puligopu AK, Uppin MS, Purohit AK. Suprasellar Arachnoid Cyst with Spontaneous Intracystic Hemorrhage: A Rare Complication - Role of MR and Illustration of a Case. Pol J Radiol. 2014 Nov 18;79:422-5. doi: 10.12659/PJR.890992. eCollection 2014. PubMed PMID: 25422677; PubMed Central PMCID: PMC4238756.