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intracranial_arachnoid_cyst

Intracranial arachnoid cyst

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

These cystic lesions are congenital.

Epidemiology

Arachnoid cysts account for only 1% of all intracranial space-occupying lesions.

Intracranial arachnoid cysts have a predilection for the temporal fossa.

Classification

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

Supratentorial are divided into:

Sylvian fissure arachnoid cyst

Cerebral convexity

Interhemispheric arachnoid cyst

Sellar region

Intrasellar arachnoid cyst

Retrosellar arachnoid cyst

Suprasellar arachnoid cyst

Intraventricular.

Quadrigeminal plate cistern


see Posterior fossa arachnoid cyst

Etiology

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 1).

Clinical features

Most of them are asymptomatic and are detected as incidental findings on Computed Tomography or Magnetic Resonance Imaging of the head carried out for other reasons.

There are multiple case reports of arachnoid cysts becoming symptomatic with hemorrhagic complications following head trauma. In such cases, the bleeding is often confined to the side ipsilateral to the arachnoid cyst. Occurrence of contralateral subdural hematomas in patients with temporal fossa arachnoid cysts has rarely been observed and is reported less frequently in the medical literature 2).

Usually they remain stable in size and are asymptomatic, however, a few cysts contain remnants of the choroid plexus or arachnoid granulations leading to secretion of CSF resulting in an increase in size with time. These cases may present with features of compression of adjacent structures (Kallman syndrome, precocious puberty, bitemporal hemianopia in suprasellar lesions, cranial nerve palsies etc.) and/or raised intracranial pressure due to their large size or hemorrhage. Spontaneous hemorrhage is supposed to be due to a minor trauma with rupture of intracystic or bridging vessels 3) 4).

The symptoms related to the presence of arachnoid cysts in the Central Nervous System depend on the size of the cyst and its growth rate, its location and, in some cases, the associated CSF dynamic disorder. Sometimes there is acute clinical presentation due to cyst rupture or acute bleeding.

Treatment

ACs with mass effect are detected frequently in asymptomatic patients. Conversely, symptomatic patients may present without imaging signs of a focal mass effect that emphasizes the difficulty of relying on imaging as the sole criteria in surgical selection.

Although it is generally accepted that asymptomatic or paucisymptomatic cysts do not require surgical treatment, there is no consensus on the therapeutic approach of choice in symptomatic cases 5).

Acetazolamide known to reduce CSF production, might mimic surgical decompression and therefore could serve as a decision-making tool in patients with ACs.

A total of 103 patients with radiographically proven ACs were initially identified. Twenty (19.4%) were symptomatic and underwent a trial of oral AZM. Data were collected meeting inclusion/exclusion criteria for this cohort study and analyzed retrospectively/prospectively. Results Overall, 17 patients were able to tolerate the AZM and had at least some subjective improvement in their symptoms during the AZM challenge and underwent surgical therapy. Surgery was beneficial in 16 patients (94.1%). Following surgery, symptoms resolved in 13 patients (76.5%) and improved in 3 (17.6%).

The AZM challenge may support the clinical decision to recommend surgery in those patients whose symptoms improve during AZM therapy 6).


Craniotomy and fenestration of membranes is one of the main treatment options for symptomatic arachnoid cysts. Open surgery advantages include, direct inspection of the cyst, biopsy sampling, fenestration in multilocular cysts and, in certain locations, cyst communication to basal cisterns 7).

Surgery for AC can be performed with a fairly low risk of complications and yields significant improvement in quality of life correlated to postoperative improvement in headache and dizziness. These findings may justify a more liberal approach to surgical treatment for AC 8).

Complications

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 9) 10).

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 11).

Outcome

Surgery can be performed with a fairly low risk of complications and yields significant improvement in quality of life correlated to postoperative improvement in headache and dizziness. These findings may justify a more liberal approach to surgical treatment 12).

Sports participation with arachnoid cysts

There is currently no consensus on the safety of sports participation for patients with an intracranial arachnoid cyst (AC).

A survey was prospectively administered to 185 patients with ACs during a 46-month period at a single institution. Cyst size and location, treatment, sports participation, and any injuries were recorded. Eighty patients completed at least 1 subsequent survey following their initial entry into the registry, and these patients were included in a prospective registry with a mean prospective follow-up interval of 15.9 ± 8.8 months.

A total 112 patients with ACs participated in 261 sports for a cumulative duration of 4410 months or 1470 seasons. Of these, 94 patients participated in 190 contact sports for a cumulative duration of 2818 months or 939 seasons. There were no serious or catastrophic neurological injuries. Two patients presented with symptomatic subdural hygromas following minor sports injuries. In the prospective cohort, there were no neurological injuries

Permanent or catastrophic neurological injuries are very unusual in AC patients who participate in athletic activities. In most cases, sports participation by these patients is safe 13).

Case series

A total of 13 patients < 1 year of age with intracranial cysts were operated on between 2005 and 2013. Six presented with hydrocephalus, four presented with seizure, one with abnormal head movement, and two had large asymptomatic cysts. Four children had infratentorial arachnoid cysts; of these, three required a transaqueductal procedure. All the patients underwent endoscopic cystoventriculostomy and/or cystocisternostomy and third ventriculostomy in selected cases with a biopsy from the cyst wall.

Clinically and radiologically all children showed significant improvement with an average follow-up ranging from 8 months to 6 years. There were no intraoperative complications. Three children developed subdural hygroma that subsided with conservative treatment, and one child with pseudomeningocele required a cystoperitoneal shunt at a later date.

A symptomatic intracranial arachnoid cyst or a large asymptomatic cyst are indications for neurosurgical intervention, and endoscopy is a good treatment option with the advantage of minimal invasiveness and fewer complications. Endoscopic surgery has to be tailored according to the location and presentation 14)

1) , 4) , 10)
Gunduz B, Yassa MIK, Ofluoglu E, et al. Two cases of arachnoid cyst complicated by spontaneous intracystic hemorrhage. Neurology India. 2010;58:312–15.
2)
Pillai P, Menon SK, Manjooran RP, Kariyattil R, Pillai AB, Panikar D. Temporal fossa arachnoid cyst presenting with bilateral subdural hematoma following trauma: two case reports. J Med Case Rep. 2009 Feb 9;3:53. doi: 10.1186/1752-1947-3-53. PubMed PMID: 19203370; PubMed Central PMCID: PMC2646743.
3) , 9)
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.
5)
Ros López B, Martín Gallego Á, Iglesias Moroño S. [Arachnoid cysts of the central nervous system. Algorithms and recommendations for management]. Neurocirugia (Astur). 2015 Apr 7. pii: S1130-1473(15)00025-1. doi: 10.1016/j.neucir.2015.02.002. [Epub ahead of print] Spanish. PubMed PMID: 25861895.
6)
Kershenovich A, Toms SA. The Acetazolamide Challenge: A Tool for Surgical Decision Making and Predicting Surgical Outcome in Patients with Arachnoid Cysts. J Neurol Surg A Cent Eur Neurosurg. 2016 Jul 14. [Epub ahead of print] PubMed PMID: 27415592.
7)
Saura Rojas JE, Horcajadas Almansa Á, Ros López B. [Microsurgical treatment of intracraneal arachnoid cysts]. Neurocirugia (Astur). 2015 Apr 16. pii: S1130-1473(15)00029-9. doi: 10.1016/j.neucir.2015.02.006. [Epub ahead of print] Spanish. PubMed PMID: 25891259.
8)
Mørkve SH, Helland CA, Amus J, Lund-Johansen M, Wester KG. Surgical Decompression of Arachnoid Cysts Leads to Improved Quality of Life: A Prospective Study. Neurosurgery. 2016 May;78(5):613-25. doi: 10.1227/NEU.0000000000001100. PubMed PMID: 26540351.
11)
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.
12)
Mørkve SH, Helland CA, Amus J, Lund-Johansen M, Wester KG. Surgical Decompression of Arachnoid Cysts Leads to Improved Quality of Life: A Prospective Study. Neurosurgery. 2015 Nov 4. [Epub ahead of print] PubMed PMID: 26540351.
13)
Strahle J, Selzer BJ, Geh N, Srinivasan D, Strahle M, Martinez-Sosa M, Muraszko KM, Garton HJ, Maher CO. Sports participation with arachnoid cysts. J Neurosurg Pediatr. 2016 Apr;17(4):410-7. doi: 10.3171/2015.7.PEDS15189. Epub 2015 Dec 4. PubMed PMID: 26636254.
14)
Raju S, Sharma RS, Moningi S, Momin J. Neuroendoscopy for Intracranial Arachnoid Cysts in Infants: Therapeutic Considerations. J Neurol Surg A Cent Eur Neurosurg. 2015 Aug 4. [Epub ahead of print] PubMed PMID: 26241198.
intracranial_arachnoid_cyst.txt · Last modified: 2016/07/25 14:18 (external edit)