Intracranial arachnoid cysts: Review of natural history and proposed treatment algorithm

Abstract

Background: With a prevalence of 1.4%, intracranial arachnoid cysts are a frequent incidental finding on MRI and CT. Whilst most cysts are benign in the long-term, clinical practice, and imaging frequency does not necessarily reflect this. Methods: A literature review was conducted searching the Medline database with MESH terms. This literature was condensed into an article, edited by a consultant neurosurgeon. This was further condensed, presented to the neurosurgery department at Princess Alexandra Hospital for final feedback and editing. Results: This review advises that asymptomatic patients with typical cysts have a low risk of cyst growth and development of new symptomatology, thus do not require surveillance or intervention. The minority of symptomatic patients or those with cysts in sensitive areas may require referral to a neurosurgeon for clinical follow-up or intervention. Conclusion: Greater than 94% of patients are asymptomatic, practitioners can be confident in reassuring patients of the benign nature of a potentially worrying finding. Recognizing the small number of symptomatic patients and those with cysts in areas sensitive to causing hydrocephalus is where GP decision making in conjunction with specialty input is of highest yield.

Intracranial Arachnoid Cysts in Childhood: Pathogenesis, Clinical Features, and Management

“…Other common locations are convexity, retrocerebellar region, suprasellar cistern, quadrigeminal region, cerebellopontine cistern, and interhemispheric. [2,4,7] PATHOPHYSIOLOGY This is not a fully understood topic, but most authors agree that it is a congenital condition. The cyst originates from a failure in the embryological development of the arachnoid, by its division or duplication, leading to a trapping of cerebrospinal fluid.1 There are also reports of patients who developed arachnoid cysts after traumatic brain injury, with predominance in early childhood and clinical manifestation in the following 24 months.…”

“…Depending on its location, growth, rupture, bleeding, or mass effect, the patient may develop more specific symptoms. [1] Clinical signs of intracranial hypertension, focal deficits such as hearing loss, visual alteration, nystagmus, facial paralysis, hemiparesis, and dysphasia are some reported symptoms, [1,2,6,7] with varied prevalence and incidence. Headache is the most reported symptom.…”

“…Intracranial arachnoid cysts appear on computed tomography (CT) (Figure 1) and magnetic resonance imaging (MRI) (Figure 2 A and B) as simple, extra-axial, thin-walled, and well-circumscribed cysts. [7,15,16] They can displace and deform adjacent brain tissue, cause bone remodeling, and, classically, have no internal components or contrast uptake. [17] They are isodense to CSF on CT, and all MRI sequences, with no restriction on diffusion or any heterogeneous signal in FLAIR sequence.…”

“…Rarely, bleeding or flow changes within the cyst may modify the appearance on MRI. [7,17,18] At cisternography, arachnoid cysts are classified as early filling, when filled by contrast in the first 24 hours, or late, when this occurs after this period. [19]…”

“…ACs have several possible differential diagnoses, with the epidermoid cysts (EC) being one of the most mentioned in the literature. [7,18,[24][25][26] On CT, such pathologies can be difficult to differentiate, since both present with homogeneous and low-density content. Still, the CAs usually have rounded, thin and well-defined margins, unlike the irregularity seen in the periphery of the EC.…”