From the Guidelines
Arachnoid cysts should be monitored with MRI scans, prioritizing sequences that can differentiate them from other pathologies like vestibular schwannoma (VS), with a suggested initial evaluation including standard T1- and T2-weighted sequences, diffusion-weighted imaging (DWI), and fluid-attenuated inversion recovery sequences, as recommended by recent guidelines 1.
When evaluating arachnoid cysts, it's crucial to use MRI protocols that can accurately identify and characterize these lesions. The use of diffusion-weighted imaging (DWI) is particularly useful in differentiating arachnoid or epidermoid cysts from vestibular schwannomas, as noted in the eano guideline on the diagnosis and treatment of vestibular schwannoma 1.
Key considerations for monitoring arachnoid cysts include:
- Initial evaluation with contrast-enhanced MRI to establish a baseline and rule out other pathologies
- Use of specific MRI sequences such as T1-weighted, T2-weighted, DWI, and fluid-attenuated inversion recovery sequences to accurately characterize the cyst
- Monitoring frequency, which may vary depending on the size and location of the cyst, as well as the presence of symptoms
- The importance of detecting potential growth or symptom development, which may necessitate surgical intervention
Given the benign nature of most arachnoid cysts, the primary goal of monitoring is to identify those that may become symptomatic or show signs of growth, allowing for early intervention and prevention of potential complications, as supported by the most recent and highest quality studies 1.
From the Research
Arachnoid Cyst MRI and Monitoring
- Arachnoid cysts are non-neoplastic, intracranial cerebrospinal fluid (CSF)-filled spaces lined with arachnoid membranes 2
- MRI is the diagnostic procedure of first choice for arachnoid cysts because of its potential to demonstrate the exact localization, extent, and relationship of the arachnoid cyst to the spinal cord or surrounding structures 3, 4
- MRI can clearly demonstrate arachnoid cysts with associated subacute intracystic and subdural hematoma that may be overlooked with CT 4
- Follow-up imaging studies, including MRI, are essential to monitor the size of the arachnoid cyst after treatment, with a mean postoperative follow-up period of 6.9 years 5
- The goal of surgical treatment is neural decompression and prevention of refilling of the cyst, which is best accomplished by complete resection of the cyst and closure of the communication between cyst and subarachnoid space 3
Treatment Options
- Several surgical management options exist for arachnoid cysts, including open surgery for fenestration, endoscopic fenestration, or cystoperitoneal shunting 5, 2, 6
- Endoscopic fenestration is a safe and effective treatment option for arachnoid cysts, particularly for suprasellar, quadrigeminal, and prepontine cysts 5, 6
- Cystoperitoneal shunting can achieve rapid good radiological outcome, but it has the danger of shunt dependency and complications 5
Monitoring and Follow-up
- Regular follow-up imaging studies are necessary to monitor the size of the arachnoid cyst and to detect any potential complications or recurrence 5, 3
- The follow-up period can range from 1 to 14 years, with a mean follow-up period of 6.9 years 5
- MRI is the preferred imaging modality for follow-up and monitoring of arachnoid cysts 3, 4