CT cisternography in intracranial symptomatic arachnoid cysts: classification and treatment

The symptom and neuroimaging as indications for treating arachnoid cysts (ACs) are not adequate. Understanding the communication between cyst and subarachnoid space is helpful for decision-making. We took a dynamic study of ACs using CT cisternography (CTC) and proposed a classification of arachnoid cysts.

Total 52 symptomatic patients with ACs were enrolled in this prospective study. CTC images were ordered, in all enrolled patients, at the 1, 3, 6, 12, 24 and 48 h after the intrathecal Omnipaque administration. Enhancement in cysts was measured quantitatively and was compared with neighboring subarachnoid spaces. All enrolled patients were allocated randomly in 2 groups. The CTC result was considered before treatment in one group (CTC group), while another group was surgically treated without considering CTC results (surgical group).

ACs in our study were classified into 3 types: complete (cyst filling time at 1 h), incomplete (filling time began at 3 h) and noncommunicating cysts (no or slight filling after 24 h). Twenty-two patients in CTC group with incomplete communicating, or noncommunicating cysts underwent surgeries. And other 6 patients with complete communicating cysts were closely observed. In CTC group, the symptom of all surgical patients was relieved, and 5 out of 6 observational patients showed clinical improvement or no deterioration during the follow-up. In surgical group, only 18 out of 24 patients showed clinical improvement after surgeries, and there were 6 patients showing no difference before and after surgeries in symptom and in imaging.

This classification based on dynamic CT cisternography is useful for the decision of surgical indication. Some symptomatic patients with complete communicating ACs may not need surgical intervention.