Diagnosis of communicating intracranial arachnoidal cysts by 111-In-Ca-DTPA cisternography.

The distinction between communicating and non-communicating intracranial arachnoidal cysts is important in medical management. Mainly the latter type will benefit from surgery which aims at establishing a communication between the cyst and the subarachnoidal space or ventricular system. We report the case history of two patients in whom congenital cerebral arachnoidal cysts are diagnosed at adult age and illustrate the role of scintigraphy with 111-In-Ca-DTPA to prove the communication of the cysts with the subarachnoidal space. This technique is safe and simple and gives less irradiation and discomfort to the patient than other methods.