Cerebrospinal fluid pseudocysts: sonographic appearance and clinical management.

Eight patients with 10 intraperitoneal cerebrospinal fluid pseudocysts occurring as a complication of ventriculoperitoneal (VP) shunt procedure were reviewed to determine the sonographic characteristics as well as the etiologic basis for the pseudocysts. An additional 10 patients with VP shunts, being routinely evaluated for genitourinary tract abnormality, were reviewed to determine the sonographic characteristics and the amount of fluid present in the abdomen with a normally functioning VP shunt in place. We found that a small amount or no peritoneal fluid is found in the patient with a normally functioning VP shunt. Larger, localized, simple or loculated fluid collections are abnormal and compatible with pseudocyst formation. Debris was identified in the majority of the fluid collections. We believe that ultrasonography is the method of choice in evaluation of complications of the distal end of the VP shunt. Our series suggests that infection is the principle cause for pseudocyst development despite the frequent absence of systemic signs of infection. Appropriate treatment involves removal of the peritoneal catheter and treatment of the infection. The catheter may later be replaced intraperitoneally.