Pudenz antisiphon device tear as a cause of shunt malfunction.

Antisiphon device (ASD) tear was found in nine patients who underwent ventriculoperitoneal (VP) shunt revision of a Pudenz three-piece system. In six cases this was the only finding, in three, there was an associated distal malfunction. Repair of ASD tear constituted 27% of our shunt revision procedures. The locus minoris resistentia of the Pudenz ASD is the attachment of the diaphragm to the cylinder. ASD tear should be suspected whenever a noninflammatory fluid collection of a CSF leak are found at the proximal extracranial section of this system.