LAUSR

OBJECTIVE This study aims to present a practical method to accurately diagnose ventriculo-peritoneal shunt (VPS) malfunction and to detect the exact level at which the system has failed in order to tailor VPS revision at that level only. METHODS A tertiary-referral, single-center algorithm for diagnosis of VPS malfunction is proposed. Based on clinical symptoms and confirmed ventricular dilatation on computed tomography, the VPS reservoir is punctured: if no cerebrospinal fluid (CSF) is obtained, ventricular catheter replacement is recommended. Conversely, if CSF is obtained, a sample is sent for cultural exam and the macroscopic integrity of the whole system is checked via plain x-rays in the angiographic suite. Then, through the injection of iodate contrast medium into the reservoir and selective exclusion of the proximal and distal catheters, the patency and correct VPS functioning are investigated. RESULTS 102 (56 males, mean age 41.5, range 1-86) patients underwent VPS function test from 2012 to 2018: 59 (57.8%) cases of VPS malfunction were diagnosed. Ventricular catheter obstruction/damage/displacement occurred in 12/59 (20.3%) cases, valve damage in 11/59 (18.6%) cases, distal catheter obstruction/damage/displacement in 17/59 (28.8%) cases and two-levels (valve/proximal catheter or valve/distal catheter) obstruction/damage/displacement in 16/59 (27.1%) cases. Subclinical infection was diagnosed in 3 patients (5.1%). VPS revision was performed selectively at the level of failure. CONCLUSIONS The proposed algorithm is a practical, simple and minimally-invasive technique to accurately diagnose VPS malfunction, identifying the exact level of system failure and allows to tailor surgical VPS revision, avoiding unnecessary complete system replacement.