Evaluation of Shunt Failures by Compliance Analysis and Inspection of Shunt Valves and Shunt Materials, Using Microscopic or Scanning Electron Microscopic Techniques

Abstract

Shunt dysfunction or malfunction in the treatment of hydrocephalus still causes multiple difficulties in the clinical management of this condition. In this study the results of micro-inspection of explanted shunt valves and tubes by light and scanning electron microscopy are presented. From our findings in 36 patients aged from 1 month to 79 years (mean age 49.03 years) we discovered that 61.1% of the patients had shunt related defects which led to tissue migration into the shunt lumens or to tissue adherence to the tube surface. Calcification and destruction of the silicone-elastomer tubing was found in all cases of shunt tube occlusion (25%). There were shunt fractures in 11.1% of the tubes. Histological analysis verified foreign body tissue reactions on all explanted alloplasts. In five cases (13.8%) migration of chorioid plexus or glial cells to the inner lumen of the ventricular catheter was found. Of 36 patients who underwent compliance (Co), reabsorption resistance (R), and cerebrospinal fluid (CSF) formation rate (F) analysis, one patient required a valve replacement due to significant intracranial content compliance changes after craniostenosis surgery. Furthermore, four of 36 patients had shunt infections, three cases with bacteria Staphylococcus aureus (8.3%), and one case with Candida albicans (2.8%) hyphae inside the valve lumen. Work-bench valve tests, following the ISO/DIS 7197 protocol (1989), clarified that of seven valves tested, six did not match the CSF-drainage requirements for an individual patient.