Animal experiments to evaluate complications of foreign materials on silicone with shunt catheters: Preliminary results

Abstract

Objective: Use of silicone to manufacture hydrocephalus shunts has been critical for the successful introduction of modern shunt therapy. However reactions to foreign material cause biodegradation, calcification, and massive scarring, and their impact on the still high shunt failure rate might have been undervalued in the past. We established an animal model to simulate the conditions and reactions with the silicone catheter in human patients. Methods: We implanted catheters from different hydrocephalus shunt manufacturers available on the world market in 12 four-week old Wistar rats. To mimic shearing forces and tensile stress, the tubes were firmly fixed proximally and distally in a growing rat. The catheters remained in the subcutaneous tissue for 1 year before being removed and studied using scanning electron microscopy and histological studies. Results: All of the implanted long catheters showed fractures and calcification on their surfaces, whereas the short fragmented catheters did not. Conclusion: The immunological reactions with silicone and the biodegradation of the material can be simulated in this animal model to study details of the pathophysiology of this process. © 2009 Springer-Verlag Vienna.