Neuropathological findings after intracerebral implantation of microdialysis catheters

The neuropathological and immunocytochemical changes in the sheep forebrain following 7 days of microdialysis, using a catheter approved for human use, are described. There was no behavioural dysfunction and light microscopy revealed mild astrogliosis and patchy macrophage infiltration immediately adjacent to the catheter track. The surrounding neuropil was normal. There was one small subcortical haemorrhage (10 x 1.5 mm). These findings are similar to those following microdialysis in rodents and suggest that the risk of significant damage to the human brain is low, that neuropathological changes in the brain around the catheter should not interfere with local brain metabolism, and that the catheter should be affixed in such a way as to minimize movement-induced damage to the brain.