A new active microendoscope for exploring the sub-arachnoid space in the spinal cord

This paper presents the design, development and preliminary test of a new active microendoscope for neuroendoscopy and therapy of the spinal cord. Endoscopy of the spinal sub-arachnoid space is useful for some pathologies, but it is a very challenging task for several reasons: the navigation space is very narrow, there are many blood vessels and delicate structures which could be damaged by maneuvers and large forces and, finally, the CerebroSpinal Fluid (CSF) is a peculiar environment which must be preserved. An innovative method for active safe navigation in the sub-arachnoid space has been devised, based on hydrojets sustentation of the endoscope. The hydrojets, if appropriately tuned and oriented, allow the tip of the endoscope to avoid the delicate structures of the spinal cord and could also assist propulsion. A MATLAB simulation of the hydrojets is illustrated and a digital controller for the regulation of the hydrojets is demonstrated. The pressure ripple is about 5%, as tested experimentally on a 2D simulator. A prototype of steerable microendoscope whose tip is equipped with hydrojets has been fabricated and tested in an artificial path simulating the sub-arachnoid space. Performance are quite interesting.