MEMS (micro-electromechanical-systems) for hydrocephalus treatment

Treatment of hydrocephalus is beset by low shunt reliability, high overall surgical revision rate, infection, device obstruction, and over/under drainage. These failures are in part due to the physical design of traditional shunts which are comprised of a short catheter which leads from the cerebral ventricle into a valve which regulates CSF flow into a long catheter that directs fluid into distal spaces for absorption such as the peritoneum. This design is entirely dependent on components which direct CSF flow away from the intracranial space. Micro-electromechanical systems (MEMS) are uniquely suited for the treatment of hydrocephalus because MEMS based valves have the potential to make the catheters of standard shunts obsolete. By incorporating a micro-scale valve directly into the biological CSF flow pathway, the overall implant footprint could be drastically reduced. Theoretically, as the implant footprint decreases the like hood of infection and clogging drastically decreases. We have developed a micro-scale hydrogel check valve designed to be implanted in the Dura layer between the cerebral subarachnoid space and the superior sagittal sinus. Thus CSF flow can be regulated within the skull, eliminating external catheters. The hydrogel check valve is a passive, normally-closed valve which only opens when the pressure between the cerebral cortex and the sinus is greater than 20 to 110 mmH2O or 196 to 1078 Pa. Additionally the hydrogel check valve has almost no leakage, a common problem with shunts and other MEMS based valves, even if reverse pressures as high as 700 mmH2O are applied. By removing catheters, decreasing the total footprint of the implant and moving the location of implantation, a MEMS based valve/shunt design could completely transform the treatment of hydrocephalus.