Paul A. House and William T. Couldwell
Paul A. House, Joel D. MacDonald, Patrick A. Tresco and Richard A. Normann
Researchers at The Center for Neural Interfaces at the University of Utah have designed and produced a silicon-based high-density microelectrode array that has been used successfully in mammalian models. The authors investigate the ability to transfer array insertion techniques to humans and examine the acute response of human cortical tissue to array implantation.
Six patients who were scheduled to undergo temporal lobectomy surgery were enrolled in an Institutional Review Board–approved protocol. Before the patients underwent lateral temporal cortical resection, one or two high-density microelectrode arrays were implanted in each individual by using a pneumatic insertion device. Cortical tissue was then excised and preserved in formalin. The specimens were sectioned and stained for histological examination.
Pneumatic insertion of a microelectrode array into human cortex in the operating room was feasible. There were no clinical complications associated with implantation and no evidence of significant insertion-related hemorrhage. Tissue responses ranged from mild cortical deformity to small focal hemorrhages several millimeters below the electrode tines. Based on initial results, the insertion device was modified. A footplate that mechanically isolates a small area of cortex and a calibrated micromanipulator were added to improve the reproducibility of insertion.
A high-density microelectrode array designed to function as a direct cortical interface device can be implanted into human cortical tissue without acute clinical complications. Further modifications to the insertion device and array design are ongoing and future work will assess the functional significance of the tissue reactions observed.
Spencer S. Kellis, Paul A. House, Kyle E. Thomson, Richard Brown and Bradley Greger
The goal of this study was to determine whether a nonpenetrating, high-density microwire array could provide sufficient information to serve as the interface for decoding motor cortical signals.
Arrays of nonpenetrating microwires were implanted over the human motor cortex in 2 patients. The patients performed directed stereotypical reaching movements in 2 directions. The resulting data were used to determine whether the reach direction could be distinguished through a frequency power analysis.
Correlation analysis revealed decreasing signal correlation with distance. The gamma-band power during motor planning allowed binary classification of gross directionality in the reaching movements. The degree of power change was correlated to the underlying gyral pattern.
The nonpenetrating microwire platform showed good potential for allowing differentiated signals to be recorded with high spatial fidelity without cortical penetration.
Walavan Sivakumar, Michael Jensen, Julie Martinez, Michael Tanana, Nancy Duncan, Robert Hoesch, Jay K. Riva-Cambrin, Craig Kilburg, Safdar Ansari and Paul A. House
The authors designed a randomized, double-blinded, placebo-controlled trial to evaluate intravenous acetaminophen as a scheduled adjunct with our standardized craniotomy pain control regimen. No statistically significant effect was found in narcotic consumption at 24 or 48 hours after surgery. At 24 but not 48 hours, patients treated with intravenous acetaminophen did report significantly lower pain scores than patients given the placebo. These data provide only modest support for using intravenous acetaminophen to improve postoperative craniotomy pain.