Transnasal implants in the nasal cavity and sphenoid sinus for minimally invasive deep brain stimulation: measurement of electric field in cadavers.

Abstract

Deep brain stimulation (DBS) is increasingly used in treating motor disorders, neurodegenerative conditions, and mental health conditions. However, treatments are limited to the most severe cases due to the invasiveness of the surgical procedure. We propose stimulating ventral brain areas using electrodes inserted through the nose and placed in contact with the inferior skull base bones, under the olfactory cleft and in the sphenoid sinus. We designed a compact, low-power stimulation implant that fits in the sphenoid sinus and tested the implant insertion and operation in cadaveric heads, measuring the electric field obtained in deep brain regions. Using commercial multielectrode probes and an external stimulator, we also measured the electric field in cadaveric brains generated by different electrode placements to characterize the focus and steering that can be achieved. The implant can generate electric fields in the brain above 10 V/m, likely sufficient for neuronal activation. It is powered using either a 3 V battery which can generate almost 100 000 pulses from a 1 mAh charge, or alternatively, using inductive wireless power transfer, with the primary coil placed around the circumference of the head. This first-of-its-kind sphenoid implant demonstrates the possibility of minimally-invasive, focused deep brain stimulation. By enabling stimulation of deep brain regions without requiring surgery, transnasal stimulation can drastically improve the accessibility of some DBS treatments and broaden its applicability to additional mental health conditions.