Andreas Spiegelberg, Andrea Boraschi, Fariba Karimi, Myles Capstick, Arya Fallahi, Esra Neufeld, Niels Kuster, and Vartan Kurtcuoglu, IEEE Transactions on Biomedical Engineering 2022, online 28 June 2022; doi: 10.1109/TBME.2022.3186748
The clinical management of several neurological disorders relies on diagnostic information obtained by measuring intracranial pressure to determine craniospinal compliance. However, the procedures involved are invasive in nature. Here, we aimed to determine whether noninvasive measurement of naturally occurring periodic changes in the dielectric properties of the head could serve as a biomarker and surrogate for craniospinal compliance. To achieve this goal, we developed a highly sensitive device with head-mounted electrodes, and we characterized the properties of the device-electrode-head system through measurements involving healthy volunteers as well as computational and electromechanical modeling. The signals obtained from the volunteers revealed the characteristic cardiac and respiratory modulations of interest that can be attributed primarily to changes in the electrical resistance properties of the head. Hyperventilation tests subsequently confirmed that the measured signal contained information of intracranial origin: hyperventilation-induced end-tidal CO2 reduction, which primarily affects intracranial vasculature, resulted in a signal amplitude decrease associated with a cardiovascular action. If confirmed in larger cohorts, including patients with various disorders, these results suggest that noninvasive measurement of changes in the dielectric properties of the head is a promising approach for obtaining a biomarker that could serve as a surrogate for craniospinal compliance.
The scientific and technical impact of the study can be summarized as: