Natural Resonance Frequency of the Brain Depends on Only Intracranial Pressure: Clinical Research

Abstract

The need to understand and control intracranial pressure (ICP) is required for treatments in various clinical situations. The ICP value can only be measured by direct intracranial catheter or sensor placement, and a non-invasive ICP prediction method has not yet been established. We focused on the natural resonance frequency (NRF) of the brain to predict the ICP value. The ICP value, pulse waveform of intracranial pressure (PWICP) and cervical carotid pressure waveform (CCPW) were simultaneously collected from patients who had undergone ventricular drainage or ICP sensor placement for medical treatment in our institute. A total of 43 data were obtained from 27 patients, age ranged 14-48 (mean: 54) years, body height 137-187 (mean 163) cm and body weight 32-103 (mean 61) kg. The total measured time was 29,653 seconds and the measured mean ICP value in each data ranged from 3.82 to 69.39 (mean 25.9) hPa. Consecutive data was cut into 10.24 seconds, which was called a column. To decrease respiratory modulation, the largest positive peak of cardiac pulsation of CCPW was picked up in each column, as well as one ICP pulse waveform. The picked-up CCPW and PWICP were averaged by the weighted average method. The transfer characteristics from CCPW to PWICP were calculated by the transfer function method. The first initial negative peak of transfer characteristics was judged as the NRF of the brain. The relationship between the ICP value and the NRF of the brain was presented on the quadratic functions graph (ICP = 0.0329(NRF)2 + 0.0842NRF). These parameters were strongly correlated to each other (R2= 0.9952 coefficient of determination). The individual NRF, which was calculated by the transfer function method, only depends on the measured ICP value and their relationship can be presented in the simple quadratic functions. Funding: This research was funded by Japan Science and Technology Agency (JST) A-STEP feasibility study in 2012, and by Japan's New Energy and Industrial Technology Development Organization (NEDO) in 2013, and by Grants-in-Aid for scientific research in Ministry of Education, Culture, Sports, Science and Technology-Japan from 2015 to 2017 and 2018 to 2020. Receiver: Kenji Furihata. Declaration of Interest: Although the authors (T.G., K.F. and K.H.) have some patents of non-invasive intracranial pressure monitoring apparatus, the claim of the patents belong to affiliated university not to individuals. All of authors had already opened their COI disclosure in Japanese Neurosurgical Society. The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described. Our proposing theory is a quite new concept. We strongly believe that there is nothing to competing interest declaration. Ethical Approval: The simultaneous measurement of intracranial pressure and cervical carotid artery pressure waveform was approved by Ethical Committee of Shinshu University School of Medicine. “Development of non-invasive intracranial pressure monitoring” approved number 2343.