Non Invasive Monitoring Of PIC (Intracranial Pressure) – NIM-O-PIC

The coordinating partner of this project invented and patented several methods allowing changes in intracranial pressure (ICP) to be measured noninvasively through the ear. These methods are based upon the concept that ICP changes are transmitted, within a few tens of seconds, to the inner ear fluids and that any increase in pressure results in predictable changes in the mechanical impedance of sound-transmitting and sound-processing structures. This impedance determines the physical characteristics of several signals (sounds or electric potentials) reflecting cochlear function that can be detected in a few seconds in the ear canal of subjects, as part of their routine audiological check-up. Novel noninvasive ICP measuring devices have been built by a startup company, Echodia, created in the coordinating partner’s laboratory, and have proved their interest in detecting pressure-dependent auditory conditions.

The goal of this project is, in cooperation with the company and a few local researchers and clinical partners, to extend the field of applications of the device to patients who may develop ICP increase along the course of their disease. In many cases, the use of invasive ICP monitoring is impossible at present, so that clinicians use indirect clinical signs to suspect, then treat intracranial hypertension, so as to prevent its detrimental effects – pain or brain damage. Many patients might benefit from some noninvasive and fast means of monitoring ICP, and the system that operates though the ear is a good candidate. However, the current version has to be modified, because this application supposes that patients can be monitored at months’ intervals, during which confounding effects may show up and modify the signals coming from the ear in such a way that they no longer reliably detect ICP changes. Notably, middle-ear pressure has to be controlled and stabilized. The technological goal of this project is to modify the existing system to make it usable on long time intervals, and the practical goal is to check that the modified system is sensitive and specific enough to genuine ICP changes.

We will test the modifications on samples of patients with interesting profiles of ICP. In two of the target samples (patients who suffered from meningeal hemorrhage and brain tumors), our clinical partners know how to efficiently monitor the clinical signs of a relapsing increase in intracranial hypertension, and to complete their analysis using periodically updated CT scan data. For both conditions, it is expected that patients with a certain profile should develop increased ICP. The challenge of our system will be to effectively detect this increase, and not detect any change as long clinical signs are absent. A third category of pathologies will concern migraine (at present the idea that migraine comes with increased ICP is contentious, and as direct ICP measurements are totally excluded in patients, our system would help solve the controversy). The interest of the migraine model is two-fold. First, an animal model mastered by one of our partners can serve as a reference in which direct ICP measurements will calibrate the outcome of our noninvasive system. Second, attacks of migraine in the chosen patients are predictable and unfold over a time scale that does not make it too critical to have a finalized version of the intended product at the start. In this framework, each evolution of the planned equipment will be suitably tested along the project’s duration in the migrainous patients.

Ultimately, the goal of the project is to validate the extension of an already existing equipment, built and distributed by a French spin-off of a research laboratory, allowing a large variety of noninvasive tests in patients who are at risk of developing intracranial hypertension and might thus be monitored at much lower costs and risks than at present.