A Wireless Intracranial Brain Deformation Sensing System for Blast-Induced Traumatic Brain Injury

Abstract

Blast-induced traumatic brain injury (bTBI) has been linked to a multitude of delayed-onset neurodegenerative and neuropsychiatric disorders, but complete understanding of their pathogenesis remains elusive. To develop mechanistic relationships between bTBI and post-blast neurological sequelae, it is imperative to characterize the initiating traumatic mechanical events leading to eventual alterations of cell, tissue, and organ structure and function. This paper presents a wireless sensing system capable of monitoring the intracranial brain deformation in real-time during the event of a bTBI. The system consists of an implantable soft magnet and an external head-mounted magnetic sensor that is able to measure the field in three dimensions. The change in the relative position of the soft magnet WITH respect to the external sensor as the result of the blast wave induces changes in the magnetic field. The magnetic field data in turn is used to extract the temporal and spatial motion of the brain under the blast wave in real-time. The system has temporal and spatial resolutions of 5 μs and 10 μm. Following the characterization and validation of the sensor system, we measured brain deformations in a live rodent during a bTBI.

Cognition based bTBI mechanistic criteria; a tool for preventive and therapeutic innovations

“…In addition, the numerical brain displacement was predicted to be between the experimental results obtained for the live rat, the dead/3D printed rat. Note that as the implanted soft magnet moves away from the reference transducer on the skull during the blast, the system has an innate tendency to overestimate displacement, as described previously 10 , and the degree of overestimation increases the further away the magnet moves. The results, along with this observation, suggest that the numerical model is able to capture the physics of the blast exposure.…”

“…Consistent with clinical observations in human mild bTBI, our mild bTBI rats are acutely asymptomatic with unremarkable neuroimaging findings 8 , 9 . Despite the initial subclinical nature of our model, we observed empirical evidence that mild blasts can incite relative displacement of the rat brain with respect to the skull of the order of hundreds of microns to millimetres 10 . Consistent with other independent mild bTBI investigations 11 , 12 , we also report acute blood-brain barrier disruption 8 , downstream secondary oxidative stress elevations and neuroinflammatory alterations 8 with later-onset behavioural and neurophysiologic alterations 9 , 13 .…”

“…2B ). The model validation was performed against prior brain motion tracking experimental data 10 , see Supplementary Information Fig. S6.…”

“…Motor, cognitive, affective, and psychosocial behavioural assessments after mild bTBI in this model after animals were subjected to the same blast exposure conditions used herein have been documented previously as summarised in Fig. 1 8 – 10 . Myofacial hypersensitivity was newly assessed as part of the present investigation (see Supplementary Information Fig.…”

“…The experiments conducted by the authors in a previous work provided the displacement of a soft magnet implanted on the surface of the brain in living rat, dead rat and 3D printed rat brains during blast exposure 10 . Consistent with in vivo experimental procedures, head fixations were applied in the in silico experiments, thus ensuring that the analysis of wave interactions from primary blast events is made in isolation from secondary and tertiary injuries.…”