Electroosmosis Based Novel Treatment Approach for Cerebral Edema

Abstract

Objective: Cerebral edema characterized as 4 an abnormal accumulation of interstitial fluid has not been 5 treated effectively. We propose a novel edema treatment 6 approach to drive edematous fluid out of the brain by di-7 rect current utilizing brain tissue's electroosmotic property. 8 Methods: A finite element (FE) head model is developed 9 and employed to assess the feasibility of the approach. 10 First, the capacity of the model for electric field predic-11 tion is validated against human experiments. Second, two 12 electrode configurations (S and D-montage) are designed 13 to evaluate the distribution of the electric field, electroos-14 motic flow (EOF), current density, and temperature across 15 the brain under an applied direct current. Results: The 16 S-montage is shown to induce an average EOF velocity 17 of 7e-4 mm/s underneath the anode by a voltage of 15 V, 18 and the D-montage induces a velocity of 9e-4 mm/s by a 19 voltage of 5 V. Meanwhile, the brain temperature in both 20 configurations is below 38°C, which is within the safety 21 range. Further, the magnitude of EOF is proportional to 22 the electric field, and the EOF direction follows the current 23 flow from anode to cathode. The EOF velocity in the white 24 matter is significantly higher than that in the gray matter 25 under the anode where the fluid is to be drawn out. Conclu-26 sion: The proposed electroosmosis based approach allows 27 alleviating brain edema within the critical time window by 28 direct current. Significance: The approach may be further 29 developed as a new treatment solely or as a complement to 30 existing conventional treatments of edema. 31 Index Terms-Cerebral edema, Electroosmotic flow, 32 Electric field, FE head model. 33 I. INTRODUCTION 34 C EREBRAL edema is defined as the accumulation of water 35 in extracellular and intracellular spaces, leading to high 36 morbidity and mortality [1], [2]. Among a variety of pathogenic 37 factors, traumatic brain injuries (TBIs) constitute the primary 38 cause for brain swelling that could also lead to other serious

Designing electrode configuration of electroosmosis based edema treatment as a complement to hyperosmotic therapy

“…The direct current applied to the anode flows across the brain along the direction from anode to cathodes, indicating that the induced EOF will be directed to the regions underneath the cathodes. Therefore, for the 2-electrode model with a cathode located near SAS in line with our previous study [45], the activated region with high EOF velocity is mainly located under and between the edema region and SAS. For the 3-electrode model and 5-electrode model, due to the existence of extra cathodes, the excess fluid in the edema region is driven to flow along direct current pathways to surrounding normal brain tissue, resulting in the reduction of abnormal accumulation of fluid within the edema region.…”

“…The electrical and thermophysical properties of the head tissues except WM and eWM are regarded as homogeneous and isotropic obtained from the literature [3,5,9,10,13,17,42,45], in line with previous studies in the field of direct current stimulation (Table 1). For edema regions, the electrical and thermal conductivities of eWM and eGM are calculated based on the WC variation obtained from the (7)…”

“…The patient-specific FE head model is generated via a personalization approach by morphing a baseline model developed and validated earlier [45]. The baseline model includes eight compartments, including the scalp, cortical bone, cancellous bone, dura mater, white matter (WM), gray matter (GM), CSF, and the ventricular system (Fig.…”

“…Details of the baseline model development Fig. 1 CT images of a patient with localized edema and the personalization approach can be found in our earlier studies [32,45].…”

“…In a previous study, we presented a novel electroosmosis based approach for CE treatment utilizing the brain tissue's electroosmotic property [45]. Our approach is to induce electroosmotic flow (EOF) in the brain tissue by applying an external direct current to the head; as brain tissue is an electroosmotic material consisting of an electrical double layer (EDL) in the extracellular space, the cations driven by the electrical force move along the micro-channels through the extracellular space, which will pull the adjacent fluid to flow together by a viscous drag force, resulting in EOF [14,40].…”