Bio-heat transfer model of deep brain stimulation-induced temperature changes

Abstract

There is a growing interest in the use of chronic deep brain stimulation (DBS) for the treatment of medically refractory movement disorders and other neurological and psychiatric conditions. Fundamental questions remain about the physiologic effects of DBS. Previous basic research studies have focused on the direct polarization of neuronal membranes by electrical stimulation. The goal of this paper is to provide information on the thermal effects of DBS using finite element models to investigate the magnitude and spatial distribution of DBS-induced temperature changes. The parameters investigated include stimulation waveform, lead selection, brain tissue electrical and thermal conductivities, blood perfusion, metabolic heat generation during the stimulation and lead thermal conductivity/heat dissipation through the electrode. Our results show that clinical DBS protocols will increase the temperature of surrounding tissue by up to 0.8 degrees C depending on stimulation/tissue parameters.

Thermal analysis of injectable, cellular-scale optoelectronics with pulsed power

“…0.3 Wm −1 K −1 and thermal diffusivity approx. 1.31 × 10 −7 m 2 s −1 ) [17,18] are similar to those of tissue (thermal conductivity 0.6 Wm −1 K −1 and thermal diffusivity 1.58 × 10 −7 m 2 s −1 ) [19,20]. Figure 2 shows a schematic of the analytic model for a single µ-ILED in the tissue.…”

The Modeling of Shock-Wave Pressures, Energies, and Temperatures Within the Human Brain Due to Improvised Explosive Devices (IEDs) Using the Transport and Burgers' Equations

“…Here, γ represents the heatdiffusion coefficient equal to 1.39 × 10 −7 m 2 /s, verified from data given by Elwassif et al [12]. We should consider that, unlike the energy defined by Burgers' equation in Equation (190), the Heat-Diffusion equation yields the total energy, for zero initial temperature, of the system as:…”

“…At x = 0 when t = 0, we may adopt both Dirichlet and Neumann boundary conditions, u (t, 0) = u 0 , u (t, L) = u 0 , u (0, x) = u (x) = φ (x) and u x (t, 0) = u x (t, L) = 0, so that periodic boundary conditions enable the solution to be satisfied at the given limits, and where the brain's own natural heat-source, u 0 , represents the normal temperature or energy of the human brain at both x = 0 and t = 0. Given the absence of any IEDenergy pulse, in adopting the Heat-Diffusion equation, we may assume that the temperature profile will oscillate about the brain's natural temperature, [12][13][14][15][16][17], to some extent so that, under normal circumstances u 0 → 37 • C (or 310.15 Kelvin) as t → ∞ .…”

“…During their analysis of the effects of Joule heating on the "Bio-heat transfer model of deep brain stimulation-induced temperature changes, " Elwassif et al [12], and others [13][14][15], pointed out that even slight temperature fluctuations significantly affect brain function. They also indicate that temperature increases occurring between 37 • C and 37.5 • C cause "changes in cell excitability"; between 37.5 • C and 38 • C, there are "changes in network function/blood-brain barrier (BBB) breakdown"; a "sustained increase" from 38 • C to 39 • C "can have profound effects on brain function, " with "severe effects on tissue function likely"; and "cell damage/tissue ablation is observed at sustained temperatures over 40 • C. The authors further assert that many reasons for such adverse brain functionality are due to changes in voltage, conductivity, resistance and capacitance, thus affecting neuronal and synaptic firing, given that temperatures affect each of these factors very significantly, as is known within the Electronic and Electrical Engineering industries.…”

Predicting and managing heat dissipation from a neural probe

“…Probe thermal resistance decreases as the probe is inserted due to the increased thermal spreading that occurs within the probe 560 μm and heated region extends to the end of the probe. Elwassif et al (2006) state that a temperature increase of even one degree Celsius is enough to cause cellular death. Therefore the baseline heat input was selected to be 0.7742 mW based on producing a temperature change of 1°C for the baseline model.…”