Journal: Spine Surgery and Related Research

Article Title: Novel Modular Spine Blocks Affect the Lumbar Spine on Finite Element Analysis

doi: 10.22603/ssrr.2021-0197

Figure Lengend Snippet: Top (upper) and lateral views (lower) of the seven lumbar spine finite element models.

Article Snippet: A three-dimensional degenerative finite element spine model was constructed using ANSYS 14.5 (ANSYS Inc., Canonsburg, PA, USA).

Techniques:

Journal: Journal of neural engineering

Article Title: On the parameters used in finite element modeling of compound peripheral nerves

doi: 10.1088/1741-2552/aaeb0c

Figure Lengend Snippet: (a, d, g) Three-dimensional finite element models of compound nerves (two fascicles (a and d) or 10 fascicles (g)) with a monopolar partial cuff electrode (a) or with a bipolar circumneural cuff electrode (d and g). (b, e, h, i) Transverse cross sections showing the cuff electrode around the nerve containing two small fascicles (0.1 mm radius) or 10 fascicles (0.3 and 0.1 mm radii for the centre fascicle in panels (h) and (i), respectively). The cross section in panel (b) is through the centre of the single electrode contact. The cross sections in panels (e), (h), and (i) are through the centre of the bottom electrode contact. (c and f) Longitudinal cross sections showing vertical extent of cuff electrodes. Orientation of longitudinal cross sections is indicated with dashed lines on panel (a). Potential distributions are shown in response to 1 mA monopolar stimulus or +1 mA & −1 mA bipolar stimulus. Note the different colour axis bounds for the two electrode designs, with matched colours for 0 V. (j) Schematic of the FEM cross section outlining the parameters examined in the perineurium and endoneurium resistivity studies. Note that in the perineurium studies with simplified nerve geometry, we only modeled the centre fascicle.

Article Snippet: Three-Dimensional Finite Element Models of Nerves and Cuff Electrodes We implemented FEMs of a compound peripheral nerve and cuff electrode in COMSOL Multiphysics v5.3 (Burlington, MA) ( ) with the geometrical and electrical parameters outlined in .

Techniques:

Journal: Journal of neural engineering

Article Title: On the parameters used in finite element modeling of compound peripheral nerves

doi: 10.1088/1741-2552/aaeb0c

Figure Lengend Snippet: Potential distributions ((a) and (b)) and magnitude of electric fields ((c) and (d)) for two electrode configurations with 2D FEM of fascicle with individually-modeled axons (Figure 3). Inset in panel (a) shows fibre packing within dashed box. The colour map of the electric fields spanning 0 to 5 kV/m is the same as Figure 6 to permit direct visual comparison.

Article Snippet: Three-Dimensional Finite Element Models of Nerves and Cuff Electrodes We implemented FEMs of a compound peripheral nerve and cuff electrode in COMSOL Multiphysics v5.3 (Burlington, MA) ( ) with the geometrical and electrical parameters outlined in .

Techniques: Comparison

Journal: Journal of neural engineering

Article Title: On the parameters used in finite element modeling of compound peripheral nerves

doi: 10.1088/1741-2552/aaeb0c

Figure Lengend Snippet: Using the bipolar circumferential cuff and a 2 μm axon in the centre of the middle fascicle (see illustration of methods in Figure 2), thresholds for activation ((a) and (b)) and block ((c) to (e)) with different representations of the perineurium (x axis labels A to D) and estimates of perineurium resistivity (i to ix; see Table 2). Panels (b), (d), and (e) show the Method B data (constant ρ). Panels (a), (c), and (d) show thresholds for the single fascicle model. Panel (b) shows thresholds for the single fascicle and multifascicular nerve models. Panel (e) shows thresholds for the multifascicular model; the labels i to viii in panel (d) also apply to panel (e). Results for other electrode designs, fibre diameters, fascicles, and axon locations are provided in Supplement D.

Article Snippet: Three-Dimensional Finite Element Models of Nerves and Cuff Electrodes We implemented FEMs of a compound peripheral nerve and cuff electrode in COMSOL Multiphysics v5.3 (Burlington, MA) ( ) with the geometrical and electrical parameters outlined in .

Techniques: Activation Assay, Blocking Assay

Journal: Journal of neural engineering

Article Title: On the parameters used in finite element modeling of compound peripheral nerves

doi: 10.1088/1741-2552/aaeb0c

Figure Lengend Snippet: Activation thresholds for axons in 3D FEMs of nerves and cuff electrodes across different values of endoneurial resistivity (see illustration of methods in Figure 2). The default resistivities (red asterisks) were 12 Ω-m for ρendo-transverse and 1.75 Ω-m for ρendo-long. In the last column, the ratio of the transverse resistivity to the longitudinal resistivity was constant at 12 Ω-m/1.75 Ω-m = 6.9. All simulations used 2 μm axons and ρperi = 1149 Ω-m (DC, 37°C). First and second rows: Thresholds for the nerve model with two fascicles for different cuff electrode geometries. Third row: Thresholds for the nerve model with 10 fascicles and the bipolar circumneural cuff geometry. Data with four axon locations per fascicle – with the addition of thresholds for 2 and 10 μm axons placed in all fascicles of the multifascicular model – are provided in Supplement F.

Article Snippet: Three-Dimensional Finite Element Models of Nerves and Cuff Electrodes We implemented FEMs of a compound peripheral nerve and cuff electrode in COMSOL Multiphysics v5.3 (Burlington, MA) ( ) with the geometrical and electrical parameters outlined in .

Techniques: Activation Assay