High-Resolution Episcopic Imaging for Visualization of Dermal Arteries and Nerves of the Auricular Cymba Conchae in Humans

Babak Dabiri; Stefan Kampusch; Stefan H Geyer; Van Hoang Le; Wolfgang J Weninger; Jozsef Constantin Széles; Eugenijus Kaniusas

doi:10.3389/fnana.2020.00022

High-Resolution Episcopic Imaging for Visualization of Dermal Arteries and Nerves of the Auricular Cymba Conchae in Humans

Front Neuroanat. 2020 May 12:14:22. doi: 10.3389/fnana.2020.00022. eCollection 2020.

Authors

Babak Dabiri¹, Stefan Kampusch^{1

2}, Stefan H Geyer³, Van Hoang Le¹, Wolfgang J Weninger³, Jozsef Constantin Széles⁴, Eugenijus Kaniusas^{1

2}

Affiliations

¹ Institute of Electrodynamics, Microwave and Circuit Engineering, Vienna University of Technology, Vienna, Austria.
² SzeleSTIM GmbH, Vienna, Austria.
³ Division of Anatomy, MIC, Medical University of Vienna, Vienna, Austria.
⁴ Department for Vascular Surgery, University Clinic for Surgery, Medical University of Vienna, Vienna, Austria.

Abstract

Therapeutic applications of auricular vagus nerve stimulation (VNS) have drawn recent attention. Since the targeted stimulation process and parameters depend on the electrode-tissue interaction, the lack of structural anatomical information on innervation and vascularization of the auricle restrain the current optimization of stimulation paradigms. For the first time, we employed high-resolution episcopic imaging (HREM) to generate histologic volume data from donated human cadaver ears. Optimal parameters for specimen preparation were evaluated. Anatomical 3D vascular and nerve structures were reconstructed in one sample of an auricular cymba conchae (CC). The feasibility of HREM to visualize anatomical structures was assessed in that diameters, occupied areas, volumes, and mutual distances between auricular arteries, nerves, and veins were registered. The selected region of CC (3 × 5.5 mm) showed in its cross-sections 21.7 ± 2.7 (mean ± standard deviation) arteries and 14.66 ± 2.74 nerve fibers. Identified nerve diameters were 33.66 ± 21.71 μm, and arteries had diameters in the range of 71.58 ± 80.70 μm. The respective occupied area showed a share of, on average, 2.71% and 0.3% for arteries and nerves, respectively, and similar volume occupancy for arteries and nerves. Inter-centroid minimum distance between arteries and nerves was 274 ± 222 μm. The density of vessels and nerves around a point within CC on a given grid was assessed, showing that 50% of all vessels and nerves were found in a radial distance of 1.6-1.8 mm from any of these points, which is strategically relevant when using stimulation needles in the auricle for excitation of nerves. HREM seems suitable for anatomical studies of the human ear. A 3D model of CC was established in the micrometer scale, which forms the basis for future optimization of the auricular VNS. Obviously, the presented single cadaver study needs to be validated by additional anatomical data on the innervation and vascularization of the auricle.

Keywords: 3D modeling; auricular vagus nerve; cymba conchae; electrical stimulation; episcopic imaging.