Vascular Supply of the Human Spiral Ganglion: Novel Three-Dimensional Analysis Using Synchrotron Phase-Contrast Imaging and Histology

Xueshuang Mei,Sumit K Agrawal,Rudolf Glueckert,Annelies Schrott-Fischer,Hao Li,Hanif M Ladak,Helge Rask-Andersen

doi:10.1038/s41598-020-62653-0

Abstract

Human spiral ganglion (HSG) cell bodies located in the bony cochlea depend on a rich vascular supply to maintain excitability. These neurons are targeted by cochlear implantation (CI) to treat deafness, and their viability is critical to ensure successful clinical outcomes. The blood supply of the HSG is difficult to study due to its helical structure and encasement in hard bone. The objective of this study was to present the first three-dimensional (3D) reconstruction and analysis of the HSG blood supply using synchrotron radiation phase-contrast imaging (SR-PCI) in combination with histological analyses of archival human cochlear sections. Twenty-six human temporal bones underwent SR-PCI. Data were processed using volume-rendering software, and a representative three-dimensional (3D) model was created to allow visualization of the vascular anatomy. Histologic analysis was used to verify the segmentations. Results revealed that the HSG is supplied by radial vascular twigs which are separate from the rest of the inner ear and encased in bone. Unlike with most organs, the arteries and veins in the human cochlea do not follow the same conduits. There is a dual venous outflow and a modiolar arterial supply. This organization may explain why the HSG may endure even in cases of advanced cochlear pathology.

Highlights

Human spiral ganglion (HSG) cell bodies located in the bony cochlea depend on a rich vascular supply to maintain excitability
Results revealed that the HSG is supplied by radial vascular twigs which are separate from the rest of the inner ear and encased in bone
The cochlea-vestibular artery (CVA) was identified in the internal auditory canal (IAC) (Fig. 3A,B) and could be followed into the cochlea where it divided into a vestibular and a cochlear branch running in opposite directions

Summary

Introduction

Human spiral ganglion (HSG) cell bodies located in the bony cochlea depend on a rich vascular supply to maintain excitability. These neurons are targeted by cochlear implantation (CI) to treat deafness, and their viability is critical to ensure successful clinical outcomes. The CA is often missing in certain anatomic variants, and in these cases, the cochlear branch of the CVA supplies the entire cochlea Both the cochlear and vestibular branches are believed to supply the capillary regions of the human spiral ganglion (HSG). According to Axelsson[9], all human cochleae are different with respect to connections between the two venous systems From the literature, it remains unclear which role the tractus arteriosus spiralis foraminosus (TASF) plays: arterial, venous, or both. It is a prominent channel running on the upper side of the lower basal turn[5] According to Nabeya, the PSV begins at the junction between the lower two-thirds and the upper one-third of the basal coil and is involved in the drainage of the upper HSG

Objectives

Methods

Results

Discussion

Conclusion