News | 30 June 2018

Researchers produce unique 3D images of the inner ear

Scans reveal detailed structures and individual nerves

Researchers at Maastricht UMC+ have succeeded in producing exceptionally detailed 3D images of the anatomy of human inner ear, an organ so complex, sensitive and inaccessible that it is difficult to study and whose detailed micro-anatomical structures remain uncharted territory. Now, researchers have used advanced analytical software, micro-CT scans, and a special contrast dye to visualise those structures. Dr Raymond van den Berg, a specialist in vestibular disorders, describes the visualisations as "fascinating and artistic": "It's amazing to see at a glance how thousands of nerves, rolled up in spiral, reach the miniscule sensors of the inner ear." The researchers have described and illustrated their findings in Frontiers in Neuroanatomy.

micro-CT-scan of the inner ear. in yellow: nerve structures, in blue: membrane and bone structures. Copyright: Maastricht UMC+ micro-CT-scan of the inner ear. in yellow: nerve structures, in blue: membrane and bone structures. Copyright: Maastricht UMC+ The inner ear is four centimetres long and embedded deep in the petrous bone of the skull behind the outer ear. It consists of the cochlea (hearing organ) and the vestibular system (balance organ). The first detects sound waves and the second detects position and motion. They convert these signals into impulses. The conversion takes place in thousands of tiny structures. The impulses are then transmitted to the brain across microscopically thin nerves, allowing us to hear and creating a sense of balance. By way of comparison, one of these nerves is a hundred times thinner than a human hair.

Detailed knowledge
At the moment, medical science often makes do with two-dimensional, "flat" images and simplified models of the inner ear. These visualisations do not provide enough information about the spatial positioning of its anatomical structures, however, and offer too little detail to reveal individual variations. To produce their images, the researchers used a special contrast dye, osmium tetroxide. The contrast dye combined with micro-CT scanning and a special image-processing algorithm developed by the researchers themselves produced detailed visualisations of the whole inner ear. Details of unique structures and even individual neurons were visible on the resulting three-dimensional renderings. This information can be used to improve existing treatments and the search for new innovations, for example an improved cochlear implant or an artificial vestibular system.

The research was carried out in cooperation with various universities in Austria and Switzerland.

micro-CT-scan of the inner ear. in yellow: nerve structures, in blue: membrane and bone structures. Copyright: Maastricht UMC+