Research team in Halle first to show that vestibular receptors continue to function after removal of ear tumor
Every year, several dozen people in Germany are diagnosed with a schwannoma in the cochlea of the inner ear. The tumor can be surgically removed by removing part of the cochlea. But – according to the prevailing school of thought – such an impairment to the cochlea, which is the size of a pea, would normally lead to a failure or significant disruption of the receptors in the organ responsible for equilibrium. An international team led by Professor Stefan Plontke from University Medicine Halle has demonstrated for the first time that the receptors responsible for the sense of balance retain their functionality regardless of whether the cochlea is present or not.
The tumor is a very rare subtype of the more familiar vestibular schwannoma, also called an acoustic neuroma, which usually grows in the internal auditory canal. Even though such cochlear tumors are usually benign and very slow growing, they destroy the sensory cells that convert sound signals into electrical nerve impulses. As a result, patients suffer from hearing loss and sometimes also dizziness.
The two receptor systems – one in the cochlea for hearing and one in the vestibular system for balance – are located in the so-called membranous labyrinth of the inner ear. They share the same fluids which contain a certain concentration of ions necessary for normal receptor function. Until now, it has been assumed that when the cochlea is damaged or even surgically removed, the other system also stops functioning. “Ear surgery requires a very high degree of precision and a great deal of experience. Tumors in the inner ear are usually only a few millimeters in size. During the operation, however, major sections or sometimes almost the entire cochlea have to be removed. Our measurements on all five vestibular receptors in our 27 patients before and after the surgical procedures revealed that the vestibular receptors continued to function on their own despite damage to the auditory system,” says Professor Stefan Plontke, Director of the Department of Otorhinolaryngology, Head and Neck Surgery at University Hospital Halle. Further research is needed to find out why this is the case. It can, however, be explained in part by the special surgical technique used in Halle.
The study is providing new insights into the function and operation of the inner ear and thus opens up new avenues for the treatment of patients, not only with vestibular schwannoma. It has accordingly been well received by experts around the world. The authors also believe that it could lead to significant improvements in devices such as cochlear implants (CIs), which use peripheral stimulation to enable patients to hear again.
The results of the study were published in the renowned Nature journal “Communications Medicine” (“A case series shows independent vestibular labyrinthine function after major surgical trauma to the human cochlea”).
Prof Dr Stefan Plontke
Tel: +49 345 557 1840
“A case series shows independent vestibular labyrinthine function after major surgical trauma to the human cochlea”, www.nature.com/articles/s43856-021-00036-w,