Nearly half of people who are over 65 experience dizziness and problems with balance. But the tests that are conducted to pinpoint the causes of such problems are mostly painful and can risk hearing damage. To counter this, researchers from Chalmers University of Technology, Sweden, have developed a new testing device using bone conduction technology, which is much more advantageous compared to the current tests.
Hearing and balance share something common. For patients who suffer from dizziness, this relationship is brought into play to diagnose issues with balance. Commonly, a ‘VEMP’ test (Vestibular Evoked Myogenic Potentials) is required to be performed. A VEMP test uses loud sounds to stimulate a muscle reflex contraction in the neck and eye muscles,which is triggered by the vestibular system – the system in charge for our balance. Researchers from Chalmers University decided to use bone conducted sounds to achieve better results.
“We have developed a new type of vibrating device that is placed behind the ear of the patient during the test,” says Bo Håkansson, a professor in the research group ‘Biomedical signals and systems’ at Chalmers University.
The vibrating device is small and compact in size, and is optimized so that it can provide an adequate sound level so that it can trigger the reflex at frequencies as low as 250 Hz. Previously, no vibrating device has been able to achieve this directly adaptable style for this type of test to check if the balance system is functioning properly.
During the bone conduction transmission, sound waves are transformed into vibrations through the skull, which stimulates the cochlea within the ear, just as when sound waves normally go through the ear canal, the eardrum and the middle ear. Bo Håkansson has worked for more than 40 years in this field and has also previously developed hearing aids using this technology.
A lot of people over 65 experience dizziness, but the causes of this problem can be often quite difficult to diagnose- and for several reasons. In almost half of these cases, dizziness is because of problems in the vestibular system. But the VEMP methods that we use today have major shortcomings, and can often cause hearing loss and discomfort for patients.
For example, the VEMP test uses extremely high sound levels, and might, in some cases, cause permanent hearing damage itself. If the patient already suffers from certain types of hearing loss, it might be much more difficult, in fact impossible to reach any conclusions from the test- something that the Chalmers’ method can tackle.
“Thanks to this bone conduction technology, the sound levels which patients are exposed to can be minimised. The previous test was like a machine gun going off next to the ear – with this method it will be much more comfortable. The new vibrating device provides a maximum sound level of 75 decibels. The test can be performed at 40 decibels lower than today’s method using air conducted sounds through headphones. This eliminates any risk that the test itself could cause hearing damage,” says postdoctoral researcher Karl-Johan Fredén Jansson.