Ricerc@Sapienza

Background: In patients with bilateral vestibulopathy, the
regular treatment options, such as medication, surgery, and/
or vestibular rehabilitation, do not always suffice. Therefore,
the focus in this field of vestibular research shifted to electri-
cal vestibular stimulation (EVS) and the development of a
system capable of artificially restoring the vestibular func-
tion. Key Message: Currently, three approaches are being
investigated: vestibular co-stimulation with a cochlear im-
plant (CI), EVS with a vestibular implant (VI), and galvanic
vestibular stimulation (GVS). All three applications show
promising results but due to conceptual differences and the
experimental state, a consensus on which application is the
most ideal for which type of patient is still missing. Summa-
ry: Vestibular co-stimulation with a CI is based on “spread of
excitation,” which is a phenomenon that occurs when the
currents from the CI spread to the surrounding structures
and stimulate them. It has been shown that CI activation can
indeed result in stimulation of the vestibular structures.
Therefore, the question was raised whether vestibular co-
stimulation can be functionally used in patients with bilat-
eral vestibulopathy. A more direct vestibular stimulation
method can be accomplished by implantation and activa-
tion of a VI. The concept of the VI is based on the technology
and principles of the CI. Different VI prototypes are currently
being evaluated regarding feasibility and functionality. So
far, all of them were capable of activating different types of
vestibular reflexes. A third stimulation method is GVS, which
requires the use of surface electrodes instead of an implant-
ed electrode array. However, as the currents are sent through
the skull from one mastoid to the other, GVS is rather unspe-
cific. It should be mentioned though, that the reported
spread of excitation in both CI and VI use also seems to in-
duce a more unspecific stimulation. Although all three ap-
plications of EVS were shown to be effective, it has yet to be
defined which option is more desirable based on applicabil-
ity and efficiency. It is possible and even likely that there is a
place for all three approaches, given the diversity of the pa-
tient population who serves to gain from such technologies.