Vestibular implant as a novel peripheral neuromodulation strategy for complex movement disorders. A pilot study in patients with Parkinson’s disease associated with bilateral vestibular dysfunction

Background Parkinson’s disease (PD) is increasingly recognized as a disorder of distributed sensorimotor networks, in which axial symptoms such as gait impairment and postural instability frequently become refractory to conventional therapies. The vestibular system provides continuous input to basal ganglia, cerebellar, thalamic, and cortical pathways involved in motor control, representing a potential target for peripheral neuromodulation. This study investigates the effects of chronic vestibular implant (VI) stimulation in patients with PD and concomitant bilateral vestibular hypofunction (BVP). Methods Six patients received a VI, including three patients with PD-associated BVP. All participants were prospectively evaluated before implantation and 12 months after device activation. Outcomes were compared with a matched cohort of three patients with isolated BVP receiving the same implant. Motor results were assessed using the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale part III (MDS-UPDRS III), together with dynamic balance, quality-of-life measures, comprehensive vestibular testing, and dopaminergic neuroimaging using 123I -Ioflupane SPECT (DaTSCAN). Results All patients with PD-associated BVP demonstrated clinically relevant motor improvement following VI activation, with MDS-UPDRS III reductions of 45, 20, and 27 points, respectively. The most consistent improvements involved bradykinesia, gait, freezing of gait, and postural stability, whereas tremor-related items showed a more variable response. Dynamic balance and sensory integration improved after implantation, with functional outcomes approaching those observed in patients with isolated BVP. DaTSCAN analysis revealed differences in striatal 123I -Ioflupane binding between vestibular implant ON and OFF conditions in all PD patients, although the magnitude and distribution of changes varied across individuals and striatal regions. Conclusion Chronic vestibular neurostimulation through an implantable device may be associated with changes in motor performance and sensorimotor network function in patients with PD and concomitant BVP. These preliminary findings support vestibular implantation as a potential peripheral neuromodulation strategy for complex movement disorders. Larger controlled studies are required to determine whether clinical improvements primarily reflect restoration of sensory input, central network modulation, or a combination of both.