Objective: To investigate the sacculocervical reflex of patients with PD with the assessment of changes of the parameters of VEMP depending on the severity of postural disorders and axial rigidity.

Background: Postural instability is one of the main symptoms of the advanced stage of PD which is based on the degeneration of the brain stem structures, including the vestibulospinal system. Vestibulospinal tracts ensure the implementation of rectifying and static postural reflexes that stabilize posture. With the help of VEMP can assess the condition of the sacculocervical reflex and objectify the abnormalities in vestibulospinal paths, the disturbances of which contribute greatly to the development of postural instability of patients with PD.

Methods: We conducted a study of 65 patients with PD and 30 healthy individuals aged 38 to 65 years. The study of VEMP was conducted with hardware-software complex with the module EP25 (company InterAcoustics (Denmark)).We evaluated the latent period (LP) P1 (p13) and N1 (n23), the coefficient of vestibular asymmetry, the time interval P1-N1. The severity of postural instability was evaluated as follows: 0 – normal; 1 – retropulsion, but can independently restore the balance; 2 – cannot maintain his balance and falls without support; 3 – severe instability, lose balance spontaneously; 4 – can not stand without help.

Results: We discovered a significant increase in the LP P1 and N1 components in a group of patients with PD in comparison with the control group, indicates a slowdown of the vestibular-spinal conducting due to disorders in central vestibular pathways. Moreover, this slowdown was more evident on the side of prevalence of clinical symptoms of PD. The conducted correlation analysis revealed a strong correlation between the severity of postural disorders (estimated in points) and LP P1, N1 components and the time interval P1-N1. A characteristic feature of patients who had axial rigidity has been a significant increase in the time interval P1-N1 compared to patients with PD who had no axial rigidity.

Conclusions: Our data show that the study can evaluate the pathophysiological processes underlying postural disorders. The elongation of P1-N1 interval can probably be a neurophysiological pattern of axial muscles’ rigidity.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/research-of-vestibular-evoked-myogenic-potentials-vemp-in-the-diagnosis-of-postural-instability-in-parkinsons-disease/