Introduction Today, vestibular evoked myogenic potentials in cervical (cVEMP) and ocular (oVEMP) recording are an indispensable part of the diagnostic armamentarium for labyrinth disorders in all 5 sensors. While recording cVEMP is generally considered to reflect the function of the saccule under gravity conditions, little attention has been paid to its sensitivity to different stactic body positions.
Methods We employ a rotating chair, whose frame is fixed to the ground while the seat can be rotated freely along all 3 axes in space by 360 degrees. The “TRV-Chair®“, named after Thomas Richard-Vitton, is balanced individually for each patient and can be fixed in distinct positions by means of electromagnetic brakes and mechanical stoppers. We examined 12 healthy individuals using cVEMP for the left and right side in upright, supine and upside-down positions.
Results According to first experience, the saccular response is modulated by body position, while the signal is markedly weaker in upside-down compared to upright position. Preload of the sternocleidomastoid muscle was maintained constant throughout the examination using continuous EMG recording. A moderate bias was noted by individuals in terms of Eustachian tube dysfunction in upright-down position, probably due to venous plethora of middle ear and tube mucosa.
Discussion Although it is known that the macular organs of utricle and saccule are not oriented entirely in one dimension, there is little experience in macular sensitivity for opposite body positions. The results raise the question to what extent examination positions for macular function should be focused on more closely in terms of standardization. Recording VEMP in different body positions may have the potential to create new aspects for clinical questions.
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