To determine the optimal stimulation intensity for frontal stimulation with a modified slit lamp holder and to compare the reliability and symmetry of bone-conducted ocular vestibular evoked myogenic potentials (oVEMPs) using two stimulation sites: frontal medial and mastoid.
This observational study included 33 healthy volunteers (15 women, 18 men; mean age 24.5years) at the University Hospital of Lausanne. Participants underwent otoneurological assessments, and those with normal results were included. Bone-conducted oVEMPs were recorded using a Brüel and Kjaer mini-shaker type 4810. A modified slit lamp holder was used for frontal stimulation to ensure consistent application pressure, freeing the examiner's hands. Mastoid stimulation was performed manually.
The best reproducibility of oVEMP recordings was observed at 70dB nHL. Frontal stimulation demonstrated lower dispersion of data and lower asymmetry ratios of latencies (up to 7%) and amplitudes (up to 50%) compared to mastoid stimulation (up to 40% for latencies). Single stimulations at both frontal and mastoid sites were sufficient to obtain reliable measurements of both utricles.
Frontal stimulation at 70dB nHL using a modified slit lamp holder is recommended for bone-conducted oVEMP recordings due to its superior reproducibility, comfort, and reliability. This study establishes a new standard for optimal stimulation intensity and supports the use of frontal stimulation in clinical practice.