Vestibular-Evoked Myogenic Potentials of the Masseter Muscle (MVEMPs): a review of current knowledge and future perspective.

Background: Masseter vestibular-evoked myogenic potentials (MVEMPs) are an emerging technique for testing the vestibulotrigeminal pathways. Their methodology and clinical usefulness are not fully defined. This narrative review summarises current evidence on MVEMPs and their role in balance disorders. Methods: A literature search was conducted in PubMed, Scopus and Web of Science using combinations of terms related to VEMPs and the masseter muscle. Studies addressing vestibulomasseter physiology, MVEMPSrecording characteristics, clinical applications, or comparisons with cervical and ocular VEMPs were included. Results: MVEMPs reflect an inhibitory otolithic reflex arising predominantly from the saccule and conveyed via the inferior vestibular nerve to medial vestibular nuclei, with crossed projections to trigeminal motor nuclei. Optimised protocols employ tonic jaw clenching with zygomatic electrode montage and high-intensity 500 Hz tone-burst or narrow-band CE-chirp stimulation, yielding P1 ≈ 11 ms and N1 ≈ 21 ms biphasic components. MVEMPSabnormalities—typically reduced amplitudes and prolonged latencies—have been reported in vestibular disorders, sometimes revealing dysfunction when cervical vestibular-evoked myogenic potentials (CVEMPs) or ocular vestibular-evoked myogenic potentials (OVEMPs) findings are normal or discordant. Conclusions: MVEMPs are an interesting tool for testing the vestibulotrigeminal pathway and complement CVEMPs and OVEMPs. However, adoption is constrained by dependence on masseter pre-activation, variability in protocols, and lack of normative data and diagnostic cut-offs. Standardised methodologies, larger studies, and integration with other tests, such as imaging exams and clinical assessment, are required to establish the diagnostic and prognostic role of MVEMPs.