ID 267 – Vestibulo-masseteric reflex and acoustic-masseteric reflex: Normative values

Objective To provide normative values on the vestibulo-masseteric (VMR) and acoustic-masseteric reflexes (AMR) for age/gender groups. Methods Sixty healthy volunteers (27 males, 33 females; 45.8 ± 17.4 years old), divided in 6 age groups ( 65 years), underwent click-evoked VMR (p11 wave) and AMR (p16/n21 wave). Zygomatic and mandibular electrode-montages and intensity-thresholds (98-138 dB SPL, at 5 dB intervals) were tested. Results For unilateral stimulation, peak-latency values were: p11 = 11.42 ± 1.05 ms; p16 = 15.81 ± 1.22 ms; n21 = 20.58 ± 1.74. Corrected amplitudes were: p11 = 0.47 ± 0.18; p16/n21 = 0.49 ± 0.2. VMR and AMR were elicitable from 112/120 and 108/120 ears, respectively. Bilateral stimulation induced higher amplitudes compared with unilateral stimulation ( p F 5,59  = 7.004, p F 5,59  = 3.265, p  = 0.012) whereas only VMR amplitude decreased ( F 5,59  = 3.742, p  = 0.003). The p1-peak latencies were shorter in females than males (VMR: p  = 0.009; AMR: p  = 0.002). Optimal thresholds were 128 dB for the VMR. The zygomatic montage was associated to higher amplitudes (VMR: p  = 0.034; AMR: p  = 0.004). Conclusions VMR and AMR behave similarly to commonly used myogenic potentials. Key message Characterization of VMR and AMR in normal subjects adds value for their use in clinical settings where they are increasingly used to assess brainstem function.