Clinical Study Of Cervical Vestibular Evoked Myogenic Potential Response Characteristics And The Influence Of Neck Muscle Force And Different Acoustic Stimulation

Objective1.To analyse and explore cervical vestibular evoked myogenic potential(cVEMP) of the main influence factors and mechanism, finding out the best parameters for cVEMP, thus unifying test parameters and establishing the objective test standard.2.To observe and explore the relationship between electromyography (EMG) of sternocleidomastoid (SCM) and cervical vestibular evoked myogenic potentials(cVEMP),Analysis of the EMG effect on amplitude of cVEMP.3.The current study explored differences among cervical vestibular evoked myogenic potentials (cVEMP) that were evoked by CE-chirp and click and tone pip (Blackman pip) in healthy controls, and explored the feasibility and mechanisms of cVEMP induced by CE-chirp.MethodsA. Subjects1.106healthy subjects (212ears;15males and15females; age range;20-30 years),3.A total of30healthy college medical students were introduced as subjects (60ears;9males and21females; age range;20-30years with a mean of24), all were without history of acute and chronic ear illnesses,were enrolled in this study. Before the test, All subjects received otoscopy, acoustic impedance, ear drum intactness and pure tone audimetry. Those with all the pretests results being within normal range were recruited as the subjects.And the3subjects showed favorable differentiation of cVEMP waves induced by Blackman pip.2.30healthy subjects (60ears;15males and15females; age range;20-30years), without history of acute and chronic ear illnesses,were enrolled in this study. Before the test, All subjects received otoscopy, acoustic impedance, ear drum intactness and pure tone audimetry. Those with all the pretests results being within normal range were recruited as the subjects. In addition, the recruited subjects also showed favorable differentiation of cVEMP waves induced by Blackman pip.B. ProceduresSubjects were required to maintain a sitting posture. After cleaning the subject’s skin with75%ethyl alcohol and a facial scrub, surface electromyographic (EMG) electrodes were placed on the upper half of each sternocleidomastoid (SCM) muscle, the reference electrodes were placed on the sternal notch, and the ground electrodes were placed on the forehead. Then, insertion type earphones were fixed approximately0.5cm deep into the external auditory canal to record cVEMP of the bilateral SCM. During the period of recording, subjects were required to turn their heads to the contralateral side until the lateral margin of the SCM could be observed with the naked eye, and the recorded SCM was maintained at tetanic contraction and as steady as possible. EMG activity was recorded using a ME6000-T8type surface electromyography (MegaWin, MN,Holland) or a commercial system (AEP module, Audera V2.7, Grason-Stadler, MN, USA) and was monitored at50μV. The EMG signal was amplified and bandpass filtered (10-1500Hz). Electrode resistance was less than2K. The sound stimulus of tone pip (Blackman pip) was set to100dB nHL, rarefaction500Hz,2-ms rise/fall time, and1-ms plateau. The stimulus was transmitted through inserted earphones, and the repetition rate was9.0Hz. The analysis time was54ms and500consecutive runs were averaged for each trial. Two consecutive trials were collected for averaging and further analysis. The CE-chirp Octave Band (CE-chirp, Audera V2.7) and click stimuli of0.1ms duration were used to elicit cVEMP responses. The hardware settings and procedures were the same as for Blackman pip stimuli. The only difference was the intensity of click, which was set at94.5dB nHL. Similarly, data from2consecutive trials were collected for averaging to increase the reproducibility of data.C. cVEMP ResponsesThe latency P1was defined as the positive polarity of the biphasic wave that appeared at approximately13ms, and the latency N1was defined as the negative polarity of the biphasic wave that appeared at approximately23ms. The initial positive-negative polarity of the waveform with peaks, was determined for the presence or absence of cVEMP responses. The following recorded double phase was nominated as P2(positive wave) and N2(negative wave). The amplitude was defined as the peak-to-peak P1-N1maximum energy in μV. cVEMP induced by different acoustic stimuli were recorded and the latencies of each peak (P1,N1, P2, and N2), peak to peak duration (P1-N1interval), and peak to peak amplitude (P1-N1amplitude) were measured and compared between the3different procedures. cVEMP and EMG were recorded in different head position(with sagittal at90°,60°,45毒and30°angle).D. Statistical AnalysisAll statistical analyses were performed using SPSS19.0for Windows. A value of P<0.05was accepted as statistically significant.Paired t-tests and two-way analysis of variance (ANOVA) were used to compare differences between stimuli. Descriptive analyses were performed for the following variables:P1latency, N1latency, P1-N1amplitude, and P1-N1interval. Data are presented as mean±standard deviation (SD).ResultsIn the case of the different EMG level:P1latency:12.50±2.39ms; N1latency:19.79±3.16ms, and the latencies proved no statistical difference (P>0.05).The amplitude was affected by EMG level,there were significant differences between the amplitudes(F=55.47, P<0.001).The different head positions on subjects their EMG level or area of EMG effects were statistically significant (P<0.001).The study found a linear dependence of the amplitude from the EMG leve(r2=0.59, Adjusted-r2=9.59,P<0.001).The response rates of cVEMP were93%for click and100%for both Blackman pip and CE-chirp. The P1and N1latencies of cVEMP evoked by CE-chirp were the shortest, followed by click, with Blackman pip the longest (F=6686.852, P<0.001). All indices of cVEMP evoked by the three stimuli showed no significant difference between the left and right ears. cVEMP responses were significantly different between the three stimuli. Compared with the currently used stimulus, CE-chirp can evoke cVEMP with shorter latencies and demonstrates increased speed and reliability.ConclusionThe cVEMP amplitude increased as a function of EMG target level, and the latency remained constant. The quantized data will increase the amplitude in clinical diagnosis application of sensitivity, and it will improve the diagnosis of the vestibular system diseases and some related diseases. The results obtained from the current study demonstrate that CE-chirp is a novel, sensitive, efficient, and reliable stimulus of cVEMP. Compared with conventional stimuli, CE-chirp can evoke cVEMP with shorter latencies and produce a more stable reaction. Additionally, previous research has shown that the origin of cVEMP is not related to cochlear hair cells or the cochlear nervous system. However, the physiological structure of the cochlea (e.g. the frequency characteristics of the basement membrane of cVEMP latency) may be associated with cVEMP latency.