| Vestibular evoked myogenic potential (VEMP) can be recorded from the bilateral contracting stemocleidomastoid (SCM) muscle by stimulation with loud sound.VEMP is a objective and noninvasive electrophysiology test and have been thought to be a manifestation of the vestibulocollic reflex.VEMP may supplement the current test battery by providing diagnostic information about saccular and /or inferior vestibular nerve function. VEMP applied with Electronystagmography(ENG) have important clinic signification to diagnose and distinguished diagnose of vestibular and pertinent disease. 1 Materials and methods In eighty-six normal subjects aged from 11 to 60 years. twenty-five normal old man.one hundred twenty-six patients with vestibular system and deaf disease,VEMP, elicited binaurally and monaurally by 95 dBnHL tone burst stimulus, were recorded from surface electrodes over the SCM muscles. The provocation rates, latencies, amplitudes, interaurallatency difference, interaural amplitude ratio, interaural asymmetric ratio were then calculated. Tone burst stimuli at 500Hz are presented at 95dBnHL.Bandpass filtered and 2 cycle rise/fall time with no plateau is utilized.Responses to 100 stimuli are averaged and two or three responses are obtained from each side.Recording waveforms have four main components in the averaged response:p13, n23, n34 and p44 according to Colebatch advice.P13-n23 has clinic application signification because provocation rates of pl3-n23 is higher than n34-p44.VEMP provocation rates, latencies, amplitudes, interaural latencies, interaural amplitude ratio and interaural asymmetric ratio of p 13 ,n23 were research.1. 2 Objective The purpose of this study was to investigate the characteristics of VEMP healty young and old subjects,using binaural tone burst stimulation, and to establish our parameter certerions;compare with provocation rates and parameter that recording from surface electrodes over the SCM muscles and masseter in old subjects , vestibular systerm and deaf disease ;discuss the characteristics of VEMP and diagnostic clinic signification in vestibular systerm and deaf patients.2. Results2. 1 In eighty-six normal subjects aged from 11 to 60 years.VEMP provocation rates for binaural tone burst stimulation that recording from surface electrodes over the SCM muscles were 90%(77/86 no provocation subjects aged exceed fifty years). VEMP provocation rates for binaural acoustic stimulation and monaural ipsilateral acoustic stimulation were both 90%, and the provocation rate for the contralateral, acoustic stimulation free ear was only 45.9 %.VEMP latencies of p13 and n23 for the binaural and monaural ipsilateral acoustic stimulations were 17.16±2.59ms and 24.87 ±4.04 ms respectively. There was no significant difference between the VEMP latencies for the binaural and monaural ipsilateral acoustic stimulations, but there was notable difference between the above latencies and those for the contralateral, acoustic stimulation free ear (P<0.05) . Amplitudes differ significantly between binaural acoustic stimulation, monaural ipsilateral acoustic stimulation(P<0.05), and monaural contralateral acoustic stimulation (123.35 ± 73.06 μ V,150.05 ± 76.58 μ V ,84.02 ± 55.80 μ V respectively) (P<0.01) . The binaural and monaural acoustic stimulations were significant different in interaural amplitude ratio (P<0.05) . The contralateral latencies delayed, compared with ipsilateral ones in response to monaural acoustic stimulation, showing a significant difference in interaural latency difference (P<0.01) . There were marked difference existed in interaural asymmetric ratio between binaural and monaural acoustic stimulations (P<0.01) . 2.2 Clinic utility. 2.2.1 Sensorineural deafness VEMP provocation rates were 60%(27/45). no provocation subjects whose age exceed fifty years account for 95% (17/18). another no provocation subject exhibited semicircle canal paralysis.Hearing loss is not relation with VEMP provocation rates.2.2.2 Sudden hearing loss VEMP provocation rates were 83%(10/12). no provocation subjects is relation with age and attend by semicircle canal paralysis synchronously.2.2.3 Meniere disease VEMP provocation rates were 50%(10/12).Ten patients attend by profound sensorineural deafness and five patients accompany with semicircle canal paralysis.2.2.4 Auditory neuropathy Twenty-three patients exhibited low frequency profound sensorineural deafness .Auditory brainstem responses are notprovocated in all patients.Distortion product otoacustic emissions are provocated.ENG exhibited semicircle canal paralysis in eight patients. VEMP provocation rates were 40%(9/23).In nine patients VEMP latencies of p13 and n23 were notable prolong (28.23± 4.20ms and 35.65 ± 3.30 ms respectively). Amplitudes of p13 -n23 were notable low (65.82 ± 22.45 μ V).2.2.5 Vertigo symptom Two/10patients exhibited profound sensori- neural deafness. Five patients accompany with semicircle canal paralysis.nine patients attend by positional nystagmus. VEMP provocation rates were 50%(5/10)2.2.6 Hunt syndrome In all five patients showed normal hearing.Two accompany with semicircle canal paralysis. VEMP provocation rates were 20%(l/5).Amplitudes of pl3 -n23 were notable low (43.70 μ V).2.2.7 Benign paroxysmal positional vertigo In all three patients VEMP gave no responses and two patients aged exceed sixty years.2.2.8 Acoustic tumor Sicken-ears showed profound sensorineural deafness. One patients accompany with semicircle canal paralysis. One patient showed no response to tone burst whereas another showed p13 -n23 low amplitudes.2.2.9 Delayed endolymphatic hydrop This patient accompanis with bilateral profound sensorineural deafness. ENG exhibited monaural semicircle canal functional disorder. VEMP amplitudes of p13 -n23 were notable low .2.2.10 Large vestibular aqueduct syndrome This patient accompanis with bilateral profound sensorineural deafness. VEMP amplitudes of p13 -n23 were notable large .2.2.11 Congenital deafmutism symptom This patient accompanis with bilateral serve-profound sensorineural deafness. VEMP latencies of p13and n23 were prolong .Amplitudes of p13 -n23 were notable low . 2.2.12 Conductive and mixed deafness Thirteen patients were study.These patients include four patients with otitis media with effusion and six patients with chronic suppurative otitis media.Another three patients carried out radical mastoidectomy.VEMP are no responses by tone burst stimulation. 2.3 In twenty-five normal subjects aged exceed 60 years, VEMP provocation rates for binaural tone burst stimulation that recording from surface electrodes over the SCM muscles were 36%(9/25). VEMP latencies of pl3 and n23 were 17.47 ± 2.16ms and 25.20 ± 2.89 ms respectively.VEMP amplitudes were 51.51±20.38μV. Provocation rates for binaural tone burst stimulation that recording from surface electrodes over masseter were 36%(9/25). Latencies of p13 and n23 were 17.55 ± 2.07ms and 25.30 + 2.69 ms respectively. Amplitudes of p13 - n23 were 106.78 + 40.69 μV.In one hundred twenty-six patients with vestibular system and deaf disease, provocation rates for binaural tone burst stimulation that recording from surface electrodes over the SCM muscles and masseter were 48%(61/127) and 77%(98/127) respectively. 3 Conclusion3.1 Waveforms of VEMP are steadable, legible and good repetition by binaural 95dBnHL,500Hz tone burst stimulation that recording from surface electrodes over the SCM muscles. VEMP provocation rates were 90%. We have established our parameter certerions. Amplitudes differ significantly between binaural acoustic stimulation, monaural ipsilateral acoustic stimulation, and monaural contralateral acoustic stimulation (P<0.01) . Amplitude of VEMP using binaural tone burst stimulation, and to comparewith that using monaural tone burst stimulation, is symmetrical. Test with binaural tone burst stimulation can save time and have practical signification.3.2 In twenty-five normal subjects aged exceed 60 years, VEMP provocation rates for binaural tone burst stimulation that recording from surface electrodes over the SCM muscles were 36%(9/25).This showed that provocation rates is relation with age. Provocation rates ,evoked myogenic potential by masseter, were 84%(21/25) .This showed that evoked myogenic potential by masseter is not relation with age. In vestibular system and deaf disease, provocation rates for binaural tone burst stimulation that recording from surface electrodes over the SCM muscles and masseter were 48% (61/127) and 77% (98/127) respectively.3.3 Provocation of pl3-n23 is not relation with sensorineural hearing loss . Profound and serve-profound sensorineural deafness can provocate VEMP.In mixed deafness VEMP are no responses by tone burst stimulation.3.4 In auditory neuropathy VEMP provocation rates were 40%(9/23). VEMP latencies of p13 and n23 were notable prolong and amplitudes of p13 -n23 were notable low ,This showed that auditory neuropathy most accompany with vestibular neuropathy.3.5 The result of VEMP and ENG may not be consistent because they reflect different pathological changes of vestibular otoliths.3.6 VEMP applied with ENG may comprehend roundly the function of vestibular vesicle spot and semicircle canal and have important clinic signification to diagnose and distinguished diagnose of vestibular and pertinent disease.3.7 The pathway and signification for the evoked myogentic potential of...
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