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Objective@#To introduce the method of galvanic vestibular stimulation-vestibular evoked myogenic potentials (GVS-VEMP) as well as to observe and analyze the parameters and elicited rate of GVS-cVEMP and GVS-oVEMP in healthy young people in China.@*Methods@#Twenty six normal young subjects were recruited for conventional examinations of GVS-VEMP. The subjects were 21-37 years old, average age was (25.8±3.7) years old, including 13 males and 13 females. The galvanic stimulation intensity of 3 mA/1 ms was used to evoke cVEMP and oVEMP on the sternocleidomastoid and inferior extraocular muscles respectively, and the intensity of stimulus was decreased until the response disappeared, the threshold, latency, amplitude, interval phase and interaural amplitude ratio(IAR) were calculated. SPSS18.0 software was used for statistical analysis.@*Results@#All subjects were elicited normal GVS-cVEMP and GVS-oVEMP under 3 mA/1 ms, the elicited rate was 100%. The threshold of GVS-cVEMP was (1.18±0.47) mA, p1 latency was (10.43±1.54) ms, n1 latency was (17.91±1.20) ms, the amplitude was (102.47±56.77) uV and IAR was (0.26±0.20). The threshold of GVS-oVEMP was (1.12±0.50) mA, n1 latency was (8.46±1.05) ms, p1 latency was (11.83±1.27) ms, the amplitude was (9.12±6.82) uV and IAR was (0.25±0.20). In terms of gender and lateral comparison, only the GVS-oVEMP amplitude was higher for male than for female, which had significant statistical difference (P<0.05), and there was no statistical difference in the other parameters between GVS-cVEMP and GVS-oVEMP.@*Conclusion@#GVS-cVEMP and GVS-oVEMP could be elicited in healthy youth population, and the parameters could provide reference for subsequent vestibular function evaluation.
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Objective@#To estabilsh animal methods of bone-conducted vibration elicited cervical vestibular-evoked myogenic potentials (BCV-cVEMP) and ocular vestibular-evoked myogenic potentials (BCV-oVEMP) in healthy guinea pigs.@*Methods@#Eleven healthy (250-350 g) and awake guinea pigs were selected and undertake conventional BCV-cVEMP and BCV-oVEMP examination in prone position. Parameters of waveforms were cauculated.@*Results@#The BCV-cVEMP and BCV-oVEMP both could be elicited in 100% (22/22) in guinea pigs respectively, threshold was (85.5±10.8)dB SPL and (90.7±10.6)dB SPL for cVEMP and oVEMP; n1 latency was (4.5±1.3)ms and (4.3±1.5)ms for cVEMP and oVEMP; p1 latency was (5.8±1.4)ms and (5.6±1.7)ms respectively; n1-p1 interwave latency was (1.2±0.4)ms for cVEMP and (1.4±0.6)ms for oVEMP, amplitude was (21.5±17.3)μV and (24.0±16.3)μV respectively.@*Conclusion@#Both BCV-cVEMP and BCV-oVEMP can be successfully elicited in healthy guinea pigs.
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Objective@#To observe the parameters of the results of suppression head impulse paradigm (SHIMP) in healthy adults, and to provide reference for evaluating vestibular oculomotor reflex function in patients with peripheral vertigo.@*Methods@#Fifty healthy adults, 22 males and 28 females, aged from 23-65 years, with an average age of (38.5±11.6) years, were recruited from January to March 2018. Parameters provided by the video head pulse software included the gains, the latency and the peak velocity of saccades, and comparison was made with head impulse paradigm (HIMP).@*Results@#All subjects were elicited anti-compensatory saccades in SHIMP. The normal values of left and right gains were 1.02 and 1.10 in HIMP, and 0.93 and 1.01 in SHIMP respectively. The left and right saccades latency were (201.1± 50.8)ms and (187.0± 42.9)ms, and the peak saccadic velocity were (302.7±58.5)°/s and (291.5±46.5)°/s in SHIMP; there were small but significant difference between two sides about gains in HIMP and SHIMP, as well as latency in SHIMP(P<0.05); there were small but significant difference between HIMP and SHIMP about gains in ipsilateral(P<0.01); there were no significant difference between two sides about peak saccadic velocity in SHIMP(P>0.05).@*Conclusions@#SHIMP can be used for the examination of vestibular oculomotor reflex function in adult population. It is easy to be operated and is convenient for clinical application. Combined with head pulse test, the function of the semicircular canal can be evaluated together.
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<p><b>OBJECTIVE</b>To investigate the clinical significances and formation mechanism by analyzing the characteristics of the reverse phase nystagmus parameters from benign paroxysmal positional vertigo (BPPV) positioning test.</p><p><b>METHODS</b>There were 183 cases with BPPV, including 108 cases (59.0%) of posterior semicircular canal canalithiasis, 55 cases (30.1%) of horizontal semicircular canal canalithiasis, and 15 cases (8.2%) of horizontal and posterior semicircular canal cupulolithiasis and 5 cases (2.7%) of anterior semicircular canalithiasis . The video-nystagmography was utilized in positioning tests to induce nystagmus. The direction, intensity, time parameters characteristic of vertical nystagmus in Dix-Hallpike test and horizontal nystagmus in roll test were analyzed and compared.</p><p><b>RESULTS</b>There were no reversal phase nystagmus in 15 cases of semicircular canal cupulolithiasis and 5 cases of anterior semicircular canalithiasis. After the disappearance of vertical nystagmus which induced by hanging position (the first phase nystagmus) in 108 cases of posterior semicircular canalithiasis of Dix-Hallpike test, there was 54 cases(50.0%) of posterior semicircular canal canalithiasis displayed downward vertical nystagmus (reverse phase nystagmus) . The latency, duration time and intensity of the first phase nystagmus and reverse phase nystagmus were [(2.00 ± 1.10) s, (3.54 ± 1.42) s], [ (16.27 ± 4.95) s, (61.65 ± 33.69)s] and [ (51.80 ± 25.25) °/s, (10.65 ± 6.29)°/s] respectively; 43 cases(78.2%) of horizontal semicircular canal canalithiasis displayed the opposite to turning head (reverse phase nystagmus) after the horizontal nystagmus, similar with turning head disappeared in Roll test. The latency, duration time and intensity of the first phase of nystagmus and reverse phase nystagmus were [ (1.67 ± 1.07) s, (3.57 ± 1.89)s], [ (25.19 ± 9.74) s, (70.48 ± 40.26)s] and [ (68.47 ± 30.18) °/s, (11.22 ± 8.78)°/s] respectively. Comparing with the latency, duration time, intensity of first phase nystagmus and reverse phase nystagmus of posterior and horizontal semicircular canal canalithiasis, the differences had statistical significances (P < 0.05). Comparing with the first phase nystagmus of reverse phase and no reverse phase nystagmus canalithiasis, the difference of nystagmus intensity had statistical significances (P < 0.05); but the differences of latency and duration of nystagmus had no significant difference (P > 0.05).</p><p><b>CONCLUSIONS</b>It is common in PSC-Can and HSC-Can patients that reverse phase nystagmus is one of the clinical features of canalithiasis. It appears in side head position of Rolling test or the hanging of Dix- Hallpike test. More power of the first phase nystagmus has, reverse phase nystagmus will be induced much easier. In comparison of the reverse phase nystagmus, the first phase nystagmus has the shorter incubation and duration, but it has more power. It is helpful to avoid interruptions of clinical statolith positioning and reset since we recognize the reverse phase nystagmus. The mechanism might be similar to the vestibular mirror image nystagmus. It is another form of the vestibular mirror image nystagmus in BPPV patients.</p>