| ObjectiveBenign paroxysmal positional vertigo(BPPV) is a transient vertigo when the head moves to some position, and it is a self-cured vestibular disease. Recently, video nystagmo graph(VNG) provides great convenience for the parameters’judgments. This article applied VNG to record and discuss the objective characteristics and mechanism of nystagmus direction, intensity and time in kinds of benign paroxysmal positional vertigo.MethodsTotal of715patients with BPPV, whereas Horizontal Semicircular Canalithasis (HSC-Can), horizontal semicircular canal cupulolithiasis(HSC-Cup) and Posterior Semicircular Canal Canalithasis(PSC-Can) were involved in208,68and439respectively. The induced nystagmus in Rolling test and Dix-Hallpike test recorded by VNG, which direction, intensity and time characteristics were compared in various BPPV.ResultsHorizontal nystagmus was both induced by turning left or right in HSC-Can Rolling test. Vertical nystagmus was both induced by hanging or sit in Dix-Hallpike test. The direction of induced nystagmus is the same with turning head in HSC-Can and PSC-Can. The latency, duration time and intensity turning to lesion side were (1.916±1.493)s and (1.452±0.811)s,(24.924±10.105)s and (22.003±10.824)s,(55.413±31.054)°/s and (26.128±13.889)°s in HSC-Can. The latency, duration time and intensity turning to lesion side were larger than normal side (t=3.697,15.051and3.897, P＜0.01), the difference is statistically significant, and the intensity rate is about2:1. The direction of the induced nystagmus is opposite to turning in HSC-Cup. The intensity turning to normal side was larger than lesion side obviously. The intensity rate is about2:1, the difference is statistically significant (t=-8.012, P<0.01). While the latency of turning to normal side and lesion side was not statistically significant. The latency and intensity of turning to lesion side in HSC-Can were larger than turn to normal side in HSC-Cup, and the difference without statistically significant(P>0.05). The latency, duration time and intensity turning to lesion side were (2.670±1.810;366±1.204),(15.040±8.777;14.090±8.111) and (27.438±19.269;14.126±9.437)°s in PSC-Can. The latency and intensity in hanging were larger than sit, and the intensity rate is about2:1.(t=14.477, P<0.01), while the difference between duration time is not statistically significant (t=0.916, P>0.05).The induced nystagmus of turning to lesion side in Rolling test or hanging in Dix-Hallpike test includes two styles in Canalithasis:reversal phase nystagmus and no reversal phase nystagmus.379(58.6%) cases of canalthasis displayed reverse phase nystagmus. The intensity of first phase nystagmus is bigger than reversal phase nystagmus, and the difference between duration time is statistically significant(P<0.01). The latency and duration time is shorter than reversal phase nystagmus, and the difference between duration time is not statistically significant (P>0.05). Comparing with the latency, duration time, intensity of first phase nystagmus and reverse phase nystagmus in posterior and horizontal semicircular canal canalithasis, the differences were all statistically significant(P<0.01). Comparing with the first phase nystagmus of reverse phase and no reverse phase nystagmus canalithasis, the difference of nystagmus parameters were statistically significant (P<0.01). The reversal phase nystagmus can’t be seen in the other head-position of PSC-Can and HSC-Can.Conclusions(a)The induced nystagmus intensity in Rolling test and Dix-Hallpike test of BPPV both follow Ewald’s law. BPPV is either a disease, or a physical model to study the single semicircular-nystagmus effect;(b)These nystagmus parameters of VNG in Rolling test and Dix-Hallpike test are an objective guideline for BPPV diagnose;(c)Reverse phase nystagmus is common in canalthasis. It is a clinical characteristic of canalithasis. The mechanism is similar to the vestibular mirror image nystagmus, and it is another form of the vestibular mirror image nystagmus in BPPV patients. |
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