| ObjectiveBenign paroxysmal positional vertigo(BPPV)is the commonest vertigo in clinic,and is the most commonly clinically encountered as one of two variants: posterior canal BPPV or horizontal canal BPPV.It is defined as a spinning sensation produced by changes in head position relative to gravity,and treated as a self-cured vestibular disease.Usually,clinicians diagnose BPPV when vertigo associated with nystagmus is provoked by positional test.With the VNG recording the provoked nystagmus in Roll test and Dix-Hallpike test,this article discusses the mechanism of nystagmus and the application of positional test,providing objective and reference evidence in various benign paroxysmal positional vertigo.MethodsA total of 740 patients with benign positional vertigo(PV).735 patients(237male and 498 female)with canalithasis,whereas 510 PSC-Can,183 HSC-Can and 42HSC-Cup were involved respectively.Besides,5 LC patients were diagnosed at the same period.The medical history of each patient was thoroughly investigated,and all the patients performed neuro-otological examinations,otoscopic examination and imageological examinations have except central vestibular lesion,spontaneous nystagmus and other types of positional vertigo.The induced nystagmus in Roll test and Dix-Hallpike test recorded by video nystagmo graph(VNG),whose direction,intensity and time characteristics were compared in various BPPV.Using the SPSS19.0 statistical software for date analysis.ResultsVertically upward nystagmus was induced by hanging in PSC-Can Dix-Hallpike test,and the nystagmus reverse and turn weaker by sit.The intensity turning to lesion side by hanging and sit were(29.5±12.7)°/s and(13.1±7.2)°/s,the difference is statistically significant(t=18.615,P <0.05).The duration turning to lesion side by hanging and sit were(13.7±7.1)s and(13.5±6.9)s,while the difference between duration time is not statistically significant(t=0.089,P>0.05).However,no nystagmuswas induced in PSC-Can Roll test.Horizontal nystagmus in the same direction with turning were induced in HSC-Can Roll test.The intensity turning to lesion side and normal side were(41.5±15.8)°/s and(20.2±7.7)°/s,the duration turning to lesion side by hanging and sit were(22.1±6.1)s and(21.3±5.9)s,and the both difference are not statistically significant(t=10.637 and 3.724,P<0.05).Furthermore,169patients’ horizontal nystagmus were induced in HSC-Can Dix-Hallpike test.Horizontal nystagmus in the opposite direction with turning were induced in HSC-Cup Roll test.The intensity turning to lesion side and normal side were(18.0±8.1)°/s and(40.27±16.6)°/s,the difference is statistically significant(t=-15.803,P<0.05).And all the HSC-Cup patients’ horizontal nystagmus were induced in Dix-Hallpike test.Horizontal nystagmus in the same direction with turning were induced in LC patients’ Roll test.The duration is more than 1 minute.The intensity turning to strong side were(10.6 ~ 27.8)°/s,the intensity turning to weak side were(7.4~15.6)°/s.Conclusions(a)Dix-Hallpike test is the effectively diagnostic method of PSC-Can.The patients perform vertical nystagmus in hanging and sit in the test,which direction is anticlockwise or clockwise respectively.Dix-Hallpike test also can be used to diagnose HSC-Can who performs horizontal nystagmus in hanging and sit.Roll test only has significance in diagnosing HSC-Can.Therefore,we suggest using Dix-Hallpike test at first for patients with the complain of positional vertigo.According to the horizontal nystagmus to judge whether using Roll test or not.(b)LC patients performes geotropic direction-changing positional nystagmus in Roll test and Dix-Hallpike.The null plane where the induced nystagmus disapper has valuable significance. |
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