Observation Of Nystagmus Parameters Of Roll Test In Patients With Horizontal Semicircular Canal Benign Paroxysmal Positional Vertigo

Objective: With the help of video nystagmus,the nystagmus parameters of patients with horizontal semicircular canal benign paroxysmal positional vertigo(HSC-BPPV)induced by rolling test were recorded,the characteristics of nystagmus parameters induced by HSCBPPV were summarized,so as to provide objective references for the diagnosis and treatment of responsible semicircular canal.Methods: A total of 125 outpatients with HSC-BPPV in our hospital were collected,and their clinical parameters were recorded.The parameters of nystagmus including direction,latency,duration and nystagmus intensity.induced by the rolling test to the left and right were recorded under the observation of video nystagmus in all patients.Meanwhile,the occurrence of reverse phase nystagmus and the above characteristics of reverse phase nystagmus were recorded.Finally,the characteristics of nystagmus were summarized.Results: Of the 125 patients with HSC-BPPV,93 cases were HSC-BPPV with Canalithasis and 32 cases were HSC-BPPV with Cupulolithiasis.The nystagmus of HSC-BPPV patients with Canalithasis were all geotropic nystagmus and lasted less than 1 minute.The parameters of nystagmus in head rotation to the affected side were significantly higher than those to the healthy side,and the difference was statistically significant(P < 0.01),and the nystagmus intensity ratio was about 2:1.The nystagmus of HSC-BPPV patients with Cupulolithiasis was all the apogeotropic nystagmus and lasted more than 1 minute,of which 10 patients lasted more than 3 minutes,the nystagmus intensity of head rotation to the affected side was less than that to the healthy side,the ratio was about 1:2,and the difference was statistically significant(P < 0.01),and the latency of head rotation to the affected side was larger(P <0.05).No reverse phase nystagmus was found in 32 cases of HSC-BPPV with Cupulolithiasis.Among 93 cases of HSC-BPPV with Canalithasis,62 cases showed reverse phase nystagmus,accounting for 66.6% of HSC-BPPV with Canalithasis,accounting for49.6% of all HSC-BPPV.Among them,20 cases had reverse phase nystagmus on both the affected side and the healthy side,and 42 cases had reverse phase nystagmus only on the affected side.The nystagmus intensity of all patients with reverse phase nystagmus was significantly higher than that of patients without reverse phase nystagmus,and the difference was statistically significant(P < 0.01).Reverse phase nystagmus always occurred on the side of strong nystagmus,that is the affected side.And the duration of reverse phase nystagmus in most patients was more than 1 minute,which was significantly longer than that of the first phase nystagmus(P < 0.01).In addition,Light cupula nystagmus was also one of the types of nystagmus induced by rolling test,the nystagmus characteristic is between Canalithasis and Cupulolithiasis,the direction of it was all geotropic,lasting more than 1 minute,and the nystagmus intensity without fatigue.Conclusions:(1)The nystagmus direction can identify the attributes of BPPV in the rolling test,and the nystagmus parameters could be used as the objective index for identifying the affected side of HSC-BPPV.The characteristics of nystagmus conform to Ewald’s law and could be used to study the physiological effects of horizontal semicircular canal.(2)In HSCBPPV,the incidence of reverse nystagmus is very high,which is mainly related to the intensity of nystagmus.Attention should be paid to distinguish reverse nystagmus and avoid wrong location of the affected side of semicircular canal in the rolling test.(3)Light cupula nystagmus should be distinguished from Canalithasis and Cupulolithiasis.