The Analysis Of Smooth Pursuit Test In Unilateral Vestibular Peripheral Vertigo

ObjectiveThe visuo-oculomotor systerm is the foundation of serial vestibular function examination.Through the functional status of the visuo-oculomotor systerm and interaction together with vestibular systerm,we can not only understand the functional status of the vestibular systerm, but also distinguish abnormality of vestibular systerm belongs to perpheral part or central part. That is very important to assess vestibular function in clinic.At present there are two category tests to exam the foundation of visuo-oculomotor systerm,including tracking test and optokinetic test.The saccadic pursuit test and smooth pursuit test belongs to the former and the optokinetic nystagmography test belongs to the latter. In our study,we want to summary the oculomotor characteristic of nomal persons and parametric range of normal values at first,then we want to analyze smooth pursuit test(SPT) with the qualitation and quantilation for unilateral vestibular peripheral vertigo and investigate its influencing factors.The purpose of our study is to provide reliable references for our clinic in diagnosis of vertigo and abnormal ocular movements.Methods185 patients (male 98,female 87) who visited the balance center from July 2006 to September 2007 with unilateral vestibular peripheral vertigo and the latest attack of vertigo within one month were enrolled in this study as experimental group. All patients were accepted related otology, neurology or imageology examination to exclude patients with vestibular central vertigo. They were diagnosed with sudden deafness with vertigo in 167, vestibular neuritis in 4,Hunt's syndrome in 14.Meanwhile,51 normal persons (male 25,female 26) who accepted examinations at the same period were enrolled in this study as control group.They have no cases history of otology,vertigo,intracalvarium and nervous disease, the results of ophthalmology were also normal.185 patients with unilateral peripheral vertigo(experimental group) and 51 normal persons (control group) were performed with SPT,ST,OKN,and spontaneous nystagmus (SN) by Video-Nystagmography (Synapsys, France), to make sure of parametric range of normal values in visuo-oculomotor systerm.Also the gain of SPT and SN were selected as the observation parameters in order to analyze the qualitation and quantilation of SPT and the relativity between SN and the gain of SPT.Results1.In control group,the waveforms of horizonal saccadic movement present as calm baseline,rapid upstroke and decendent rectangle.There may appear little jumping, overshoot or insufficient waves to rectify,but in general these could not exceed 10% in the trating amplitude.The latency and velocity of sinistrad movements are (223±29)ms, (325±49.7)°/s, meamwhile the parameters of dextrad are (226±34)ms,(338±46.3)°/s; The waveforms of horizonal smooth pursuit movement present as symmetrical and derased sine, The latency, velocity,gain and dissymmetry ratio of sinistrad movements are(97±8.4)ms,(33±7.9)°/s,0.83±0.08,(4±3.4)%,also the parameters of dextrad are(99±6.9)ms,(32±9.3)°/s,0.82±0.07,(4±3.4)%; The waveforms of optokinetic nystagmography test present as spination.There are two parts of each nystagmus called slow phase and rapid phase,they reflect two processes named slow deflecttion and quick reposition of eye movements.These two processes were reflected in the eye to track the target and slow as the next target offset and watch the two fast reset process,the formation of such a repeated rhythm of optokinntic nystagmus.When the speed of light spot get to accelerate,the frequency of optokinetic nystagmography also chang to increase. There are no statistical significanct differences between man and women in parametric range of normal values(P<0.05).2.0f the 185 patients,105(56.8%),72(38.9%) and 8(4.3%)cases produceⅠ,Ⅱ,Ⅲwaveforms. Of these patients,58(31.4%) exist SN and none haveⅣwaveform. While of 51 normal persons,38(74.5%),13(25.5%)persons produceⅠ,Ⅱwaveforms and there were noⅢ, IVand SN. There is statistical difference between the stong and weak gain of SPT in these two groups. There are also statistical significanct differences in weak gain between two groups. The stong and weak gain of SPT in case group are 0.86±0.06,0.80±0.06; 0.78±0.09,0.65±0.1;0.68±0.13,0.45±0.12. The relativity between SN and the gain of SPT is positive when they have same direction (rs=-0.63, P<0.05)and negative when they have opposite direction(rs=0.43,P<0.05). ConclusionsIn our study,we can show that there are no statistical significant differences between man and women in parametric range of normal values.Ⅰ,Ⅱwaveforms of SPT could be appeared in normal persons,andⅢ,Ⅳtwo waveforms of SPT could not be appeared.The gain of SPT is approximately 0.8;Ⅰ,Ⅱ,Ⅲwaveforms of SPT could be appeared in unilateral vestibular peripheral vertigo and the corresponding gains are gradually descending. SN is the influencing factor of SPT.