The Role Of Frequency Complementarity Of Vestibular Tests In The Evaluation Of Vestibular Function

ObjectiveJust as the auditory system and its damage,both the vestibular system and its damage also have frequency characteristic.Caloric test,head-shaking test and vibration test present clinical tests which detect very low frequency(≤0.025Hz),high frequency(2Hz) and very high frequency(92Hz) areas of vestibular system respectively.The role of frequency complementarities of vestibular tests in the evaluation of vestibular function was analyzed by performing the above three tests in patients with unilateral vestibular peripheral vertigo.Then more accurate vestibular function can be evaluated of those patients and will be very useful for the vestibular treatment and rehabilitation.Methods195 patients(male 91,female 104) 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.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 63,vestibular neuritis in 44,Hunt syndrome in 35,unilateral otitis media with labyrinthitis in 19,M(?)ni(?)re's disease in 27,acoustic neuroma in 2 and delayed endolymphatic hydrops in 5.All patients underwent routine vestibular items and CT, HST and VT by VNG(Synapsys,France).The unilateral weakness(UW),headshaking nystagmus(HSN) and vibration-induced nystagmus(VIN) were selected as the observation parameters in order to compare the frequency characteristic of abnormal vestibular function of those patients.Cross-check of three tests were evaluated through consistency test by SPSS11.5.195 patients were divided into four levels according to the value of UW,and the relationship between UW and VIN,UW and HSN were identified by using Cochran Armitage trend test respectively.Results1.Of the 195 patients,130(66.67%),138(70.77%)and 127(65.13%)cases showed VIN,HSN,abnormal UW respectively.14,18 and 14 cases had an isolated VIN, HSN and abnormal UW respectively.62(31.79%)cases had combination abnormality of two tests,75(38.46%)had abnormal results in all three tests,183(93.85%)showed abnormal results in any of the three tests,and 12(6.15%)had no abnormality in all those three tests.2.There were 138 patients showed HSN,including 94 decreased HSN(beat towards healthy side in 84 and towards affected side in 10),31 recovered HSN(beat towards lesion side in 29 and towards uninjured side in 2),13 bi-phases HSN.No perverted HSN had been observed.3.There were 130 patients showed VIN which were mainly horizontal(122 cases).VIN had both horizontal and vertical component in 8 cases.None of 130 patients showed absolute vertical VIN.In the majority of patients(123 cases),the direction of VIN was toward the healthy side,whereas 7 patients with MD showed VIN toward the affected side.VIN were evoked on mastoid in 115(104 on bilateral mastoid,7 on uninjured side mastoid,4 on lesion side mastoid) and on forehead or the vertex in 29,VIN were evoked on all four sites in 14.4.Through consistency test,CT and HST(Kappa₁=0.144,P=0.043＜0.05),CT and VT(Kappa₂=0.167,P=0.019＜0.05),VT and HST(Kappa₃=0.167,P=0.019＜0.05) showed low consistency among them and have statistics significance.5.Cochran Armitage trend test indicated VIN and HSN were more likely to be evoked with the increasing of the UW(χ_VIN²= 8.83,P＜0.05;χ_HSN²=8.91,P＜0.05).ConclusionsVestibular damage of the patients with unilateral vestibular peripheral vertigo could reflect at isolated very low,high,very high frequency or multi-frequency bands.Thus,the CT(≤0.025Hz),HST(2Hz) and VT(92 Hz) all make significant contributions to multiple-frequency analysis of vestibular function and showed a well complementarities.Besides telling the frequency band of the damage involved, the three tests also indicate a serious vestibular lesion if the damage affected several frequency bands.So they can be used in evaluating the overall function of the vestibular system and the status of vestibular rehabilitation according to course of disease.