Study Of The Diagnostic Value Of Eye Movement Assessments In Acute Vestibular Syndrome

BackgroundThe acute vestibular syndrome(AVS)is defined as the sudden onset of acute,continuous vertigo(lasting longer than 24 hours),associated with nausea,vomiting and head motion intolerance.AVS accounts for 10-25% of vertigo cases in emergency departments,with 75% caused by unilateral peripheral vestibular lesions and 25±15% by strokes.However,distinguishing between benign vestibular lesions and potentially dangerous strokes is challenging,particularly since 20% of patients with posterior circulation strokes do not exhibit obvious neurological symptoms.In recent years,the development of neuroimaging has improved the detection rate of stroke in AVS,but there are still limitations,such as a low detection rate of posterior circulation stroke by computed tomography(CT)and false negatives in early(magnetic resonance imaging,MRI).Bedside eye movement examination by neuro-ophthalmologists is more effective than early MRI,however its use in non-neuro-ophthalmologists is of limited value.The advent of video head impulse tests(v HIT)and videonystagmography(VNG)has made it possible to record and quantify eye movements,thereby reducing the reliance on operator.Current research on the diagnostic value of eye movement assessment based on video equipment in AVS primarily focuses on single eye movement tests such as the Caloric Testing and video head impulse test to evaluate vestibulo-ocular reflex(VOR)or eye movement pathway.The diagnostic value of different combinations of eye movement tests and ocular tilt reaction(OTR)for AVS remains uncertain.ObjectiveAssessing the diagnostic value of VOR function,eye movement evaluation,OTR,and different combinations of eye movement tests in AVS.MethodsPatients from outpatient and neurology department of our hospital from May2020 to August 2021 were included.(1)This study prospectively included 217 patients with AVS who underwent v HIT,VNG tests(including spontaneous nystagmus,head shaking nystagmus,gaze-induced nystagmus,saccade,and smooth pursuit),caloric test,and MRI examination within 10 days of symptom onset.Clinical data,such as age,gender,vascular risk factors,previous history of vertigo,and accompanying symptoms/signs,were also collected.Stroke confirmed by MRI was considered the gold standard for stroke.Univariate analysis was performed to compare the differences in different eye movement indices between the stroke and nonstroke groups,and logistic regression was used for risk factor analysis.Receiver operating characteristic curve analysis was performed to compare the diagnostic efficacy of single eye movement tests and different combinations of eye movement tests in identifying stroke in AVS.(2)This study enrolled 40 patients with acute central vascular vertigo(ACVV),including 20 with unilateral brainstem infarction(BI)and 20 with unilateral cerebellum infarction(CI).Twenty patients with unilateral peripheral vestibular disorders(UPVD)were used as the control group,and OTR tetralogy evaluation was completed within one week of symptom onset.The diagnostic value of OTR tetralogy in acute central vascular source vertigo was analyzed.Results(1)VOR pathway evaluation:(1)The v HIT gain value of the stroke group(0.99±0.21)was significantly higher than that of the non-stroke group(0.86±0.28),and the gain asymmetry(0.06±0.04)was significantly lower than that of the non-stroke group(0.15±0.14)(P<0.05).A total of 33 people in the stroke group had compensatory saccades,of which peak velocity <100°/s accounted for 31.4%,peak velocity 100-200°/s accounted for 51.4%,and peak velocity >200°/s accounted for 17.2%;in the non-stroke group,97 people exhibited compensatory saccades,among which the peak velocity <100°/s accounted for 12.4%,the peak velocity of 100-200°/s accounted for 16.5%,and the peak velocity >200°/s accounted for 71.1%.In the stroke group,covert saccades accounted for 3.3%,overt saccades accounted for 60.3%,and mixed saccades accounted for 36.4%.In the non-stroke group,covert saccades accounted for 3.1%,overt saccades accounted for 28.9%,and mixed saccades accounted for 68.0%.(2)Among patients with head shaking nystagmus,the incidence of head shaking nystagmus in the stroke group(52.9%)was significantly higher than that in the non-stroke group(25.3%)(P<0.05).(3)The canal paresis(CP)value in the stroke group(18±22%)was significantly lower than that in the non-stroke group(49±29%)(P<0.05).When the CP value was≤32%,the area under the curve(AUC)for predicting stroke was 0.825(95 %CI:0.761~0.877).(2)Eye movement pathway evaluation: the positive rates of gaze evoked nystagmus,central gaze evoked nystagmus,abnormal saccade,and abnormal smooth pursuit in the stroke group were 32.8%,60%,50.8%,and 63.9%,respectively,which were significantly higher than those in the non-stroke group12.7%,10.5%,12.2%,14.7%(P<0.001).(3)Combined eye movement tests evaluation: Binary logistic regression analysis showed that the peak velocity of compensatory saccades 100-200°/s(OR=9.614,95%CI=2.255-40.987),and abnormal saccades(OR=4.709,95%CI=1.579~14.048),abnormal smooth pursuit(OR=12.758,95%CI=4.305~37.809),CP value(OR=0.009,95%CI=0.001~0.109)was an independent factor affecting stroke(P<0.05).VNG +v HIT+caloric test(AUC=0.927,95%CI=0.879~0.0.961),VNG+ caloric test(AUC=0.923,95%CI=0.874~0.958),VNG test+ v HIT(AUC=0.885,95 %CI=0.835-0.924),v HIT+caloric test(AUC=0.847,95%CI=0.786-0.896)were higher than any single eye movement test in predicting stroke(P<0.05).However,among the four combined eye movement examinations,there was no significant difference in the differential diagnosis efficacy of VNG test+v HIT+ caloric test,VNG test+ caloric test,VNG test+v HIT in distinguishing peripheral/central AVS(P>0.05),but better than v HIT+ caloric test(P<0.05).(4)OTR evaluation: Skew deviation(SD)of BI group(6.60±2.70°)in ACVV was significantly greater than that of UPVD group(1.80±1.30°)(P<0.05).In ACVV without cerebellar damage,the AUC of using SD to predict the occurrence of brainstem damage was 0.92(95%CI: 0.73-1.00),and when SD≥3°,the sensitivity of diagnosing brainstem damage was 100%.The specificity was 80%,and there was no difference between SD(1.33±0.58°)and UPVD(1.80±1.30°)in CI group(P>0.05).Conclusions(1)VOR assessments such as v HIT,caloric test and head shaking nystagmus;eye movement assessments including gaze-evoked nystagmus,saccade,smooth pursuit and OTR are crucial in detecting stroke in AVS(2)Compensatory saccade peak velocity of 100-200°/s,abnormal saccades,and abnormal smooth pursuit are independent risk factors for stroke in AVS patients.Additionally,the CP value is an independent protective factor for stroke in AVS patients.(3)Combined eye movement tests are more effective in differential diagnosis of AVS than single eye movement tests.Among them,VNG+v HIT+caloric test,VNG+ caloric test,and VNG+v HIT have no significant difference in diagnostic efficiency among the three combined tests,but all are better than v HIT+ caloric test.When facing patients with AVS,clinicians can choose different eye movement test combinations to aid in their diagnosis,depending on the individual circumstances.