Ja-Won Koo1, Ji-Soo Kim, Sung Kwang Hong. 1. Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Gyeonggi-do, South Korea.
Abstract
OBJECTIVE: To validate the role of vibration-induced nystagmus (VIN) detecting vestibular asymmetry by comparing several vestibulo-ocular reflex (VOR) parameters in the yaw plane. STUDY DESIGN: Prospective validation study for diagnostic test. SETTING: Tertiary referral center. PATIENTS: Seventy-four patients with unilateral vestibular loss of acute onset without a history of fluctuating vestibular function and 24 healthy volunteers. INTERVENTION: Spontaneous nystagmus, head-shaking nystagmus (HSN), and VIN using a 100 Hz handheld vibrator were recorded using a videonystagmography system. Canal paresis on the caloric test and the time constant (TC) on the step velocity test were examined as parameters of the laboratory test. MAIN OUTCOME MEASURES: Correlation analysis between horizontal VOR parameters was performed. Receiver operating characteristic (ROC) curves of these parameters were plotted, and the area under the ROC curve (AUC) was compared according to the lower limiting value of TC on step velocity test as well as the presence of unilateral vestibular loss. RESULTS: VIN was observed in 64 (86%) of 74 patients, and it was directed toward the contralesional side in 98%. VIN showed a significant positive correlation with the canal paresis (r=0.416, p<0.001) and a negative correlation with the TC (r=-0.351, p<0.005). ROC curves of several VOR parameters were compared according to the presence of unilateral vestibular loss. The AUC of VIN was 0.882, and the cutoff intensity of VIN was 2.5 degrees per second. The AUCs of the HSN and spontaneous nystagmus were 0.774 and 0.661, respectively. CONCLUSION: The lateralization value of VIN was comparable with caloric test and superior to HSN. VIN is a useful vestibular test detecting vestibular asymmetry in the evaluation of dizziness.
OBJECTIVE: To validate the role of vibration-induced nystagmus (VIN) detecting vestibular asymmetry by comparing several vestibulo-ocular reflex (VOR) parameters in the yaw plane. STUDY DESIGN: Prospective validation study for diagnostic test. SETTING: Tertiary referral center. PATIENTS: Seventy-four patients with unilateral vestibular loss of acute onset without a history of fluctuating vestibular function and 24 healthy volunteers. INTERVENTION: Spontaneous nystagmus, head-shaking nystagmus (HSN), and VIN using a 100 Hz handheld vibrator were recorded using a videonystagmography system. Canal paresis on the caloric test and the time constant (TC) on the step velocity test were examined as parameters of the laboratory test. MAIN OUTCOME MEASURES: Correlation analysis between horizontal VOR parameters was performed. Receiver operating characteristic (ROC) curves of these parameters were plotted, and the area under the ROC curve (AUC) was compared according to the lower limiting value of TC on step velocity test as well as the presence of unilateral vestibular loss. RESULTS: VIN was observed in 64 (86%) of 74 patients, and it was directed toward the contralesional side in 98%. VIN showed a significant positive correlation with the canal paresis (r=0.416, p<0.001) and a negative correlation with the TC (r=-0.351, p<0.005). ROC curves of several VOR parameters were compared according to the presence of unilateral vestibular loss. The AUC of VIN was 0.882, and the cutoff intensity of VIN was 2.5 degrees per second. The AUCs of the HSN and spontaneous nystagmus were 0.774 and 0.661, respectively. CONCLUSION: The lateralization value of VIN was comparable with caloric test and superior to HSN. VIN is a useful vestibular test detecting vestibular asymmetry in the evaluation of dizziness.