The Significance of Head-Shaking Nystagmus in the Vestibular Evaluation of the Chronic Dizzy Patient

ABSTRACT

OBJECTIVES: Nystagmus after rapid head-shaking (head-shake nystagmus) is transient horizontal nystagmus which is observed after passive horizontal headshake by yaw axis. It has been used for the evaluation of the remnant vestibular function. This study compared one patient group complaining of chronic vertigo with another normal group with no symptom. We tried to confirm the efficacy as a tool for the evaluation of the vestibular function in the old who had less knowledge of diasease itself, by searching the occurrence rate of head-shake nystagmus by age. MATERIALS AND METHODS: Of dizzy patients under Vertigo Index III, 19 patients with normal ENG and 20 patients showing only the decrease of the gain on the rotatory test were selected, and head-shake nystagmus was evaluated. Normal control (n=12) were all the heathy patients without any history of the otologic illness after consideration of their age. Eye movement was recorded with ENG testing and Frenzel glasses for 1minute in the dark room after vigorous head shaking at a frequency of 2Hz. Presence or absence of the head-shake nystagmus was judged by two otolaryngologist. RESULTS: Only 41% (16/39) of the dizzy patients showed headshake nystagmus. On the other hand, 8% (1/12) of normal control group revealed headshake nystagmus(p < 0.03). 50% (10/20) of the patient group showing the decrease of the gain, and 31% (6/19) of the another group with normal vestibular function revealed headshake nystagmus. When the detection rate of the nystagmus is compared according to the testing methods, it is 33% (17/51) by ENG testing, 12% (6/51) by Franzel glass test. Incidence rate of the headshake nystagmus by age is 25% (5/20) in the dizzy patient group under 50 years old, 58% (11/19) in the group over 50 years old(p < 0.03). CONCLUSION: Head-shake nystagmus showed some difference according to the vestibular compensatory periods, but Its sensitivity was 41% and it is thought to be used convenient just in the old. However, attention should be paid to observe the nystagmus in case of using the Frenzel glasses.