The Clinical Significance of Head-shaking Nystagmus in the Patients with Acute Vestibular loss

초록

Background and Objectives : In unilateral peripheral vestibular loss patients, head-shaking induce a bias from remaining aymmetric vestibular sensor and cause the imbalance in velocity-storage mechanisms. Head-shaking Nystagmus(HSN) is the transient nystagmus induced by shaking the head in the horizontal plane for a few seconds and have slow phases directed toward the side of vestibular loss. We evaluated the usefulness of the HSN in acute unilateral peripheral vestibular loss patient with reference to spontaneous nystagmus(SN), bithermal caloric test, and slow harmonic acceleration(SHA) test. Materials and Methods : 18 patients of acute unilateral peripheral vestibular loss(nine vestibular neuronitis, four acute unilateral ototoxicity, two sudden sensorineural hearing loss, one acute suppurative labyrinthitis, one vestibular neurectomy, one Ramsay-Hunt syndrome) who had SN and symptoms of acute prolonged vertigo were analyzed retrospectively. The examiner performed passive head rotation in 30 degree anteflexed position with eyes closed and oscillated about 60 degree to each side, 2 Hz for 20 cycles. The nystagmus was observed with Frenzel glasses immediately after head was stopped and more than three consecutive beats of nystagmus were considered a positive. SN were recorded with video-nystagmography. We defined a positive if CP>25%, DP>30% in bithermal caloric test. Low gain and asymmetry in SHA test were defined abnormal if abnormalities were recorded in more than two consecutive frequencies. Results : The prevalance of HSN was 89%(16/18). During follow-up period, direction of nystagmus was changed 28%(13/18) in SN, but in HSN, direction was fixed in all subjects. SN and HSN directed toward the same side in 75%(12/16) but in four cases(25%), direction could not compared because the direction of SN was changed during follow up peroid. In 69%(11/16) of subjects, HSN persisted after the disappearance of SN. In comparison of HSN with bithermal caloric test, directi