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Hyperventilation-Induced Nystagmus in Vestibular Neuritis: Pattern and Clinical Implication

Background: It was the aim of this study to investigate the pattern of evolution of hyperventilation-induced nystagmus (HIN) in vestibular neuritis (VN) and to determine whether HIN influences the dizziness outcome at the last follow-up visit. Methods: Fifty-three consecutive patients with VN underwent a quantitative vestibular function test including hyperventilation and the Korean version of the Dizziness Handicap Inventory during the acute period and the follow-up visit. Results: The incidence of HIN was higher in the acute (62%, 33/53) than in the chronic (17%, 9/53) stages of VN. Approximately 70% (6/9) of patients who continued to have persistent HIN at the last follow-up reported dizziness compared to only 27% (12/44) of patients who had no HIN. Patients who complained of persistent dizziness were significantly more likely to have persistent HIN and high Korean Dizziness Handicap Inventory scores at the last follow-up compared with patients who did not suffer from dizziness. In terms of the degree of recovery of dizziness, patients with HIN initially beating toward the contralesional side exhibited significantly more improvement than patients with HIN initially beating toward the ipsilesional side. Conclusions: The presence of either HIN beating toward the ipsilesional side at the acute stage of VN or persistent HIN at the follow-up visit is associated with persistent dizziness.