Can hyperventilation test and duration of spontaneous nystagmus help differentiate between vascular and inflammatory aetiology of acute unilateral vestibular deficit?

OBJECTIVE: To relate clinically the duration of spontaneous nystagmus and hyperventilation-induced nystagmus (HVIN) to vascular or inflammatory aetiology of acute unilateral vestibulopathy observed in a very early stage. METHODS: This is a retrospective study on 198 patients with acute unilateral vestibulopathy. RESULTS: In the short-lasting nystagmus group (spontaneous nystagmus < 48 h), mean age and cardiovascular risk were significantly higher; the rates of negative HVIN and paretic HVIN were 41.7% and 58.3%, respectively. In the long-lasting nystagmus group (spontaneous nystagmus > 48 h), mean age and vascular risk were lower; HVIN was absent in 12.6% of the cases, HVIN excitatory patterns were observed in 40.3% of cases and a paretic pattern in 47.1%. CONCLUSIONS: A vascular aetiology should be considered the most likely in patients with spontaneous nystagmus < 48 hours: all patients were > 60 years old, cardiovascular risk was higher and HVIN was always absent or paretic. In the group with nystagmus > 48 hours, similarly, data indicate a higher incidence of paretic HVIN in older patients and higher vascular risk, even if the data does not allow us to lean clearly towards one of the two aetiological hypotheses.