Objective: To evaluate the utility of positional testing in peripheral and central acute vestibular syndrome (pAVS, cAVS, respectively).
Study design: Prospective; observational.
Setting: Tertiary referral center.
Patients: Consecutive AVS patients.
Interventions: Video-oculography in upright, supine and head hanging positions at presentation, 3-month and 1-year follow-up.
Main outcome measures: Positional modulation of spontaneous nystagmus; co-occurrence of central paroxysmal positional nystagmus (CPPN).
Results: Fifteen pAVS [mean age (SD), 53.3 (16.6) (11 males)] and 15 cAVS [mean age (SD), 56.5 (17.8) (11 males)] patients were included (p=0.49). Acutely, in supine, in patients whose nystagmus was present in both head rotation sides, 12 of 13 (93%) pAVS and only 4 of 12 (33%) cAVS patients showed direction-fixed positional nystagmus which was stronger when turning the head to the slow phase side. The remaining cAVS patients showed either direction-fixed positional nystagmus which was stronger when turning the head to the fast phase side (5), or direction-changing positional geotropic nystagmus (2). One patient in each group showed direction-changing positional apogeotropic nystagmus. During follow-up, direction-changing positional apogeotropic and geotropic nystagmus became common in both groups. Acutely, in head hanging, 5 (33%) cAVS patients showed vertical CPPN and 2 showed positional saccadic intrusions. Positional downbeat nystagmus and saccadic intrusions became chronic.
Conclusions: The presence of acute direction-changing positional geotropic nystagmus, stronger direction-fixed positional nystagmus when turning the head to the fast phase side, and acute or chronic head hanging vertical CPPN should raise the suspicion for central AVS. Chronic geotropic and apogeotropic nystagmus following AVS constitute an underrecognized manifestation of vestibular compensation.