Abstract
Objectives The acute nystagmus characteristics of posterior circulation stroke (PCS) were assessed and compared to acute vestibular neuritis (AVN) in the emergency department (ED)
Methods Video-nystagmography (VNG) was prospectively conducted in ED at one Australian metropolitan tertiary referral hospital over a three-year period, recording ictal nystagmus in 101 patients with radiologically confirmed PCS and 104 patients with AVN.
Results PCS locations were in the brainstem alone (34.7%), cerebellum alone (29.7%), both cerebellum and brainstem (19.8%) or other/multiple locations (15.8%) were recruited. Common PCS territories included: posterior-inferior-cerebellar-artery (38.6%), multiple-territories (20.8%), pontine-perforators (18.8%), anterior-inferior-cerebellar-artery (6.9%) and posterior-cerebral-artery (5.9%).
In PCS, 50.5% of patients had no spontaneous nystagmus. Remaining PCS patients had primary position horizontal (37.2%), vertical (8.9%) and torsional (3.9%) nystagmus. Horizontal nystagmus was 51.7% ipsiversive and 48.3% contraversive in 29 lateralised PCS. 28.4% of PCS patients had pathologic gaze-evoked nystagmus. Most PCS patients with horizontal nystagmus (60.5%) had unidirectional ‘peripheral-appearing’ nystagmus
In contrast, AVN patients almost universally (98.1%) had primary position horizontal nystagmus. No AVN patient had gaze-evoked nystagmus. Horizontal nystagmus with SPV≥5.4○/s distinguished AVN from PCS with sensitivity and specificity of 90.3% and 89.1%.
Absent nystagmus, gaze-evoked direction-changing nystagmus, and vertical/torsional nystagmus were all highly specific for PCS (100%, 100% and 98.1%).
Conclusion Most patients with PCS had concerningly benign features such as absent nystagmus or unidirectional ‘peripheral-appearing’ horizontal nystagmus acutely. Comparatively, all AVN patients had nystagmus acutely. This study reinforces a new paradigm in vestibular neurology that absence of findings does not equate to absence of pathology.
