Radiographic horizontal gaze deviation in the setting of acute PICA territory ischemia: A potential mimic of large vessel occlusion

PURPOSE: Horizontal gaze deviation (HGD) is a predictor of acute large vessel occlusion (LVO) and helps to expedite the triage of patients to CTA and endovascular-capable sites. Patients with acute cerebellar ischemia, particularly involving the PICA territory, can also exhibit HGD. MATERIALS AND METHODS: We reviewed 2260 CTA stroke assessment cases between January 2016 and May 2020. Forty-six patients with CTA-proven acute PICA occlusions were identified and compared with 114 patients with acute LVO (ICA, M1, and M1/2). Both clinical and radiographic HGD were examined. The degree of radiographic HGD was measured for each patient. Site of ischemia was confirmed on subsequent MRI. RESULTS: Of the 46 patients with acute PICA occlusions, 20 (43.5%) patients had radiographic (+) HGD with either ipsilateral or contralateral gaze deviation, 6 of whom (13.0%) displayed clinical HGD. Of the 114 patients with LVO (control group), 72 (63.2%) patients had radiographic (+) HGD, all ipsilateral, 49 of whom (68.0%) displayed clinical HGD. The mean degree of HGD between PICA and LVO were 30.0° vs. 22.9°, respectively, p < 0.001; AUC = 0.68. CONCLUSION: Patients with acute PICA occlusion can exhibit either ipsilateral or contralateral HGD and a higher degree of HGD than LVO occlusion on NECT. In hyperacute stroke, the presence of radiographic HGD > 30° in the absence of ischemic changes in the MCA territory should prompt clinicians to closely evaluate for features of early ischemic changes in the cerebellar hemispheres that suggest acute PICA occlusion.