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Updated: Nov 26, 2025
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Published on: July 21, 2023
Radiographic horizontal gaze deviation in the setting of acute PICA territory ischemia: A potential mimic of large
Nan N Jiang1, Demetrios J Sahlas2, Crystal Fong1
1Department of Diagnostic Radiology, Hamilton General Hospital, McMaster University, United States of America.
Insights
Horizontal gaze deviation (HGD) can indicate posterior circulation artery (PICA) occlusions, not just large vessel occlusions. A higher degree of HGD may suggest PICA occlusion in acute stroke evaluation.
Area of Science:
- Neurology
- Radiology
- Stroke Imaging
Background:
- Horizontal gaze deviation (HGD) is a recognized indicator of acute large vessel occlusion (LVO), aiding in rapid patient triage.
- Acute cerebellar ischemia, especially involving the posterior inferior cerebellar artery (PICA) territory, can also manifest as HGD.
Purpose of the Study:
- To investigate the characteristics of HGD in patients with acute PICA occlusions compared to those with acute LVO.
- To determine if HGD can differentiate between PICA territory ischemia and LVO.
Main Methods:
- Retrospective review of 2260 CT angiography (CTA) stroke assessments from January 2016 to May 2020.
- Identified 46 patients with CTA-proven acute PICA occlusions and compared them with 114 patients with acute LVO (ICA, M1, M1/2).
- Assessed both clinical and radiographic HGD, measuring the degree of radiographic HGD and confirming ischemia site with MRI.
Main Results:
- 43.5% of PICA occlusion patients had radiographic HGD (ipsilateral or contralateral), with 13.0% showing clinical HGD.
- 63.2% of LVO patients had radiographic HGD (ipsilateral only), with 68.0% showing clinical HGD.
- Mean HGD degree was significantly higher in PICA occlusions (30.0°) versus LVO (22.9°), p < 0.001; AUC = 0.68.
Conclusions:
- Acute PICA occlusions can present with ipsilateral or contralateral HGD, and a greater degree of HGD than LVO on non-contrast CT.
- Radiographic HGD > 30° without MCA territory ischemia should prompt evaluation for early cerebellar ischemic changes suggestive of acute PICA 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.
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