Imaging Guidelines for Transient Homonymous Hemianopsia

Introduction to Imaging Recommendations

The American Heart Association recommends a head CT scan for all patients presenting with homonymous hemianopsia, even if symptoms have resolved spontaneously, to rule out ischemic or hemorrhagic stroke requiring urgent attention 1, 2.

The sudden onset of focal neurological symptoms, including homonymous hemianopsia, is presumed to be of vascular origin until proven otherwise, and brain imaging is therefore mandatory 1, 2.
It is impossible to clinically distinguish whether symptoms are due to ischemia or hemorrhage 1, 2.

A non-contrast head CT scan is the first-line examination due to its immediate availability, rapid execution, and high sensitivity for detecting acute hemorrhage 3, 4, 5.
CT is considered the gold standard for identifying acute intracranial hemorrhage 1, 2.
MRI with gradient-echo or susceptibility-weighted sequences is also sensitive for detecting acute blood, but time, cost, proximity to the emergency department, and availability of MRI may limit its use in emergencies 1, 6, 2.

Expansion of the hematoma occurs early after intracranial hemorrhage (typically within 24 hours) and is associated with poor functional outcomes and mortality 3, 7, 4.
In patients who undergo CT within 3 hours of symptom onset, 28-38% have hematoma expansion 1, 6, 2.

Urgent non-contrast head CT scan for all patients with homonymous hemianopsia, even if resolved 3, 4, 5.
Obtain a focused history including the exact time of symptom onset, history of stroke, hypertension, diabetes, smoking 2, 6.
Document use of anticoagulant, antiplatelet medications, and sympathomimetics like cocaine 6, 4.

If the initial CT is negative but clinical suspicion is high, brain MRI without and with contrast is recommended because it is more sensitive for detecting small infarcts and subtle lesions 8.
If there is an acute presentation with homonymous hemianopsia, brain MRI without and with contrast is the optimal examination for evaluating post-chiasmal lesions 8.
If hemorrhage is detected, consider CT angiography in the first hours to identify patients at risk of hematoma expansion 3, 7.

Do not rely solely on the spontaneous resolution of symptoms: even transient homonymous hemianopsia of 30 minutes can indicate an ischemic or hemorrhagic stroke requiring urgent intervention 1, 2.
Do not delay imaging: hematoma expansion and early deterioration are frequent in the first hours 1, 2.
Consider secondary causes: tumors, arteriovenous malformations, cerebral venous thrombosis can present with homonymous hemianopsia and require complementary vascular imaging (CT/MRI angiography) if clinically or radiologically suspected 1, 6, 2.