Which type of TIA would most likely cause bilateral vision loss?

Bilateral vision loss in the context of a transient ischemic attack (TIA) is often associated with vertebrobasilar TIAs. The vertebrobasilar system supplies blood to the brainstem and the posterior circulation of the brain, which includes critical areas responsible for visual processing. When blood flow to these regions is compromised, it can lead to visual disturbances, including bilateral vision loss.

The brainstem houses important pathways involved in eye movement and sensory integration, including connections to the lateral geniculate nucleus and other visual centers. Therefore, an interruption in blood flow from a vertebrobasilar TIA can lead to symptoms that may affect both eyes simultaneously.

In contrast, carotid artery TIAs primarily affect the anterior circulation, which is less likely to cause bilateral vision loss since they mainly impact the visual pathways associated with one hemisphere. Cardiac TIAs relate to emboli that may affect various brain regions, but they don't specifically target the posterior circulation. Transient vehicular TIAs is not a recognized medical term and would not provide a relevant clinical context for this scenario.

Thus, the nature of the vascular supply involved is key to understanding why vertebrobasilar TIAs are more likely to produce bilateral visual symptoms.