What is the most likely effect of thrombosis of the anterior cerebral artery?

The anterior cerebral artery primarily supplies the medial portions of the frontal lobes and the superior medial parietal lobes. When thrombosis occurs in this artery, the areas of the brain it supplies can become ischemic, leading to specific deficits in function.

The most significant effect of this type of thrombosis is often contralateral lower extremity weakness. This occurs because the control of the lower extremities is primarily localized to the region of the motor cortex that is supplied by the anterior cerebral artery. In particular, the leg area of the motor homunculus resides in the medial aspect of the motor cortex, which is influenced directly by this artery. Therefore, impairment in this region due to arterial thrombosis results in weakness or paralysis of the leg muscles on the opposite side of the body (contralateral), manifesting as contralateral lower extremity weakness.

While other symptoms might arise depending on the extent of the damage, such as facial weakness or cognitive issues, these are typically less pronounced or associated with thrombosis in different areas of the brain.