A CT angiography scan of a 64-year-old female shows a blockage in one of her anterior cerebral arteries. A blockage this artery would likely cause which of these symptoms?

Question

A CT angiography scan of a  64-year-old female shows a blockage in one of her anterior cerebral arteries. A blockage this artery would likely cause which of these symptoms?

BlackTom AI · Accepted Answer

The anterior cerebral artery (ACA) supplies the medial surfaces of the frontal and parietal lobes, including the paracentral lobule, which contains the primary motor and sensory cortical representations for the contralateral lower limb and foot. A blockage of the ACA therefore most commonly produces contralateral weakness (loss of motor control) and sensory loss that is greatest in the leg and foot.

1) Relevant knowledge points and concepts
- Vascular territories: ACA supplies medial frontal/parietal lobes; middle cerebral artery (MCA) supplies lateral convexity; posterior cerebral artery (PCA) supplies occipital lobes.
- Somatotopic organization: The motor and sensory homunculus places lower limb/foot representation on the medial surface (paracentral lobule), while face and upper limb are lateral.
- Lesion laterality: Cortical lesions produce contralateral deficits because corticospinal and sensory pathways cross to the opposite side.

2) Step-by-step reasoning
- Identify the artery: ACA occlusion.
- Determine region affected: medial frontal and parietal cortex, specifically paracentral lobule.
- Map region to function: paracentral lobule contains lower limb/foot motor and sensory areas.
- Predict deficit: contralateral weakness and sensory loss predominantly in the leg and foot.

3) Intermediate steps (anatomical mapping)
- ACA → medial frontal/parietal cortex → paracentral lobule.
- Paracentral lobule → motor & sensory representation of contralateral lower limb/foot.
- Result → loss of mobility (motor) and sensation in the contralateral foot.

4) Why the correct answer is correct
Because the ACA territory includes cortical regions devoted to the contralateral lower extremity, an ACA blockage classically causes motor and sensory deficits in the opposite leg/foot. The offered choice precisely names loss of mobility and sensation in the contralateral foot, matching this vascular-anatomical relationship.

5) Why other options are incorrect
- Inability to hear: primary auditory cortex lies in superior temporal gyrus (lateral surface) supplied by MCA branches, not ACA.
- Loss of vision: primary visual cortex is in the occipital lobe supplied by PCA, not ACA.
- Difficulty producing speech (Broca’s aphasia): Broca’s area is on the lateral frontal lobe (usually left) typically served by MCA superior division.
- Inability to move the face contralaterally: face motor cortex is lateral (MCA territory), so ACA lesions spare the face.

6) Conclusion
The pattern of deficits from an ACA blockage is best described by loss of mobility and sensation in the contralateral foot, which matches the provided correct answer.

A CT angiography scan of a 64-year-old female shows a blockage in one of her anterior cerebral arteries. A blockage this artery would likely cause which of these symptoms?单项选择题

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