Neuroscience · Year 2 · from Neuroscience
Case 3: Anterior Cerebral Artery Stroke
Patient Presentation
Demographics: 68-year-old male
Chief Complaint: Weakness in right leg noticed upon awakening
History of Present Illness: The patient went to bed feeling normal last night. When he woke this morning and tried to get out of bed, his right leg felt "heavy" and he fell. He notes the leg is significantly weaker than his arm, which feels "almost normal." His wife describes that he seems "less interested in things" and has not initiated conversation, which is unusual for him. Medical history includes hypertension, diabetes mellitus type 2, and a 40-pack-year smoking history.
Physical Examination:
- Vital signs: BP 156/94, HR 70, T 36.9C
- General: Awake, flat affect, answers questions with minimal elaboration
- Neurological:
- Mental status: Alert, oriented; flat affect with decreased spontaneous speech; follows commands appropriately; no aphasia
- Cranial nerves: Intact; no facial asymmetry; eyes midline
- Motor: Right arm 4+/5, right leg 2/5, left side 5/5 (leg weakness >> arm weakness)
- Sensory: Decreased sensation to pinprick on right leg more than arm
- Reflexes: Right leg hyperreflexic with upgoing Babinski; right arm reflexes normal
- Gait: Cannot walk independently due to leg weakness
Workup:
- Non-contrast CT head: No hemorrhage
- MRI brain with DWI: Restricted diffusion in the left medial frontal lobe extending along the interhemispheric fissure, including the paracentral lobule (motor and sensory cortex for leg)
- MR angiography: High-grade stenosis of left A2 segment of anterior cerebral artery
- CT angiography of neck: Mild atherosclerotic disease of bilateral carotid bulbs, not hemodynamically significant
- Echocardiogram: Normal; no cardioembolic source identified
- HbA1c: 8.2%
Diagnosis: Left anterior cerebral artery territory infarction from intrinsic ACA stenosis/thrombosis
Treatment:
- Dual antiplatelet therapy (aspirin + clopidogrel for 21 days, then aspirin alone)
- High-intensity statin
- Blood pressure optimization
- Diabetes management with goal HbA1c <7%
- Physical therapy for gait training and strengthening
Clinical Course: The patient's leg strength gradually improved to 3+/5 by discharge on day 5. His affect remained flat but improved over several weeks. At 3-month follow-up, he walked with a cane and had 4/5 right leg strength. His wife noted his personality had returned closer to baseline.
Clinical Pearl: ACA stroke presents with the opposite pattern from MCA stroke: leg weakness greater than arm and face, reflecting the somatotopic organization of the motor homunculus (leg representation on the medial surface supplied by ACA, face and arm on the lateral convexity supplied by MCA). Personality changes and abulia (lack of will/initiative) can occur with medial frontal involvement. The relative sparing of the arm helps distinguish ACA from MCA territory infarction.
Clinical Image
Image Description: Axial CT scan demonstrating loss of gray-white differentiation in the left MCA territory, representing acute ischemic changes. The insular ribbon sign (loss of insular cortex definition) and obscuration of the lentiform nucleus are early CT findings of MCA territory infarction that may be visible within the first few hours.
Attribution: Image from Radiopaedia (https://radiopaedia.org/), Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license.