April 2017 Imaging Case of the Month

Michael B. Gotway, MD and John K. Sweeney, MD

Department of Radiology

Mayo Clinic Arizona

Scottsdale, Arizona USA

Clinical History: An 86-year-old man with a previous history of transcatheter aortic valve implantation 1 year earlier, coronary artery disease status-post coronary artery bypass grafting surgery 12 years earlier, atrial fibrillation on warfarin, and pacemaker placement 8 years earlier presented with altered mental status.

The patient’s white blood cell count was borderline elevated at 10.3 x 10³/mcl (normal, 4.8 – 10.8 x 10³/mcl)  and hyponatremia was noted (serum sodium = 129 mEq/L, normal =  136 – 145 mEq/L). The patient’s anticoagulation profile was within the therapeutic range (INR = 1.4), and the platelet count was normal. Oxygen saturation on room air was normal. The patient’s medication list included warfarin, digoxin, aspirin, metoprolol, montelukast, and atorvastatin.

Frontal chest radiography (Figure 1) was performed.

Figure 1. Frontal (A) and lateral (B) chest radiography.

Which of the following statements regarding the chest radiograph is most accurate? (Click on the correct answer to proceed to the second of eight pages)

1. Frontal chest radiography shows a cavitary lung mass
2. Frontal chest radiography shows focal consolidation suggesting aspiration pneumonia
3. Frontal chest radiography shows increased pressure edema
4. Frontal chest radiography shows malposition of the patient’s left subclavian pacemaker
5. Frontal chest radiography shows rib fractures

Cite as: Gotway MB, Sweeney JK. April 2017 imaging case of the month. Southwest J Pulm Crit Care. 2017;14(4):141-52. doi: https://doi.org/10.13175/swjpcc042-17 PDF

Medical Image of the Week: Artery of Percheron Infarction

 

Figure 1. T2 weighted MRI demonstrating bilateral infarcts of the rostral midbrain (A, orange box) and thalami (B, orange box).

 

Figure 2. CT angiogram of posterior cerebral artery circulation demonstrating normal vascularization (A) and artery of Percheron (B, white arrow) (1).

A 55-year-old African-American man presented to the Emergency Department for acute altered mental status which started 4 hours ago. His medical history was significant for heart failure with reduced ejection fraction, diabetes mellitus, marijuana and opioid use. On admission, the patient appeared to be in a deep sleep, unarousable, with grimacing to noxious stimuli. He occasionally moved all extremities. He was intubated for airway protection. Initial CT head non-contrast demonstrated a previous right MCA infarct, with no new acute hemorrhage. MRI/MRA brain revealed complete infarction of the artery of Percheron (AOP), likely due to a left ventricular thrombus (Figure 1). The patient remained somnolent throughout hospitalization with minimal neurologic improvement, and was ultimately transferred to a long-term care facility after a tracheostomy and PEG placement.

The artery of Percheron is a rare, normal intracranial vascular variant in which a single arterial trunk originates from the posterior cerebral artery, giving rise to the vascular supply of both thalami and upper midbrain (Figure 2) (2). Acute occlusion of the artery results in posterior circulation infarction and is associated with impairment of consciousness, sleep and alertness. Diagnosis is usually based on magnetic resonance imaging demonstrating bilateral thalami and midbrain infarct. Management primarily consists of supportive measures, as reperfusion of cerebral microvascular carries significant surgical risk. Given the rarity of incidence, the prognosis of AOP infarct is unknown (3).

TC Ta¹, ET Vo¹, KS Goldlist², B Barcelo¹, JM Dicken³

¹Department of Internal Medicine

²Department of Internal Medicine at University of Arizona at South Campus

³University of Arizona College of Medicine.

University of Arizona

Tucson, AZ USA

References

1. Shetty A, Jones J. Artery of Percheron. Radiopedia. Available at: https://radiopaedia.org/articles/artery-of-percheron (accessed 3/24/17).
2. Lazzaro NA, Wright B, Castillo M, et al. Artery of Percheron infarction: imaging patterns and clinical spectrum. AJNR Am J Neuroradiol. 2010 Aug;31(7):1283-9. [CrossRef] [PubMed]
3. Amin OS, Shwani SS, Zangana HM, Hussein EM, Ameen NA. Bilateral infarction of paramedian thalami: a report of two cases of artery of Percheron occlusion and review of the literature. BMJ Case Rep. 2011 Mar 3;2011. [CrossRef] [PubMed] 

Cite as: Ta TT, Vo ET, Goldlist KS, Barcelo B, Dicken JM. Medical image of the week: artery of Percheron infarction. Southwest J Pulm Crit Care. 2017;14(3):127-8. doi: https://doi.org/10.13175/swjpcc037-17 PDF