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 

Medical Image of the Week: Renal Infarction

Figure 1. Contrast enhanced CT of the abdomen showing the majority of the right kidney infarcted with some preservation of the superior pole. 

A 79-year-old woman with past medical history of persistent atrial fibrillation not on anticoagulation, coronary artery disease, hypertension, diabetes, and hyperlipidemia presented with right flank pain accompanied by nausea and vomiting for two days. Laboratory studies showed leukocytosis with creatinine of 1.2. Urinalysis was negative for signs of infection and red blood cells. However, despite being on analgesic, she continued to have flank pain. The patient subsequent underwent CT scan of the abdomen and pelvis the next day, which showed that the majority of the right kidney was infarcted. Interestingly, there were two right-sided renal arteries and a thrombus was seen in the inferior main right renal artery. The superior pole of the right kidney was preserved as a result of the patent accessory renal artery. Due to delayed presentation of more than 48 hours after onset of pain, the tissue could not be re-vascularized by vascular surgery. Her renal function remained intact and her flank pain gradually improved. 

Acute renal infarction is difficult to diagnose as it is mimicked by more commonly seen causes such as pyelonephritis and nephrolithiasis. Pain in the unilateral flank and/or abdomen is the hallmark presenting feature, however nausea, vomiting, and fever are also common. New or increasingly severe hypertension is found in approximately half of acute renal infarction diagnosis, a sign that should raise clinical suspicion in similar clinical scenario. Proteinuria is another feature that may be present on urinalysis. Creatinine elevation consistent with acute kidney injury (AKI) occurs in approximately 30-40% of cases (1). Leukocytosis is commonly seen in as many as three-quarters of patients with renal infarct. The most common laboratory finding in renal infarction is elevation of LDH, although this is nonspecific and does not necessarily aid in specific diagnosis (2). Diagnosis is usually made through contrast enhanced CT abdomen, however angiography may also be used.

Our patient also had two renal arteries supplying her right kidney, allowing for the superior pole of her renal parenchyma to be spared and thus her kidney function. The kidney tolerates ischemia for approximately 12 hours, making early diagnosis paramount. In patient’s such as the one described here that involves all or majority of one kidney, embolectomy is recommended because of favorable outcomes in prior studies (3). In summary, the challenge of early diagnosis of renal infarction lies in the recognition of nonspecific clinical symptoms and signs in an already rare occurrence. Recognizing these signs within hours of presentation may be the difference between viable renal tissue and death of a kidney. Keeping a high suspicion in patients with atrial fibrillation will also aid in early diagnosis.

Jessica August MD and Jennifer J Huang DO

Department of Internal Medicine

University of Arizona

Tucson, AZ

References

1. Bae EJ, Hwang K, Jang HN, Kim MJ, Jeon DH, Kim HJ, Cho HS, Chang SH, Park DJ. A retrospective study of short- and long-term effects on renal function after acute renal infarction. Ren Fail. 2014;36(9):1385-9. [CrossRef] [PubMed]
2. Antopolsky M, Simanovsky N, Stalnikowicz R, Salameh S, Hiller N. Renal infarction in the ED: 10-year experience and review of the literature. Am J Emerg Med. 2012;30(7):1055-60. [CrossRef] [PubMed]
3. Tsai SH, Chu SJ, Chen SJ, Fan YM, Chang WC, Wu CP, Hsu CW. Acute renal infarction: a 10-year experience. Int J Clin Pract. 2007;61(1):62-7. [CrossRef] [PubMed]

Reference as: August J, Huang JJ. Medical image of the week: renal infarction. Southwest J Pulm Crit Care. 2015;10(4):195-6. doi: http://dx.doi.org/10.13175/swjpcc023-15 PDF