Asymptomatic carotid artery stenosis is associated with cerebral hypoperfusion.

OBJECTIVE: We have shown that almost 50% of patients with asymptomatic carotid stenosis (ACS) will demonstrate cognitive impairment. Recent evidence has suggested that cerebral hypoperfusion is an important cause of cognitive impairment. Carotid stenosis can restrict blood flow to the brain, with consequent cerebral hypoperfusion. In contrast, cross-hemispheric collateral compensation through the Circle of Willis, and cerebrovascular vasodilation can also mitigate the effects of flow restriction. It is, therefore, critical to develop a clinically relevant measure of net brain perfusion in patients with ACS that could help in risk stratification and in determining the appropriate treatment. To determine whether ACS results in cerebral hypoperfusion, we developed a novel approach to quantify interhemispheric cerebral perfusion differences, measured as the time to peak (TTP) and mean transit time (MTT) delays using perfusion-weighted magnetic resonance imaging (PWI) of the whole brain. To evaluate the utility of using clinical duplex ultrasonography (DUS) to infer brain perfusion, we also assessed the relationship between the PWI findings and ultrasound-based peak systolic velocity (PSV). METHODS: Structural and PWI of the brain and magnetic resonance angiography of the carotid arteries were performed in 20 patients with ≥70% ACS. DUS provided the PSV, and magnetic resonance angiography provided plaque geometric measures at the stenosis. Volumetric perfusion maps of the entire brain from PWI were analyzed to obtain the mean interhemispheric differences for the TTP and MTT delays. In addition, the proportion of brain volume that demonstrated a delay in TTP and MTT was also measured. These proportions were measured for increasing severity of perfusion delays (0.5, 1.0, and 2.0 seconds). Finally, perfusion asymmetries on PWI were correlated with the PSV and stenosis features on DUS using Pearson's correlation coefficients. RESULTS: Of the 20 patients, 18 had unilateral stenosis (8 right and 10 left) and 2 had bilateral stenoses. The interhemispheric (left-right) TTP delays measured for the whole brain volume identified impaired perfusion in the hemisphere ipsilateral to the stenosis in 16 of the 18 patients. More than 45% of the patients had had ischemia in at least one half of their brain volume, with a TTP delay >0.5 second. The TTP and MTT delays showed strong correlations with PSV. In contrast, the correlations with the percentage of stenosis were weaker. The correlations for the PSV were strongest with the perfusion deficits (TTP and MTT delays) measured for the whole brain using our proposed algorithm (r = 0.80 and r = 0.74, respectively) rather than when measured on a single magnetic resonance angiography slice as performed in current clinical protocols (r = 0.31 and r = 0.58, respectively). CONCLUSIONS: Interhemispheric TTP and MTT delay measured for the whole brain using PWI has provided a new tool for assessing cerebral perfusion deficits in patients with ACS. Carotid stenosis was associated with a detectable reduction in ipsilateral brain perfusion compared with the opposite hemisphere in >80% of patients. The PSV measured at the carotid stenosis using ultrasonography correlated with TTP and MTT delays and might serve as a clinically useful surrogate to brain hypoperfusion in these patients.

Infrapopliteal Arterial Pseudoaneurysm Development Secondary to Blunt Trauma: Case Series and Literature Review.

OBJECTIVES: Infrapopliteal arterial pseudoaneurysms (IAP) following blunt trauma with associated orthopedic injuries are uncommon, often present in a delayed fashion, and encompass a diagnostic and therapeutic dilemma. Herein, we present a series of IAPs that were diagnosed following blunt trauma and their management. METHODS: Case series consisting of 3 patients and a review of the international literature. RESULTS: Our case series included 3 patients presenting with IAPs following blunt trauma with associated orthopedic injuries. They were all identified in a delayed manner (>3 weeks) after the orthopedic injuries were treated. All patients presented with pain and a pulsatile mass while one concurrently had neurologic deficits. The pseudoaneurysms were diagnosed by duplex ultrasound and confirmed by angiography to be originating from the tibioperoneal trunk, anterior tibial, and posterior tibial arteries respectively. Two patients were treated with surgical excision. Of these, one required an arterial bypass procedure while the other underwent direct ligation only. The third patient was treated by endovascular coiling. A literature review from 1950 to the present found 51 reported cases of IAP resulting from blunt trauma. Ninety percent of trauma-related infrapopliteal injuries occurred in men with a mean delay in diagnosis of 5.6 months (median 1.8 months) after injury. Since 1950, management has shifted from primarily ligation to incorporating minimally invasive endovascular techniques when appropriate. CONCLUSIONS: Infrapopliteal artery pseudoaneurysms are rare following blunt skeletal trauma. A delay in diagnosis often occurs and can result in major morbidity and extensive surgical intervention. We recommend a high index of suspicion and a thorough vascular examination in patients with lower extremity skeletal trauma to help identify and treat these injuries early and effectively.