Péter Siró

Absent Collateral Function of the Circle of Willis as Risk Factor for Ischemic Stroke

Background: Autopsy studies show a higher prevalence of circle of Willis anomalies in brains with signs of ischemic infarction. Our goal was to examine the collateral function of the circle of Willis in ischemic stroke patients and to assess in a case-control study if a collateral deficient circle of Willis is a risk factor for ischemic stroke in patients with severe internal carotid artery (ICA) occlusive disease. Methods: Our case-control study included 109 patients with an acute ischemic stroke in the anterior circulation and 113 patients with peripheral arterial disease and no known history of cerebral ischemia. The collateral function of the anterior and posterior communicating arteries of the circle of Willis was assessed by means of transcranial color-coded duplex ultrasonography (TCCD) and carotid compression tests. Results: TCCD was successfully performed in 75 case patients (mean age 64 years, range 41–91 years) and in 100 control patients (mean age 61 years, range 35–89 years). In 26 cases and 19 controls, a ≧70% stenosis or occlusion of the ICA was found. A nonfunctional anterior collateral pathway in the circle of Willis was found in 33% of the cases and in 6% of the controls (p < 0.001). The posterior collateral pathway was nonfunctional in 57% of the cases and in 43% of the controls (p = 0.02). In patients with severe ICA occlusive disease, the odds ratios of a nonfunctional anterior and a nonfunctional posterior collateral pathway were 7.33 (95% confidence interval, CI, = 1.19–76.52) and 3.00 (95% CI = 0.77–12.04), respectively. Conclusions: Patients who suffer ischemic stroke in the anterior circulation have a higher incidence of collateral deficient circles of Willis than those with atherosclerotic vascular disease without ischemic cerebrovascular disease. The presence of a nonfunctional anterior collateral pathway in the circle of Willis in patients with severe ICA occlusive disease is strongly associated with ischemic stroke.

Clinical applicability of a mathematical model in assessing the functional ability of the communicating arteries of the circle of Willis

BACKGROUND The brain collateral blood supply, which is essential in patients suffering from significant stenoses or occlusions of the extracranial arteries, remains difficult to assess accurately in practice. We compared data obtained from transcranial color-coded duplex sonography (TCCD) combined with carotid compression tests to morphometric autopsy data and to results given by a mathematical model of the cerebral macrocirculation. METHODS AND RESULTS In 16 moribund patients, anterior and posterior communicating arteries of the circle of Willis were divided into functional and non-functional based on the results of the TCCD combined with carotid compression tests. After death of the patients diameters and lengths of the main intracranial arteries were measured at autopsy and these values were treated with a mathematical model for calculating blood flow and blood pressure in all the segments of the arterial network. The diameters and the blood flows through the communicating arteries were found to be significantly higher in the group of functional arteries than in that of non-functional ones. However, blood flow was also shown to be dependent on other parameters such as the pressure difference between the two ends of the vessel. CONCLUSION Our data indicate that functional ability of the Willisian collaterals depends on morphological and functional parameters, and is therefore better assessed by a functional method, such as TCCD, than by a solely morphological one, such as cerebral angiography. Mathematically based circulation modeling, when it will be possible, could be a more comprehensive tool for delineating patients at a higher risk for hemodynamic cerebrovascular insufficiency.

Carotid intima-media thickness and cerebrovascular reactivity in long-term type 1 diabetes mellitus.

Diabetes mellitus (DM) is one of the leading risk factors for cerebrovascular diseases. Both macro‐ and microvascular damage may occur. The aim of the present work was to assess intima‐media thickness as well as cerebral vasoreactivity in patients suffering from type 1 diabetes mellitus (IDDM).

Assessment of cerebral tissue oxygen saturation in septic patients during acetazolamide provocation-A near infrared spectroscopy study

UNLABELLED Sepsis-associated encephalopathy is a multifactorially determined process of the brain parenchyma. Among other factors, vasogenic causes have been shown to play a role in its development. The aim of the present work was to assess whether cerebral tissue oxygen saturation is influenced by administration of acetazolamide in septic patients compared to controls. PATIENTS AND METHODS 15 patients with severe sepsis and 10 healthy controls were studied. Cerebral oxygen saturation was assessed by INVOS 51 OOC Cerebral Oxymeter (NIRS) before and after administration of 15 mg/kg BW acetazolamide in both groups. RESULTS The maximal rise that has been found in the partial pressure of CO(2) in the arterial blood of septic patients after administration of acetazolamide was from 35 ± 5 mmHg to 41.1 ± 6.3 mmHg. For the partial pressure of O(2) the observed increase was from 123.7 ± 47.1 mmHg to 139.9 ± 49 mmHg. Vasodilatory stimulus resulted in a similar maximal increase in cerebral oxygen saturation in septic patients and in controls (8.9 ± 6.5% for septic patients and 9.2 ± 4.6% for healthy persons, respectively). CONCLUSIONS Cerebral vasoreactivity to acetazolamide is preserved in patients with severe sepsis.