Transcranial color Doppler sonography in the emergency diagnosis of middle cerebral artery occlusion in a patient after head injury.

The purpose of this report is to highlight the utility of transcranial color Doppler sonography (TCCDS) in the emergency diagnosis of an ischemic stroke in a 64-year-old patient after head injury. An emergency CT identified a subdural hematoma, subarachnoid hemorrhage, a brain contusion and edema. The patient's status deteriorated after admission, and a second CT revealed an intracerebral hematoma and marked mass effect. Transcranial color sonography revealed no flow in the ipsilateral middle and anterior cerebral arteries, which was consistent with ischemic stroke. This case demonstrates that transcranial color Doppler sonography performed early after head injury may be useful in detecting associated occlusion of cerebral vessels.

Effect of endogenous estrogen on blood flow through carotid arteries.

BACKGROUND AND PURPOSE: Recent evidence suggests that physiological changes in the concentration of endogenous estrogens may influence stroke outcome. The purpose of this study was to determine a menstrual cycle-related profile of blood flow through the carotid arteries and its correlation with estrogen concentration. METHODS: The flow velocity and cross-sectional area of the common carotid artery, internal carotid artery (ICA), and external carotid artery (ECA) were measured with duplex Doppler sonography throughout the menstrual cycle in 14 healthy women. Concentration of plasma 17beta-estradiol, progesterone, hematocrit, hemoglobin, and blood pressure were also determined. RESULTS: In the follicular phase, the concentration of estrogen increased to reach a peak on day 14, whereas concentration of progesterone remained low. The mean and end-diastolic velocities in the ICA increased on average by 15% of their base values, along with increasing concentrations of estrogen (r=0.59 and 0.65, respectively). The profile of flow velocity changes in this artery corresponded to the profile of estrogen concentration. In contrast to the ICA, flow velocities in the ECA decreased from their base value, reaching their minimum in the luteal phase. The mean flow velocity in the common carotid artery increased on day 14 by just 2% of its base value. The lumen of the carotid arteries was stable throughout the cycle. Hematocrit, hemoglobin, and systolic blood pressure also remained unchanged. CONCLUSIONS: Increased concentration of endogenous estrogen correlates with substantial augmentation of flow in the internal carotid artery. This promotion of flow is caused mainly by decreased cerebrovascular resistance with consequent "stealing" of blood from the ECA.

Academic achievement among undergraduate nursing students: the development and test of a causal model.

This article tested relationships among variables depicted in a causal learning model of academic achievement developed by the authors. The Learning and Study Skills (LASSI), Life Experience Survey (LES), and ASSET test were administered to 134 first-semester nursing students at a 2-year community college. The path analysis supported 11 of the 14 pathways tested. Language ability, reading ability, and self-efficacy were found to be direct effects on academic achievement. When self-efficacy was the criterion, students' language ability, math ability, motivation, and concentration and preparation for class were direct effects. Life stress, motivation, and self-monitoring/use of study strategies were found to be direct effects on students' concentration and preparation for class. In turn, when the ability to self-monitor and use study strategies was the criterion, motivation was the only direct effect. Overall, the model explained 46% of the variance in academic achievement.