Computerized tomography angiography may help determine appropriate treatment for stroke patients
Two studies from the Screening Technology and Outcomes Project in Stroke (STOPStroke) suggest that early use of computed tomography (CT) of the head with contrast (also known as CT angiography, or CTA) can help clinicians decide on the proper treatment for stroke patients with artery blockages near the affected brain region (proximal arterial occlusions). Each study used the same population of 741 stroke patients at 2 university hospitals, enrolled in STOPStroke between March 2003 and January 2006, to investigate different aspects of the usefulness of CTA in these patients. All of the patients underwent CT scans without contrast, with contrast (CTA), and followup scans to confirm the presence of an infarct region (area of dead tissue due to lack of oxygen). The study was funded in part by the Agency for Healthcare Research and Quality (HS17344).
Maas, M. B., Furie, K. L., Lev, M. H., and others (2009, September). "National Institutes of Health Stroke Scale score is poorly predictive of proximal occlusion in acute cerebral ischemia." Stroke 40(9), pp. 2988-2993.
The researchers sought to determine whether they could find a threshold score at hospital admission on the National Institutes of Health Stroke Scale (NIHSS) above which CTA was most useful for determining the presence of proximal arterial occlusion in stroke patients. A number of recent treatment studies have used a NIHSS score of 10 or higher as the cutoff for inclusion. However, limiting early use of CTA to this group of patients would miss a majority (55 percent) of patients with such blockages. Based on the sample, all patients with NIHSS scores of 2 or greater would have to undergo CTA to detect 90 percent of proximal occlusions. Yet nearly a third (29 percent) of patients with NIHSS scores as low as 0 had proximal occlusions, the researchers found. In fact, it is the patients with low-to-moderate NIHSS scores and presenting with proximal blockages who are ideal candidates for further interventions, note the researchers. That is because they are more likely to have a large region of tissue at risk of losing blood flow.
Maas, M. B., Lev, M. H., Ay, H., and others (2009, September). "Collateral vessels on CT angiography predict outcome in acute ischemic stroke." Stroke 40(9), pp. 3001-3005.
This paper used CTA to monitor regional blood flow in stroke patients with proximal middle cerebral artery (MCA) occlusion at 1 hour after hospital admission and at 12 to 24 hours after admission. Most of the 134 patients who had early evidence of MCA blockage were able to increase the flow in nearby arteries to follow a clinical course similar to that of 235 stroke patients without MCA blockage, the researchers found. However, a group of patients with MCA blockage, who had continued reduced blood flow in nearby regions of the brain (the sylvan fissure, leptomeningeal convexity, or both), were nearly four times as likely as patients without MCA blockage to worsen (show increases in NIHSS scores) over 12 to 24 hours. The researchers suggest that this group of patients with diminished collateral blood flow may be an ideal population for receiving blood flow-enhancing treatments.
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