Undertaking thrombolysis on the basis of magnetic resonance imaging (MRI) findings in patients with stroke of unknown onset time may double their chances for a good outcome, say researchers.
Dong-Wha Kang (University of Ulsan College of Medicine, Seoul, South Korea) and team used perfusion- and diffusion-weighted MRI (PWI and DWI) and fluid-attenuated inversion recovery (FLAIR) imaging to ascertain if patients were in the early stages of their stroke.
Patients who had at least a 20% mismatch between PWI and DWI lesions, plus negative or very subtle FLAIR changes within an acute DWI lesion underwent thrombolysis.
The study included 83 patients with stroke of unclear onset time - 63 of these patients had stroke symptoms on waking ("wake-up" stroke), while 20 had unwitnessed daytime strokes. They were aged a median of 67 years and had relatively severe strokes, with a median National Institutes of Health Stroke Scale (NIHSS) score of 14. Most patients - 69% - were treated with intra-arterial thrombolysis alone; 11% had intravenous thrombolysis and the other patients had combined therapy.
Eight patients had intracerebral hemorrhage - five (6.0%) with any decline in NIHSS score and three (3.6%) with at least a 4-point decline.
"These bleeding complication rates are probably acceptable considering the potential benefit of reperfusion therapy," Kang et al write in Stroke.
About half of the treated patients achieved immediate or early recanalization, and 61.0% of these achieved a good functional outcome (modified Rankin Scale [mRS] 0-2), compared with 27.5% of those with delayed or no recanalization.
Outcomes were significantly better than those of 156 patients who had unclear-onset stroke but did not undergo thrombolysis; the overall good outcomes rates were 44.6% versus 32.7%. After accounting for confounders, thrombolysis was associated with a 2.25-fold increased odds for a good outcome.
The control patients were identified in prospective registries, so patients were not randomly assigned to receive thrombolysis; moreover, control patients did not undergo MRI.
"It is time to launch a well-designed, randomized, controlled trial to confirm the benefit and safety of reperfusion therapy in this important (yet so far, neglected) group of patients," say the researchers.
They note that, although much studied, a PWI-DWI mismatch may not identify patients with very recent stroke onset who are likely to be within the accepted thrombolysis treatment window, as it can reportedly persist for up to 24 hours after onset. By contrast, a DWI-FLAIR mismatch appears to be very specific for recent onset, albeit with relatively low sensitivity.
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