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Determinants of the distribution and severity of hypoperfusion in patients with ischemic stroke

From the Department of Neurology (O.Y.B.), Samsung Medical Center, Sungkyunkwan University, South Korea; and Departments of Neurology (O.Y.B., J.L.S., J.R.A., B.O., D.S.L.) and Emergency Medicine (S.S.), University of California, Los Angeles, CA.

Address correspondence and reprint requests to Dr. Oh Young Bang, Department of Neurology and Stroke Center, Samsung Medical Center, Sungkyunkwan University, 50 Irwon-dong, Gangnam-gu, Seoul, 135-710, South Korea nmboy{at}unitel.co.kr

Background: In acute cerebral ischemia, two variables characterize the extent of hypoperfusion: the volume of hypoperfused tissue and the intensity of hypoperfusion within these regions. We evaluated the determinants of the intensity of hypoperfusion within oligemic regions among patients who were eligible for recanalization therapy for acute ischemic stroke.

Methods: We analyzed data, including pretreatment diffusion-weighted imaging (DWI) and perfusion-weighted imaging, on 119 patients with acute middle cerebral artery infarctions. The intensity of hypoperfusion within oligemic regions was characterized by the hypoperfusion intensity ratio (HIR), defined as the volume of tissue with severe hypoperfusion (Tmax 8 seconds) divided by the volume of tissue with any hypoperfusion (Tmax 2 seconds). Based on the DWI data, we divided the patients into four stroke phenotypes: large cortical, small (<1 cm diameter) cortical, border-zone, and deep pattern.

Results: The mean (SD) volume of severe hypoperfusion was 54.6 (52.5) mL, and that of any hypoperfusion was 140.8 (81.3) mL. The HIR ranged widely, from 0.002 to 0.974, with a median of 0.35 (interquartile range 0.13–0.60). The volume of any hypoperfusion did not predict the intensity of hypoperfusion within the affected region (r = 0.10, p = 0.284). Angiographic collateral flow grade was associated with HIRs (p value for trend = 0.019) and differed among DWI lesion patterns. In multivariate analysis, diastolic pressure on admission (odds ratio 0.959, 95% CI 0.922–0.998) and DWI pattern of deep infarcts (odds ratio 18.004 compared with large cortical pattern, 95% CI 1.855–173.807) were independently associated with a low HIR.

Conclusions: The intensity of hypoperfusion within an oligemic field is largely independent of the size of the oligemia region. Predictors of lesser intensity of hypoperfusion are lower diastolic blood pressure and presence of a deep diffusion-weighted imaging lesion pattern.

GLOSSARY: AIF = arterial input function; DWI = diffusion-weighted imaging; HDL = high-density lipoprotein; HIR = hypoperfusion intensity ratio; ICA = internal carotid artery; IQR = interquartile range; LDL = low-density lipoprotein; MCA = middle cerebral artery; MR = magnetic resonance; MRA = magnetic resonance angiography; NIHSS = NIH Stroke Scale; OR = odds ratio; PWI = perfusion-weighted imaging.

Supplemental data at www.neurology.org

*See appendix.

Supported by NIH/National Institute of Neurological Disorders and Stroke 1K23NS054084-01A1 (to D.S.L.).

Disclosure: The authors report no disclosures.

Received February 28, 2008. Accepted in final form August 25, 2008.