Clinical significance of brain swelling without concomitant parenchymal hypoattenuation. A subtype of early CT signs

Although parenchymal hypoattenuation (PH) indicates severe ischemic injury, brain swelling without concomitant hypoattenuation (BS) is thought to be more benign. We have clarified the clinical significance of BS. A total of 53 patients (34 men, 19 women, mean 69.7 years old) with acute embolic stroke was enrolled. PH and BS were evaluated on baseline CT. Residual cerebral blood flow (rCBF) was determined by 99mTcHMPAO SPECT performed within 6 hours of onset. Difference in patients' age, gender, neurological severity (NIHSS), CT time and rCBF, were evaluated among patients with PH, BS and negative early CT signs (NEG) using one-way ANOVA with Scheffe' s post hoc analysis. The CT time (F=4.369, P=0.018) and the rCBF (F=7.881, P=0.001) were significantly different among NEG (16 patients), BS (5 patients), and PH (32 patients) groups. BS was observed within 3 hours of onset. CT time was significantly longer in PH group compared to NEG group. PH and BS groups exhibit significant lower rCBF compared to NEG group, although no statistical difference was observed between BS and PH groups. We speculated that BS was observed within early hours of onset, and then accompanied by concomitant parenchymal hypoattenuation. (author)