To date no other published acute stroke studies have correlated TCD FD with CT angiographic measures of collateral flow, nor have examined associations with perfusion lesion

volumes and long-term functional outcome. We did not find any significant association between the presence of FD and the total volume of the perfusion lesion despite the admission NIHSS being lower in patients with ACA FD. In contrast, we demonstrated a strong and independent association between FD and the volume of the CTP defined infarct core. This finding suggests the importance of collateral flow and its TCD correlate in predicting acute infarct volume [34] and clinical outcome. Patients with ICA occlusion are more likely to have compromised ACA collateral flow. This was demonstrated AG-014699 purchase in the results, where, 55% of patients with combined ICA + MCA occlusion showed no FD as

opposed to 42% of patients with MCA occlusion showing no FD (derived from Table 2). When accompanied by major reperfusion, FD significantly increased the chances of a favourable outcome in keeping with other reports Epigenetics Compound Library of a potential synergistic effect between LMC and major reperfusion [12] and [16]. In our study, 43% of FD positive patients who did not undergo major reperfusion had a favourable outcome suggesting that LMCs are capable, in some patients, of perfusing the territory of an occluded artery to a level sufficient to avoid infarction even without complete recanalization [11], ACA FD therefore appears to be a rapid onset internal protection mechanism for the ischemic area, mitigating infarct core expansion. TCD is recognised to accurately reflect recanalization status of the MCA when compared to catheter angiography [35] and TCD defined TIBI recanalization grades recognised to correlate with baseline cAMP stroke severity and clinical recovery [36]. There is, however, limited

data describing recanalization characteristics in the initial hours following acute MCA stroke and no data correlating TCD recanalization characteristics with reperfusion status and the extent of early infarction. Alexandrov et al. [37] described a cohort of 65 patients treated with intravenous tissue plasminogen activator within 3 h of stroke onset and monitored with TCD post-thrombolysis. Similar to our findings, major improvements in TIBI grades (in this study over time periods of less than 30 min) were associated with significantly lower 24 h post-thrombolysis NIHSS. Using transcranial colour coded duplex (TCCD) the Duplex Sonography in Acute Stroke Study group performed TCCD 30 min and 6 h post-thrombolysis in patients with a variety of ICA and MCA occlusion patterns [38]. In this patient group, cases showing recanalization assessed by TIBI grade change also showed significant improvements in 24 h NIHSS when compared to those without TCCD features of recanalization.