Background and Purpose--This study defines significant thrombolysis associated intracranial hemorrhage (ICH) by identifying an objective threshold volume that predicts clinical deterioration attributable to ICH.

Methods--Prospectively collected clinical and radiographic information, from 103 consecutive patients who underwent intraarterial thrombolysis for acute ischemic stroke, was reviewed. Multiple paired comparisons between stratified hematoma volume and change in National Institutes of Health Stroke Scale (NIHSS) score by 24 to 36 hours and by time of hospital discharge was used to identify significant differences. Associations between hemorrhage volume and infarct volume in relation to clinical outcomes were examined. Rates of hemorrhagic transformation (HT), symptomatic hemorrhage, and parenchymal hematoma involving over 30% of the infarct were compared with hemorrhage volume. Multivariate regression analysis was used to determine the relationship between change in discharge NIHSS score and hemorrhage volume adjusting for known predictors of clinical outcomes.

Results--Multiple paired comparisons indicate that hemorrhage greater than 25 mL (HV25) had a more distinct impact on NIHSS score by time of hospital discharge than at 24 to 36 hours. Twenty-seven (26.2%) patients had HT and 12 (11.7%) had HV25. Among symptomatic hemorrhage, parenchymal hematoma involving over 30% of the infarct, and HV25, HV25 appeared more reflective of clinical deterioration from ICH. Hemorrhage volume increased with infarct volume but they were independently associated with change in NIHSS score on regression analysis.

Conclusion--Clinical deterioration from ICH and ischemic injury are more effectively distinguished at time of hospital discharge. The authors propose to define significant hemorrhage associated with thrombolysis as hemorrhage volume greater than 25 mL.