A grading scale to predict outcomes after intra-arterial thrombolysis for stroke complicated by contrast extravasation

Abstract

Objective: Contrast extravasation after intra-arterial thrombolysis for stroke occurs frequently and is identifiable on a computed tomographic (CT) scan, but it is often unrecognized or misdiagnosed. Few articles describing this phenomenon have been published. The clinical outcomes of patients after contrast extravasation are poorly understood. We designed a grading system to predict outcomes after contrast extravasation and tested the grading scale prospectively.

Methods: We studied 27 patients who had contrast extravasation exhibited on a CT scan immediately after intra-arterial thrombolysis. The National Institutes of Health Stroke Scale was used to quantify neurological examinations preoperatively, postoperatively, and at follow-up an average of 3 months later. A grading scale from 0 to 10 was developed from a retrospective analysis of the first 18 patients using odds ratios and Fisher's exact test. The grading system was then applied prospectively to the next 9 consecutive patients.

Results: Six components of the grading system were weighted approximately proportional to corresponding odds ratios: 1) incomplete recanalization (3 points), 2) prolonged angiographic blush (2 points), 3) hyperdensity greater than 150 Hounsfield units (2 points), 4) lesion volume greater than 50 cc exhibited on a CT scan (1 point), 5) lesion in eloquent parenchyma (1 point), and 6) hypodensity demonstrated on an immediate postoperative CT scan (1 point). The contrast extravasation grades for each outcome category (excellent, fair, poor, died) increased in stepwise fashion. There was a direct linear correlation between the assigned grade and National Institutes of Health Stroke Scale score improvement at follow-up.

Conclusion: This grading system should prove useful as a preliminary guide for predicting outcomes of patients with contrast extravasation after intra-arterial thrombolysis for stroke. Further analysis in a large cohort of prospective patients is necessary to ensure extensibility.