Quantification of Target Population for Ultrasound Enhanced Thrombolysis in Acute Ischemic Stroke

BACKGROUND AND PURPOSE Insonation of the occluded target vessel (sonothrombolysis) has been reported to increase the effect of intravenous thrombolysis in ischemic stroke. Its use has predominantly been described in middle cerebral artery (MCA) occlusions. Sufficient insonation conditions are a mandatory precondition. The impact of these limitations on eligibility rates for sonothrombolysis has not been reported so far. METHODS Consecutive patients treated with rt-PA and examined by either CT- or MR-angiogram before treatment and by transcranial color-coded duplex sonography (TCCS) during inhospital stay were identified retrospectively at three hospitals from ongoing data registries. RESULTS One-hundred and seventy-nine patients (age [years], median [IQR]= 75 [65-83]; 42% female; NIH Stroke Scale [NIHSS], median [IQR]= 10 [6-17]) were analyzed. MCA occlusions were detected in 39% of patients (N= 69) with 48 (27%) occlusions in the proximal M1-segment and 21 (12%) in a distal M2-segment. Arterial occlusions others than MCA were seen in an additional 9% (N= 16). TCCS (without contrast agent) revealed sufficient bone windows in 70% of patients with MCA occlusions (N= 48) corresponding to 27% of all patients treated with thrombolysis. CONCLUSION Conventional sonothrombolysis is restricted to a minority of stroke patients suitable for intravenous thrombolysis. Extending the applicability by utilization of ultrasound contrast agents and targeting non-MCA-occlusions warrants further evaluation.