Background and purpose: The intravenous t-PA thrombolysis is not thought to be effective in most patients with internal carotid artery (ICA) occlusion. However, we have sometimes observed dramatic recovery in patients with ICA occlusion after t-PA therapy. The aim of the present study was to investigate the mechanism of dramatic recovery in such patients.
Methods: Consecutive ICA occlusion patients treated with t-PA were prospectively studied. MRI, including MRA, was performed before and within 1 h and 24 h after t-PA thrombolysis. Patients were divided into 2 groups: dramatic recovery (D group) and non-dramatic recovery (ND group).
Results: The subjects consisted of 21 consecutive stroke patients (14 males; mean age, 76.5+/-8.4 years). Six (28.6%) patients (D group) had dramatic improvement and 15 (71.4%) patients (ND group) did not. The frequency of partial or complete recanalization within 1 h and 24 h after t-PA infusion was 14.3% and 50.0% for the ICA, 9.5% and 40.0% for the MCA, and 23.8% and 65.0% for the ICA or MCA, respectively. There was no difference in the frequency of ICA recanalization 24 h after t-PA infusion between the 2 groups (66.7% for D group vs. 42.9% for ND group, P=0.629); however, MCA recanalization was more frequent in the D group than in the ND group (100.0% vs. 14.3%, P=0.0004).
Conclusion: Recanalization of the MCA, which provides collateral flow, appears to play an important role in dramatic recovery after t-PA therapy in patients with ICA occlusion.