Additive Effects of Intra-arterial Tenecteplase for Successful Thrombectomy Due to Acute Basilar Artery Occlusion

Inclusion Criteria: 1. Age 18 - 80 yro； 2. Acute symptomatic basilar artery occlusion identified by neuroimaging modalities (CTA/MRA/DSA)； 3. NIHSS ≥ 6 before thrombectomy； 4. Time from symptom onset (or last seen normal) to arterial TNK/placebo is less than 24 hours； 5. pc-ASPECTS ≥ 6 and Pons-midbrain-index ≤ 2 6. Successful recanalization（eTICI 2b-3）at the end of procedure（The maximum will be six passes or six aspirations for the patient）；Patients with an eTICI score 2b/3 on the diagnostic cerebral angiography before the onset of MT are also eligible for the study. 7. Exclusion of parenchymal hemorrhagic transformation (DynaCT/XpertCT) before intra-arterial agent administration； 8. Pre-morbid mRS ≤ 1； 9. Patient or legal proxy is able to understand and willing to provide written inform and consent. Exclusion Criteria: 1. Patient received thrombolysis prior to EVT 2. NIHSS score on admission \>25 3. Contraindication to IA TNK as per local national guidelines (except time to therapy) 4. Use of stents during the endovascular procedure requiring dual antiplatelet therapy during the first 24h 5. Female who is pregnant or lactating or has a positive pregnancy test at time of admission 6. Current participation in another investigation drug or device treatment study (except observational study) 7. Known hereditary or acquired hemorrhagic diathesis, coagulation factor deficiency 8. Known coagulopathy, INR \>1.7 or use of novel anticoagulants \< 48h from symptom onset 9. Platelets \<100,000 10. Renal Failure as defined by a serum creatinine \>3.0 mg/dl (or 265.2 μmol/l) or glomerular Filtration Rate \[GFR\] \<30. 11. Subject who requires hemodialysis or peritoneal dialysis, or who have a contraindication to an angiogram for whatever reason 12. Any hemorrhage on CT/MRI 13. Clinical presentation suggests a subarachnoid hemorrhage, even if initial CT or MRI scan is normal 14. Suspicion of aortic dissection 15. Subject currently uses or has a recent history of illicit drug(s) or abuses alcohol 16. History of life threatening allergy (more than rash) to TNK or contrast medium 17. SBP \>185 mmHg or DBP \>110 mmHg refractory to treatment 18. Serious, advanced, terminal illness with anticipated life expectancy \<6 months 19. Pre-existing neurological or psychiatric disease that would confound evaluation 20. Presumed vasculitis or septic embolization 21. Unlikely to be available for 90-day follow-up (e.g. no fixed home address, visitor from overseas) 22. Other conditions at investigators' discretion which are not appropriate for participation.