Abstract
Introduction: Free hemoglobin’s release into CSF from blood breakdown is a primary instigator of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Early clearance of subarachnoid blood with intrathecal (IT) fibrinolytics has shown potential to decrease incidence of DCI. However, the dosage of fibrinolytic needed is not known. We investigated the ability of low dose tissue plasminogen activator (tPA) to rapidly remove subarachnoid clot. Material and methods: We performed a single center retrospective review of aSAH patients who received IT tPA. Dosing consistent with the CLEAR III trial for IVH was utilized—tPA (1 mg) administered every 8 h via an external ventricular drain (EVD) for up to three doses. CT imaging was obtained before initiation and after the final dose. Subarachnoid clot was quantified using the Hijdra score on initial and follow-up scans. The IT tPA group was compared to a large retrospective cohort without IT tPA. Results: Eight aSAH patients received IT tPA treatment for the purpose of increasing blood removal after aSAH. CT imaging indicated that the Hijdra Score had a 70–100% reduction in all patients in the first 4 days with a mean 81.6% reduction compared to 41.3% reduction in a prior natural history cohort, p = 0.001. No ventriculitis or hemorrhagic complications were observed the treatment group. Clinical DCI and radiographic vasospasm was observed in two of the patients. Conclusion: Low dose IT tPA delivered through an EVD after aSAH is sufficient to rapidly increase CSF blood clearance on CT imaging. © The Author(s) 2025.