Abstract 155: Rate, Clinical Features, Safety Profile and Outcome of Intravenous Thrombolysis for Acute Ischemic Stroke in Patients with Negative Brain Imaging

INTRODUCTION: The exigent time demand for intravenous (IV) r-tPA administration in acute ischemic stroke (AIS) may not give the necessary time for thorough evaluation in patients presenting with AIS symptoms. As a result, IV thrombolysis of transient ischemic attack (TIA) or conditions mimicking stroke but with a subsequent different diagnosis might occur. In addition, IV r-tPA may sufficiently resolve ischemia such that subsequent brain diffusion weighted MR imaging (DWI-MRI) is negative in some patients. It would be expected that brain CT scan and the more sensitive DWI-MRI would be negative in all these cases. We sought to determine the rate, clinical characteristics, safety profile and outcome of brain imaging-negative patients treated with IV r-tPA for AIS in our large volume stroke center. METHODS: We retrospectively reviewed the medical records and brain imaging of patients who received IV rtPA for AIS within 4.5 hours of symptom onset from January 2006 to April 2014 at our center. A subset of patients with absence of acute infarct/ischemia on their follow- up brain imaging were identified. We recorded age, admission NIH stroke scale (NIHSS), discharge NIHSS, discharge modified Rankin Score (mRS), symptom onset to treatment time, clinical manifestations, discharge diagnosis and evidence of intracranial hemorrhage (ICH) on follow up images for these patients. RESULTS: A total of 637 patients received IV thrombolysis in our center during a 9.4 years period. Thirty seven (5.8%) were found to have no evidence of acute ischemia/infarct on their follow up imaging. DWI-MRI was available for 31 patients. Mean age was 65.2 ± 14, mean admission NIHSS was 8 and mean discharge NIHSS was 0. The mean time of symptom onset to IV thrombolysis was 2.5 hours. Twenty two (59%) had TIA or averted stroke and the rest had non-vascular stroke mimics. The most common stroke mimics were complicated migraine, seizure disorder and psychogenic disorders. No patient developed ICH on follow up brain imaging. All patients were functionally independent on discharge, mRS 0-1. CONCLUSION: IV thrombolysis is generally safe in patients with suspected AIS who have a follow -up negative brain imaging and delaying IV r-tPA administration in cases of doubt is not appropriate.