Immune thrombotic thrombocytopenic purpura associated with acute large vessel occlusion

Introduction: Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy caused by ADAMTS13 deficiency and characterized by platelet-rich microthrombi. Neurological findings are common, but presentation with acute ischemic stroke, and particularly with large vessel occlusion, is rare. This report describes the clinical course of a young patient who underwent mechanical thrombectomy for acute MCA occlusion and was subsequently diagnosed with immune TTP.Case: A 27-year-old woman with no chronic illness or regular medication presented with acute-onset focal neurological deficit. On examination she was alert, oriented, and cooperative, with left central facial paralysis, left hemiparesis (1/5), dysarthria, and a left plantar extensor response. NIHSS was 20 and ASPECTS was 8. CT angiography showed right MCA occlusion; mechanical thrombectomy was performed, and TICI 3 reperfusion was achieved. Contrast extravasation at the ICA terminus during the procedure was controlled with endovascular methods. The platelet count, 166,000 at baseline, fell to 24,000. The peripheral smear showed schistocytes and signs of microangiopathic hemolysis. ADAMTS13 activity was 6 IU/dL, and the inhibitor was positive. Antiphospholipid antibodies and lupus anticoagulant were negative, and blood cultures showed no growth. Echocardiography raised suspicion of thrombus at the mitral valve and right atrium; TEE could not be performed because of clinical instability. With a diagnosis of immune TTP, plasma exchange and steroid therapy were started, and the platelet count rose to 37,000. The patient died within one month in the setting of a large right MCA infarct, hemorrhagic transformation, and systemic clinical deterioration (Figure 1–4).Discussion/Conclusion: Although TTP is fundamentally a disease of microvascular thrombosis, it may rarely be associated with large vessel occlusion as well. In our patient, the embolic right MCA occlusion was successfully opened by mechanical thrombectomy, but severe thrombocytopenia, microangiopathic hemolysis, ADAMTS13 activity below 10%, and inhibitor positivity developed during follow-up, leading to the diagnosis of immune TTP. The suspected cardiac thrombus suggested that the systemic thrombotic process may not be confined to the microvascular bed. This case is noteworthy because it shows that opening the vessel does not mean the thrombotic process has ended. In young patients, thrombocytopenia and microangiopathic hemolysis that develop during follow-up after a large vessel occlusion should be an important warning sign for TTP. A systemic thrombotic process that continues despite successful reperfusion may be a critical factor determining the clinical course.Keywords: