Homonymous hemianopia caused by occipital lobe infarction in heparin-induced thrombocytopenia and thrombosis syndrome.

A 73-year-old woman developed mental confusion and finger pain after treatment with enoxaparin following arthroplasty. A platelet count was 163,000/microL. Because digital embolism was suspected, she was emergently treated with heparin and recombinant tissue plasminogen activator (rTPA). During rTPA infusion, she reported sudden hemifield loss, so the infusion was aborted. Brain CT disclosed a non-hemorrhagic occipital infarct. Platelets had fallen to 63,000 over eight days, and antibodies against a complex of heparin and platelet factor 4 were detected. These findings led to the diagnosis of heparin-induced thrombocytopenia and thrombosis syndrome (HITTS), an immune-mediated disorder in which venous and arterial thromboses occur. Right lower extremity deep venous thromboses were later diagnosed, and an MRI disclosed multiple cerebral infarcts of recent onset but different ages. Previous reports have documented brain arterial strokes in HITTS, mostly in the distribution of the middle cerebral artery, but clinical documentation is sparse, and there have been no imaging reports. This is the first report to document the clinical and imaging features of a HITTS stroke and the first to describe a stroke presumptively caused by a low molecular weight heparin. It emphasizes that HITTS may cause stroke even when the platelet count is normal. Diagnosis of HITTS should prompt immediate cessation of heparin treatment and substitution of a direct thrombin inhibitor or fondaparinux.