Neurologic complications in immune-mediated heparin-induced thrombocytopenia

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Abstract
Objective: To evaluate neurologic complications in patients with immune-mediated heparin-induced thrombocytopenia (HIT) with respect to incidence, clinical characteristics, outcome, and therapy. Methods: One hundred and twenty consecutive patients with immune-mediated HIT were recruited over a period of 11 years and studied retrospectively for the occurrence of neurologic complications. Diagnosis of HIT was based on established clinical criteria and confirmed by detection of heparin-induced antibodies using functional and immunologic tests. Results: Eleven of the 120 patients (9.2%) presented with neurologic complications; 7 suffered from ischemic cerebrovascular events, 3 from cerebral venous thrombosis, and 1 had a transient confusional state during high-dose heparin administration. Primary intracerebral hemorrhage was not observed. The relative mortality was much higher (Chi-square test, p < 0.01) in HIT patients with neurologic complications (55%) as compared to patients without neurologic complications (11%). The mean platelet count nadir in neurologic patients was 38 ± 25 × 109/l on average, and was lower in patients with fatal outcome compared to those who survived (21 ± 13 × 109/l versus 58 ± 21 × 109/l; p < 0.05, Wilcoxon test). In three patients neurologic complications preceded thrombocytopenia. There was a high coincidence of HIT-associated neurologic complications with other HIT-associated arterial or venous thrombotic manifestations. Conclusion: Neurologic complications in HIT are relatively rare, but associated with a high comorbidity and mortality. HIT-associated neurologic complications include cerebrovascular ischemia and cerebral venous thrombosis. They may occur at a normal platelet count.