Heparin-induced thrombocytopenia and thrombosis following subarachnoid hemorrhage - Case report

The authors present a case of heparin-induced thrombocytopenia and thrombos is (HITT) that occurred after aneurysmal subarachnoid hemorrhage (SAH), and they review the relevant literature. An immune-mediated syndrome, HITI is characterized by moderate thrombocytopenia and paradoxical vascular thrombo ses. Although it has been estimated in prospective studies that HITT occurs in between 1 and 3% of patients receiving heparin, it is underrecognized i n the neurosurgical literature. In the present case, a 49-year-old woman un derwent clipping of a right posterior communicating artery aneurysm after s uffering a Hunt and Hess Grade III SAH. She had an uncomplicated postoperat ive course with good clip positioning and no vasospasm observed on a cerebr al angiogram obtained on Day 7. On Day 23, the patient developed a right hemiparesis and experienced a gran d mal seizure. A head computerized tomography scan revealed a hemorrhagic i nfarct in the left middle cerebral artery distribution. Repeated cerebral a ngiograms did not show vasospasm. She was thrombocytopenic (platelet count as low as 46 X 10(9)/L on Day 28 compared with 213 X 10(9)/L on Day 1) and had been receiving heparin flushes to maintain intravenous catheter patency . An assay for HITT-associated antibodies was positive. The heparin flushes were discontinued and the platelet count recovered (121 X 10(9)/L). She im proved neurologically, but was left with a significant right hemiparesis at discharge. This patient had assay-proven heparin-induced thrombocytopenia despite minimal exposure to heparin. Because there was no evidence of vasos pasm or other factors to account for her delayed hemorrhagic infarction, an HITT-related disorder seemed most likely. Despite a large body of literatu re describing HITT in nonneurosurgical patients, only three previous neuros urgical cases have been published. This case report may serve to heighten a wareness of this disorder.