First Reported Cases of Blood Clots Causing Stroke in Young Adults Following COVID-19 Vaccination

Three cases of ischemic stroke have been reported in young adults following the administration of the Oxford AstraZeneca vaccine.

Blood clots in the arteries (arterial thrombosis) are the most common cause of stroke (ischemic stroke) and were first reported in detail in young adults receiving the Oxford AstraZeneca covid-19 vaccine in a letter from British stroke specialists, published online in Journal of Neurology Neurosurgery & Psychiatry.

Although rare cases of blood clots have been reported previously following the administration of the Oxford AstraZeneca covid-19 vaccine, these have affected veins and especially veins in the brain (cerebral venous sinuses).

People who have had this unusual form of stroke (cerebral venous sinus thrombosis) also have a low platelet count (thrombocytopenia) and antibodies to platelet factor 4 (PF4) – proteins that help clot form.

The most common form of stroke, in which blood clots occur in arteries supplying blood to the brain (ischemic stroke), has not previously been described as the presenting feature of thrombosis following the administration of the Oxford AstraZeneca vaccine, but the authors of this letter report three cases in detail.

In all cases, the ischemic stroke was associated with blockages of great arteries (both carotid and middle cerebral artery) and two patients also had venous thrombosis involving the portal and cerebral venous system. All three also had extremely low platelet counts, confirmed anti-PF4 antibodies, and increased D-dimer (also linked to clotting).

The first patient, a woman in her thirties, got occasional headaches on the right side and around her eyes six days after the vaccine. Five days later she woke up with a feeling of drowsiness and weakness in her left face, arm and leg. Imaging revealed a blocked right middle cerebral artery with ischemic stroke and blood clots in the right portal vein thrombosis. She underwent brain surgery to relieve pressure in her skull, plasma removal and replacement, and received the anticoagulant fondaparinux, but sadly died.

The second patient, a woman in her late thirties, had headache, confusion, weakness in her left arm, and vision loss on the left side 12 days after she received the vaccine. Imaging showed blockages in several blood vessels, including both carotid arteries (the main blood supply to the cerebral hemispheres), arteries supplying the heart and lungs (pulmonary embolism), and the left transverse sinus (one of the cerebral venous sinuses). Her platelet count increased after plasma removal and replacement and after intravenous corticosteroids. She then got fondaparinux and improved.

The third patient, a man in his early 40s, reported problems speaking and understanding language (dysphasia) 3 weeks after his vaccination. Imaging showed a clot in the left middle cerebral artery, but there was no evidence of clots in the cerebral venous sinuses. He received a platelet and plasma transfusion and fondaparinux and remains stable.

The lead author, Professor David Werring of the Stroke Research Center, UCL Queen Square Institute of Neurology, says the cases described suggest that, in addition to cerebral venous thrombosis, vaccination-induced immune thrombotic thrombocytopenia (VTT) can also lead to clots that block arteries that block the brain, causing an ischemic stroke.

“Young patients with ischemic stroke after receiving the [Oxford-AstraZeneca] vaccine must be urgently evaluated for VITT with laboratory tests (including platelet count, D-dimer, fibrinogen and anti-PF4 antibody), and administered by a multidisciplinary team (hematology, neurology, stroke, neurosurgery, neuroradiology) for quick access to treatments, including intravenous immunoglobulin, methylprednisolone, plasmapheresis and non-heparin anticoagulants, eg fondaparinux, argatroban or direct oral anticoagulants, ”said the authors.

In a linked commentary, Professor Hugh Markus of the Department of Clinical Neuroscience at the University of Cambridge writes: “ This report highlights that the immune-mediated coagulopathy can also cause arterial thrombosis, including ischemic stroke, although venous thrombosis and especially cerebral venous sinus thrombosis is more common . “

He adds, “During the current period of covid vaccination, a high index of suspicion is required to identify post-vaccination thrombotic episodes. However, it is important to remember that these side effects are rare and much less common than both cerebral venous thrombosis and ischemic stroke associated with covid-19 infection itself. “

References:

“Ischemic Stroke as a Presenting Characteristic of ChAdOx1 nCoV-19 Vaccine-Induced Immune Thrombotic Thrombocytopenia” May 25, 2021, Journal of Neurology Neurosurgery & Psychiatry.
DOI: 10.1136 / jnnp-2021-326984

“Ischemic stroke may follow COVID-19 vaccination, but is much more common with COVID-19 infection itself” May 25, 2021, Journal of Neurology Neurosurgery & Psychiatry.
DOI: 10.1136 / jnnp-2021-327057